Hi again Francis:
Thanks for the kudos. Glad I can help.
<< Is it right for me to assume that the difference is the maximum distance
from which they can get this magnification? I plan to take macro shots for
medical purposes so distance is not an issue with me. >>
That would be one difference. Read on for more.
<< I may at some time in the future use it for nature shots. I may have some
future use for 1:1 reproduction, and looking at the chart the so I guess the
80 mm macro is the best for this application unless i use the 90mm with a
extension tube. Which do you think is the better combination? >>
Going with extension tubes on a floating element lens imposes limits on the
reproduction ratios that one can use. That is because you need to keep the
helical controlled focus of the lens racked all the way out to engage the
Close Focus Aberration Correction. The magnification ranges that you get by
adding different length tubes must be considered as "stepped" ranges (i.e.,
discrete ratios resulting from the tube itself and not any change in the
helical focusing mount). In contrast, the 80 mm f/4 Auto Macro Zuiko on
either the Bellows or the Telescoping Extension Tube offers a stepless range
from about 2:1 to 1:2 and 1:1.2 to 1:2, respectively. There is even a fine
adjustment helical focusing available on the 80 mm. That lens doesn't have
floating elements, which are unnecessary due to the restricted magnification
ratio.
The 135 mm f/4.5 Macro Zuiko was marketed as a medical lens and probably a
partial answer to the Nikkor 200 mm with built-in ring flash. As we have
seen, medical use is a niche that the OLY's still have a strong hold in, so I
would assume this lens has met with success.
I suspect the 90 mm f/2.0 will hold a place in optical history as one of the
sharpest lenses ever produced for the 35 mm format. (Read: collectable). I
would love to have one and it would certainly relegate my 135 macro to the
seldom used shelf if I did. I've never seen any published optical tests on
the 135 mm and I've not taken the time to give it a thorough evaluation,
primarily because it resides in a too often left behind camera bag. But
recent results from it, shooting a plant new to science, were considered
"stunning" by my collegues. I was shooting in the 1:5 to 1:10 range, so it
utilized the best the lens had to offer. If you do medical shooting at about
1/5th life-size, then this is one of the few lenses optimized for that ratio.
I just located in storage my tripod mount for the Telescoping Extension Tube.
I'm going to give it another chance at infinity and be sure I'm using that
mount to ensure the best results.
Gary Reese
Las Vegas, NV
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