Removing the front element from a 19-inch Apochromat Artar in barrel

[Paul Kinzer]

I have one, and the rear element just unscrews, but the front will not. Should it? Or is there a set screw or something that I'm missing? It's probably just stuck, but doesn't look dented or damaged in any way.

[Paul Kinzer]

Hmmm... No responses. I'd really like to put this in a shutter some day, and might know a machinist (or two!) who can do it, so I'm really curious about how to get it apart. I'd be grateful if someone who has one can tell me if it should come apart easily.

Here's a photo. I think it should separate where I've placed the black arrow. Am I right?

172931

I won't try too hard to get it apart, but if I know for certain where to grip it, I can give it a bit of effort. The diameter of the threads on the rear element seem a perfect match for an Ilex #4 shutter.

[Bernice Loui]

No, the front cell separates at the front edge of the barrel. While this is not a 19" Artar. the construction is much the same for Goerz lenses of this vintage. On the 19" there s a ring that is threaded on on the very front of the front lens cell. This ring is often stuck on good. It is where the 90 degree prism would have been attached.

See images:
172932

172933


Bernice



Hmmm...
Here's a photo. I think it should separate where I've placed the black arrow. Am I right?

172931

I won't try too hard to get it apart, but if I know for certain where to grip it, I can give it a bit of effort. The diameter of the threads on the rear element seem a perfect match for an Ilex #4 shutter.

[Carsten Wolff]

Alternatively, and esp. with a focal length that long, it becomes quite easy to just front-mount it into a shutter, thereby not screwing up collimination etc.. I mounted mine onto an Alphax #4 a while back, just getting a simple adapter made by a local fitter and turner. Also saved me engraving another aperture. Another bonus: You save a bit of bellows. You do lose a litte bit of max. IC, thats it.

[Luis-F-S]

I'd really like to put this in a shutter some day, and might know a machinist (or two!) who can do it, so I'm really curious about how to get it apart. I'd be grateful if someone who has one can tell me if it should come apart easily.


I don't believe it will just screw in to a #4 and if it did, the spacings would probably not be correct. Why don't you let whomever is going to mount it to the #4 to take it appart? My 2ç's worth. L

[Jim Galli]

That front has 2 threads. The front extension that sticks out past the glass will come off, and also the barrel with the glass unscrews right at the barrel extension up front. Don't be afraid of it. Get two pieces of old rubber inner tube for grips and set it on the floor on top of one of them. Put the other grip on top and use your foot to apply torque. The front shade area may come off first. That's OK. Then repeat with the main part.

[mdarnton]

Thanks. I'll try that. I've been trying to get the front component off of my 14" for decades. The back component is easy, and the front ring comes off fine, then. . . . nothing.

[Paul Kinzer]

Thanks. I'll try that. I've been trying to get the front component off of my 14" for decades. The back component is easy, and the front ring comes off fine, then. . . . nothing.

That's exactly my problem! I cannot try the foot-lever idea because I have pretty severe back issues (I walk with two canes if I need to travel more than a few dozen yards). But I've gotten other lenses apart by doing something similar with a couple of tools made out of plywood. They look like this (https://ae01.alicdn.com/kf/HTB1RBmWdZLJ8KJjy0Fnq6AFDpXaC/2pcs-easy-hood-Filter-Wrench-62mm-67mm-72mm-77mm-Camera-Lens-Filter-Removal-Tool.jpg), but are much more robust. I just cut them out of scrap wood with a bandsaw and a hole saw of a slightly larger size than the lens diameter. I'll put some rubber in there to get more friction.

The main thing I needed to know is just where to grip the lens. So thanks very much!

[Jim Galli]

That's exactly my problem! I cannot try the foot-lever idea because I have pretty severe back issues (I walk with two canes if I need to travel more than a few dozen yards). But I've gotten other lenses apart by doing something similar with a couple of tools made out of plywood. They look like this (https://ae01.alicdn.com/kf/HTB1RBmWdZLJ8KJjy0Fnq6AFDpXaC/2pcs-easy-hood-Filter-Wrench-62mm-67mm-72mm-77mm-Camera-Lens-Filter-Removal-Tool.jpg), but are much more robust. I just cut them out of scrap wood with a bandsaw and a hole saw of a slightly larger size than the lens diameter. I'll put some rubber in there to get more friction.

The main thing I needed to know is just where to grip the lens. So thanks very much!

You've probably got the back problems from lugging around brass Artars. They weigh a ton. ;~'))

[Paul Kinzer]

It is amazingly dense.

