Articles

Nightscapes using AstroTrac Tracking Mount

Nightscapes using AstroTrac Tracking Mount

by Steve Perry

Like most landscape photographers, I look forward to amazing clouds at sunset. There’s just nothing quite like a dramatic sky and a successful image to close out the day. On the other hand, there’s nothing quite as discouraging as facing a bland, barren sky as the sun slides towards the horizon. Or at least that’s the way I used to think… Everything changed one crystal clear night in the backcountry of Northern Michigan. I had been plagued by a week of cloudless sunsets and out of sheer frustration to get something on the memory card, I finally decided to attempt some star trails. That did it – I was hooked. Little did I know star trails were the gateway drug for nighttime landscape photography! However, it didn’t take long to figure out that star trails can get tedious if they are the centerpiece of EVERY nighttime shot you make. (A conclusion arrived at, in part, by my family grumbling, “Seriously, star trails AGAIN??”)

 

 

I came to a point where I wanted to capture the night sky the way I saw it – without trails and maybe with the long arm of the Milky Way reaching through the frame. I started without the aid of a tracking device but quickly discovered the stars would trail ruthlessly on my 24MP Nikon D3x – and the high ISO wasn’t so hot either. I soon graduated to a D800, but its tightly packed pixels happily showed trails for any exposure over 20 seconds – even with wider lenses.

On top of that, I really wanted to keep the ISO to 1600 or less. Many of my clients purchase large prints, and heavy noise just wasn’t an option. Even more importantly, I also wanted to gather more luminance from the night sky. I envisioned crisp stars normally invisible to the naked eye making appearances in my frame, as well as galaxies and even an occasional nebula from time to time. Sure, some stellar phenomena might be tiny in the final photo, but I wanted the viewer to “discover” them when they were viewing a large print.

So, I did a little research and decided I needed a tracking device of some sort. Options varied wildly from expensive mounts for telescopes to DIY kits that could (allegedly) be put together for lunch money. Then I stumbled upon the AstroTrac TT320X-AG Kit. While it isn’t cheap, (coming in at just over $700) it seemed easy to setup and it was designed specifically for photography.

Before long, I was the proud owner of the following kit:

  • AstroTrac TT320X-AG

  • AstroTrac Illuminated Polar Scope

  • AstroTrac 12v car adapter

  • AstroTrac 12v “AA” Battery Pack

If you decide to purchase one of these for yourself be sure to get all the accessories listed above. I discovered some companies sell them separately and you really need everything listed to pull this off (except for maybe the 12v car adapter which, ironically, was the only accessory that was included with my AstroTrac.)

The unit itself is built really well and much more robust than I expected. When I ordered it I anticipated a frail device that would need significant cushioning every step of the way. And though I’d hesitate to let it bounce around in my truck and I certainly wouldn’t want to drop it, I’m very impressed with the overall build quality.

Using the AstroTrac was surprisingly easy. Initially I was intimated by all the talk of proper polar alignment, adjusting azimuth and altitude, but it’s actually pretty simple as long as you have a rudimentary knowledge of the night sky. The first challenge was mounting the thing to my tripod – Here’s that setup in detail. First, keep in mind that with the entire rig put together and a camera perched on top, it’s not exactly a featherweight. I highly recommend starting with a very solid tripod paired with a very sturdy ball head (if your ball head “drifts” under load this will NOT work). I use a Gitzo 3 series and a Really Right Stuff BH-55 Ball Head.

(Note on the ball head – I think if you happen to have a dedicated tripod for this, mounting the AstroTrac to a pan head or geared head would make alignment a much easier proposition. I just don’t want to carry yet another tripod when I travel!)

I also wanted the ability to quickly mount the AstroTrac to my tripod head, so I needed some sort of quick release that would fit the 3/8” socket on the unit. The folks at RRS had a solution – a TH-DVTL-55 quick release plate. That’s when I came across the first problem. The AstroTrac is a narrow device and the screw that comes with the RRS plate is just a bit too long, bottoming out before the plate is tight. A large washer was all it took to save the day.

Astro-Trac-Quick-Release-Washer-Mt

Astro-Trac-Quick-Release-Washer-Mt

Astro-Trac-QR-Mounted.jpg

The next glaring problem is that you actually need a way to mount the camera to the rig, now that your tripod head is being used to support the AstroTrac.

My solution was a retired – but good quality – ball head that had been collecting dust in my closet. I mounted this to the AstroTrac then the quick release to the camera so my setup looks like this:

astro-trac-basic-tripod-setup

Once you’re to this point, it's time to get ready to shoot!

I recommend waiting until at least an hour and a half after sunset before you begin. I quickly discovered when I first started doing stars that just because you can see them doesn’t mean it’s dark enough for long exposures. I’ve had the sky blow out to completely white on some “impatient” evenings when I thought it was dark enough.

Next, you need to do a polar alignment. In the simplest terms, this just means pointing the AstroTrac squarely at Polaris, the North Star. The instructions go into great detail about the procedure, so I’ll just note some highlights and pitfalls below.

To get started I recommend sort of “squaring up” the AstroTrac so it’s pointing roughly north and angled toward Polaris. I also suggest doing your alignment without the extra weight of the camera on the rig.

Mount the scope to the AstroTrac, noting that it comes in from the bottom, and that it’s VERY susceptible to falling out. The magnetic base is just enough to hold it, but no more. Mine has already hit the ground a time or two, so now I remove it after I get everything aligned. It’s just too easy to bump it unintentionally in the dark. (I might assemble some sort of “safety line” for it down the road.)

At one point in the procedure you’ll need to get Polaris into a little “notch” in the scope. I found that it helps to start by spotting along the top of the scope to make sure you’re in the astronomical ballpark. Also, I found it helpful to turn down the illumination a bit once I start using the scope to actually align the unit (can’t see the stars with it turned all the way up). The closer you get Polaris to that notch, the better the tracking. 

astro-trac-complete-setup

In my experience (shooting wide angle with 4 – 8 minute exposures) as long as I was close to the notch I was getting acceptable tracking. The longer your exposure and focal length, the more accurate you need to be with your placement. There’s a “fine tuning” section in the instruction manual to help.

