Lens Align and Focus Adjustements
I have had the Lens Align product since it was introduced and reported on the Luminous Landscape. I just picked up that David Farkes(Dale Photo) has written an article on it for Pro Digital Photographer. (Both great references).
So today I set out to test my 24-70/2.8 on the D3. The lens had been returned to Nikon a few months back for a different problem and Nikon indicated that they had checked the focus calibration prior to returning it to me.
In doing the tests per David s recommendations ....I ran into several issues most of which he addresses. The target is basically white with very fine black lines for calibration.....to see the fine lines you have to bring down you white point and increase the blacks. But even then its very difficult to find the absolute focus point.
The recommended camera to target distance is 25x the focal length or about 8 ft for each 100mm of focal length. So for the 24-70 thats a little less than 6 ft. I missed a little in my set it up and had it about 7ft...but thats not far off. At this distance you can do a 100% enlargement and still keep most of the target in the frame.
After playing around with the white point, contrast and the blacks ....I could see accurately to about + or - 5cm ..I could see that the best focal point was between 0 and +5 which means that the lens has very slight back focus.
This maybe OK as checking the DOF for the D3 with a 70mm lens at f2.8 and 7ft (DOFMaster) you get about 15cm..which would tell me ..no kidding a reading of between + and - 5cm will be covered easily by the DOF .
While this seems explainable ....it brings into question the subject to distance recommendation......don t you have to get closer to the target to make fine tuning possible?
As usual I am at the Knit picking level ..but this looks like a great tool and the new nikons and canons have the ability to fine tune down to a + or - 1cm.
Has anyone else tried the tool...thought I would ask before I check my other lenses.
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