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Re: [OM] ISO extension tubes

Subject: Re: [OM] ISO extension tubes
From: "John Petrush" <petrush@xxxxxxxxxxxxx>
Date: Sun, 15 Nov 1998 15:37:40 -0800
I just happened to be visiting the KEH
 http://www.keh.com/catalog/text/Om.html ) when this message arrived.  The
auto-tube 65-116 ranges from US$126 - 179 (without and with tripod mount, EX
condition).  A full set of auto extension tubes, 7mm, 14, and 25mm, in EX+
condition is UD$139.  Individual extension tubes were listed for US$20-30,
but they are not the auto variety.  Also, there was one 50mm f/3.5 macro,
EX+ condition, listed for UD$235.

Non-macro lenses will work on extension devices (bellows, auto-tube or
extension tubes).  I did close-up photo for years with 50mm and 135mm
"normal" lenses and a third party bellows.  Not optimal, but I learned a
*lot* about "seeing small" in the process.  Macro lenses are optimized for a
certain range of magnification, e.g. the 80mm macro is best at 1:1.
However, a standard 50mm f/1.8, with a set of extension tubes, opens the
door to a very interesting and exciting world of macro work.  A true macro
lens will provide better technical results, true, but also has its own set
of compromises such as cost, speed, size/weight and general utility.

In the Zuiko family, the 50mm macros (f/2 and f/3.5) and the 90mm f/2 can be
attached directly to an OM body.  The auto-20mm f/2, 38mm f/2.8, 80mm f/4
and 135mm f/4.5 macros are all supposed to be used with some form of
extension.  I know for sure the 135mm will not even fit, the rear element
protrudes too far rearward.  I believe the same is true for the auto-80mm
version - it looks like the preset one will actually fit, but I've never
tried it.  The older style 20mm and 38mm macros have a screw thread and
require and adapter (OM-PMoB??) to mate to the OM body.  These are preset
lenses and are quite good.  Just remember they are useless without the
adapter.

IMHO, you will get better results with a normal lens with a reversing ring
and extension than with a normal lens and close-up lens attachments.
However, you again have trade-offs to make.  With extension, there is an
exposure compensation required, effectively reducing the lens speed due to
light falloff from the extension.  With close-up lenses, the true lens speed
is retained.  With the reversing ring, all body-to-lens automation is lost,
leaving you with effectively a preset lens arrangement.  My extension tubes
are the non-auto style, but that has no effect on the final image.  I don't
mind the manual preset for macro anyway.  It is my intent to slow down and
"see".

Sorry, I seen to have rambled.........

John P
______________________________________
there is no "never" - just long periods of "not yet".


Red Rover <red_rover@xxxxxxxxxxxxx> wrote:


>    How much do the auto tubes go for? And where can I find them (anyone
>here maybe?) ? Also, are they only supposed to be used with the macro
>lenses? I'm saving up for a 50 3.5 but would like to do some closeup work
in
>the meantime. Would rather not have to resort to lens closeup attachments.




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