Once everything is set, carefully mount the camera to the rig (if you bump the tripod, you get to start over – a lesson I learned the hard way one 20 degree below zero night at Bryce Canyon!)

From there, it’s time to experiment. I like to start with a high ISO shot (6400) for 30 seconds just to make sure the stars are sharp and I’m getting what I want in the frame (one of the first things you learn with astrophotography is that composition at night can be a bit tricky when your viewfinder is pitch black).

Once I’m happy with my test shot, I lower the ISO to 1600 and shoot for about 4 minutes at F/2.8. Of course, you can experiment with different combos until you get the look you’re after. Some areas of the sky seem to need longer exposures than others. Keep in mind that your exposure can render a fairly bright image, so be sure you aren’t actually blowing out areas of the night sky (like nebulas). The horizon can be especially troublesome if you’re near a populated area.

Oh, and get ready to grin. When you glance at your LCD and see the sheer volume of stars and celestial detail this rig can capture it will literally blow you away! I remember just standing there with my jaw gaping over the first image – I couldn’t believe what I was seeing! Crisp stars, nebulas, and even galaxies were all right there. Pretty amazing.

Here are a couple samples from my first night experimenting with the AstroTrac (the second one had better Polar alignment than the first). These are just quickly processed in Lightroom with not much adjustment beyond a blackpoint and a little contrast. Note that I have not done any real color correction or noise reduction in these images. Both at ISO 1600, F/2.8. The first is around 4 minutes, the second a half stop longer at 6 minutes.

Once back on the computer, I pull the exposure back and / or set a black point. This gives a more realistic version of the sky plus lowers the noise level quite a bit.

While out in the field you might also consider shooting a “dark frame” or two while you’re there to help reduce noise. I've not done a lot of dark frame subtraction, so I’ll let you Google that one. (Hint – a free program called “Deep Sky Stacker” can help a lot.)

That said, even at ISO 1600 once I pulled the exposure down I was very happy with the noise level - no dark frames required. (Note: I’ve also been shooting in winter where noise from excess heat isn’t a big problem, your warm summer shootin’ mileage may vary.)

As a final caution, keep in mind that the camera is moving during the exposure, so the ground and anything anchored to it is going to end up blurry. If you’re trying to include a landscape with the stars you’ll have to shoot it separately.

 

AstroTrac TT320X-AG

 

Introduction:

Like most landscape photographers, I look forward to amazing clouds at sunset. There’s just nothing quite like a dramatic sky and a successful image to close out the day. On the other hand, there’s nothing quite as discouraging as facing a bland, barren sky as the sun slides towards the horizon. Or at least that’s the way I used to think… Everything changed one crystal clear night in the backcountry of Northern Michigan. I had been plagued by a week of cloudless sunsets and out of sheer frustration to get something on the memory card, I finally decided to attempt some star trails. That did it – I was hooked. Little did I know star trails were the gateway drug for nighttime landscape photography! However, it didn’t take long to figure out that star trails can get tedious if they are the centerpiece of EVERY nighttime shot you make. (A conclusion arrived at, in part, by my family grumbling, “Seriously, star trails AGAIN??”)

 

 

I came to a point where I wanted to capture the night sky the way I saw it – without trails and maybe with the long arm of the Milky Way reaching through the frame. I started without the aid of a tracking device but quickly discovered the stars would trail ruthlessly on my 24MP Nikon D3x – and the high ISO wasn’t so hot either. I soon graduated to a D800, but its tightly packed pixels happily showed trails for any exposure over 20 seconds – even with wider lenses.

On top of that, I really wanted to keep the ISO to 1600 or less. Many of my clients purchase large prints, and heavy noise just wasn’t an option. Even more importantly, I also wanted to gather more luminance from the night sky. I envisioned crisp stars normally invisible to the naked eye making appearances in my frame, as well as galaxies and even an occasional nebula from time to time. Sure, some stellar phenomena might be tiny in the final photo, but I wanted the viewer to “discover” them when they were viewing a large print.

So, I did a little research and decided I needed a tracking device of some sort. Options varied wildly from expensive mounts for telescopes to DIY kits that could (allegedly) be put together for lunch money. Then I stumbled upon the AstroTrac TT320X-AG Kit. While it isn’t cheap, (coming in at just over $700) it seemed easy to setup and it was designed specifically for photography.

Before long, I was the proud owner of the following kit:

  • AstroTrac TT320X-AG

  • AstroTrac Illuminated Polar Scope

  • AstroTrac 12v car adapter

  • AstroTrac 12v “AA” Battery Pack

 


If you decide to purchase one of these for yourself be sure to get all the accessories listed above. I discovered some companies sell them separately and you really need everything listed to pull this off (except for maybe the 12v car adapter which, ironically, was the only accessory that was included with my AstroTrac.)

The unit itself is built really well and much more robust than I expected. When I ordered it I anticipated a frail device that would need significant cushioning every step of the way. And though I’d hesitate to let it bounce around in my truck and I certainly wouldn’t want to drop it, I’m very impressed with the overall build quality.

Using the AstroTrac was surprisingly easy. Initially I was intimated by all the talk of proper polar alignment, adjusting azimuth and altitude, but it’s actually pretty simple as long as you have a rudimentary knowledge of the night sky. The first challenge was mounting the thing to my tripod – Here’s that setup in detail. First, keep in mind that with the entire rig put together and a camera perched on top, it’s not exactly a featherweight. I highly recommend starting with a very solid tripod paired with a very sturdy ball head (if your ball head “drifts” under load this will NOT work). I use a Gitzo 3 series and a Really Right Stuff BH-55 Ball Head.

(Note on the ball head – I think if you happen to have a dedicated tripod for this, mounting the AstroTrac to a pan head or geared head would make alignment a much easier proposition. I just don’t want to carry yet another tripod when I travel!)

I also wanted the ability to quickly mount the AstroTrac to my tripod head, so I needed some sort of quick release that would fit the 3/8” socket on the unit. The folks at RRS had a solution – a TH-DVTL-55 quick release plate. That’s when I came across the first problem. The AstroTrac is a narrow device and the screw that comes with the RRS plate is just a bit too long, bottoming out before the plate is tight. A large washer was all it took to save the day.