[Steve Goldstein]

That front has 2 threads. The front extension that sticks out past the glass will come off, and also the barrel with the glass unscrews right at the barrel extension up front. Don't be afraid of it. Get two pieces of old rubber inner tube for grips and set it on the floor on top of one of them. Put the other grip on top and use your foot to apply torque. The front shade area may come off first. That's OK. Then repeat with the main part.

Jim,

That's a great tip. I tried this with my 24" RDA and the front extension piece came free but the front cell won't budge. I suppose I could gain 200lbs and try again, but that might take a while. Any other ideas? Strap wrenches? How about applying a tiny bit of Kroil to where the front cell housing meets the barrel? I don't really care about the barrel so if I Kroil it and then leave it sitting front-cell-up for a while I don't think anything would seep into the front cell. But I'm not sure...

[mdarnton]

I tried strap wrenches on mine. They just slipped--the brass is too smooth.

[Jim Galli]

Jim,

That's a great tip. I tried this with my 24" RDA and the front extension piece came free but the front cell won't budge. I suppose I could gain 200lbs and try again, but that might take a while. Any other ideas? Strap wrenches? How about applying a tiny bit of Kroil to where the front cell housing meets the barrel? I don't really care about the barrel so if I Kroil it and then leave it sitting front-cell-up for a while I don't think anything would seep into the front cell. But I'm not sure...


this is the stuff I use.


http://tonopahpictures.0catch.com/RubberBuffer.jpg

Get it at the Napa Auto Parts store. Leaves no residue and is great for sticky almost working shutters too.

[LabRat]

Hi, (back from the hinterlands for now)

I had found several large old barrel lenses while moving this year and some were forever seeming stuck (one was an old 305mm EK Aerostigmat that was quite corroded from being outside on a junkpile for apparently years, and was totally fused on to the barrel), but decided to try to free these up while I was packing/moving...

I took the common roads of injecting the thread seams with acetone, different penetrants, found the old "America Beauty" 200W soldering iron to heat the outer barrels, used the heat gun to heat 'em, followed that with trips to the ice box overnight, then heating again or left in the hot summer sun, but still, no dice... Stuck on real good, and even one old large Tessar had teeth marks on the front element barrel from someone's long plumbing pliers attempt long ago, but still frozen...

The few lenses sat all summer with penetrant injected it the thread seam (with a hypodermic needle), but finally was loosing my patience, and took a S/S hose clamp slightly larger than the barrel, wrapped the element barrel with rubber like is used to make bicycle innertubes, tightened the hose clamp quite snug, and found a strong part of the main barrel to rest on a solid block of hardwood (with the lock on the side) , took a small to medium ballpeen hammer, and started to tap on the hoseclamp locking body (with the lock on the side of barrel while tapping downward), starting with many softer taps, and then a couple of medium hard blows, and voilà, it started to rotate... Got them all loose!!!

I think it's important to leave the tiny amount of penetrant in there for at least a few days to weeks before trying again, and the final tapping/blow force helps to slightly displace the seating... Take time for this operation (weeks, even months), don't distort/damage the body/threads, but know that they can come apart somehow...

A machinist or gunsmith are good people to consult for the difficult ones, but don't damage it beforehand...

Good luck!!!

(heading back on location soon) Steve K

[Bernice Loui]

Some years ago, purchased a Rodenstock Imagon in Compound shutter. It was cost reductioned by the seller due to the front ring being stuck on the front of the Compound shutter. Tried several methods already mention to remove it. Would not budge... at all.

Before trying to remove this front ring, took a Q-tip soaked with PB blaster penetrating oil and lightly swabbed the thread seam.

Gave up and put this lens away. Many months later out of curiosity, tried to remove the front ring again and it easily spun off by hand.

Penetrating oil soak over a long duration of time can work.



Bernice

[Paul Kinzer]

I wasn't sure if penetrating oil was a good idea for the glass, so it's nice to get the okay from folks with experience. Is there something particular to look for in a penetrating oil? Jim uses something that does not seem to be sold for the purpose. I've not done this before, and I don't want to screw this up.

My son's been sick, so I haven't gone out to the workshop yet to make the lens wrenches I want to try. My lens also has the teeth marks of someone's attempts to get it apart, so I'm getting ready for initial failure with just tools. But it's worth a try.

I have used the hose clamp and hammer technique, but only on a cheap telescope objective. I might get there with this lens, but only after long soaking.

Thanks again for all the great tips!

[Mark Sampson]

Somewhere recently I saw a comparison of penetrating oils. I'd used a spray can of PB Blaster for many years (it was a lifetime supply) but recycled it when I moved. The comparison showed Liquid Wrench was slightly superior- so I bought a can of that. It's worked fine so far... the idea of patience is a good one here. Spray a little on and wait, let it do its work, then try the various methods mentioned above.

