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Carl Zeiss Jena Sonnar 50mm f2 vs Jupiter 8
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PostPosted: Mon Sep 07, 2020 8:18 am    Post subject: Reply with quote
iangreenhalgh1 wrote:

The 8 is simply the 6e/4g Sonnar design recalculated to use Russian glass and coatings:

The 8M has been simplified for cheaper, easier mass production and only has 5 elements:


That's just the perfect example of the internet-based "knowledge" Cool
Both J8 and J8M have 6 elements in three groups. I CLAed both of those and can confirm it personally. They do have slightly different optical elements, and J8M is supposed to have higher optical resolution - 32/18 lines/mm compared to 30/14 of J8 (however, the real results are often lacking, for both of them).

J8:


J8M:


PostPosted: Mon Sep 07, 2020 8:50 am    Post subject: Reply with quote
Well, let's see if someone who has already chimed in on this thread adds their knowledge on how many elements the J8M has, rather than me quoting what they wrote about it elsewhere.


PostPosted: Mon Sep 07, 2020 12:31 pm    Post subject: Reply with quote
memetph wrote:
iangreenhalgh1 wrote:
Here's a little tip for you: Don't confuse your own opinion with fact. Another tip: Don't think you know everything about a lens produced in the hundreds of thousands based on a small sample.

The 8M not only has a different barrel design and a different aperture - the shape is a more jagged one, less round than the 8, the optical design is different too.

The 8 is simply the 6e/4g Sonnar design recalculated to use Russian glass and coatings:



The 8M has been simplified for cheaper, easier mass production and only has 5 elements:



This is why I say the 8M is generally inferior and it is - a good copy of the J8 is optically better than a good copy of the 8M, the rounded aperture of the 8 is another reason to prefer it to the 8M.

Have you dismantled J8Ms. ?
Some have 5cm , 50mm and 53mm engraved.
What is your source of information.?


I have. My source of information is First Hand. A couple years ago we had this discussion, and I took a late J8M apart to answer the question.

I've dismantled and used over 200 Jupiter-3's. Under 100 for J-8's, and about 100 pre-war and wartime Sonnars. My clever reason for charging $25 to CLA a Jupiter, shoot with a large sample size. Experiments completed. I used to charge $25 and left-over parts to convert a Sonnar to LTM. The person was responsible for supplying the Sonnar and Jupiter. So I got to take apart a lot of lenses. I currently own around 25 CZJ Sonnars and Jupiters in LTM, all cherry-picked over 15 years. The best of the best from every Russian manufacturer. Buy a lens, CLA it, shoot with it, sell it if a better one comes by. Do that for 15 years, get some really good lenses.

The Valdai lenses are the worst of all of them.


PostPosted: Mon Sep 07, 2020 3:37 pm    Post subject: Reply with quote
what can you say about the Jupiter-17? this isn't Jupiter-8M, is it? but it has five elements.

http://www.zenitcamera.com/archive/lenses/jupiter-17.html

http://www.zenitcamera.com/archive/lenses/jupiter-8.html


PostPosted: Mon Sep 07, 2020 4:44 pm    Post subject: Reply with quote
sergtum wrote:
what can you say about the Jupiter-17? this isn't Jupiter-8M, is it? but it has five elements.

http://www.zenitcamera.com/archive/lenses/jupiter-17.html

http://www.zenitcamera.com/archive/lenses/jupiter-8.html


I've never used one. Someday- hope to stumble into one.

The strangest Sonnar I have that fell into by luck- a CZJ 5cm F1.5 wattime lens in Contax mount that is a 1-3-2 configuration. Apparently a small batch, to reduce cost. The glass on mine is Ugly, so not a good lens to test. It was only $76 on Ebay, so it's a curio.


PostPosted: Mon Sep 07, 2020 7:51 pm    Post subject: Reply with quote
Things like this are confusing, 5 elements like a J-17 or 6 like a Sonnar?



PostPosted: Mon Sep 07, 2020 9:17 pm    Post subject: Reply with quote
At some point the Middle Group of the J8M was changed.

These images are from the discussion in 2013. The LTM Jupiter-8 on the Left and J-8M on the right. I no longer have the J-8M optics, used them to repair another lens. I scraped off the Black Paint on the J-8M looking for the cemented elements- easy to see two seams on the J-8 LTM. One seam is easy to spot on the J-8M.











And this is my current "parts" J-8M, scraped off the black paint and it is easy to see Two Seams.



PostPosted: Mon Sep 07, 2020 9:37 pm    Post subject: Reply with quote
fiftyonepointsix wrote:

One seam is easy to spot on the J-8M.

