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11-05-2017, 11:00 AM   #1
Pentaxian




Join Date: Jan 2016
Location: Fulton County, Illinois
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Can an owner of the orig m42 single round shafted "Asahi Bellows Unit" answer a "?"

If you have a copy of the original m42 screw mount "Asahi Bellows Unit" or "Asahi Bellows Unit S," which has a single round focusing shaft underneath it, labeled on either side with numbered scales on each side of the shaft indicating magnification levels and/or exposure increase amounts -- can you do me a favor? Can you retract the bellows to its minimum extension and measure the flange-to-flange distance of that minimum extension in millimeters?

(Yes, I checked the reviews section, and the answer is not there.)

11-05-2017, 01:13 PM   #2
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Join Date: May 2015
Location: New Orleans
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Try this pdf. Minimum magnification is .62 and on the bellows 2 minimum distance is 37mm.
https://www.google.com/url?sa=t&source=web&rct=j&url=http://extreme-macro.co...SqCs9GTiKB40J_

---------- Post added 11-05-17 at 01:40 PM ----------

Using this calculator, .62 magnification on the standard takumar 55mm with max magnification of .13x gives me 27mm. However the 55 f2 has a different magnification, not sure which 55 they mean.
Pentax-M bellows and what makes great bellows for macro stacking photography
11-05-2017, 04:30 PM   #3
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Join Date: Jan 2016
Location: Fulton County, Illinois
Posts: 2,850
Original Poster
QuoteOriginally posted by swanlefitte Quote
Try this pdf. Minimum magnification is .62 and on the bellows 2 minimum distance is 37mm.
https://www.google.com/url?sa=t&source=web&rct=j&url=http://extreme-macro.co...SqCs9GTiKB40J_

---------- Post added 11-05-17 at 01:40 PM ----------

Using this calculator, .62 magnification on the standard takumar 55mm with max magnification of .13x gives me 27mm. However the 55 f2 has a different magnification, not sure which 55 they mean.
Pentax-M bellows and what makes great bellows for macro stacking photography
Using tables for a later m42 bellows to determine the rationship between extension and magnification for the 55mm f1.8 Takumar, I computed what extension should be for the lower minimum magnification of the "Asahi Pentax Bellows Unit I" at it's minimum extension, which is less than the model the table is for. I get a minimum extension of 35.23mm for the Asahi Pentax Bellows Unit I. I'm not sure if that is the same as the Asahi Bellows Unit S, the one I am curious about, but it does look similar (but not exactly the same as) it.

Thanks for the link.

I'm glad I can still remember some algebra!
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