Quote Originally Posted by HDNitehawk
My first thought is that maybe I wasted the extra money on the long ruler. I went to the lensalign website and there is a tool that gives you the Minimum Average distance you set up the target. All my lens even the 500mm with a 1.4 extender at the minimum distance the tool says use the short ruler. Now if I go out to about 100' to do the setting on the telephoto's, only then does it recomend the longer ruller.

Indeed. See, Alan was right! Instead of stating this:


Quote Originally Posted by neuroanatomist
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).
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...maybe I should have stated this:
  • Looking at your list of lenses, you'd be fine with either the SpyderLensCal or the LensAlign Pro when testing at the recommended distances.



Quote Originally Posted by HDNitehawk
I think the average photographer would never need the $249 Lensalign Pro Plus, and could save the extra $80.
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Depends on what you mean by average. I'd say that if you have a crop body you would never need the long ruler (at the same distance, a crop body has thinner DoF than FF). But someone with a 5DII and a 400mm f/5.6 lens (which includes the 100-400mm) would benefit from the long ruler - those are 'marginal' with the standard ruler.


I just hope there are no Rabbit Lovers on this forum... [:P]