Now if you look closely on the J8 and J8M diagrams I've provided above, you'll figure why you see two seams on the J8 and only one seam on J8M, while they both still are glued triplets Rolling Eyes

fiftyonepointsix wrote:
At some point the Middle Group of the J8M was changed.

Doesn't mean that element count was changed too.


PostPosted: Mon Sep 07, 2020 10:43 pm    Post subject: Reply with quote
Alex TG wrote:
fiftyonepointsix wrote:

One seam is easy to spot on the J-8M.

Now if you look closely on the J8 and J8M diagrams I've provided above, you'll figure why you see two seams on the J8 and only one seam on J8M, while they both still are glued triplets Rolling Eyes

fiftyonepointsix wrote:
At some point the Middle Group of the J8M was changed.

Doesn't mean that element count was changed too.


The last image shown is the middle group from a J8M and clearly is different from the first. The two seams are perfectly visible.

The first image- no seam, no signs of cement, the glass appears to be one piece- unlike cemented triplets that I've seen in many other Sonnars. Are the glass elements fused rather than cemented? The original discussion concerned the differences between the J-8 and J-8M. I knew the rear group was different. I did not know about the middle group, and did not know the design of the middle group changed during production until today after taking this one apart.

Do you have an optical block diagram to explain the middle triplet in my J8M?


PostPosted: Mon Sep 07, 2020 11:38 pm    Post subject: Reply with quote
fiftyonepointsix wrote:

Do you have an optical block diagram to explain the middle triplet in my J8M?

Yes, it's higher up this thread.

But I'll make it even clearer:





PostPosted: Mon Sep 07, 2020 11:57 pm    Post subject: Reply with quote
Alex TG wrote:
fiftyonepointsix wrote:

Do you have an optical block diagram to explain the middle triplet in my J8M?

Yes, it's higher up this thread.

But I'll make it even clearer:





I'll make this even easier for you.

Look at the last image I posted.

It is the middle triplet from my J-8M.

This is the Middle triplet from the J8M that I took apart today.



Your diagram is not of it.

Do you have a diagram of the triplet that I showed or not?

On the first Middle Group of the J-8M that I photographed in 2013, there is no evidence that the glass is cemented.

I asked you if the glass elements had been fused.

You did not answer that question, you just made little red marks on my picture, which is absolutely useless.

So- I can take apart some more J8M's and look for a pattern, 50/2 vs 53/2, or just figure another undocumented change in optics on a lens while it was in production.


PostPosted: Tue Sep 08, 2020 9:00 am    Post subject: Reply with quote
fiftyonepointsix wrote:

On the first Middle Group of the J-8M that I photographed in 2013, there is no evidence that the glass is cemented.

I asked you if the glass elements had been fused.

You did not answer that question, you just made little red marks on my picture, which is absolutely useless.

Ouch. Make some effort man, would you?
I've showed you the J8M diagram taken from the official 1970 GOI catalogue. Your 2013 pictures clearly match with that diagram. You've stated there's only one seam - that's not true. I've showed you with the red marks where the second seam is.
Here's that diagram again with more data around it (I have a full PDF of that catalogue):



As for why the J8M you currently have doesn't match that diagram - I honestly don't know. All 5 or 6 J8Ms I personally disassembled were following that diagram.
Might be the earlier (or the later) version indeed. I'd very much like to see the picture of it's nameplate.


PostPosted: Tue Sep 08, 2020 11:19 am    Post subject: Reply with quote
Alex TG wrote:
fiftyonepointsix wrote:

On the first Middle Group of the J-8M that I photographed in 2013, there is no evidence that the glass is cemented.

I asked you if the glass elements had been fused.

You did not answer that question, you just made little red marks on my picture, which is absolutely useless.

Ouch. Make some effort man, would you?
I've showed you the J8M diagram taken from the official 1970 GOI catalogue. Your 2013 pictures clearly match with that diagram. You've stated there's only one seam - that's not true. I've showed you with the red marks where the second seam is.
Here's that diagram again with more data around it (I have a full PDF of that catalogue):



As for why the J8M you currently have doesn't match that diagram - I honestly don't know. All 5 or 6 J8Ms I personally disassembled were following that diagram.
Might be the earlier (or the later) version indeed. I'd very much like to see the picture of it's nameplate.


I went through the effort of taking apart the J8M that I curently own and posting the photograph.

You did not post any pictures to demonstrate your point, I did.
The problem with the design you show would be a problem with centering the rear element before cementing. The diameter is smaller than the first two elements.