 

 

The next glaring problem is that you actually need a way to mount the camera to the rig, now that your tripod head is being used to support the AstroTrac.

My solution was a retired – but good quality – ball head that had been collecting dust in my closet. I mounted this to the AstroTrac then the quick release to the camera so my setup looks like this:

 

 

Once you’re to this point, it's time to get ready to shoot!

I recommend waiting until at least an hour and a half after sunset before you begin. I quickly discovered when I first started doing stars that just because you can see them doesn’t mean it’s dark enough for long exposures. I’ve had the sky blow out to completely white on some “impatient” evenings when I thought it was dark enough.

Next, you need to do a polar alignment. In the simplest terms, this just means pointing the AstroTrac squarely at Polaris, the North Star. The instructions go into great detail about the procedure, so I’ll just note some highlights and pitfalls below.

To get started I recommend sort of “squaring up” the AstroTrac so it’s pointing roughly north and angled toward Polaris. I also suggest doing your alignment without the extra weight of the camera on the rig.

Mount the scope to the AstroTrac, noting that it comes in from the bottom, and that it’s VERY susceptible to falling out. The magnetic base is just enough to hold it, but no more. Mine has already hit the ground a time or two, so now I remove it after I get everything aligned. It’s just too easy to bump it unintentionally in the dark. (I might assemble some sort of “safety line” for it down the road.)

At one point in the procedure you’ll need to get Polaris into a little “notch” in the scope. I found that it helps to start by spotting along the top of the scope to make sure you’re in the astronomical ballpark. Also, I found it helpful to turn down the illumination a bit once I start using the scope to actually align the unit (can’t see the stars with it turned all the way up). The closer you get Polaris to that notch, the better the tracking. 

 

 

In my experience (shooting wide angle with 4 – 8 minute exposures) as long as I was close to the notch I was getting acceptable tracking. The longer your exposure and focal length, the more accurate you need to be with your placement. There’s a “fine tuning” section in the instruction manual to help.

Once everything is set, carefully mount the camera to the rig (if you bump the tripod, you get to start over – a lesson I learned the hard way one 20 degree below zero night at Bryce Canyon!)

From there, it’s time to experiment. I like to start with a high ISO shot (6400) for 30 seconds just to make sure the stars are sharp and I’m getting what I want in the frame (one of the first things you learn with astrophotography is that composition at night can be a bit tricky when your viewfinder is pitch black).

Once I’m happy with my test shot, I lower the ISO to 1600 and shoot for about 4 minutes at F/2.8. Of course, you can experiment with different combos until you get the look you’re after. Some areas of the sky seem to need longer exposures than others. Keep in mind that your exposure can render a fairly bright image, so be sure you aren’t actually blowing out areas of the night sky (like nebulas). The horizon can be especially troublesome if you’re near a populated area.

Oh, and get ready to grin. When you glance at your LCD and see the sheer volume of stars and celestial detail this rig can capture it will literally blow you away! I remember just standing there with my jaw gaping over the first image – I couldn’t believe what I was seeing! Crisp stars, nebulas, and even galaxies were all right there. Pretty amazing.

Here are a couple samples from my first night experimenting with the AstroTrac (the second one had better Polar alignment than the first). These are just quickly processed in Lightroom with not much adjustment beyond a blackpoint and a little contrast. Note that I have not done any real color correction or noise reduction in these images. Both at ISO 1600, F/2.8. The first is around 4 minutes, the second a half stop longer at 6 minutes.

 

 

 

 

Once back on the computer, I pull the exposure back and / or set a black point. This gives a more realistic version of the sky plus lowers the noise level quite a bit.

While out in the field you might also consider shooting a “dark frame” or two while you’re there to help reduce noise. I've not done a lot of dark frame subtraction, so I’ll let you Google that one. (Hint – a free program called “Deep Sky Stacker” can help a lot.)

That said, even at ISO 1600 once I pulled the exposure down I was very happy with the noise level - no dark frames required. (Note: I’ve also been shooting in winter where noise from excess heat isn’t a big problem, your warm summer shootin’ mileage may vary.)

As a final caution, keep in mind that the camera is moving during the exposure, so the ground and anything anchored to it is going to end up blurry. If you’re trying to include a landscape with the stars you’ll have to shoot it separately.

I personally use twilight or moonlight (or both) for the “landscape” portion of the shot, and then blend the stars and the land together in Photoshop. That's what I did for my first "real" photo using the AstroTrac:

 

 

Overall, I’m thoroughly enjoying the AstroTrac setup and I’m anxious to get out and use it at more locations. In fact, I think it’s safe to say that a clear sky at sunset is a welcome site for me now!

Milky Way Lens Shootout: Nikon, Zeiss, Sigma, and Rokinon compared

by Greg Benz

Capturing sharp stars and the Milky Way is one of the few genres in photography where special lenses are really a make or break deal. If your lens can’t shoot at f/2.8 or wider, you’re at a huge disadvantage (though you can always shoot log exposure star trails with such a lens). Those wide apertures are required to shoot with shutter speeds fast enough to keep the moving stars sharp.

I’ve used a Nikon 14-24mm for years with great results, including 40×60″ prints. But I’ve always had a nagging feeling that I could get better nighttime image quality with another lens. So I borrowed a few well-regarded lens and put them in a head to head test.  Below, see how the Nikon 14-24mm f/2.8, Zeiss Milvus 15mm f/2.8, Rokinon SP 14mm f/2.4, and Sigma Art 14mm f/1.8 compare in a field test shooting the Milky Way and night sky.

But first, I’d like to thank Brent of BrentRentsLenses.com for loaning the Sigma lens used in this test, and B&H for loaning the Zeiss and Rokinon lenses.  Brent runs a super-convenient rental business where he ships the lens directly to you along with a return shipping label.  The process really couldn’t be simpler.  And I’ve bought the majority of my camera equipment from B&H for years, and always been happy with their prices and service.

I’m posting a quick summary and some 100% crops from the top-right corner of each lens below.  For a much more thorough comparison of image quality, be sure to see the video. There’s much more to the story than this single group of images can tell, including: performance across the full width of the image, color quality, vignetting, and focus performance.

