review

Tokina AT-X 14-20mm F/2 PRO DX Review

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by Michael Burnham

Can you feel it? The start of Milky Way Galaxy season is less than 6 weeks away! This is the time of year when the core of the Milky Way Galaxy is up at night. It starts being visible in the predawn hours in late February and goes into September. If you shoot with a DLSR with an APS-C (DX) sensor Tokina has an amazing fast apertured super-wide angle zoom that is perfect for shooting the Milky Way Galaxy or any other astrophotography application.

Ladies and Gentlemen, if you don’t know it already please allow me to introduce the Tokina AT-X 14-20mm f/2 PRO DX lens. Not a misprint, its a constant f/2, not 2.8.

Fast Aperture

At the time of writing the constant f/2.0 is the fastest super-wide angle zoom lens available for APS-C sized DSLRs. F/2.0 is nearly a full stop faster than f/2.8 which equates to almost twice as much light entering the camera. More light entering the camera has several advantages; First, it allows the camera to focus in lower light situations. Second, it allows for more light to hit the sensor when doing long exposures at night, the faint light from more distant stars will be recorded making it perfect for astrophotography. More light gathering can also translate into shorter exposure times or lower ISO settings for sharper astro photos with less noise.

Next, the f/2.0 aperture yields a shallower depth of field than f/2.8 or slower lens. This last point allows you to isolate your subject more for a dramatic perspective. In another review I will be doing an in depth comparison of the the AT-X 14-20mm f/2 PRO DX vs the slower AT-X 12-28mm f/4 PRO DX lens so stay tuned to my blog fort that.

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Handling and Ergonomics

The Tokina 14-20mm is a weighty lens for its size weighing 735g (25.9 oz.). It feels solid, well made and balances well on PRO APS-C bodies like the Nikon 7500 or Canon 7D mkII. It will feel a little front heavy on smaller, lighter APS-C bodies like the Nikon 5600 or any of the Canon digital Rebel cameras but not too much. The reason for the weight is the amount of glass needed to accommodate the bright f/2.0 aperture and the fact that Tokina uses more metal than other manufactures in the internal barrels of the lens making them heavier but more durable.

The lens has common 82mm filter thread so there are a wide variety of filters available for image enhancement and creative possibilities.

Like all other Tokina AT-X PRO lenses, the 14-20mm has a Tokina’s exclusive One-Touch Focus Clutch mechanism for switching between auto focus and manual focus. Just pull the manual focusing ring back toward the base of the lens, the ring will snap back to engage the manual focus and then push it forward to engage auto focus again.

The lenses barrel design makes it very intuitive to handle on location in the dark. The rings are large enough and set far enough apart that I don’t get them confused in the dark or move one ring accidentally while turning the other, even while wearing gloves.

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AF

Auto focusing on the Tokina 14-20m is fast and smooth, it won’t break any speed records but its accurate. The lens does emit a little motor noise if you rack the AF between a very close subject and something far away. It’s not enough for anyone standing around you to notice but it might be heard on video using the built in mic so I would recommend using it in manual focus for video. The lens has had no problems acquiring and locking focus in a wide variety of lighting situations.

At night under the stars you will need to focus manual but that goes for any lens. A trick for getting infinity focus at night. If you have a high-power flashlight point it at something you know to be at a greater distance than the infinity scale. With a super-wide lens like the 14-20 something more than 5 meters (more than 15 feet) away, put your AF point on what you are lighting up and AF on it. Then carefully pull the manual focus light back into MF and you should be focused at infinity for the stars. After that, take a test shot and use the camera’s screen to zoom in on the stars to make sure they are in focus. If its not, start by moving the focus ring just a little to the left or right and take another test shot and check it to see if the starts are more or less focused. Repeat until the starts are sharp.

Here’s a tip; painters tape or other adhesive tape that is designed to be temporary and removable. Once you have the lens focused at infinity use a 3-4 cm (1.5 inches) long piece of painters tape to tape down the manual focus ring. That way it wont move accidentally if you move the camera to recompose your shot.

Sharpness

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Simply put, this lens is sharp, even wide open the lens is sharp. Other than the fast aperture sharpness is where this lens shines. DXO Mark gave the Tokina AT-X 14-20m f/2 PRO DX lens an over-all score of 26 which is higher than either the AT-X 11-20mm or the old 11-16mm lenses. That has been my experience with the lens as well, its the sharpest of the lenses in this class. The lens does not disappoint and you will be able to make large prints if you are using a camera with a 24+ megapixels sensor.

