How to open this rear lens group?

[newfilm]

Hi guys, I've got a Color Skopar 35mm 2.5 and I notice there is some haze in the rear element, I open it up, and end found the haze is inside this metal enclosure that shape like a mushroom.

I try to twist it a bit to see if it open up but it dint, should this one pop up if I apply some more force? Any pointer of getting this thing open is welcome 😀 many thanks!

here a picture of it:

 

[Steve M.]

I don't think you're going to, at least that's my guess from looking at that small pic. Have to send it to a place that specializes in this. It appears that collar has to be cut off, usually on a lathe, elements cleaned, and then put back together. Probably has haze between cemented elements, which is another complication. You need a machine shop and experience, along w/ an optical bench to align things properly.

Better to put it back together, sell it w/ an accurate description, and buy another that is clean (w/ a return privilege if not). MUCH cheaper. Or just get a good hood, a yellow filter to boost the haze lowered contrast, avoid shooting into the sun, and live w/ it. This lens seems prone to haze in the rear element, and I see several examples like yours that are for sale on the internet. An old Leica 35 3.5 makes great images :]

 

[rick oleson]

Steve is right - the rear cell of a Skopar will be a cemented pair, so even after you cut the brass off of it you won't reach the surface in between.

 

[newfilm]

Ouch... I have been shooting with my soviet body and lenses for a few years, and this is my first "upgrade" to a "modern" lens that I put a chunk of money on, the listing does mention a bit of haze, and I was thinking, hey, I have all this soviet stuff that was made decades ago and if there is haze they just wipe just right out, that "slight haze" is nothing to be afraid of, damn I was wrong.

Come to think again, why would something cemented have haze inside? Isn't that kind of airtight to oil and dust? I'm disappointed with "modern" lens ...

 

[ferider]

Coming from the rear, there is an isolated element and then a cemented pair.

Not sure which version you have, but on my color skopar, the rear element can be removed from the "mush-room" via a span ring.

Old lenses sometimes have haze in cemented pairs (glue deterioration, etc). This is a young lens, I bet you can clean it by removing the rear element. And no lathe required (at least on my version).

 

[giganova]

How bad do the pictures look like? Is there a need to clean it or do you not even (or barely) notice the haze in the pictures?

 

[newfilm]

@ferider: I have the LTM version. The mushroom that come out from the rear had a "dome" shape lens which come out like usual, the diagram you link dint have the mushroom shape lens group (now that when I look closer, the black thing might not be metal casing, might just be black paint, I dont want to try to chip it), maybe that's the diagram for a newer version?

@giganova: argh.... I just shoot a 10 frame of side by side comparison with my jupiter-12, but... due to my idiotic brain when I put them in my paterson tank, I put in another 10 frame strip that I was testing earlier on another lens, and guess what? two film strip overlapped! It's ruin, I have to do another test, over the weekend hopefully.

 

[rick oleson]

The haze is probably the cement itself.....

 

[newfilm]

Ok... over the weekend I shoot some test shoot comparing with my Jupiter-12 with Fomapan 100 on my Canon-P body, some how, the Jupiter give that just a little more sharpness, is that haze that cause that tiny bit loss of sharpness? I don't know, if I don't have a comparison, I'd say nothing wrong with the Color Skopar by looking at the picture, I need to run one more test with colour film, just to check if the colour are a little more "haze" or not.

At first I though maybe my body rangefinder was some how more friendly with the Jupiter, but then... at 35mm f8-11 focus on infinity, I assume both lens should not be too bother about the hair-line focus accuracy right?