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Jon A.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 25, 2005 - 09:08 pm: | 
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I recently acquired a Topcon RE Super in fantastic condition. The only problem is that the 58mm f1.4 lens will not stop down when using the depth of field preview or taking a picture. I can take the lens off and see that the tab on the body moves. Also, I can move the corresponding tab on the lens and make it stop down. It does not take much effort. But I cannot make it work on the body. The condition of the body is so nice that it looks barely used and makes me think the lens has the problem. There is oil on the aperture blades, but they seem to move smoothly when I move the tab on the rear of the lens with my finger. Should I try and clean the aperture blades too? I do not want to mess with them unless they will eventually cause problems with the lens elements.
Also, the rubber focusing grip is falling apart. It is all soft and malleable. I'd like to remove it and replace it with something, any suggestions? Even cork tape would be an improvement. Thanks for the help! |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 26, 2005 - 07:19 am: |
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My first guess would be that the oil is making the aperture blades stick open, except for your comment that they work well when off the camera. Can you confirm that the body linkage is actually moving the tab on the lens? that's the only other possibility i can think of.
I think leather makes a nice looking replacement for the rubber focusing rings.....
: ) = |
Jon A.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 26, 2005 - 10:41 am: |
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Rick-
I cannot confirm that the body tab is actually making contact with the lens tab. Is there a way to ensure they meet up? I was thinking that maybe a piece broke off of one of the tabs. They are small tabs that any variation in one of them may cause them to miss connecting with each other.
I probably have a problem with the oil on the aperature blades because when I move the tab to stop it down, they do not return to wide open on their own. I think I need to find another Topcon lens to see if my lens is missing something.
Leather is a good idea for the focusing ring, I bet I can find an old scrap piece from something in the house. Thanks for the help! |
rick
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 28, 2005 - 08:03 pm: |
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maybe if you tape a thin sheet of paper to the back of the lens so that if the aperture tab moves in its slot, it will tear the paper.... and then mount the lens and fire the shutter, and remove the lens and see if the paper is torn.
i suspect that the camera is operating the lens linkage, and that the lens is not missing anything, but internal friction from oil is preventing the lens from stopping down. but there are other possibilities, such as a damaged or disconnected spring in the lens linkage...
 = |
Jon A.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 10:07 am: |
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I tried to look at how the tabs would meet up when the lens is on the camera by holding the lens close and turning it like it would turn when I attach it. It looks like the lens should have a spring that pulls the tab that in turn pulls the blades down when the lens is off the camera. When on the camera, the body's tab pushes against the lens tab to open up the lens. So the body's tab spring is more foreful than the lens's tab spring. Then when using the depth of field lever, the body tab moves out of the way and the lens spring pulls the lens tab to close down the blades. I tested this by closing the lens blades and then putting the lens on the camera and the body tab connects with the lens tab and makes the blades open, so they are definitely meeting up.
So, I think you are right that I have either a broken or disconnected spring or the oil on the blades keeps the spring from working. I think I will do some archive searching to see how to take apart a lens and take a look inside for the spring and to clean the oil off. Plus, I found some fungus to clean off too. Thanks again for the help, Rick! |
John Shriver
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 01, 2005 - 06:06 pm: |
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Oil on the blades is a very common problem with this lens. Like most of the Auto Topcors, the mount is all aluminum, so they had to put generous lube on the helicals.
However, since this lens has such a large amount of glass in it, and they didn't want to make the outside too large in diameter, they kind of "squeezed" the design. The slots that hold the slides that keep the parts of the helical from rotating go all the way through in places, which they don't in the smaller lenses. This gives a much shorter path for the lubricant to migrate through from the helicals to the blades!
At any rate, look at the rear of the lens, with the green dot at the top. Set the iris to f/16. The tab on the right (short arc) is the auto-iris, it should be pushed to the top by a spring in the lens. Push it down, and the iris will open, let go, it should spring back instantly.
If you want to go in and clean the iris, here's the drill. Remove the rear of the lens (4 screws), and set aside. Remove the f-stop ring, don't lose the detent ball bearing(s)!
Loosen or remove the three gnat's eyebrow setscrews behind the lens hood mounting ring. Unscrew that front ring.
Now you will see a black spanner ring that holds the lens block into the helical. Almost all Auto Topcors (100mm and shorter) have a black anodized lens block that's held into the focusing mount by a ring like this in the front. You'll need a spanner wrench to remove it.
Now pull out the block. Don't lose the spacer shim.
You can unscrew the front and rear blocks from the aperture module. (Scribe them and the aperture module so you can tighten them the same amount.) Now you can work on the iris. You may need to take it apart to get all the oil out, three setscrews hold the disk on the inside. Scribe that before removing it as well.
You also should clean all the slime out of the inside of the focusing mount, or you'll be doing this again real soon.
There's a nice exploded drawing at:
http://members.cox.net/topcontechnotes/lensexpview/page7.html
on Leon Schoenfeld's site.
http://john.shriver.home.comcast.net |
Jon A.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 04, 2005 - 01:45 pm: |
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Thanks for the help and the link, John. I've been looking to start tinkering with old cameras and this is a good way to start. Another motivator: I found some fungus on the lens that I can clean off while I have it apart. |
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