As with any lens, it is sharper when stopped down and the lens’s critical aperture setting is f/4.5 - f/5.0, I could not see any sharpness difference between these aperture settings and stopping down to f/5.6 did not improve sharpness over f/4.5-5.0. But sharpness wide open is still very good which is necessary for low light photography.

Astrophotography is where this lens is really at home. The Tokina 11-20mm may have a wider angle of view but the f/2 of the 14-20mm allows more light gathering and that means more stars captured and more flexibility to change exposure time or ISO.

Coma is not bad at all and Chromatic Aberrations (CA) are well corrected. In some high contrast situations you will see a just a little purple fringing but it is easy removed in post.

Conclusion

The Tokina AT-X 14-20mm f/2 PRO DX lens is at the top of its class in both fast aperture and sharpness. The constant f/2 aperture is the fastest available in a super-wide zoom lens for APS-C lenses at this time. That coupled with amazing optics makes this lens a natural for low-light photography and a lens that anyone interested in astrophotography should seriously consider.

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Sky-Watcher Star Adventurer Review

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by Joe Gilker

TRACKING THE SKY

For the last 3 years, my lightweight portable tracker consisted of an iOptron SkyTracker. It was my primary photography tool through the winters when hauling my scope outside wasn’t always feasible, and through the summer served me well for long exposure Milky Way photography and time lapse sequences.

But while this fine little tracker served me well and provided me with some really great shots of the sky, it left me disappointed about a month back when without warning, it decided to give up the ghost on me as chronicled in this blog post. [EDIT: it has since been repaired]  Winter is rapidly approaching and I needed to get a replacement stat! Enter the Sky-Watcher Star Adventurer!

Why the Star Adventurer?

At first, I had considered replacing my SkyTracker with the new SkyTracker Pro. But looking into the different trackers a bit more in-depth, I realized the SkyTracker had several advantages over the SkyTracker series.

  1. It’s a true German equatorial mount vs a tracking platform whereas the SkyTracker series and Vixen Polarie are tracking platforms. While both provide the same function, the ability to have a counterweight to help keep tracking accurate under heavier loads was a big factor. The counterweight option is available on the SkyTracker Pro, but the Star Adventurer has a maximum payload of a full 2kg more. It seemed a better option, as I do have a couple of rather heavy lenses.

  2. The Star Adventurer comes equipped at an ST4 guide port to use with an auto-guider. This may be helpful down the road as I plan on getting a standalone autoguide (vs my current guide camera / laptop setup)

  3. It’s a multipurpose mount with pan effects for any type of time lapse photography. I’ve been getting more into time lapse photography since last summer so I figured this could be a useful tool for this purpose. I particularly look forward to using in this manner the next time I’m out shooting the Aurora Borealis.

The Bundles

The Star Adventurer is available in 3 different bundles at 3 different price points.

The first includes only the mount. While the price looks attractive, you need to provide all the extras needed to use the mount.  On its own, there’s not a lot you can do with just the mount. You can attach the mount to a normal tilt-pan head and properly align it, it’s not as easy or accurate as with the equatorial wedge designed for it.

Sky Watcher Star Adventurer.    The Astro Bundle pictured here provides you with everything you need for exceptional sky photography

Sky Watcher Star Adventurer. The Astro Bundle pictured here provides you with everything you need for exceptional sky photography

The second, the Photography Bundle, includes the equatorial wedge and ball head adapter. To me, unless you positively have everything else you need, this is the minimum bundle I would  recommend buying. You just supply the camera, a ball head and a tripod, and you’re in business.

The 3rd, the Astro Bundle, comes with everything in the previous bundle, but also includes an extra mounting bracket with a counterweight for mounting heavier loads or small telescopes. This is the package I opted to buy.

In the Box

With the Astro Bundle, you get everything you need except a ball mount and tripod. Included are:

  • Star Adventurer mount

  • equatorial wedge

  • 3/8″ ball head adaptor

  • Fine-tuning mounting assembly

  • Counterweight and bar

  • Polar scope illuminator

  • 1/4″ to 3/8″ thread adapter

  • DSLR shutter release cable

The mount body itself is a solid metal unit that feels hefty and looks to be very well built. It has very simple, easy to understand controls. On the outside is the mode control knob, a direction switch, 2 multi-function buttons, a USB port (for firmware updates and power in the field), an ST4 guide port, and a  DSLR shutter control port. Other notable features are a great right ascension clutch system that positively locks the right ascension axis, and that the unit accommodates standard Vixen-style doveplates.  Built into the body is a polar scope covered by a plastic end cap. The unit is powered by 4AA batteries or via the USB port.