The SN of the lens I took apart is 7343554, but I'm not going to go through the effort of photographing it and posting the image after your insults.
Learn some manners.


PostPosted: Tue Sep 08, 2020 11:46 am    Post subject: Reply with quote
fiftyonepointsix wrote:

You did not post any pictures to demonstrate your point

I did. You want me to find and buy the J8M (I don't currently own one) of that particular pattern, destroy it by breaking the glued triplet apart and show you the pictures only because the official documentation isn't good enough for you? That's not gonna happen.
Sapienti sat.

fiftyonepointsix wrote:

I did.

You didn't. Not even close. You've just barely scratched the surface (pun intended).

fiftyonepointsix wrote:

The problem with the design you show would be a problem with centering the rear element before cementing. The diameter is smaller than the first two elements.

That's true. And that's might be the reason why they had changed the design later.
If I were you though I'd claimed that this particular triplet doesn't come from J8M at all since you don't want to take the pictures Cool


PostPosted: Tue Sep 08, 2020 12:06 pm    Post subject: Reply with quote
Discrepancies between the optical diagram and the actual lens are relatively common. To know in practice if an optical group is a doublet or a triplet, just count the number of reflections. A doublet produces three, whereas a triplet produces four reflections, two stronger from the external air-glass interfaces, and two weaker from the internal glass-glass interfaces.


PostPosted: Tue Sep 08, 2020 12:07 pm    Post subject: Reply with quote
Alex TG wrote:
fiftyonepointsix wrote:

You did not post any pictures to demonstrate your point

I did. You want me to find and buy the J8M (I don't currently own one) of that particular pattern, destroy it by breaking the glued triplet apart and show you the pictures only because the official documentation isn't good enough for you? That's not gonna happen.
Sapienti sat.

fiftyonepointsix wrote:

I did.

You didn't. Not even close. You've just barely scratched the surface (pun intended).

fiftyonepointsix wrote:

The problem with the design you show would be a problem with centering the rear element before cementing. The diameter is smaller than the first two elements.


That's true. And that's might be the reason why they had changed the design later.
If I were you though I'd claimed that this particular triplet doesn't come from J8M at all since you don't want to take the pictures Cool



You turned a discussion into an argument.

Tried to win the argument by throwing out insults.

You destroyed your credibility, then accuse me of lying.

The triplet is from the J8M with the SN shown.

But- as I don't want to make any more effort as you state, not worth posting the image to satisfy your curiosity.

Most of the members of this forum know me from years of posts. They know you from lobbing insults.


PostPosted: Tue Sep 08, 2020 12:25 pm    Post subject: Reply with quote
fiftyonepointsix wrote:

You turned a discussion into an argument.

That was neven neither a discussion not the agrument.
That is hardcore facts backed up with official documentation vs badly informed opinion of someone who believes that the time spent on forums makes him an "expert".

fiftyonepointsix wrote:
then accuse me of lying

No, not of lying. Of ignorance.

fiftyonepointsix wrote:

Most of the members of this forum know me from years of posts. They know you from lobbing insults.

Unlike you, I care more about the information than about my public image, so whatever.
If treading on someone's unsound sensitivity deserves a ban, so be it. I can live with that.


PostPosted: Tue Sep 08, 2020 12:50 pm    Post subject: Reply with quote
Alex TG wrote:
fiftyonepointsix wrote:

You turned a discussion into an argument.

That was neven neither a discussion not the agrument.
That is hardcore facts backed up with official documentation vs badly informed opinion of someone who believes that the time spent on forums makes him an "expert".

fiftyonepointsix wrote:
then accuse me of lying

No, not of lying. Of ignorance.

fiftyonepointsix wrote:

Most of the members of this forum know me from years of posts. They know you from lobbing insults.

Unlike you, I care more about the information than about my public image, so whatever.
If threading on someone's unsound sensibility deserves a ban, so be it. I can live with that.


I've taken apart more lenses than you have, and I don't see any of your original work posted- just old diagrams and marking up my pictures.

So- yes, you just want to win an argument by throwing out insults and denying first-hand information.

The Diagram you posted may be correct for some J8M's, but is different from the two lenses that I took apart. The Photographs prove it.

So- I have first hand knowledge from examing the lenses, you have posted nothing conclusive.




Go take apart another 50 or so lenses, take pictures, get back to me on it.
So the take-away from this thread is yet another variation of the J8M. This one has a Triplet very similar to the standard J8, but made for the fixture of the J8M. The rear module looks like a standard J8M. Looking at the original diagram you showed, nice design- to hard to manufacture, and could have caused a lot of problems. They tried fixing it.

