Hi C.H, AS and all,
From: "C.H.Ling" <ch_photo@xxxxxxxxxxxxx>
>Mechanical focus precision is very important to me. I use my 24/2 a
>lot with the meter scale and when I shoot video I have to make sure my
>zoom lenses can maintain focus when I zoom, this only possible with a
>precise lens mount to CCD distance.
Many cheap adapters do focus 'a tad' past infinity, and so are advertised. I
believe it's a tolerance problem -- if they aimed to the proper distance
with such loose tolerances, a significant number of units wouldn't be able
to reach infinity, thus being nearly unuseable. But if they offset the
nominal distance to a shorter value, most (if not all) of the thicker
adapters will do infinity focusing, while the thinner ones will focus _way_
beyond infinity. Usually not much of a problem, but...
...if the lens has some sort of close-focusing aberration correction (like
the OM 18/3.5, 21/2, 24/2, 28/2, macros...) such adapter may impair
performance by setting a 'wrong' distance on the focus ring -- not sure
about the amount of it, or if it's noticeable at all, though.
From: AS <alizookoman@xxxxxxxxx>
>I second Fotodiox. I have a couple of the m42 to EOS adapters which work
nicely.
Well, a M42 adapter has much less to go wrong... Anyway, I've seen at
Fotodiox website two kinds of adapters: the cheaper, 'regular' ones (that
look much like the cheapest adapter out there) and the 'Pro' versions,
obviously at a higher price -- but their use of proper flat springs instead
of a mere slit on the lugs is a definite sign of quality.
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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