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11-21-2010, 07:17 AM   #1
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aperture problem w/ 400 mm lens

Lucky me! I was the lone bidder on a Vemar 400mm f6.3 m42 lens on eBay. Got it for under $10. The seller had a > 99.5 % feedback with over 3000 transactions. The lens arrived yesterday.


The lens has a pair of aperture rings, and I don't think they're working correctly.

First of all, I can't open the lens beyond f8. At this setting, I can turn the outer aperture ring (it clicks at each stop), but looking in the lens, nothing moves. If I stop down to f32 with the inner ring, the rings are coupled and the outer ring moves, also. This does close the blades (more on this later). When both rings are set to f32, the inner ring turns and moves the blades, but doesn't click.

What appears even worse are the blades themselves. Here's a photo of the lens wide open:

Note the strange helix formation - hard to see in the photo, but it seems that this thing is on a three dimensional axis. And things don't look much better when the lens is stopped to f22:

As for the blades themselves, do they look bent?


So, am I correct in supposing this aperture ring is broken? Would it be at all worthwhile to attempt to fix this myself? I'm reluctant to return the lens, as the shipping cost would probably be the same or more than I actually spent on the thing, and the glass looks clean.

Thanks for any help.

11-21-2010, 08:00 AM   #2
Zav
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Yes you are correct. The aperture is totally messed up.
If you have free time you can still try to fix it. But it's not worth a lot I think as a lens.
Maybe you can get crazy bokeh with this crazy aperture
11-21-2010, 08:31 AM   #3
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The aperture is a preset type, I'm too lazy to write up my own explanation so I'll quote Wheatfield from a Google search I did:

QuoteOriginally posted by Wheatfield Quote
There should be two aperture rings. One is used to "preset" the aperture, the other one is used to actually stop the lens down to that aperture.
In use, you would set the aperture ring to the shooting aperture (lets say f/8), which, with old viewfinders, could make for a very dim focusing screen.
So, you would open the lens up with the second ring, focus and then turn it until it stops, which would put you at the preset aperture for shooting.
It was a way of allowing for fast aperture setting without having to count clicks.
The first ring has a red dot at F8 so from what you explained it seems to work correctly. The aperture blades however, really messed up.

From the look, very long and slim lens I'm guessing it has very simple formula (not retrofocus?), and from what I read usually you can open these kind of lens easily without having to mess up with the glass elements inside. Since it's cheap and there's no point returning it, I say open it up and try fix the aperture. At least you'd learn something from it, hopefully
11-21-2010, 08:52 AM   #4
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If you decide to repair it a few tips.

Looking at Pic #4, those circles on the Diaphragm Ring are where the blades mount.
The blades are laid onto these 'circles', there's a hole in one end of the blade. You'll install the blades with a slight over lap, ie as if your laying out cards.

The Diaphragm is sandwiched against another circular disc. Hardest part is keeping the 2 together and then mounting in the housing.

Go here......Camera Collecting and Restoration

similar design of diaphragm and will give you an idea what the part layout is.

If a blade is bent, you're out of luck.

If it needs to be cleaned use Ronsonol Lighter fluid and let it air dry.

Good Luck, it's tedious but fun.

11-21-2010, 05:15 PM   #5
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the post by Thazooo is very good, and the photos in the link show a lot of what is going on.

I have a soligor 135mm macro bellows lens that has the same problem.

the real issue is that on many cheap lenses, the pins at the end of the blade are meerly the material punched through the blade itself and one end is swaged over to stay with the fixed part of the lens, and the "free end rides in milled slots.

the problem is that when these parts wear, there is nothing to keep the blades attached.

additionally, once bent, the blades need to bee peaned flat. I fixed mine with a hammer, litteraly, hitting them flat against an anvil.

If you decide to proceed forward, good luck it takes time and can be frustrating
11-21-2010, 05:25 PM   #6
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WOW! that looks bad. I would contact the seller, it may have been damaged in shipping and I would think he would rather refund you than risk a negative on a low priced item. It might take some crazy looking pictures though.
11-22-2010, 05:31 AM   #7
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Thanks for the responses. I checked the link that Thazoo posted, and it looked promising. The lens was fairly easy to disassemble, but the aperture assembly itself isn't very accessible (located at the end of a long tube which seems welded on.

The problem is that about 3 or 4 of the aperture blades have become dislodged from their pivot points. If you look at the last photo, you can see the pins which hold in the blades as those small circles around the edge of the ring. They're not quite as bad as Lowell said - there is a pin so they're not simply punched into the ring - but they're become completely dislodged. How this occurred is quite a mystery - there is no sign of prior disassembly of this lens, nor is there any blemish on the exterior that would show the cause of enough trauma to knock these things loose. At any rate, it's not a simple DIY repair.

Once I get the lens back together, I'll contact the seller and wee what he says. The lens might produce some interesting bokeh, but I don't think it will be very useful for shooting birds.
11-22-2010, 02:53 PM   #8
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Chalk it up to experience.

Even at a great price, and the lens isn't great, it's just never going to be worth it.

Even if the lens ISN'T defective.

You have to be really careful about the brands and models you bid on.

11-22-2010, 03:20 PM   #9
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QuoteOriginally posted by Ira Quote
Chalk it up to experience.

Even at a great price, and the lens isn't great, it's just never going to be worth it.

Even if the lens ISN'T defective.
For sure. I have bought an identical Spiratone 400 lens just for curiosity. It's in good condition but apart from a few shoots to test it out, I never think of using it again. I may use it to knock some burglar entering the house.
11-22-2010, 03:36 PM   #10
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QuoteOriginally posted by Manel Brand Quote
I may use it to knock some burglar entering the house.
I had that 400 Spiratone in like 1972. (I lived in New York where they had their actual stores.)

But back in those days, it was a really big deal. I think it retailed for $69, which was unheard of for a lens of that length.

And I think max aperture was something like 6.3.

Yeah, 6.3!
11-23-2010, 10:19 AM   #11
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QuoteOriginally posted by Ira Quote
I had that 400 Spiratone in like 1972. (I lived in New York where they had their actual stores.)

But back in those days, it was a really big deal. I think it retailed for $69, which was unheard of for a lens of that length.

And I think max aperture was something like 6.3.

Yeah, 6.3!
I've just checked it out and you are right: f32-6.3! No wonder, it's a very long tube!

My curiosity was solely motivated by the personality of Fred Spira. Quite a extraordinary guy.
11-28-2010, 08:33 AM   #12
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Update - seller has agreed to refund purchase price (less shipping). Honest mistake.

I've gotten the aperture assembly out of the lens. Lowell was right - stamped pins in the blades, and some are bent. Rather than try to get the thing to work correctly, I'm considering reassembling the lens without the blades and just shooting wide open all the time. Has anyone tried this before with decent results?
11-28-2010, 11:25 AM   #13
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QuoteOriginally posted by xxDavexx Quote
Has anyone tried this before with decent results?
Nope; I doubt you can take a sharp image with that; try it; who knows what you can came up with. Post the results if you can, just for the fun of it.
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