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Jupiter-21M - problem?
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PostPosted: Mon Mar 12, 2007 12:43 pm    Post subject: Jupiter-21M - problem? Reply with quote
Can any experts advise me please? -

My J21M produces pictures with very low contrast. The following picture shows a comparison between the J21 and a Pentacon 4/200. All the camera and lens settings are identical. Can anyone explain why this might be happening and is there anything I can do about it? Thanks



BTW, the Pentacon is the preset version, I think the first version after the Meyer Orestegon namechange. It has a damaged iris with several misplaced blades - I'm guessing the aperture is about 1/13. I'm going to have a go at repairing it - a couple of pics of this to follow.


PostPosted: Mon Mar 12, 2007 1:21 pm    Post subject: Reply with quote
I don't dare to call myself an "expert", but I have many 21Ms, and I can tell you for sure, that there is something wrong with what I see.
Sad
I'm very sorry for you, because all my copies of J-21M work fantastic. It's the first time that I read of a 21.M not working well.
I have no idea of what can be happening there, it looks like the effect of a very big flare, but very homogeneous, so not likely - also J21M is much sharper than that. So i suspect a misplaced glass element somewhere.

It's not worth to send the lens to repairs, either you are able to fix it yourself or it's just cheaper to buy a new one. The lens is really worth it. I have seen just the other day a J-21M at a nice price on the bay - I will look for it and send you a private message.

EDITED TO ADD:
I see that you have shot at very narrow apertures. Have you tried shooting at wider apertures? The J-21M does not need that much stopping down. It is already very sharp wide open. It is really useable wide open, I have shoot many great pictures with it just wide open. Please try to shoot a few pictures wide open and with apertures not smaller than f/8, and post them.


PostPosted: Mon Mar 12, 2007 3:12 pm    Post subject: Reply with quote
Here's the same shot at three different apertures Orio. These are uncropped, just resized and converted to jpg to keep the filesize down. As you see, the flare becomes worse as the aperture decreases, but the overall contrast for all three is is c**p!


PostPosted: Mon Mar 12, 2007 3:39 pm    Post subject: Reply with quote
Forget about expert, I cant call myself novice...
I have few lenses, which has this level of contrast. I usually find the defects in optics in those pieces. Use the simple "torch test", whether you are able to see the torch light across the lens without any obstruction. I have found, haze, bubbles (I think cement of glasses loosing the grip) etc in those lenses. But again, some lenses are clean but still giving this type of results. I never used those lenses after few shots Sad


PostPosted: Mon Mar 12, 2007 4:56 pm    Post subject: Reply with quote
Looks you have haze on lens. I took similar photos with Flektogon 35mm f/2.8 with haze. Buy I new one what Orio suggested.


PostPosted: Mon Mar 12, 2007 6:51 pm    Post subject: Reply with quote
That does look bad, Peter. I'm sorry.

I also think that it is an internal problem: glass displaced or haze or....

I don't think you can do a lot against it, I'm afraid.
You can rescue some pics with PS, though.

Carsten


PostPosted: Mon Mar 12, 2007 10:52 pm    Post subject: Reply with quote
Ballu wrote:
Forget about expert, I cant call myself novice...
I have few lenses, which has this level of contrast. I usually find the defects in optics in those pieces. Use the simple "torch test", whether you are able to see the torch light across the lens without any obstruction. I have found, haze, bubbles (I think cement of glasses loosing the grip) etc in those lenses. But again, some lenses are clean but still giving this type of results. I never used those lenses after few shots Sad


It looks absolutely clear Ballu, not a mark or blemish, just a few dust specks. I've reached the conclusion that lenses in mint condition are more than likely that way because they're unusable for some reason.


PostPosted: Mon Mar 12, 2007 11:13 pm    Post subject: Reply with quote
LucisPictor wrote:
That does look bad, Peter. I'm sorry.

I also think that it is an internal problem: glass displaced or haze or....

I don't think you can do a lot against it, I'm afraid.
You can rescue some pics with PS, though.

Carsten


Thanks Carsten. I didn't know for sure if there was anything wrong with it or if I was doing something wrong, or maybe wrong camera settings or something. It's sad, but I feel better to know this lens is a lemon.

I've been wondering what to do with it. I can't send it back (to Germany), l can't sell it and I don't want to have it sitting on a shelf, so I'm going to give it the special repair treatment: http://www.hermes.net.au/bayling/repair.html


PostPosted: Mon Mar 12, 2007 11:19 pm    Post subject: Reply with quote
peterqd wrote:

I've been wondering what to do with it. I can't send it back (to Germany), l can't sell it and I don't want to have it sitting on a shelf, so I'm going to give it the special repair treatment:


LOL why don't you use it to learn how to open and clean lenses instead. I would do that if I had a lens in that hopeless condition. Some day you may need to open a lens to clean it or de-fungize it... and the experience on the dead J-21M will become very useful.