This test is designed to reflect real-world image quality based on performance in the field. My conclusions below are based on shooting each of the lenses under the most comparable settings I could. I shot each at the exact same settings at f/2.8 in the same lighting conditions, and additionally shot the Sigma and Rokinon at their maximum apertures to test their unique capabilities. All lenses were manually focused on bright stars via the LCD on a Nikon D810, which is the method I most use in the field. As manual focus is an imperfect method, I took several shots (refocusing several times) to help minimize the risk that my focusing technique would skew the results. But ultimately, that’s the best gauge of the results I can truly expect with this lens.

Nikon 14-24mm f/2.8

This has been my go-to lens for years. It’s great, and I’m definitely keeping it. But for wide-angle night skies, it can’t achieve the excellent stars that the other lenses can.

dark sky travels nightscape photography magazine

ros:

  • Autofocus for daylight shooting

  • Can zoom to 24mm

  • Quality/Durability:  Rubber weather seal between lens and camera and some seals inside for better dust and moisture protection.

Cons:

  • The most difficult to manually focus at night. Manual focus extends well beyond infinity, making it hard to even find bright stars to start focusing. And the f/2.8 maximum aperture does not offer as good a live view as the Sigma and Rokinon. There’s also a bit of slack in the focusing ring, which can make precision adjustments a little more tricky. Focusing on stars manually is always difficult via live view, but I found the Nikon was most difficult. That’s a real detriment to image quality, as some images will likely be focused imperfectly. Reviewing the images carefully on the LCD is important with this lens to make sure you got the shot in the field. Thankfully focusing is easier with the new Nikon D850 (due to lower LCD noise), but I felt much more confident focusing the other lenses in this test.

  • Image quality is good across a broad range of conditions. But lack of sharpness and coma in the corners puts it behind the rest of the lenses in this group for astrophotography. On overall image quality, I would say that all three of the other lenses outperformed in this test.

  • Weight:  2.26lb.  Fairly bulky, but then you are shooting with the capabilities of an autofocus zoom lens, and it is lighter than the Sigma.

  • Available for Nikon only.

Price in US: ~$1897. Aperture range:  f/2.8-22.

Rokinon SP 14mm f/2.4

This is the lens to get if you want to save money or weight. I would shoot this lens at f/2.8 for best image quality, unless you need a little more speed for the Aurora.

dark sky travels nightscape photography magazine

Pros:

  • Excellent value for the money and the cheapest of the group.

  • Weight: 1.73lb.  The lightest of the group, and it feels quite nice.

  • Image quality is generally excellent, but the vignetting is a bit heavy.

  • Manual focus stop just past infinity helps quickly find stars.  The focusing ring is fluid, which helps manually focus precisely. The f/2.4 aperture provides a slightly improved ability to evaluate focus on the LCD.

Cons:

  • No lens profile support in Lightroom or Photoshop. Third party profiles are available for Canon, but I have yet to find one for Nikon. Given this lens has noticeable distortion, it’s an import consideration, especially if you also wish to shoot architecture or other clearly straight lines.

  • Significant vignetting, but not as bad as the Zeiss.

  • Manual focus only.

  • There is no weather sealing, but this lens feels solidly built (and you aren’t going to run into a lot of water on most Milky Ways shoots).

  • No 16-24mm coverage.

Aperture range:  f/2.4-22.

Price in US: ~ $999 for Nikon or $799 for Canon mount. (While I didn’t test it, the non-SP version of this lens is generally well-reviewed and outright cheap).

Available for Nikon and Canon.

Sigma 14mm f/1.8 DG HSM Art Lens

I love everything about this lens, except the weight. I found the image quality was the best of the bunch, if you shoot at f/2.8 for best image quality. It also offers the ability to shoot at f/1.8 for faster shutter speeds, which would be beneficial for shooting the Aurora Borealis. Note that the Sigma showed a slightly smaller angle of view than the Nikon or Rokinon, even though they are all 14mm lenses

dark sky travels nightscape photography magazine

Pros:

  • Excellent image quality, the best of this group at f/2.8. (However, image quality suffers at f/1.8, and shooting wide open should be reserved for situations where shutter speed or image noise is a high priority.)

  • Minimal vignetting.

  • Manual focusing at night is relatively very easy with the wide f/1.8 aperture.

  • The f/1.8 aperture is a huge advantage for shooting the Aurora, which requires faster shutter speeds than stars.

  • Autofocus is very responsive and accurate for daylight shooting.

Cons:

  • Weight: 2.53lb.  The heftiest of the group, you really feel it.

  • No 16-24mm coverage.

Price in US: ~$1599. Aperture range:  f/1.8-16. Available for NikonCanon, and Sigma.

Zeiss Milvus 15mm f/2.8

This is a great lens, but I see no compelling reason to buy it at this price. It just doesn’t stand out for astrophotography, and the vignetting was disappointing.

dark sky travels magazine

Pros:

  • Image Quality is very good to excellent, but there is significant vignetting in the corners.

  • Manual focus “lock” makes it easy to initially find stars for focusing.  Zeiss is known for the “lock” at infinity focus.  Zeiss even warns in the instruction manual that the focus is designed to allow over-travel (beyond infinity focus) to allow for temperature camera flange distance variations.  In other words, there is no single lens that could guarantee proper infinity focus on all cameras in a variety of temperatures.  However, the tighter range of over-travel is still useful, as it gives you an easy way to quickly get close to proper focus – so that you can at least see the stars well enough to manually focus.

  • Weather sealed.

  • Offer threads for filters (95mm). However, given existing vignetting without a filter, I have some reservations about how useful this feature may be.

Cons

  • Expensive

  • Significant vignetting at f/2.8. Deep enough to cause color issues with the Nikon D810 (the D850 should perform better, and the color cast can be corrected). If you are shooting with this lens, be sure to capture an extra frame for the foreground. That’s generally a good idea anyhow, but noisy corners could be problematic with this lens under night sky conditions if you don’t blend images.

  • Manual focus only.

  • No 16-24mm coverage.

Price in US: ~$2699. Aperture range:  f/2.8 to f/22. Available for Nikon and Canon.

