>From: "John A. Lind" <jlind@xxxxxxxxxxxx>
>
>I have two sets of tubes, the Oly set and a longer set of metal Vivitar
>auto-tubes. The Oly tubes are exceptionally well made but their lengths
>were designed primarily for use with a 50mm lens.
I think they were probably designed for use with shorter focal lengths.
"Standard" extension tubes work quite well with the helical in most 50mm
lenses, but work poorly with the 38/2.8, or not at all with the 20/2.
See last my TOPE entry for an example of what the 16/3.5 does with a 7mm
extension! This is not possible with the shortest "standard" size of 12mm --
the subject would be touching the front element, and STILL not be in focus.
But this is just a nit. I agree that An Oly set and a third party set (with
"standard" lengths) makes a great combo.
Too bad they don't have a 7mm to 65mm auto extension tube... now THAT would be
an engineering marvel!
--
: Jan Steinman -- nature Transography(TM): <http://www.Bytesmiths.com>
: Bytesmiths -- artists' services: <http://www.Bytesmiths.com/Services>
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