RE: [APML] Reducer -> Image Plane Distance

["Gene Horr" <genehorr@houston.rr.com>]

>> If you don't mind, what is that optimal distance?  We have been using
>> 2.75" from the rear of the metal of the reducer.

> With a reducer lens, there isn't any. You can place the focus at any
distance. Same with
> Barlows. Power of each lens will increase with increasing distance.

Ok, which distance gives you .75X reduction?  BTW - there not being an
optimal
distance is not consistant with my experience.  The photographic reducers
that
I have used have a fairly narrow range (1cm or less) where they will operate
well.  Once you exceed that range edge aberrations start appearing and work
their way inward.  This is in addition to the effects of the reduction
changing
with distance.

Gene Horr
genehorr@texas.net


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