Conclusions:

All of these lenses were great for astrophotography, and I’d happily shoot with any of them. They all feel high quality and offer very good to excellent image quality. While I have some strong preferences when pixel peeping the results side by side, I would be proud to print images from any of them – including my Nikon, which was ultimately showed the least impressive results. Looking back on things, I wish I had also tested the Tamron 15-30mm f/2.8, as that lens is likely also a good choice. However, I’d be shocked if it beat that zoom lens could beat the image quality of the prime Sigma Art lens, and I prefer its wider 14mm field of view. But it’s definitely an option to consider if you’re leaning towards a zoom like the Nikon.

It’s important to note that test focused specifically on shooting the night sky. I did not get a chance to shoot the Zeiss and Rokinon in sunrise/sunset conditions, so I can’t say how they might hold up for flare. I assume the Zeiss is excellent in that regard, and I wish I’d had an opportunity to test the Rokinon for flare. I found the Sigma was consistent with the level of flaring from direct sun that I see with the Nikon (or better). I captured a beautiful sunrise image with the Sigma that has me impressed that this is an excellent all around lens for landscape photography.

I would recommend the Sigma if you’re looking for the best wide-angle night image quality, the Nikon if you want the flexibility to shoot up to 24mm, and the Rokinon if you’re on a budget or want a lightweight lens for hiking. I really can’t think of any reason to choose the Zeiss – its image quality did not outperform the Sigma, and the price is substantially higher.

Personally, I ended up buying the Sigma after this test. I love it. The image quality was my favorite of the group, the wide aperture gives me lots of options for shooting auroras, the wide aperture helps get manual focus at night, the autofocus makes it easier for daytime shooting, and the price was reasonable. I’ll definitely be keeping the Nikon for for situations where I expect to zoom to 24mm. And I’ll always be a little envious of the light weight of the Rokinon.

 

Note:  All weights listed above were measured on a postal scale and may not match official manufacturer specifications.

Disclosure: This article contains affiliate links. See my ethics statement for more information.

Astrophotography 101.

Expectations and Preparations

by Eric Benedetti

dark sky travels nightscape photography magazine

Sweet, you’ve spent $1,000, pictures will be flowing from your Ethernet cord onto the world wide web tomorrow, right?! Settle down tiger, it’ll come, if there’s one thing I’ve learned over the years of doing this it’s….be patient. And read/learn as much as you possibly can. And when you think you’ve read and learned everything there is to read and learn….go find more to read and learn (hint: there’s always more).


Before we delve into making super awesome amazing pictures, let’s talk about what astrophotography is and is not. It is a rabbit hole and you are Alice, what you get out of this will depend on how far you chase the rabbit. If you are expecting amazing results out of the gate and being an awesome astrophotographer from day one you are going to be disappointed, sticking your face up to the rabbit hole will only yield mediocre returns. Astrophotography is NOT a simple or easy endeavor. You will spend long nights out in the dark, stumbling around, making stupid mistakes because you’re tired/cold/distracted, you’ll spend even longer hours reading tons and tons of articles/tutorials online and trying different editing techniques with your own photos. It IS addicting, it really really is. You’ll snap your first picture, a preview will pop up on your camera screen, and you’ll be addicted, I guarantee it. And when you finish your picture you’ll look at it and think “damn, I made that and THAT is awesome”. In my lightroom catalog I have about 20,000 pictures listed in the last 20 months, that’s not even including the thousands of shots I’ve taken for timelapse purposes. To this day, every single time I’m standing out in the dark and I’m looking at the star filled sky or at my camera screen after an exposure is done, my mind is blown. I love it, I’m addicted, I don’t think I’ll ever give it up (nor would I ever want to). It IS challenging, every single time you go out you will be presented with a different challenge, I promise you. Eventually you will figure out the recurring things that create those challenges and when you get good you will overcome those challenges faster, but they will always be there. One thing I’ve discovered is that other types of photography don’t interest me as much anymore, in fact I’d say many are borderline boring now, and I believe it’s because astrophotography (from taking the shot on location through editing the final image) presents such a unique challenge that once you figure it out the “challenge” of other types of photography isn’t as rewarding. But that’s also what makes astrophotography so addicting and why I keep going out at night to do it.

dark sky travels nightscape photography magazine

Before you ever push the shutter release button and take your first astrophotograph you should do your homework, prepare yourself for the unexpected. Be aware of the phase of the moon, each month presents a roughly 14-17 day window of shooting the Milky Way based on the moon phase, and the time of the year, the Milky Way core is visible in the Northern Hemisphere from March to October. You will be going out at night, first and foremost buy yourself a headlamp (especially one with a red-light), I bought a $20 headlamp, broke the battery cover the first night I used it, taped it up and I’m still using it….2 years later. Don’t use a regular flashlight, you’ll want both hands free at all times, especially if you’re hiking around in the dark. Before you head out do some scouting, at a bare minimum you should be using something like Google Maps to find an area to shoot. Also, understand light pollution, use this website to find locations to shoot at to limit the impact of light pollution on your shots: http://darksitefinder.com/maps/world.html I find that you CAN get images of the Milky Way in orange zones (Bortle 6, Google the Bortle scale), but no worse. Also, pick a location where you are shooting away from light pollution, even if you are 60+ miles away if you are shooting into major sources of light pollution it will be readily apparent in your images and challenging to deal with while editing.


