Cosina 50mm much sharper than my Jupiter-8 50mm

Ulfric M Douglas

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Oh dear, I was hoping my LTM-mount Jupiter-8 (being small and black and barrel-shaped and therefore WAY COOLER on my G1 than my old Cosina Prime Pentax-K fit) would make me similar photos .. but so far it can't.
These are both mounted on my Lumix G1.
Cosina; (Composite of three shots at f2)
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Jupiter;
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There is no apparent fungus or haze or dust although surely a good clean is in order now.
 

Bcostin

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I daresay that's not typical for that lens. I don't have a Jupiter-8 in LTM to test, but my less-than-pristine Industar lenses give very nice results on my E-P1, even wide open.

It would take a very visible amount of hazing or fungus to give results that soft. I'd guess the lens is misaligned or damaged in some way, or that the adapter is out of spec. Do you have other LTM lenses you could try with that mount adapter?
 

Ulfric M Douglas

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I have an Industar-61 coming, the 50mm I think ... on a Fed4 body.
The adapter allows the correct close and infinity focus : that's about all it can do. I used the lens hand-held without an adapter last week with similar results.
I guess I'll know more after the next lens arrives.

Meanwhile, here's a very cropped composite taken with the Pentax110-18mmWideangle using homemade adapter ;
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And here's my new Fed61 52mm at F2.8
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and at F4
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cosinaphile

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its my understanding that only 2 japanese companies actually manufacture their own glass from scratch

nikon and cosina ,i believe cosina also manufactuered the bodies for the much sought epson digital rf made some years back, as well as modern voigtlander lenses and the current crop of zeiss lenses . and also other products

im not surprised that the cosina is a stellar performer , the optical heritage is there
 

Brian S

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There is something wrong with the J-8, the optics are probably misassembled.

My 1955 KMZ J-8, wide-open at F2 on the Canon P.
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I had a problem with a Zeiss Sonnar that produced images like yours: the rear group was in backwards.
 

Brian S

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Good Luck! Post some pictures of the process, and ask questions. I've done a couple of these.

A few months back I repaired a Summicron for a friend that had THREE of the lens groups in backwards. I learned a long time ago to put a DOT with a Sharpie on the surface that faces outwards.
 

Ulfric M Douglas

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The rear element is a 'tubular' unit containing at least 2 lenses and cannot be disassembled further. It only goes in one way. So ... there is nothing that can be reversed in this particular lens. I can clean it and try it at different levels of 'screwed-back-togetherness'.
Here's the result on this damp grey morning ;
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Hmm ... better!
Oh hell ... WAY BETTER!
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There must have been something on the inner surface of the rear llens element. Yeay.

Here's my home-made lens-ring unscrewer device;
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I found an interesting titbit from Aoleg on MFlens forum;
There was huge quality variation among many Russian lenses. I had a copy of J37 that was unsharp on one side (fixed it now by removing and carefully re-inserting all lenses).
 

Ulfric M Douglas

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I was randomly browsing e-bay for more lenses when I bid on a Zenit SLR in case with Helios44M,58mm,f2 elns,flash and 2x adapter.
When it arrived I tried to find a local screw-to-P-K adapter since I have P-K to 4/3rds & m4/3rds already.
Found ... something ... wasn't what it said ...
Never mind, I've SUPERGLUED the helios lens onto my P-K-to-m4/3rds adapter. Yes.
At f2.8 I reckon sharp and nice;
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Ulfric M Douglas

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Hmm, but when I want to fit my Tokyo-Koki 300mm on the G1 I can't! Never mind, if I get any more 42mm thread lenses I'll buy a proper adapter.
The superglue-special does look a bit massive though, so I took my little industar to Carlisle Steam fair instead.
Lens flare!
 
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