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Explore the world of vintage lenses through repair notes, real test shots, and detailed archive threads packed with images.

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optical diagrams...?
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Posted: Sun Apr 26, 2009 5:25 pm
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Posted: Sun Apr 26, 2009 5:25 pm
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Koji gave me an inspiration...

10 air/glass surfaces and macro capabilities = macro-plasmat



As Koji mentioned in another thread, Zeiss Macro Prakticar 55/2.8 is also based on this design:



But I'm not sure, which side is the front one.


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Posted: Sun Apr 26, 2009 6:31 pm
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Posted: Sun Apr 26, 2009 6:31 pm
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the left one...


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Posted: Sun Apr 26, 2009 6:53 pm
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Posted: Sun Apr 26, 2009 6:53 pm
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Thank you. Left one for both Plasmat and Prakticar?

I'm asking because Volna 50/1.8 seems to use the same design, only reversed:



(if the left part is frontal too)


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Posted: Wed Nov 25, 2009 11:07 pm
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Posted: Wed Nov 25, 2009 11:07 pm
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I tried again the "flash-light test". Separately for front block and for rear block. Now I'm 99% sure, that Volna-9 is 6/5. In detail: 1-1-1|2-1 (it could be also 1-1-1|1-2, but that is highly unlikely).

It means, that Volna-9 has very likely the same basic optical diagram as other Volna lenses.


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Posted: Fri Dec 11, 2009 3:32 pm
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Posted: Fri Dec 11, 2009 3:32 pm
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Does anybody know optical diagram of Prakticar 50/2.4? I'm not sucessful with my search...


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Posted: Fri Dec 11, 2009 4:41 pm
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Posted: Fri Dec 11, 2009 4:41 pm
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Nope, haven't seen one yet. But I will get a Makro-Plasmat lens in a few days.

But since we're talking, has anyone ever seen one for the Carl Zeiss Jena Macro Floatar 2.8/35mm with floating element(s) (hence the name)??


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Posted: Fri Dec 11, 2009 4:49 pm
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Posted: Fri Dec 11, 2009 4:49 pm
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I'm looking forward to your macro-plasmat samples Smile

As for the Floatar, I have never heard about that lens Embarassed


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Posted: Fri Dec 11, 2009 9:56 pm
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Posted: Fri Dec 11, 2009 9:56 pm
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no-X wrote:
I tried again the "flash-light test". Separately for front block and for rear block. Now I'm 99% sure, that Volna-9 is 6/5. In detail: 1-1-1|2-1 (it could be also 1-1-1|1-2, but that is highly unlikely).

It means, that Volna-9 has very likely the same basic optical diagram as other Volna lenses.


Someone on pentax-forums.ru has disassembled the lens, and here are his findings:

1. Front lens element - positive meniscus
2. Second lens - a strong negative element
3. Third lens - a highly curved, strong positive
(aperture)
4. Fourht element - a very thick element; most probably, a cemented group of two lenses; positive overall
5. Last, a positive convexo-convex element with stronger curve on the back.

So it does sound a lot like Volna-1 (50/1.8 ).



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Posted: Mon Dec 21, 2009 2:10 pm
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Posted: Mon Dec 21, 2009 2:10 pm
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Thank you very much for these info. I'm really happy to read my guess was right Very Happy

Btw. I bought the Pentacon Prakticar 50/2.4. My model seems to be the older version (metal) - at least according to description on praktica-users

But the number of lens elements is different. Front group: three separated elements. Rear group: single element. That's 1-1-1|1 or 4/4 construction. Seems to be basic Ernostar.

Sample shot at f/2.4:




according to my opinion, sharpness is average, CA is low and bokeh is very good...
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