Neil Harrington <> wrote:
> Actually, NONE of the four you mentioned are really that good. Ordinary
> camera lenses on extension tubes or bellows may give satisfactory results
> when stopped down enough, at least for centrally placed subjects, but they
> are not designed to be used at anything like a 1:1 magnification and aren't
> likely to give good definition or flat field over the whole frame.
It depends on the lens. A 50/3.5 tessar type is very likely to
be satisfactory for the purpose. The Leitz Elmar 50/3.5 made
a quite decent enlarging lens (the historical reason why enlarger
lens mounts are very often LTM) and was quite usable for 1:1 and
larger if stopped down to middle stops. My Asahi Pentax Manual
notes that the SMC Takumar 55/1.8 is much better for close-up
work than the 50/1.4.
True macro lenses such as the B&L Micro-Tessars and the Leitz
Micro-Summars certainly did exist in the 1930s if not earlier,
but it was quite usual to use the standard lenses for macro-work.
The old Leica Manuals mention the availability of the micro-summar
lenses, but have entire chapters on using the Elmar and other standard
lenses for the purpose.
My 35mm f/2.4 CZJ lens will focus down to a 1:2 ratio and seems
remarkably good for close-up work.
>
> As you say, they're "not very sharp" -- especially the +20 close-up lens it
> would take to reach 1:1 with a 50mm prime lens.
It wouldn't take quite that much because a typical 50 mm lens for
an SLR has about 1 cm worth of focus extension: it would only take
about a +13 lens. More practical is a +4 achromat on a 135mm lens.
It wouldn't likely get you quite up to 1:1 unless your 135 is
unusually close focussing, but it will get you close and will be
quite satisfactory in use.
Peter.
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