D80 Backfocus

Started Sep 9, 2006 | Discussions thread
OP PhotoLeon1935 Senior Member • Posts: 2,305
I am back!

I was on vacation when this 9 month old thread started up again. I have completely changed the test target to help understand the problem with false backfocus.

The new link is at: http://leongoodman.tripod.com/d70focuspart5.html

What I found was that all telephoto lenses starting at 18mm have a focus problem caused by the rectangular correction lens needed to provide square images from a lens that borders on being a fish-eye lens. This includes the wonderful 18-200VR lens selling at $750 US.

The lens may focus at the center but as you look to the lleft or right the lens shows more backfocus. All the tilted targets have their image judgement areas off to the side and therefore appear to backfoucus. It is a fact of life and cannot be corrected.

Zooms starting at 28mm do not have these problems such as the inexpensive 28-200 lens.

The explanation of this is in the link above. If you have a zoom lens that goes as wide as 18mm, do not use it to judge the focus of your new camera. It may not be the camera's fault.

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