Ok, you’ve got a location picked, it looks good on google maps (use the earth feature and pull up the images while hovering over a spot to get a sense of the geography), what are some of the other things to take with you? Warm and some waterproof clothes, even if it is summer, ESPECIALLY if you are going to the mountains. In Salt Lake City it will be 100 degrees in the summer, 70-80 at night, when I go up into the mountains it will be 40-50 at night. Wool socks, thermal base layers, a nice pair of gloves that allow you to use your fingers for fine movements, a light rain jacket, a beanie/warm hat…these are things that you should take just in case. Even in places like Arches, Zion, and desert places throughout Utah I’ve found myself putting on long sleeve shirts at night, temps can fall 40+ degrees from the day and you’ll want to do everything to stay comfortable during a long night of shooting. Wear good boots or comfortable shoes, you’ll often find yourself perched in awkward positions on uneven ground not sure if the drop off in front/behind you is 6 inches or 60 feet. Comfort is important, if your feet are cold, or your legs are tired, or your ears are frozen, you’ll be distracted and not thinking about composing your shot or even just taking in the beauty of the stars. In the mountains of Utah the weather can change in an instant, it’ll be clear skies and 10 minutes later a downpour, a rain jacket is usually a safety must.

dark sky travels nightscape photography magazine

Water and snacks, pack plenty of water and don’t pack crappy snacks (fruit snacks and junk food, things that will give you a sugar rush and terrible crash later). Nothing worse than packing in a bunch of camera gear and getting that energy crash at 3am when you have to pack it all out. I find things like granola bars and mixed nuts to be invaluable for long lasting energy. As for energy drinks, I’m a coffee drinker and I’ll drink a cup before heading out, I’ll also take a total zero red bull (or any energy drink with zero sugar and zero carbs) so if I’m getting sleepy late I can keep my eyes open until the end of my shooting. If you don’t like coffee/energy drinks, don’t take them, stick to what makes you feel alert and awake. And don’t forget to drink water, water, water while you’re out there, you’ll be burning a fair amount of energy and you need to stay hydrated.


Take extra batteries (double A and triple A) for things like flashlights and your intervalometer, make sure your cell phone battery is charged (you’ll need it for aligning the polar scope on the tracking mount, even if you are out of cell range), make sure your car is in good running condition and that you have basic car things like jumper cables (I have had to get jump starts no less than 3 times…ya, it sucks). If you’re camping make sure you have all your gear and what-not. Buy yourself some hand/toe warmers (I’ll explain why later, not just for keeping your fingers/toes warm).


Ok, you’ve got all your stuff packed and ready to go, one thing I’ve found that makes my life 100 times easier is scouting the location during the day. When I first got into this hobby I’d just rely on photos/google maps posted online for scouting, I’d think about my perfect shot all day long, go out once it got dark, stumble around to find the spot I imagined, and ultimately have to settle for something less than ideal. Now I have a process, I go to my location in the early afternoon, scout my angles (there are also apps to help with this like PhotoPills for iOS and The Photographers Ephemeris for Android) at my spot(s), then go back and take a good nap. I try to sleep for 1-2 hours before I shoot, this allows me to unwind from the day and clear my mind for a long night of shooting, plus give my body a break if I’ve been hiking a bit. I wake up, eat some food, drink my coffee and then go to my location and setup my equipment during astronomical twilight. Then I’m ready to start shooting after astronomical twilight or I can make changes if my angles/location or something just isn’t right.

dark sky travels nightscape photography magazine

The last thing I want to discuss in this section is the weather and provide you with some resources. You obviously can’t shoot the stars if there is cloud cover, you should prepare your plans for shooting based on what the skies look like now and what you think they’ll look like overnight. I use this website to get regional views of the current cloud cover and trends of the clouds over the last 12-96 hours in the United States: http://www.aviationweather.gov/satellite?gis=off on the little map you can select one of the 3 digit names and it’ll pull up the current satellite image of the area. You can select Visible, Infrared (IR) either black and white or color, and water vapor. I mostly use Visible and IR, I use color IR in the summer to get more cloud contrast and B/W IR during the winter. Select a long timeframe in the drop down box and watch how the clouds move, try to get an idea of where the cloud breaks are now and where they could be in hours from now. Also, in places like the desert southwest we get monsoonal moisture, this means afternoons during the summer thunderstorms will pop up and the sky will fill with clouds. Usually by night the clouds dissipate though, so look for patterns of cloud development, don’t just see a single image full of clouds and think “oh I can’t shoot tonight, it’s cloudy now.” In 2015 I mostly operated with that mindset and only went out shooting maybe a dozen times, in 2016 I told myself I’d go out no matter what and probably 90% of the time I end up being able to shoot at least some shots. Some of my best shots this year have come after I’ve decided to head to my shooting location while the sky is completely cloud covered, only for the clouds to clear at night and be full of bright stars.


A few other things you’ll need, especially for the tracking mount, you’ll need an app to give you the precise location of Polaris (the north star) in order to align your tracking mount to the earth’s axis. I use “PolarFinder”, it gives you options for tracking mounts which will display where you need to put Polaris in your polar scope. Once downloaded, make sure you have the mount set to iOptron, and take a look through your scope to get an idea of what it looks like. I also recommend downloading Stellarium, either to your computer or your smartphone, it’s a fantastic app which will show you exactly what is in the sky at a given time and date at your location. You’ll need your GPS location for the polar finder and Stellarium (if it doesn’t set automatically), there are free apps that easily give you that, once you have your GPS coordinates you can enter that info into those apps.

Full Frame vs Crop Sensor

Article by Joe Gilker of   darkartsastro.ca

Article by Joe Gilker of

darkartsastro.ca

Full frame, crop sensor DX, APS-C, FX, full frame equivalent… These are terms that get thrown around a lot when it comes to digital cameras and lenses. And rightfully, it can also be a source of confusion for novice or intermediate-level photographers who don’t know what they mean or how it affects their photography. In this article, I’ll attempt to introduce these concepts in simple terms and how they can affect your images when they’re applied to astrophotography.

Let’s simplify the terminology

In order to understand what’s what, we first need to define these terms in a simple way. 

On 35mm film, the imaging area was 36mm (wide) by 24mm (high). There really wasn’t much more to it. You got a 35mm SLR and went about your business of taking photos. There were many options available in terms of features the camera offered like auto-focus and such, but you had 1 image size when it came to an SLR. Nowadays, we find there are far more choices available, but when speaking about DSLRs and in some case, mirrorless cameras, there are 2 basic categories that cover the vast majority of all cameras used by astrophotographers – full frame and crop sensor (the latter also known as APS-C [Advanced Photo System type-C]).  Although implemented differently by different camera manufacturers, the concept is the same. These sensor sizes are based on 35mm film camera. Crop sensors come in various physical sizes but most offer crop factors of 1.5 or 1.6x.

