I've picked up an old 210 mm Goerz (pre dagor) recently and have a problem. The glass looks to be in decent condition, but there is a fair amount of dust in the interior of the lens. My problem is that I can't get the lens apart to clean it - it seems to be stuck solid. There is obviously a section on each end with a brass center section where the iris is that all should unscrew. Do any of you have any suggestions on how to get a stuck lens apart?
"Do any of you have any suggestions on how to get a stuck lens apart?"
Very carefully, it's really old. The safest way is take it to a camera tech and have it cleaned in an ultra-sonic tank, that usually loosens the threads safely but it will need a full service after.
Good luck with it.
Dan, if the threads are frozen, the best penetrant I have ever used is "Kroil". If I had more specific information, I could give you better info. What I will say is be very careful. Do not strain anything. Glass flakes off very easily.
If you do manage to get it unscrewed, try to leave the glass elements in their specific holders as the elements might look symmetrical, but small differences in curvature may be unnoticable unless you measure them with a dioptre gauge, which is actually quite a simple procedure.
Beware of lens element spacing.. or so I've been told. Some lenses aren't idiot proof (not that you are an idiot). They are precisely set and rotated and aligned, so hamfisted skullduggery may destroy them. That being said I'd probably still try what you're doing here.
Hi, Dan: Had any luck?
The best tool for unscrewing lens cells is a Flexi-Clamp, available from Micro-Tools:
http://www.micro-tools.com/store/Sea...tegoryCode=FLX
They won't leave a mark on the brass, but can really make an impression on your hands. Use a cloth or a glove.
Sorry, I don't have an 8.25 Dagor to measure.
If you can't get one the right size, you can try a strapwrench, but be careful of applying too much torque, as inward pressure will increase as you do.
I'd be careful of applying any kind of oil to a lens, for fear that you couldn't clean it all out.
Depending on your level of daring, and your feel for hand tools, you can wrap the lens and barrel with 6, 8 or more layers of plastic electricians tape and have at it with pipe wrenches
The one method, which has never failed me, of securely holding a front cell is to take a block of wood and drill out a shallow, round depression so that the cell fits very snugly into it. Be careful the glass doesn't hit bottom. Put the block into a benchvise, and push the lens in the hole. Lay a small bead of water along the rim of the lens, and wait 10-15 minutes for the wood to swell. This setup has the extra benefit of giving you a spare hand to work with.
Have fun!
Charley
In such cases ( obstinate threads) I use either a household "Strongboy jar and bottle opener" made by Zyliss (www.zyliss.com) or, if more leverage is needed, a worm hose clamp. Usually a light tap on the clam's screw suffices to loosen the beast.
Uli
What kind of Goerz lens is this? A Doppel-Anastigmat Serie III (later DAGOR), or one of the many others?
Is it one of the ones where the lens elements are in an aluminium mount, screwed into a brass barrel? If so, those tend to be very, very difficult...
You are so very right about that, Ole. You jogged my memory. Several years ago, I bought a lens off feebay: Goerz Dagor f6.8 Series 3 No 4 Focus 9 1/2 IN No 227,6xx. The aluminum-mounted front cell was only partially screwed into the brass barrel, i.e., obviously cross-threaded and sitting at the wrong spacing distance. Neither chasing the threads with a file nor chucking the cell and barrel up on the lathe and running a tool through the threads could get them to go together properly. I set them aside to try polishing the threads sometime. Since NY Winters are shorter than Norwegian ones, I haven't gotten to it yetOriginally Posted by Ole Tjugen
The rear cell turns smooth as silk, however.
Lesson? Live with internal dust if you can; be careful if you can't.
I'm a rank amateur, incompetent machinist who shouldn't pass along advice, but I'll repeat some that I've heard - I haven't seen it mentioned lately and it deserves occasional repetition. To screw a cell into a barrel and avoid cross-threading it, start by placing the barrel on a flat surface, e,g,, a tabletop. Place the cell on the barrel as squarely as possible, and gently turn it counterclockwise, as if you were UNscrewing it. Look, listen and feel. At some point, the beginning of the thread on the cell will pass over the beginning of the thread on the barrel. As it does, the cell will drop slightly, sometimes emitting a perceptable 'click'. Now you can carefully reverse direction and screw the cell into the barrel.
Charley
A trick shown me years ago by the lens techs at Mel's cameras in Hollywood is to cut 5X5" swatches from an old inner tube and use them as grips.
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