PostPosted: Tue Mar 13, 2007 1:34 pm    Post subject: Reply with quote
peterqd wrote:
...so I'm going to give it the special repair treatment: http://www.hermes.net.au/bayling/repair.html


Please don't! These picture break my heart!

I think Orio's idea is great!

You might even understand the reason for the low contrast (loose glass or s.th.) and might be able to change it!

Carsten


PostPosted: Tue Mar 13, 2007 6:11 pm    Post subject: Reply with quote
LucisPictor wrote:
peterqd wrote:
...so I'm going to give it the special repair treatment: http://www.hermes.net.au/bayling/repair.html


Please don't! These picture break my heart!

I think Orio's idea is great!

You might even understand the reason for the low contrast (loose glass or s.th.) and might be able to change it!

Carsten


Fear not, my friend! I hate those pictures too. I am definitely going to try to repair this lens, that's if I can find the right size of anti-tank shell to open it with. It even has that smell of Russian grease, I bet it's the same sort they used on tank tracks.

I repaired a Helios 44-M4 today!! This one has an aperture pin and an A-M switch, but the pin and switch had no effect - it was like using the lens in manual mode. Despite losing another tiny ballbearing and finding it again with a magnet, I managed to get the mechanism working again with a little smear of trombone slide cream. It's a little less viscose than tank grease.


PostPosted: Tue Mar 13, 2007 7:32 pm    Post subject: Reply with quote
peterqd wrote:
Fear not, my friend!...


Thank God! But I would have been surprised if you really had destroyed the lens. It would not have been the Peter I know from forum activities. Wink

Carsten


PostPosted: Tue Mar 13, 2007 7:35 pm    Post subject: Reply with quote
peterqd wrote:

I repaired a Helios 44-M4 today!! This one has an aperture pin and an A-M switch, but the pin and switch had no effect.


Sure it was a 44M-4? I own a few of them, but they all are automatic ones. The only 44-Version with A/M switch I know is the 44M-nothing.

Michael


PostPosted: Tue Mar 13, 2007 9:25 pm    Post subject: Reply with quote
Borges wrote:
peterqd wrote:

I repaired a Helios 44-M4 today!! This one has an aperture pin and an A-M switch, but the pin and switch had no effect.


Sure it was a 44M-4? I own a few of them, but they all are automatic ones. The only 44-Version with A/M switch I know is the 44M-nothing.

Michael


Hello Michael. Yes, you're perfectly correct, it's a 44M-nothing with KMZ logo. My mistake.

Peter


PostPosted: Wed Mar 14, 2007 2:49 pm    Post subject: Reply with quote
Well, thanks to a suggestion by BobM on the other forum, I made a very temporary lens hood for the J21M with an A4 piece of dark blue card. Look at the result - same settings, with and without the hood:



PostPosted: Wed Mar 14, 2007 4:42 pm    Post subject: Reply with quote
Peter, the 21M has a built-in lens hood!
It is fitted in deeply, have you looked for it?

It must be there, besides, if it isn't there, then it means your lens has been heavily damaged/manipulated, because the lens hood of 21M just can not be lost or removed easily.


PostPosted: Wed Mar 14, 2007 5:15 pm    Post subject: Reply with quote
Hey! That looks much better.
Still, it is a quite serious thing if the flares are that big without the lens hood ... strange!

Anyway, use it with a hood and be happy!

Carsten


PostPosted: Wed Mar 14, 2007 6:39 pm    Post subject: Reply with quote
Orio wrote:
Peter, the 21M has a built-in lens hood!
It is fitted in deeply, have you looked for it?

It must be there, besides, if it isn't there, then it means your lens has been heavily damaged/manipulated, because the lens hood of 21M just can not be lost or removed easily.


Orio, there IS a built-in lens hood. Fully extended it projects about 12mm forward of the edge of the filter ring. I can see inside it isn't stuck, that's the limit. I took a shot of it for you to see. The picture with flare had the lens hood extended. The hood I made with a cardboard tube extended the width of A4, about 200mm.

Can you help me by comparing your lens with mine. At the mount end there is a black painted plate inside my lens which covers the aperture pin mechanism. You can see this in the other picture. When I look at a lamp through the lens, from the mount end, I can see light reflected off this plate. It has a semi-gloss finish and it seems to me this should be as matt finish as possible. Could you tell me if your lens is similar?