Full Frame is the equivalent of 35mm film producing an image with a 3:2 aspect ratio. The physical sensor size is 36 x 24mm, the same size as a 35mm film cell. This is the base standard for all DSLR cameras. Nikon refers to their full frame sensor size as FX.

Crop sensor, or  APS-C offers smaller sensor sizes that are a subset of the full 35mm sensor size, or a “crop” of that. The physical sensor size is smaller than a full frame (1/1.5 or 0.67x for 1.5 crop factor, 1/1.6 or 0.625x for 1.6 crop factor), but retains the same 3:2 aspect ratio of their full frame big brothers. Nikon refers to their crop sensor size as DX.

The term “full frame equivalent” is used for lenses used on APS-C cameras. The smaller sensor size affects the magnification and field of view you get from a particular focal length compared to a full frame. This will be explained in greater detail further in this article.

There are other sensor sizes like APS-H, Micro 4/3 and Medium Format. Dedicated CCD and CMOS astro-cameras come with various sensor sizes and formats as well, but for the sake of this article, we’ll be sticking with the sensor formats used by the majority of DSLRs and mirrorless cameras that are popular for astrophotography; namely, Canon and Nikon DSLRs and Sony and Fuji mirrorless.

Why does any of this matter?

So now that we have the terminology simplified, we can get to the meat of this subject. For any examples, I’ll be using a hypothetical 24 MP sensor in the various formats as my example, as this seems to be a common size many current model DSLRs are produced in today, even in entry-level models. Keep in mind that a sensor’s MP (Megapixel) count really means nothing in this case. We’re comparing different size sensors with the same pixel count in all cases unless specified.

The size of your sensor determines 2 things – how much light it can capture, and how wide your field of view will be using the same lens. The sensor itself is covered in “pixels”. The individual light collectors on your sensor chip are called photosites.  A 24 MP sensor will have 24 million colour photosites which collect the light focused on them by the lens. Like the sensor itself, the size of the photosites matter. On a full frame sensor, the individual photosites are larger to fill up the larger physical dimensions of the chip, therefore gather more light. And inversely, fitting 24 million photosites on a smaller physical chip requires making each individual photosite smaller.

One of the advantages of full frame sensors is their lower noise than crop sensors. This is because photosites will generate heat when actively collecting light. Larger photosites and larger sensors means that they’re able to dissipate heat better whereas the smaller, mode densely packed photosites on the  smaller chip are more sensitive to heat. Sensor heat is the biggest contributor to digital noise when using high ISO (gain) settings or doing long exposures – the 2 things that we do most in astrophotography. This is the reason why full frame cameras will have better noise tolerance and better low light performance than a crop sensor camera with an equivalent pixel count sensor.

The second affect of sensor size is field of view or viewing angle. This is where the aforementioned term “full frame equivalent” comes into play. With an equivalent lens (a 20mm, for example), a full frame sensor will produce a wider field of view. Depending on the crop factor of the sensor, the magnification will be increased by the crop factor of the sensor. In the case of Nikon and many other brands with a crop factor of 1.5, the full frame equivalent will be 30mm (20mm x 1.5).  On a Canon ASP-C sensor, the crop factor is 1.6x. So the lens will give the full frame equivalent of 32mm (20mm x 1.6).  The image at Figure 1 below will show how the different fields of view vary with sensor size. But the basic thing to keep in mind is that the higher the crop factor, the narrower your field of view and the higher magnification you will get from the same optics.

ark sky travels magazine

Figures 2-4  below display the different in the field of view  in the same image when rendered at the different crop values. The difference in size between the 2 APS-C sensors is noticeable, although not drastically. However, the difference between the APS-C images and the full frame is quite remarkable. A lot of the field of view is lost. This can be compensated for on an APS-C camera with a wider lens. In this case, a lens of about 8mm would have to be used in order to produce the same wide field of view the 13mm lens produced on the full frame camera.

Figure 2 – Full Frame field of view

Figure 2 – Full Frame field of view

Figure 3 – 1.5 crop APS-C field of view

Figure 3 – 1.5 crop APS-C field of view

Figure 4 – 1.6 crop APS-C field of view

Figure 4 – 1.6 crop APS-C field of view

You said pixel count doesn’t matter. Then why is this a selling point for cameras?

Pixel count does matter, but not the way people tend to think it does. High pixel count cameras are often touted as being better, but that’s not the case. A high quality, full frame 10MP camera will produce images orders of magnitude better than a low end 24 MP APS-C will. In terms of camera performance for low light and high ISO, ironically fewer pixels are better, as the individual photosites are larger on the lower pixel count. With all other things being equal (sensor technology, processor, camera features, etc), a 24 MP full frame sensor will have better low light performance and be more noise-tolerant than a 36 MP full frame sensor, as the higher resolution sensor will have smaller, more densely packed photosites. With a bit of simple math, you’ll find out that the 36 MP full frame sensor has the same pixel size and density as a  16MP ASP-C camera in order to pack that many of them onto the same sensor. The trade-off will be the high MP count sensor will be able to resolve finer details in the scene being photographed than the lower pixel count sensor.

Whether that trade-off is worthwhile for you really depends on you and what your target audience is. If you regularly print large poster size images, submit your images to agencies that require a certain pixel count,  or use smaller cropped subsections of your images, the higher pixel count is likely the better option as you’ll be able to resolve finer detail. If you photos are for print or online publication or you produce smaller prints (under 20″ wide), then the lower pixel count and better performance are likely the best choice.

Do I need a full frame camera for astrophotography?

If only there were a simple answer to this question. The debate on this issue rages on constantly. It’s difficult to get a consensus on which is better. Undoubtedly, your photography in general will benefit from a full frame sensor. Wider vistas, better low light performance and cleaner images are the obvious benefits. But there are pros and cons, just as using an APS-C camera.

For astrophotography using a telescope or a long zoom lens on a tracker, an APS-C sensor is often preferable. The smaller sensor means you’ll be able to get extra magnification and a tighter field of view. On small galaxies, planetary nebulae and globular clusters, you’ll get a larger image (1.5 or 1.6x larger) and be able to resolve finer detail than a full frame camera with an equivalent pixel count. The narrower field of view also means you’ll experience less vignetting than you would using a larger sensor. Many APS-C cameras are smaller and lighter than their full frame counterparts. The payload you have on your mount is always an issue for astrophotography, so being able to shave off some extra weight is always helpful and it will generally make your rig easier to balance.

