I’ve been using the LensAlign MkII for a year now. In this time I’ve used it on about 20 lens-camera combinations, and on some combinations more than once. Here are my thoughts.
As I mentioned before I was a bit worried about the long term durability of the device panels, being made of nothing more than flexible plastic. I’ve been keeping the LensAlign assembled for long periods, and have only taken it apart about 5 times. Still, there is now a bit of give in the panels, and it worries me. I do feel every time the device is assembled the interconnects get worn down a little bit.
At the beginning aligning the device was really difficult and time consuming. It got easier after a few times. Now it takes me under a minute to get the initial alignment setup. The difficulty now is in lighting and getting repeatable AF from the lens. As mentioned before each time you use AF you are likely to end up in a slightly different location.
The manual says to use AF-S when testing, but I’ve found with some lenses AF-C gives more repeatable results. I usually shine a desk lamp on the device to ensure there are no AF issues. Even then, with some lenses I’ve had AF progress from say 8, 9, 10, then at 11 it’s suddenly the same position as at 8! What can you do but try and try again? I’ve spent over an hour on some lenses.
Also, you have to test both ends of a zoom lens, and they will not match exactly. You have to decide how many points of variation to accept before sending it in for repairs.
As you see, even with the proper equipment it is not a trivial thing to calibrate your lenses.
Because of the results from using LensAlign I have sent a couple of lenses into service and rejected a lens purchase. Without the device I may have only caught half of these issues, and even then I wouldn’t have been confident enough to ask for warranty replacement.
This is one extreme example of a back focused combination. In this case you would notice the issue even in normal shooting situations. This would be a good reason to return a product, but if you didn’t have that choice you would need to work out the AF tune setting and hope that it is enough.
By embossing the image and looking at the it at 100%, you can see where the focus actually is and adjust the AF tune setting accordingly.
Ultra-wide angle lenses
There is a special difficulty in testing ultra-wide angle lenses. As you can see, the device takes up very little of the frame. Since an AF point is not exactly where the marker is in the viewfinder, it can be hard to know if the AF point is actually in the right place. It could be focusing on the ruler instead, for example. Also due to the small size it may be hard to see the area in focus on the ruler accurately.
While the LensAlign MkII is no panacea for focus issues, it is the best available tool on the market. But in the end there’s no easy way out, it’s all hard work even with the best tools at your disposal.