Thanks

Lens hood fully extended:


Semi-shiny plate inside mount end:


PostPosted: Wed Mar 14, 2007 7:15 pm    Post subject: Reply with quote
peterqd wrote:

Orio, there IS a built-in lens hood. Fully extended it projects about 12mm forward of the edge of the filter ring.


It should extend much more, I don't have a meter at hand but by eye I would say about 2,5 cms forward of barrels edge.

Quote:
I can see inside it isn't stuck, that's the limit.


But that's not normal

Quote:
I took a shot of it for you to see. The picture with flare had the lens hood extended. The hood I made with a cardboard tube extended the width of A4, about 200mm.


This is way too much, a 2,5 cm hood like the original should block out all flares

Quote:
Can you help me by comparing your lens with mine. At the mount end there is a black painted plate inside my lens which covers the aperture pin mechanism. You can see this in the other picture. When I look at a lamp through the lens, from the mount end, I can see light reflected off this plate. It has a semi-gloss finish and it seems to me this should be as matt finish as possible. Could you tell me if your lens is similar?


All my four copies have that part, it is of definitely matte surface, and feels a bit rough also if you touch it with a finger.
In my copies that part does not seem to bounce any torch light significantly.
Also the position might be relevant. In my copies, that part is almost parallel to the lens' main axis. It should therefore not get any direct light from the rear glass. Check if your element is maybe a bit tilted.

It is possible that by fixing the position of that part, or removing it alltogether (it should only affect the pin, but if you use the lens with a digital reflex, you don't need the automation feature), your problem could be solved. Although you may perhaps have to use a hood that reach the supposed lenght, which is longer than what your built-in hood allows (but an A4 lenght is way too much).


PostPosted: Wed Mar 14, 2007 7:53 pm    Post subject: Reply with quote
I think neither the internal hood nor the plate is the reason. As far as I can see it's all on its designated place.

Michael


PostPosted: Wed Mar 14, 2007 9:50 pm    Post subject: Reply with quote
Orio wrote:
(but an A4 lenght is way too much)


Of course. This was only an experiment and I didn't want to cut the cardboard until I'd seen the results. Tomorrow I will cut the cardboard and take test shots to work out the minimum length/dia needed. I'm hoping one of these Click here to see on Ebay might work. Otherwise that's the end of this lens Sad

I had a close look (with a magnifier) at the screws on the barrel near the mount end. It looks as though the screw heads have been sheared off, probably because of the threadlock, so it looks as though someone else has been trying to cure this problem.


PostPosted: Wed Mar 14, 2007 11:09 pm    Post subject: Reply with quote
peterqd wrote:
Orio wrote:
(but an A4 lenght is way too much)

Of course. This was only an experiment and I didn't want to cut the cardboard until I'd seen the results. Tomorrow I will cut the cardboard and take test shots to work out the minimum length/dia needed. I'm hoping one of these Click here to see on Ebay might work. Otherwise that's the end of this lens Sad
I had a close look (with a magnifier) at the screws on the barrel near the mount end. It looks as though the screw heads have been sheared off, probably because of the threadlock, so it looks as though someone else has been trying to cure this problem.


I hope that you can recover the lens Peter.
If the lens was opened, then of course the one who sold it to you was aware of the problem. So why not ask for a refund, or at least give negative feedback.

Ok now I can move this thread to the Equipment maintenance and repairs forum.


PostPosted: Sat Mar 17, 2007 3:18 am    Post subject: Reply with quote
Very Happy Very Happy Very Happy
So... dramatic change with so simple solution. Idea As usually, in entire history of mankind. Untill I saw your post, with the hood-extension solution, I was tempted to think that the balsam between the lens was leaked. The result of it is that kind of haze. Similar. But... keep on, with that hood! Very Happy In my short experience with a MC Jupiter 37-AM I was bothered by some central glow on the picture. So, I use the hood, or (sometimes) I just keep my arm against the direct sun light. The result... is fully satisfactory to me.


PostPosted: Sat Mar 17, 2007 2:09 pm    Post subject: Reply with quote
Thanks Angel. The 200mm long shade helps at about 90° to the sun, but as soon as I turn the lens towards the sun the flare returns. Besides the flare there is an overall loss of contrast which seems to be present most of the time. The flare is invisible in the viewfinder so it's difficult to work out how to use my hand for shading and I can't get consistent results with experimental shots. Besides, I need my left hand to steady this heavy lens.

I am going to remove the front lens when I have the right tool. I can't get at the rear lenses yet without cutting the barrel - I might well do that just to be able to learn about this problem. Any more info you have on the balsam would be interesting.


PostPosted: Sat Mar 17, 2007 2:44 pm    Post subject: Reply with quote
http://en.wikipedia.org/wiki/Canada_balsam
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