So, I'm happy with ny first hand-knowledge more than what is in the documents you show. Anyone else still reading this thread, you've gained some knowledge about the J8M, it's design problems, and evolution. This may account for so many J8M's being very poor performers and ultimately being replaced by the Helios-103.


PostPosted: Tue Sep 08, 2020 2:31 pm    Post subject: Reply with quote
fiftyonepointsix wrote:

So, I'm happy with ny first hand-knowledge more than what is in the documents you show. Anyone else still reading this thread, you've gained some knowledge about the J8M, it's design problems, and evolution. This may account for so many J8M's being very poor performers and ultimately being replaced by the Helios-103.

Like 1 Thank you! Thank You Dog


PostPosted: Tue Sep 08, 2020 2:54 pm    Post subject: Reply with quote
Thanks Brian, you've cleared up a misconception and increased our knowledge.

So the 8M does have 6 elements, but as we thought, it had been altered for easier, cheaper production and this means the 8M is often a poorer performer.

The point still stands though that the only way to know which are the good lenses is to try them and find the good copies. I'm lucky, I have several 50s J8s in Kiev and screw mounts and they are all good lenses that produce good results and give me a lot of pleasure.


PostPosted: Tue Sep 08, 2020 3:21 pm    Post subject: Reply with quote
fiftyonepointsix, first of all, I appreciate your pictures of 1975 J8M. That's a valuable input for the whole community, not just for me. Indeed. It's always nice to have another piece of the puzzle.

But as for another copy, you know, it is a bit funny to watch how you're keep trying to "oppose" my point while actually confirming it by posting the pictures of that plain old "stepped triplet" design straight from the book and claiming proving something by not noticing the second seam 7 years ago (I'm not even sure how one can prove there's only two elements without cutting the whole damn thing in half lengthwise). I wouldn't probably noticed it myself without having the diagram at hand, that's true, but I have a hard time imagining myself sticking to a 7-year-old conclusions even after gaining the new data.

That'll be all from me. Cheers!


PostPosted: Tue Sep 08, 2020 3:33 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
it had been altered for easier, cheaper production and this means the 8M is often a poorer performer.

Oh c'mon.
That "easier, cheaper" version of the J8M triplet is exactly the same (in terms of manufacturing process and cost) as every regular J8 has.
Means exactly nothing.
Poor performance of both J8 and J8M comes mostly from the sloppy barrel parts tolerances, not from the glass.


PostPosted: Tue Sep 08, 2020 4:03 pm    Post subject: Reply with quote
The Middle Triplet from the J8M was a surprise- not at all like the one I took part in 2013.

I took apart a J8 to compare and measure the two.

The front element of the J8M is ~0.5mm larger diameter than the J8.
The middle triplet has about the same diameter, but the thickness of the J8M is about 0.2mm more than the J8.

I take a part a lot of lenses. The seam on the rear doublet of the J8M is easy to spot. I'll probably pick up more J8M's to take apart, they used to be dirt cheap- like $2 at a camera show.

My Parts Bin of Jupiter and Sonnar lenses:


I have two slide-boxes filled with complete lenses "not in use", and 12 J-3's, 8 5cm F1.5 Sonnars, 2 5cm F2 Sonnars, and 3 J-8's all in LTM.
I've focused more on LTM Jupiter lenses, not so much on the J8M. I have one that is on my Kiev that has not been talen apart, now I am curious.

The Same J8M that I took apart yesterday, same triplet- compared with a J8.










So- The J8M had a new triplet formulated to replace the earlier design. It is just not a J8 triplet stuck into the lens. Another lens that you open up and get a surprise.


PostPosted: Tue Sep 08, 2020 4:49 pm    Post subject: Reply with quote
Alex TG wrote:
iangreenhalgh1 wrote:
it had been altered for easier, cheaper production and this means the 8M is often a poorer performer.

Oh c'mon.
That "easier, cheaper" version of the J8M triplet is exactly the same (in terms of manufacturing process and cost) as every regular J8 has.
Means exactly nothing.
Poor performance of both J8 and J8M comes mostly from the sloppy barrel parts tolerances, not from the glass.


Oh, but we mustn't criticise anything made in Ukraine, right?

Grow up.


PostPosted: Tue Sep 08, 2020 5:51 pm    Post subject: Reply with quote
Alex TG wrote:
Poor performance of both J8 and J8M


iangreenhalgh1 wrote:
Oh, but we mustn't criticise anything made in Ukraine, right?


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