[Jim Galli]

... the idea of patience is a good one here.

I don't know how many times I've set a lens down before damage sets in and picked it up a week - month - year later and it just falls apart like it never was stuck. Temperature? Humidity? Alignment of the planets? dunno. I've got a 10X12 Raptar that I've picked up and put down a dozen times over 5 years. Still waiting for that one. Maybe I'll pick it up today and do the PB blaster with the q tip thing and put it back down.

[Bernice Loui]

Kroil/AeroKroil is reputed to be one of the better penetrating oils on the market.
http://www.kanolabs.com/penLub.html

The DIY penetrating oil with a proven record is 50% Automatic transmission fluid, 50% Acetone mixed.


In all cases when using penetrating oils to help loosen a stuck lens cell, swab on with a Q-tip swab or similar. Applying too much risk getting PO on to the lens elements which could adversely affect them.

And yes, time can do wonders.


Bernice





Somewhere recently I saw a comparison of penetrating oils. I'd used a spray can of PB Blaster for many years (it was a lifetime supply) but recycled it when I moved. The comparison showed Liquid Wrench was slightly superior- so I bought a can of that. It's worked fine so far... the idea of patience is a good one here. Spray a little on and wait, let it do its work, then try the various methods mentioned above.

[Paul Kinzer]

Well, I made the plywood lens wrenches and gave them a try, with rubber to provide grip. No luck. I'll get some penetrating oil tomorrow, apply it, and try to be patient.

[Paul Kinzer]

Success! And it didn't even take very much patience. I bought this today at my local auto parts store (just because it was the least expensive of several choices):

173063

I sprayed a tiny bit on a Q-tip and wiped it around the circumference of the lens where the front cell meets the barrel. I wiped off the excess, waited two hours, and did it again. An hour after that, I put a thick rubber band over the cell's exposed ring of metal, and used channel locks to remove the cell. After an initial sticking that took a little effort to break, it let loose and came off easily!

While I was waiting for the stuff to penetrate, I put a tiny bit around the aperture ring. The aperture was very stiff, especially after being upstairs in our home, where we keep it pretty cool in these Wisconsin winters. Immediately after applying it and wiping off the excess, I exercised the aperture, and it instantly got looser. Now it's stiff enough to hold its position, but easy to shift, just like a new lens.

Once I had the front cell off, I was able to take it apart and get at both sides of both elements. The outer lens comes out of the housing completely. It had what I thought was fungus etching in the glass. I had tried to clean it while in the housing, but now I was able to just let it soak in some Dawn dish-washing liquid and water. I left it there for about half an hour, then gently rubbed it with a wash cloth, and finally rinsed it with water, then alcohol. The fungus was gone, as was some residue of something around the edge. The front cell is now cleaner than the rear (which has some extremely fine rub marks in a few spots). Both the inner elements were perfect, so I didn't touch them.

I'm very pleased; thanks for all the help!

[Steve Goldstein]

Another thank you for the help provided in this thread!

I was able to separate the front element of my 24" RDA from the barrel today too. I used Kroil since I've had a can of it for about forever, a little goes a long way! But now that I've got the cell out I can't get it apart. There's some kind of knurled ring on the inside, which of course won't turn :( Is it secured with some sort of thread locker?

[Bernice Loui]

There is a good reason to take the lens cell apart? It is an air spaced cell and highly likely aligned and adjust at Goerz when it was made. Unless there is a very, very, very good reason to take it apart.. do not.


Bernice



Another thank you for the help provided in this thread!

I was able to separate the front element of my 24" RDA from the barrel today too. I used Kroil since I've had a can of it for about forever, a little goes a long way! But now that I've got the cell out I can't get it apart. There's some kind of knurled ring on the inside, which of course won't turn :( Is it secured with some sort of thread locker?

[Paul Kinzer]

There is a good reason to take the lens cell apart? It is an air spaced cell and highly likely aligned and adjust at Goerz when it was made. Unless there is a very, very, very good reason to take it apart.. do not.


Bernice

You make a good point. I'm glad that I did have a good reason, since the outer elements in both the front and rear cells were filthy and needed soaking. I'd be feeling very sheepish right now otherwise, since I know that air-spaced telescope objectives need to be aligned with each other properly for best viewing. Still, on second thought, that's a different case, since images are magnified hundreds of times in a telescope. At lower powers, misaligned elements in a well-made telescope objective are not distinguishable. I plan on using this lens on a 14x17 camera, from which I'll just be making contact prints, so no magnification at all.

By the way, the inner elements are sealed into their housing, but the outer elements just float in the cell housing and drop out when it's turned over. So, care is needed.