Disassembling front element of Summitar?

S

sychan

Guest
Does anyone have any guidance on disassembling the front optical block of the Summitar?

Its not so different from a collapsible 'cron right? I can unscrew the front block, but I don't see notches for a spanner on front of the lens block, and no signs of screws along the side.

I picked up a "lost cause" lens - under the front element is some condition that I can't easily identify - it looks like it could be either a really odd combination of separation and maybe fungus, or the glass may have cracked somehow. I want to take a look at it before deciding what to do with it.

Steve
 
I have the front off my collapsible 'cron right now. There are 2 very small spanner notches in the metal ring that sits between the name ring and the outer chrome shell on my version. Once that is loose, you can remove the name ring and a wide washer beneath it, next the front element and, finally, a very slim aluminium spacer under the front element.

Sorry, but I don't know if your lens is the same.
 
Brian,

You need a tool called a lens spanner, or pin wrench, a device with two legs that end in either round or flat points that fit in the grooves on the securing ring. The distance between the legs can be adjusted quite accurately.

You can get good ones from Microtools, and you can find them on ebuy, but don't buy the really cheap ones from India - either they will never arrive, or will be of inferior quality.

You could make a bespoke tool using 1.5mm HSS drill bits and a piece of 1/4" steel - braze or silver solder the drill bits into the steel at the right centres, then harned and temper.

I have attached a shot of the groove in the securing ring, it is a normal right-hand thread.

Hope that helps.
 

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John,
I've been looking at the Summitar for the notches for the len spanner (I have one already) and have yet to see them. The notches are pretty easy to find on most lenses, and my rigid 'crons have them, but not this Summitar. I'll include a photo so that you can see the front of the lens (as well as the nasty condition of the glass).
 

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If the name ring does come off, you will need a lens bung. It's basically a friction tool. However,it may be that the whole front ring screws off. I can't see properly from the pics but try to see where the "joins" are. This should lead you to the way to undo it.

Kim
 
Hi Brian,
FWIW, Arax will take a doublet, seperate the elements, polish and recoat them before cementing them back together.

Kim
 
I believe that lens breaks apart at the junction between the large knurled band at the very front of the lens and the narrow one for the aperature ring immediately next to it. The front element block should unscrew. Don't quote me on this as I don't want to ruin your lens.

Nikon Bob

I had to try it to make sure, sorry for the poor handheld images.
 
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oh man, i wish this thread was here before i took apart my 50 summicron.
i just removed the front element and it turns out there is no haze just that the front of the front element must have been exposed to a sand storm. i could not believe that someone could do that to a lens. my lenses stay great and without filters. this was just abusive...

so this should go off to arax or i'll need to find another 50 collapsible.

anyone have a 50 elmar with nice glass for sale?
 
Kim Coxon said:
Hi Brian,
FWIW, Arax will take a doublet, seperate the elements, polish and recoat them before cementing them back together.

Kim
Click to expand...
Fact is ARAX wrote me back only a couple of days ago that it would only polish and recoat the isolated glass elements I could send them...
Wouldn't dismantle or CLA my 2.8/50 Elmar.
Nuno
 
They are quite happy to do a doublet as long as you send the glass only. Here's the reply I received:

Hello Kim.

Thank you for e-mail of Saturday, March 4, 2006.

KC> Many thanks for the quick reply. I have another lens and question. Can you
KC> polish and recoat a cemented doublet? I can send the glass only but the 2
KC> glass elements are cemented together.

Yes, no problem. You'll pay for 4 surface polishing and covering ($60)
and recementing and cementing work - $30
Shipping, handling, insurance - $9

Not cheap but it depends on the value of the lens.

Kim



nrb said:
Fact is ARAX wrote me back only a couple of days ago that it would only polish and recoat the isolated glass elements I could send them...
Wouldn't dismantle or CLA my 2.8/50 Elmar.
Nuno
Click to expand...
 
Thanks for all the replies - RFF is an awesome site because of how helpful everyone is!

After looking at Nikon Bob's photos, I tried to unscrew the front retaining ring, but can't get it to budge. I'd rather not apply too much force to it if there is a way to finesse the ring off.

Any suggestions?
 
Well, the front cell wouldn't come loose, so I decided to use stupid thermal expansion tricks - I put the front cell in the freezer for a few hours to get it nice and cold and then got a cup of hot water ready (the temperature is "tea temperature", about 170 degrees). Took the lens cell out of the freezer, dunked the lower half in the water for a few seconds so that it would start expanding, and kept the upper half out of the water so that it wouldn't expand as quickly.

I used a pair of those rubber kitchen dishwashing gloves to get more traction on the lower section and managed to twist them apart.

Taking a look at the upper section, it seems pretty clear that the glass problems I'm seeing are inside the first element. Unless the lens bonded to the frontmost ring is a cemented doublet, it looks like the lens is a lost cause.

Does anyone know if that front element is actually an element, or a cemented group? If its a group, I can try heating an oven up to 350 degrees and melting the balsam. But all the block diagrams of these double gauss lenses seem to indicate that it is a single element, and not a group.
 
One of my reference books states that the front element is a cemented double on the Summitar.

Nikon Bob
 
Bob,
Thanks - any suggestions for separating the lens pair from the ring? I can't tell how it is bonded and what the best way is to separate them.

Steve
 
Looks like Kim is right about it being a pro job and not a cheap one from the amount of work involved.

Nikon Bob
 
Nikon Bob said:
I believe that lens breaks apart at the junction between the large knurled band at the very front of the lens and the narrow one for the aperature ring immediately next to it. The front element block should unscrew. Don't quote me on this as I don't want to ruin your lens.

Nikon Bob

I had to try it to make sure, sorry for the poor handheld images.
Click to expand...


I am trying to dissassemble a col. cron, and this won't work. Do I need more tension? Does it even unscrew on the cron?
 
I've got exactly similar marks on my summitar rear element inner surface (only two small ones, the rear element is a single element, your front element is a cemented doublet). I thought they were soft coating marks and ignored.

Did your lens take ok photos?

Noel
P.S. I thought the Summitar was a 2 2 2 1 lens.
P.P.S. If it is on the lens surface dont rub it, you will be sorry...
 
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Matt

I was referring to a Summitar not a Summicron collapsible. Can't help with the Cron.

Bob
 
nrb said:
Fact is ARAX wrote me back only a couple of days ago that it would only polish and recoat the isolated glass elements I could send them...
Wouldn't dismantle or CLA my 2.8/50 Elmar.
Nuno
Click to expand...

Hi. Who is ARAX and how do I contact him to clean a lens? Thanks.

Is this ARAX?
 
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