Symmar 150mm f/5.6 rear cell disassembly advice

[DKirk]

Looking for a little advice - Recently purchased a Symmar 150mm in a shutter (as it worked out cheaper to buy it, than purchase a shutter on it's own. . .), there is a touch of haze/initial "fingers" of fungus or something in between the two groups in the rear cell.
How do I disassemble the thing?
- I've removed the rear retaining ring, there's no little grub screws that I can see - did they cement the groups in? (already rescued a Linhof selected 210 Symmar-S with a similar affliction- but the rearmost group of cells was not cemented in, and easily came out with a suction cup. Was a nice bargain, though I'll need to see if I can fix the filter ring into a more usable state than it currently is). All I need to do is to transcribe the aperture scale from the well and truly broken modern Copal to the older Compur shutter.

Not looking to send it off to Grimes or anyone, as it's just not cost-effective, even more less so once you factor in shipping and mucking about with customs.

[ic-racer]

I have used heat in these situations. The barrel expands more than the glass, loosening the fit and potentially allowing the lens elements to come out.

[EdSawyer]

agreed, try a heat gun.

[Kevin Crisp]

Not totally clear on what you are asking, and your reference to "rear retaining ring" could mean a couple different things.

That being said, unscrew the rear cell from the shutter.
Get an SK Grimes lens wrench with the flat tips. It is superior to anything I've seen for this.
Look carefully at the rear (big side) of the rear element. There will be a thin retaining ring that screws in clockwise to the cell body, holding in the rear (larger) elements. That thin retaining ring should have two slots in it, 180 degrees apart.
Position the tips of the lens wrench in order to get them flat and fitting fully in the two slots. They be pointing in toward each other, or splayed out. It depends on the size of the lens.
Holding the cell firmly in one hand, with full contact on the wrench tips in the slots, try unscrewing the ring. If it moves a little, you can usually use a fingernail to help it the rest of the way without risking damage to the glass. You usually get one shot at this and you really don't want to skip out of a slot, stripping it or scratching the glass.

Now...if the rear element has been dropped and the rim bent, you're done for. Even if it has been straightened and "will take a filter." That's my experience.

Once the retaining ring is out, turn the element face down over a soft towel. The rear group should slide out. Sometimes they are so tight you can hear the air hiss as they go. That should give you access to the inside of both the front and rear elements of the rear lens group for cleaning. If it is really fungus, clean it well I'd even do a final with acetone. I'd avoid getting acetone into the glued gap in the glass.

Nothing should be glued in, the subgroups are glued glass to glass, but nothing to the mount.

[DKirk]

Not totally clear on what you are asking, and your reference to "rear retaining ring" could mean a couple different things.

... There will be a thin retaining ring that screws in clockwise to the cell body, holding in the rear (larger) elements. That thin retaining ring should have two slots in it...

That's the ring I was referring to, so it's off to find the heat gun. . . and that'll be a bit of a task it's in a "safe place". . .

[Kevin Crisp]

You shouldn't need a heat gun on the retaining ring that holds the glass in. Not if you have a proper wrench and the rim is not bent.

[EdSawyer]

he has the ring out (presumably). heat shouldn't be needed at all generally, esp. on a semi-modern lens but it wont' hurt if used in moderation.


Sometimes slapping the lens group into the palm of your hand can encourage the element to come out nicely.

[Kevin Crisp]

Oh. That wasn't how I read it. I never had one that needed more than a gentle thump on my palm. Assuming the retaining ring for the glass is out.