Comments on MFA

[neuroanatomist]

So far my set up has only been a little more advanced than Bryan's Ice Cream Box he used to calibrate lenses in his review. He recomended the "Datacolor SpyderLensCal Focus Calibration Tool". Do you think there is any advantage in getting a diffrent product. In the video the Datacolor Tool looked very small.

I started with a simpler setup, too, but a little more than an ice cream box. [] I used a printed test chart where you cut out and folded a target so you could focus on something flat at a 45° angle to the printed ruler. It was a little kludgy, but it did convince me that I had some AF adjustment issues on my T1i, and that was one factor in my decision to upgrade to the 7D.


Datacolor has some nice stuff - I use and like their SpyderCube. TheSpyderLensCal looks convenient in that it folds flat, which the LensAlign does not. The flat target/angled ruler concept is the same, but I think the LensAlign offers two advantages.


The first is alignment - theDatacolor product has a level, and you can level your camera (hotshoe bubble level or built-in electronic on the 7D), but then you also would want to translationally align them. The LensAlign has a second piece parallel to and behind the focus target, and that second piece has bullseye dots that you align through holes in the focus target, meaning you can align the camera to the target at any angle rather than only level and orthogonal. Note that here I'm talking about the LensAlign Pro, not the basic version which lacks the rear plate and uses a mirror instead. Actually, I went to check that and noticed they have a new Mark II version (of the older basic one) which has the rear plate and disassembles to store flat. It lacks the Enumerator, though, which I find useful (that's a set of sliders that let you record the adjustment you applied right in the shot, although you could use a Post-It note for that, or just look at the EXIF in DPP).


The second advantage is the ruler itself, or rather the availability of a longer one. The standard ruler that comes with the LensAlign appears to be about the same length as the one with theSpyderLensCal, and that's fine for most lenses. But in some cases it's not long enough (i.e. the DoF of the focal length/distance/aperture being tested is nearly as long or longer than the Z-dimension of the ruler, i.e. the base of the right triangle where the ruler is the hypotenuse). Looking at your list of lenses, you'd be fine with either product when testing at 25 x focal length (which is what LensAlign recommends). But there are situations where you'd want a longer ruler - for example, wide angle but slow lenses on FF, a 400mm f/5.6 lens on FF or if you wanted to test your supertelephoto primes at a distance grater than 25 x focal length, such as the 50 x focal length that Chuck Westfall recommends). For those cases, LensAlign has a Long Ruler Kit that magnetically attaches to the standard ruler (and includes a larger focus target that also magnetically attaches).

[Richard Lane]

...TheSpyderLensCal looks convenient in that it folds flat, which the LensAlign does not. The flat target/angled ruler concept is the same, but I think the LensAlign offers two advantages.
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A lot of good info here. Thanks Guys!


Later this month, LensAlign will be releasing a less expensive, MKII model ($80) thatfolds flat. I take it that they needed to compete with the less expensive SpyderLensCal.


http://www.lensalign.com/


http://www.rawworkflow.com/


Rich