Hasselblad 80mm stopping down slightly when moved past 2.8

[illumiquest]

I've had the same problem on several 80mm hassy lenses. basically when it's in the preview mode, if you set the aperture on anything past 2.8 the aperture stops down to what looks like F/4. My repair guy says that it's a broken mechanism and whatever is holding the aperture open wears out and lets the blades slip down slightly. I've just seen it on enough that I'm wondering if other folks have had the same trouble and what they do about it.

 

[Q.G.]

Yes. You're repairman is right.
It will still work, though, opening nicely to f/2.8, when you fire the shutter.
So it only results in an a bit dimmer viewfinder.
So i leave it be, until the shutter needs work for another reason, and do nothing (except use the lens) until then.

 

[brucemuir]

hmmm, have not run across this yet.

Could you elaborate what version (C, CF, CFI, CB?)

At first I though the lens wouldn't open fully ...ever.
I guess it's a seperate part in there that holds the aperture open for "dof preview", and another part the stops the lens down to the appropriate aperture after you fire the shutter? ? ?

btw I'm shooting all "C" lenses...

 

[Q.G.]

It's a thing i have only ever seen with (old and tired) C lenses. I think it's confined to C lenses too.

What happens as far as we can see is that the lens will open to the full aperture when set to f/2.8, but closing down to something like f/4 when set to any other aperture. As a result, the focussing screen will be a bit darker than it should be. Not a big deal, i think.
When you fire the shutter, the aperture works perfectly o.k.

 

[bdial]

I've seen lenses that do this, it's really only noticeable when you look at the aperture.
So don't do that.

 

[Andrew K]

I repaired Hasselblads for a while - it is a common problem, and one that cannot be fixed. It is caused by wear and tear on the base of the shutter unit - basically it is something that cannot be repaired without replacing a part (the shutter casting) that is no longer available...

It usually happened to older chrome lenses, although I didi see it on later lenses as well...

It doesn't effect exposure, as if you have your aperture set to 2.8 then the aperture ring holds the aperture fully open. As you said it's only when you stoip down a half stop that the aperture blades "close" a bit...

All my hasselblad lenses have doen this, and it's never caused a bad photo