While everything looked incredible and solid, 2 things stood out to me as being a little flimsy. The plastic cap that covers the polar scope is of a very stiff, but light plastic. The 2 prongs that attach it into place don’t seem very solid to me. I fear that this plastic will be terribly brittle in the cold and could potentially break easily. A softer plastic cap or an aluminium cap that screws on would in my opinion be a better choice. It would increase the cost of the unit a bit, but would be worth it.

The cover to the battery compartment is also made of this same plastic. To me, it feels cheap when comparing it to the solid aluminium the rest of the unit is made of. It seems to work and fits well. I don’t think it would fall out. But it just looks odd to have something feeling so flimsy on such a solid unit.

The equatorial wedge attaches to the bottom of the mount with a standard 3/8″ connector like most camera equipment. It also has a good weight and is built of solid materials to ensure there is no flex. It has standard locking altitude and azimuth controls with fine-tuning screws that make polar alignment very easy. Anyone who’s used an equatorial mount with a telescope will be immediately familiar with this setup.

Also included is an illuminator for the polar scope. It attaches to the front of the mount and provides a red light to illuminate the  polar scope during alignment.

The next 2 items are the mounting options. The first is a small ball head adapter used for tracking with just a camera. It attaches to any standard ball head with a standard 3/8″ connector. On this underside of this adapter are Vixen dovetail plate rails that allow it to be locked securely into the Star Adventurer. This option is used when you’re just tracking with a lighter-weight camera and lens combo.

The second is a Vixen dovetail plate with a “Fine Tuning Mounting Assembly” on one end. This is used for mounting heavier loads like cameras with heavy lenses or small telescopes. On one end of the plate is the fine tuning mount. It has a 1/4″ screw to attach it to a camera or small telescope. A 3/8″ adapter is also included for attaching to other equipment. This acts as the declination axis of the equatorial mount. Its clutch system is similar to the main RA clutch on the Star Adventurer and very solid. It also includes a knob that acts as a slow motion control on the dec axis to make framing your target even more convenient.  At the other end of the dovetail is a threaded hole into which the counterweight bar is screwed to balance out the load.

The package also includes a DSLR shutter control cable to allow the Star Adventurer to control your camera’s shutter. Cables are available to cover most of the popular camera models from Nikon, Canon, Sony, Olympus and so on.

What’s Not Included

While you get a great set of accessories with the 2 higher bundles, it doesn’t include everything you need to get started. You’ll need to supply:

  • a sturdy tripod

  • a sturdy ball head

  • a 3-way tilt-pan head if you only bought the basic unit

  • 4x AA batteries or an external USB power supply

Onboard Functions

The Star Adventurer has very simple controls for basic operation. A mode dial allows you to switch from 7 different tracking rates. You get Celestial (1x sidereal), solar, lunar, 0.5x, 2x, 6x and 12x tracking rates. The first 3 are for their intended purposes, whereas the other 4 tracking rates can be used for time lapse photography. Adjusting the wedge at 90º, the tracker can be used as an azimuth panner for landscape time lapse photography. The N/S direction switch controls the direction.

Although I didn’t use it, the onboard camera shutter control is a nice touch for someone traveling light. For deep sky tracking, it can be set for 50 or 100 second exposures in the northern hemisphere, but only 100 second in the south. I didn’t find the onboard shutter control terribly useful with only 2 selectable shutter times for celestial photography, but that’s more of a matter of personal preference. I prefer the programmability of my intervalometer and would rather use that instead. Switching the mode dial to alternate tracking rates change the shutter modes. These different rates and panning patterns are fully explained in the manual if you need more information on the subject.

It’s to be noted that only basic panning and shutter function is available with the stock firmware. By installing the advanced firmware, it’s possible to adjust different panning angles, shutter lengths, etc. This can be quite useful for some really creative motion time lapse.

As noted, the unit comes with an ST4 guide port allowing you to use the unit with an autoguider scope and camera. It will accept single axis RA guiding corrections from any guide camera / computer combo or standalone auto guiding unit. which makes this mount a potential deep sky monster that could potentially allow you to tracks 15+ minute exposures  without any drift.

