At Thu, 03 Oct 2002 15:00:31 +0200 Thomas Bryhn wrote
>snip
>. The lens is optimized for infinity (1:infinity), so
>the *optimum* macro range would in fact be infinity:1. That would of
>course take one **** of a bellows, take forever to expose, and have zero
>field of view ;-)
>snip
When one looks into the Olympus macro group manual, bellows section,
one can find the following statement (German manual of 8/1979, p.37,
own translation):
"Most universal lenses are optimised in such a way, that they
will reach their optimum quality at distances which roughly equal
30 times their focal length. Such it is advisable with magnifications
greater than 1 to reverse the lens in the bellows as to enable
maximum resolution. This is valid for the standard lenses
for the OM-1 and the Zuiko Macro lens 1:3.5/50mm."
End of quotation.
To enable exactly this, the original OM bellows allows the
reversal of the complete lens mount. With the use of the double
cable release, the automatic diaphragm works fine.
Against common belief, most standard lenses are not optimised
for infinity but for a distance between 1.5 and 3 metres.
So in general use
distance [object to lens] is much bigger than [distance lens to film].
Thus with magnifications bigger than 2:1 and reversed lens the
lens operates far closer to the (standard) optimal situation than
non reversed. Of course the special macro lenses 38mm or
20mm might yield better results but definitely at a price.
Quite overlooked is another possibility:
a simple lens coupling ring with a filter thread on both
sides can be a very cheap macro solution. I got good results
with a 200/5 on the camera coupled with a) the 85/2 (M2.35:1)
and b) the 50/3.5 (M4:1)
a) all f-stops ok (on the 200mm), b) best results with f8 (200mm)
There is no general advise here, some combinations work
fine, some not at all. But for about $20 + 2 or 3 rolls of b&w-film
and a saturday mornig test time this might be the cheapest way
to magnifications bigger than 1. (Of course, this is always only
ONE fixed magnifiction with any one combination.)
I do admit, that the discussion did move away a little bit from
Iwert's original question to the feet/meter scale :-)
---
Reinhold
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