Need help removing lens from lens board

[saman13]

I got this lens already attached to a Busch Pressman lens board, but I can’t get it off! There isn’t a simple retaining ring like on other lenses I’ve seen. I’ve tried to get it off so I can take measurements of the dimensions of this lens board for the past 5 days or so with no luck. Am I just dense or is there no easy way to remove the lens?

 

[Sirius Glass]

Try a lens wrench.

 

[Dan Fromm]

Instead of a retaining ring it has a flange. That's the disk with three countersunk holes. I'd be tempted to hold the shutter with one hand and the flange with a jar lid remover. Unscrew the flange from the shutter.

My dial calipers will measure that board, why can't yours?

 

[shutterfinger]

As Dan says its a mount flange not a retaining ring, a common practice in the day. Put a lens spanner wrench in 2 of the three holes then turn both the shutter and spanner counter clockwise at the same time.

 

[saman13]

This is what I've tried the whole time. This particular lens might be destined to stay on this lens board.

 

[BradS]

Maybe, there is some other way to get the dimensions of a Busch Pressman lens board... ????

 

[jim10219]

Unscrew the lens elements first, and put them somewhere safe. That way you don't scratch them. Then, you can try dropping some penetrating oil around the retaining ring threads, and see if that helps. If that doesn't do anything, try some acetone. Sometimes they glue stuff in, and acetone is great at eating old glue. It's also great at eating plastic and paint, so be very, very careful with it. If you're not sure about using acetone, use rubbing alcohol and see if that helps. Rubbing alcohol is a lot safer, and while it doesn't east as many types of glue, it also doesn't eat as many types of paint or plastic.

If that doesn't work, you can try heating or freezing it. The idea here is to make either the retaining ring, or the shutter metal contract or expand enough to loosen it's grip. Try throwing the whole thing in the freezer (minus lenses) for a bit and see if that helps. If not, try running heating it up with hair dryer. Don't go rapidly from one to the other though. Rapid swings in temperature can cause things to break. Also, if there are any plastic pieces, be careful with the hair dryer. Don't let anything plastic get too hot, or it might melt.

Those are techniques I use to get things unstuck. When working on old cameras, finding things stuck together is pretty common and one develops several techniques to deal with them.

 

[saman13]

I thought it would be easiest to get some spare ones made by bringing a lens board in to a machine shop. However, if I do this I did not want to leave a lens and shutter attached.

I was also going to try my hand at making my own, and being able to have the flat lens board lay on the material I'm using would be helpful. Just measuring the dimensions does not help me much because the corners are rounded.

 

[saman13]

Unscrew the lens elements first, and put them somewhere safe. That way you don't scratch them. Then, you can try dropping some penetrating oil around the retaining ring threads, and see if that helps. If that doesn't do anything, try some acetone. Sometimes they glue stuff in, and acetone is great at eating old glue. It's also great at eating plastic and paint, so be very, very careful with it. If you're not sure about using acetone, use rubbing alcohol and see if that helps. Rubbing alcohol is a lot safer, and while it doesn't east as many types of glue, it also doesn't eat as many types of paint or plastic.

If that doesn't work, you can try heating or freezing it. The idea here is to make either the retaining ring, or the shutter metal contract or expand enough to loosen it's grip. Try throwing the whole thing in the freezer (minus lenses) for a bit and see if that helps. If not, try running heating it up with hair dryer. Don't go rapidly from one to the other though. Rapid swings in temperature can cause things to break. Also, if there are any plastic pieces, be careful with the hair dryer. Don't let anything plastic get too hot, or it might melt.

Those are techniques I use to get things unstuck. When working on old cameras, finding things stuck together is pretty common and one develops several techniques to deal with them.

I'll try using alcohol. Forgot about that trick.

 

[BradS]

I thought it would be easiest to get some spare ones made by bringing a lens board in to a machine shop. However, if I do this I did not want to leave a lens and shutter attached.

I was also going to try my hand at making my own, and being able to have the flat lens board lay on the material I'm using would be helpful. Just measuring the dimensions does not help me much because the corners are rounded.

I have not looked recently but Midwest Photo, Dead Link Removed used to sell brand new lens boards for the Busch Pressman 4x5. you might call them or send them an email (their website seems to not accurately reflect their true inventory).

Another thought, surely a machine shop could figure out the dimensions of the lensboard without needing to remove the shutter...they probably could remover the shutter pretty easily too...

 

[saman13]

I found at least one place to make the 4x5 Pressman lens boards, but I have a 2x3. They seem to be in short supply.

 

[shutterfinger]

If you're not sure about using acetone, use rubbing alcoho

DO NOT use rubbing alcohol, it contains water and oil, use 90% Isopropyl Alcohol.
Penetrating oil on the threads left overnight to two days should do the trick. The mount ring/flange has a tendency to fuse to the shutter after many years and may require 100+ foot pounds of torque to break loose.

 

[BradS]

I found at least one place to make the 4x5 Pressman lens boards, but I have a 2x3. They seem to be in short supply.

Again, I suggest that you give the good folks at Midwest Photo a call. They used to sell both sizes...I think they were having them custom made, which means they have dimensions, and possibly CAD drawings.

 

[Mr Bill]

I was also going to try my hand at making my own, and being able to have the flat lens board lay on the material I'm using would be helpful. Just measuring the dimensions does not help me much because the corners are rounded.

Hi, if it turns out to be too much trouble to get the lens loose, there are still ways to get "good enough" measurements. The rounded edges are likely a "fixed radius," that is, a circular shape. You can make your own "radius gages" by using a cheap carpenter's compass to draw some circles on stiff paper. Measure the inside diameter as best you can (radius is one-half diameter), using a good-quality rule under a magnifier. Then label each before using a scissors to cut a small-enough section that you can hold underneath a corner of the lens board. (Don't try to cut out the radius; just get the piece small enough to hold against the lens board while you match up the pencil circle.) Use trial and error to get a close-enough match.

Once you have the correct radius, keep in mind that the center of radius may not be placed to perfectly blend into the sides of the lens board; it may be placed a bit further out. So measure the diagonal of the lens board vs theoretical to confirm (this will take a little mental gyration on top of some mechanical aptitude).

Anyway, once you know the measurements, closely enough, you can mark out directly on metal, or whatever, or even on stiff paper to use as a template. Just an alternative way to do things.

 

[saman13]

I got it off! I let some 99% isopropanol soak down into it, gave it a few taps with a hammer, then used a spanner wrench in two of the holes to break it loose. It must have been on that lens board for a while because it was really on there.

Got my new lens mounted on it without an issue. Still want to pick up one or two other lens boards so I might give Midwest photo a call.

Thanks for all your help

 

[shutterfinger]

Good job.