George wrote:
>>>Earlier in the week you mentioned using some sort of macro adapter from an
IS-1 with your OM lens. Are these still available somewhere and what are
they called?
<<<
It is the IS-1/2 A-MACRO H.Q. Convertor. This thing is a multicoated,
multielement closeup adapter. You might want to see if Olympusguy has one
otherwise I don't know where you could get one these days. I bought mine
back when the IS-1 was new and really liked it. It has the 49mm thread,
wheras the IS-3 version has the 55mm thread.
Quality is excellent and I find that except for a slight loss in contrast
it is as good as extending the host lens. Nikon also has them in their
thread size which are also extremely good lenses.
I'm equipment testing as I type this, and mounted on my 100/2.8, it takes
me between about 10-15" working distance and a horizontal image dimension
of 3.5-5.5".
In Comparison, the 100/2.8 mounted on a 14mm extension tube tives me a
horizontal image dimension of 5" but loses about one stop.
If I combine the 14mm extension tube with the adapter on the 100/2.8 I get
a 7" working distance and a 2.25" horizontal image dimension. Put 39mm of
extension on this and I get 1:1. Resolution might be getting a little
sketchy at 1:1, but I rarely go deeper than 1:2 anyway.
Best of all, and I just discovered this: It corrects my 100/2.8 to
flatfieldness! Wow! Just using extension tubes alone the 100/2.8 varies
the focus from center to edge by 2-4mm, but with the closeup adapter lens
it completely sharpens up the image edge-to-edge.
George, I'm also forwarding this onto the list since this information could
be useful to others too. Thanks for asking.
Anyway, my macro kit was haphazardly assembled out of various components,
but based on this new testing I am married to the closeup adapter with the
100/2.8 and these two extension tubes. This setup will get me from 1:1 to
infinity. Someday, I'll get a REAL macro lens, but until then...
The reality is that at whatever magnification you are working at, you can
figure that the closeup adapter gives you an additional stop over adding
more extension.
Ken Norton
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