And there’s also the cost benefits that need to be considered. Outside of a few high end models, APS-C cameras are significantly less expensive than full frame. Their lenses require significantly less glass to produce, so they also tend to be significantly cheaper as well.  You can often find top shelf  wide aperture crop format lenses for the same price as less capable mid range full frame lenses. On a side note, you can also use full frame lenses on a crop sensor camera, so if you plan on eventually getting a full frame camera, you can start buying your full frame lenses and using them with your crop sensor camera.

On the flip side, large galaxies like the Andromeda Galaxy or large clusters like the Pleiades or Double Cluster in Perseus may not fit into your field of view when your camera is paired with a higher focal length telescope, requiring you to do a mosaic in order to get the full object in one final image. When shooting widefield landscape images like Milky Way or aurora, you’ll have a narrower field of view and not be able to expose your images as long as with a full frame on equivalent lenses (see the Rule of 500 in my  How To Shoot The Milky Way And Night Sky With A DSLR Camera article for more information). Although as mentioned above, this last point can always be remedied by using a shorter focal length lens.

For widefield landscape astrophotography, it’s hard to beat a full frame camera. The superior low light sensitivity and more robust noise of full frame sensors mean you get cleaner, brighter images. Your use through a telescope will also benefit from the wider field of view and better noise tolerance, particularly if shooting long, guided exposures. A series of long (5+ minute) exposures at ISO 1600 will reveal details you won’t be able to capture as easily with an APS-C sensor without adding significantly more integration time at lower ISO settings to maintain the same low noise levels.

However, on many telescopes, the vignetting you experience may be quite significant. As an example, the vignetting I experience using my my Nikon D750 on my 8″ Meade LX90 optical tube with a 0.63x focal reducer is so bad that I only get a usable image area the same size I would if I were using an APS-C camera. This can be partly correct by shooting flat frames, but is still an annoyance. But this really depends on the telescope used. When I use the D750 on my ED80 refractor, the vignetting is negligible. Your results will vary.

Another disadvantage of shooting deep sky through a telescope with a full frame sensor is shooting smaller objects such as planetary nebulae, globular clusters and small, distant galaxies. Your targets will be tiny in your final image compared to APS-C. Unless you’re looking for a wide field of view, you’ll have to crop your images to get them larger, which will give you a final result with less fine detail than if shot with an equivalent APS-C camera. This, however, is an area where high pixel count (like 36MP) sensors can help significantly. They won’t perform as well in terms of noise and sensitivity, but they’ll be able to resolve finer details that lower pixel count sensors won’t.

Which is right for me?

As with most things in life, budget will often be the single biggest determining factor that guides your purchase. While it may be nice to rock the latest and greatest Nikon D5 or Canon 1D, the harsh reality is that not everyone can afford to spend as much as a small car on their camera, not to mention their lenses and other equipment required to complete the kit. When buying new, even mid-range enthusiast-grade full frame camera bodies run the $2000-$3000 range, which is a large sum of money, particularly to someone just starting out.

In reality, most of us mere mortals have to follow a budget in order to make ends meet. Therefore, splurging for high end equipment, particularly when just starting out, is overkill. And someone just starting out often overlooks other essential equipment required. Spare batteries (not cheap, and 1 battery is NOT enough!), memory cards, a sturdy tripod, a tripod head, intervalometer, extra lenses, and of course, a bag that you can carry all this stuff in all add up very quickly. There’s more to photography than just the mere camera body.

So this is my recommendation; I won’t give you any specific brand or model to choose, but I will point you towards the right type of equipment that you need.

If you plan on buying new, my personal recommendation for a DSLR for astrophotography would be a mid to high-range APS-C camera. It’s hard to go wrong with something in this price range. You can get something good from Canon or Nikon in the 500-1000 USD range that can potentially last for years and perform admirably. There are other brands as well, but these 2 will likely be your best performers for astro. For widefield or landscape astrophotography shots like the Milky Way or aurora, add a Rokinon / Samyang / Bower 14mm f/2.8 lens (300 USD) and it will be your best friend. There are few lenses this good in this price range. It’s all manual, but a pure gem that you’ll continue using even if you get more expensive lenses.  If you plan on using your camera on a telescope, I highly recommend a camera that has a flip-out screen. It’s really nice to be able to easily tilt your screen to see what’s going on when your telescope is pointed at high angles that would otherwise have you on your knees and straining your back and neck to view your screen.

If your pockets are bit deeper but you’re still on a limited budget, the lower end full frame cameras will cost you about 1500 USD range. Add the same 14mm lens mentioned above (yes, it’s a full frame compatible lens) and you’ll have an incredible camera for landscape astrophotography. If you plan on using it with a telescope, just be aware of the vignetting issue you may experience. This will be totally dependent on the scope you’re using.

If you’re ok with buying used you can often get incredible deals on barely used equipment. You may be able to get a fairly recent model full frame camera for roughly the same price as a high end new APS-C camera. Or you can just get a used APS-C camera body and use those extra dollars you saved on the required accessories.

Really, with current state of sensor and camera technology, it’s hard to go wrong with any DSLR made in the last 5 years. It all comes down to what suits your requirements best and what you can afford. There is no “right answer”. Only what’s right for you.

Final words

In an ideal world, having both formats available to you is best. I use both crop and full frame cameras regularly, depending on the requirement at hand. Having this flexibility has become essential to me. I honestly couldn’t imagine having to shoot with only 1 format at this point. But if I had to choose 1 only, I would likely go for a high end APS-C, because to me, it offers me a level of versatility for astrophotography that I can’t simply get with a full frame. It may have marginally worse noise and low light performance, but overall, the differences are minimal enough that I can easily work around them in post-processing.

The biggest thing to take away from this article is that your camera is just a tool. The camera is only as good as the photographer using it. A better camera won’t automatically take better pictures. It will just open up some possibilities you didn’t necessarily have before.

So until next time, clear skies, and keep those eyes and lenses pointed up!