But of course, all this is nice to have on paper. It means nothing if the mount doesn’t perform as expected in the field. And that’s where the true test is.

In The Field

After a quick scan of the manual, I knew everything I needed to know about how to set it up and use it for basic operation and was ready to take it for a test drive. I drove out to one of my favourite spots at Camden Lake near Moscow, Ontario, and set up my gear. I mounted the Star Adventurer on my trusty Manfrotto 055PROB mount, which is a pretty solid tripod. It should be noted that if you have a lightweight, wobbly tripod, you likely won’t get good results. Even without a camera, the SkyTracker is fairly hefty. Add the counterweight and fine-tuning mount, and you add even more weight before the camera is even added. I could trust my lighter duty Manfrotto 190PROB with my iOptron SkyTracker, but  I would consider my 055PROB to be the minimum I could get away with using the Star Adventurer. A lightweight tripod won’t cut it. If you plan on buying any tracker, invest in a solid tripod first.

The alignment was fairly simple, but not as smooth as I hoped it would be. I had assumed the larger teeth and controls on the wedge would perform better than the SkyTracker. The azimuth controls work flawlessly, but I found that locking the altitude axis will cause the mount to shift a bit from polar alignment. I had to fiddle with it a bit to get it perfect. It takes a bit of over or under adjustment at times so that Polaris will be at the right position after the axis is locked. The effect is less pronounced than it was on my SkyTracker, but it exists here as well. I was hoping that a mount that was way more solid wouldn’t have this type of loose tolerance in the wedge. It’s not a show stopper, and once locked into place, it’s solid. But it is an annoyance when aligning.

Another sore point I had during the alignment process was the polar scope illuminator. It’s a removable part that clips into the top of the mount when you align. And in terms of providing light, it works well. Its design, however, is rather cheap and not well thought out. There’s no power switch. Switching it off requires unscrewing the battery cover. You have to unscrew it  almost 100% of the way out in order to turn the light off. This means the cap can easily fall off and be lost. Failing to unscrew it enough means the illuminator battery will be dead the next time you use it. Why Sky-Watcher thought this was a good idea as opposed to a small power switch boggles my mind. In my opinion, it wouldn’t have been hard to illuminate the mount internally, which would have done away with this nuisance of a part and been far useful.

A minor gripe I have with the polar scope and alignment is that you align the mount without a load, which can cause a slight shift after you mount your equipment. When using the fine-tuning mount and counterweight, you can still look through the polar scope to check for alignment, albeit without the illuminator (I used a red flashlight for the job). When using the ball head adapter, the polar scope is completely obscured. But despite this, within a few minutes, I was aligned, my camera was attached, and I was ready to start shooting.

Beyond this, operation of the Star Adventurer was simple and effortless. There’s nothing really really more to say here. If you’ve done your alignment properly, you’ll have accurate tracking for exposures up to several minutes, depending on the focal length of your lens.

Performance

As they say, a picture is worth a thousand words. While I wasn’t able to shoot under ideal conditions, the results posted above do show that tracking is accurate and the mount performs as advertised for night sky photography. As with any equatorial tracking mount, good polar alignment is key. Once you’re aligned, the Star Adventurer is a solid mount capable of tracking the sky accurately. And that’s what really matters.

CONCLUSION

The Good

  • solid build quality

  • impressive maximum payload of 5kg (11lbs)

  • ease of use

  • superb tracking

  • onboard control for camera shutter

The Bad

I’ll preface this list by stating that these points aren’t anything necessarily wrong with the mount, but rather things that could have been done better.

  • the wedge could be made to better tolerances so that tightening the lock doesn’t cause the mount to shift position

  • plastic scope cover feels cheap and weak

  • plastic battery cover seems to cheapen the overall feel of the unit

The Ugly

  • the polar illuminator is utter rubbish in build and design. Yes, it works, but it’s an inconvenience in so many ways I would rather not use it.

Bottom Line

If you’re looking for a a solid equatorial tracking mount for your camera, then the Star Adventurer will provide everything you need. It’s an easy to use system that will have you up and running in minutes. It has some impressive features and modes for night sky photography, and even more to offer for other forms of motion time lapse photography. That’s even truer if you install the advanced firmware.

If you’re looking for a solid tracking mount for you camera, the Sky-Watcher Star Adventurer should be one of the top contenders on your list.