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06-28-2009, 03:38 AM   #1
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77mm and 43mm Lens technical report by Jun Hirakawa- Scientific Publication

Lens technical report. SMC Pentax FA77mm, F1.8 Limited and FA43mm, F1.9 Limited.
Science Links Japan | Lens technical report. SMC Pentax FA77mm, F1.8 Limited and FA43mm, F1.9 Limited.


This paper introduces features the titled lenses on the following items: 1) Standard and middle range telephoto lenses for a 35 mm single-lens reflex cameras sold by Pentax, 2) design concept and performance; unique expression with high quality picture, 3) exterior; machined aluminum body to provide high grade sense, 4) focal length; 43 mm (diagonal length of 35 mm size film) and 77 mm (lucky number among 70-80 mm), respectively, 5) both AF and MF operation possible, 6) helicoid screw at focus part provides torque feeling, 7) realization of smooth AF operation by a little reduced gear ratio of drive unit and 8) lens aberration compensation; priority to practical photographs expression than numerical evaluation.

There is also another scientific publication by ADACHI MASAMITSU:

Trial use report. SMC Pentax FA77mm, F1.8 Limited and FA43mm, F1.9 Limited.
Science Links Japan | Trial use report. SMC Pentax FA77mm, F1.8 Limited and FA43mm, F1.9 Limited.


This paper introduces features of the titled exchange lenses on the following items: for 35 mm single-lens reflex cameras 1) Al exterior provides high grade feeling to both and little allowance at aperture and helicoid parts provides precise structure sense, 2) FA 77 mm/ F1.8 Limited; folded in hood, "finger point" for lens exchange without visual index confirmation, a little noisy in AF operation, good MF operation, natural back and front gradation by circular aperture and soft portrait expression and 3) FA 43 mm/F1.9 Limited; focal length equivalent to diagonal dimension of 35 mm size film and clear and gradation expression by high reflection, multi and ghost-less coated glasses.

For those who does not know, Jun Hirakawa is the lens designer of the 43mm and 77m Limited as well as other Pentax lenses (including the new DA* 55mm f/1.4).
Both articles are published in Photographic Industries journal

I wonder if someone from Japan can get access to this journal (from a Library) and scan and post the full articles. This would be very valuable for many Pentaxians.

12-13-2013, 07:29 PM - 2 Likes   #2
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Articles worth preserving

A recent discussion here on PF about Pentax lens design philosophy got me interested in the original translation effort over on DPReview (see original thread), where dpreview user "nottoohairy" translated the Technical Report by Hirakawa Jun from Japanese to English using scans of photocopies of the original articles.

Unfortunately, "nottoohairy" never translated the second Trial Use report (any volunteers?) and hasn't been heard from since 2011.

So in an effort to preserve the articles, I've compiled them, their abstracts and "nottoohairy's" English translation into a single PDF.

Lens Technical & Trial Use Reports. SMC Pentax FA77mm and FA43mm. Hirakawa Jun & Adachi Masamitsu (2000)
(download 1.87 MB)
12-14-2013, 12:03 AM   #3
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Thanks for this, highly interesting stuff!

I wonder who designed the 31mm Limited and the K-series classics like 200mm f2.5?

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