bubbles on Jupiter ( 9 )

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spiderfrank

just a dreamer
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Hi all, I recently bought a Jupiter-9 for my Kiev II : it's all silver, from 1959, the glass is clean and clear, but there are some little bubbles in an internal lens.
Sunday I made some test shots and i'm happy, but I have a some question for you:

is it normal to find bubbles in this lens? (I read somewhere they are caused by the use of high quality glass, and that they have almost no effect on the final image)

in an out-of-focus "bokeh-test" i see some little black dots in the light circles: are those dots my little bubbles?

J9_447_2web.jpg
 
Nice shots! A certain small number (say 2 or 3) of small bubbles (say << 1mm) in optical glass is regarded as normal. Some of the finest Zeiss lenses ever made have the occasional tiny bubble or two.
 
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I'd say your J-9 is fine. I have a '57 from Arsenal and a '58 LTM from KMZ that are bubble free, but I don't think minor bubbling is a problem. The proof is in the photos.
 
I'm not worried about bubbles: if these are the results nera f2 in a rainy gray day, with a very cheap film, I'm sure it can do great things ;-)
My curiosity is about that little black points in the out o focus lights on the left: they are in two lights and are absolutely identical, so I thought they was caused by the lens, but of course it's possible that one of the points is the reflex of the other, created by the window of the shop.
 
All of my Jupiter lenses have bubbles. On one of the 35/2.8s, it's a largish bubble in the rear element and, with f/stops closed down, is visible on the image as a fuzzy dark spot akin to a dust speck.

My Nikon literature from the 1950s enthuses about their lack of bubbles and says, a bit wryly, that other leading manufacturers tell buyers that their imperfect bubbled glass is a sign of high quality.
 
VinceC said:
My Nikon literature from the 1950s enthuses about their lack of bubbles and says, a bit wryly, that other leading manufacturers tell buyers that their imperfect bubbled glass is a sign of high quality.
Click to expand...

Are they referring to the other manufacturers who's lens designs they copied? Not very "wry" at that point, I'm thinking.
 
The little black dots look like defects on something close to or in the front of the lens. Could indeed be the bubbles. You should be able to count and match the pattern :)

For example, this was shot through a mosquito screen (i.e. behind her):

51007481_6h9Mo-L.jpg


There are also some example of people glueing paper shapes in front of their lens to have funny bokeh shapes (like hearts for Valentine's).

Otherwise, ignore the bubbles and be happy about a great lens :)

Cheers,

Roland.
 
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40oz said:
Are they referring to the other manufacturers who's lens designs they copied? Not very "wry" at that point, I'm thinking.
Click to expand...

Nikon did not copy the Zeiss lenses. They had to recompute the optical prescriciption for the specific glass that was used. The earliest J-3's were copies of the Zeiss Sonnar as they were made using the same glass stock left over from the war. When that ran out, the Russian's had to recompute the optical prescription for the new glass that they developed. I've just added an early J-3 to the collection, and will be testing it against a Wartime Zeiss Sonnar in LTM and a first-rate 1955KMZ lens made with the new Russian glass. The '53 J-3 is one of the best that I've come across. Bubbles and all.
 
I had heard that the odd bubble in optical glass actually improved their performance. I have a couple of J9s and a J11 and all three have a small bubble in there. I am extremely happy with the negatives I get, they are sooo good!
 
As one of the optical engineers at work told me "You're up against a Fourier transform, it doesn't make a difference".

Small bubbles, cleaning marks, even some scratches- no measurable difference. Now, significant haze on an element, misaligned elements, misassembled optics, misassembled helical, incorrect shims- worth worrying about.
 
Optical Engineers have enough problems getting the lens to focus images on the film plane. I'm told that they do not worry about the out-of-focus areas...And computers really did make things easier.
 
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