Originally Posted by
John Chardine
Last night I decided to have a look at the AF micro-adjustment on my 400DO/1DIV combo. This was all done in the house under relatively low incandescent light. I set a target up about 20+ feet away and made some comparisons with different adjustments. I was amazed to find that under these conditions the rig was quite severely front focusing and required a +15-20 adjustment to make the images sharp. This was consistent with the bare lens and the 1.4 and 2 x TCs, and repeatable.
This morning under much better light I repeated the experiment and the +15-20 micro adjustment requirement has vanished and I'm back to close to where I was, about +5). Could low, warm light cause this effect? Anything else?