LensAlign MkII fixes these problems by providing a method for perfect alignment and easy evaluation of results. Put simply, it works.
But with all the images on their webpage being computer generated graphics, it’s very hard to judge the construction and quality of the device. With many sites out there concentrating on its effectiveness for AF tuning, here I address the question of whether spending ~$95 to have one delivered is worthwhile to the average photographer.
LensAlign MkII is delivered in a simple flat rate envelope with no extra padding.
As you can see it did get squashed in a few places and I would have expected better packaging to protect the box. My box for example no longer closes properly which is both annoying and disappointing.
Inside are all the parts needed to build the LensAlign MkII as well as assembly instructions. The base is made of foam sandwiched between aluminium plates, while the other plates are made of polystyrene. It is similar to the stuff used to make disposable plastic cups, but a bit thicker.
Since the exact alignment of every plate was very important, I was a little worried about whether the plates would warp with time. Here is how much the main ruler bends under its own weight.
As you can see the plastic isn’t very stiff, and care should be taken how the parts are stored. The smaller plates come in a small plastic bag and the base plate has a special slot in the box, but the ruler just hangs around loose in the box.
Alignment is achieved by aligning the red dot on the back plate with the hole in the front plate. The idea is simple enough, but it is difficult construct such precise alignment in DIY solutions which instead often use mirrors.
The LensAlign MkII tries to guarantee repeatable correct alignment by the precision machined base and stiff interconnects on the plastic plates. Once assembled the construct doesn’t have any wiggle room at all. However the stiffness of the interconnects is also a concern for me. The connectors take quite a bit of force both to engage and disengage.
When I took the device apart after the first use, I noticed the scratches the plastic plates made on each other in the interconnect.
While the tightness vouches for the accuracy of the assembly, it doesn’t bode well for the long-term durability of the device.
I also noticed that some edges of the plates weren’t cleanly cut and had jagged edges.
Once the device is assembled, you may want to start testing your lenses but unfortunately there are some bits of information missing:
- Your AF tune values will differ at the wide and tele ends of zoom lenses. Which side should you test? (maybe closer to tele end, maybe somewhere in the middle)
- Do you test macro lenses at normal or macro distances? (macro work often involves manual focus adjustment anyway)
- Do you defocus to zero or infinity? (you should defocus to zero)
- What distance should you test from? (you must go to LensAlign’s site for a calculator to determine the optimal distance)
Especially with the last point, if you are too close the results won’t be accurate. If you are too far the DOF will be too great for the supplied ruler.
One point that is not mentioned, your camera must be on hard floor and not on carpet. Even using remotes, timers, and mirror delay, I found results on carpet to be consistently innaccurate. That is, you will bet an AF tune number, but it will be very wrong.
You may think that with SWM/USM/HSM today’s lenses should focus very consistently. They don’t. If you start from zero and infinity AF positions, your AF will end slightly in front of and behind the subject respectively. Also, with zoom lenses at the tele and wide positions, you will find your AF tune numbers will also vary.
When something is already in focus, if you don’t move anything and keep activating autofocus, it is possible the lens focus will move a little – even with prime lenses.
This is all within the makers’ tolerance, and is just a fact of life.
Place a focus chart at around 45 degrees on a table and focus on a line in the middle. Cheap and easy. The only problem is that any DSLR capable of AF fine tune will probably also be able to focus on white paper with ease.
Half the time you would be focusing on the paper slightly in front of the line, hence all the reports of front focusing lenses on forums.
Staggered blocks are recommended by most lens companies for focus testing. However it is near impossible to set them perfectly perpendicular to the camera. It is also very hard to set them up for fine measurements, so you can only get a rough idea of AF accuracy.
Is it worth it? Lens AF accuracy isn’t really great anyway, so if you have one body and 3 lenses, a LensAlign won’t really help you much. You might want to spend $10 once a year to hire one just to find out how your lenses fare.
However I think it is more important to calibrate a lens to perform equally to 2 bodies than to test a lens on a single body. So if you have more than one body, it may be worthwhile owning one simply because of the time it takes to test a set of lenses.