Help :( Aperture blades don't open to the correct size but stay the same when set to lower numbers (contax 159mm SLR)

Hi, I'm a bit sad to find out that on my Contax 159mm SLR has a problem, again.
The blade opening when selected at smaller apertures appear to be the same size... for example on 28mmf2.8 lens, f2.8 and f4 opens correctly but anything below is the same size... meaning it would overexpose. Same on the 50mm f1.4 lens, only at f1.4, f2, f2.8 it opens correctly. The camera can detect the selected aperture and shows it in the viewfinder digitally but just doesn't open correctly. Both lenses aperture blades can be closed to the correct size detached from camera and it works properly adapted on digital too.

I did drop the camera once and that made the meter incorrect but it's been working okay, and I usually shoot wide open so I didn't notice the problem until I test fired and looked at the opening.

Any help would be appriciated!

On a Contax/Yashica camera, with the lens off the camera, the lens should stop down to the selected aperture. If you look at the lens from the rear, at the bottom there is a lever, flicking this lever to the left should open the lens to full aperture for viewing. (There is another pin near the top of the lens that moves as you turn the aperture ring, that's how the lens communicates aperture setting to the camera).

When you look at the camera without lens, at the bottom of the lens mount, there is a lever that sits to the subject's right, holding the aperture open for viewing. When you fire the shutter or press the DOF preview button, this lever should move all the way over to the left (subject's left, photographer's right), allowing the lens to stop down fully.

My guess is that one or more linkages are bent or restricted after dropping, resulting in incorrect metering and the body not allowing the lens to stop down fully. It would help to see pictures of the body's lens mount.

reddesert said:

On a Contax/Yashica camera, with the lens off the camera, the lens should stop down to the selected aperture. If you look at the lens from the rear, at the bottom there is a lever, flicking this lever to the left should open the lens to full aperture for viewing. (There is another pin near the top of the lens that moves as you turn the aperture ring, that's how the lens communicates aperture setting to the camera).

When you look at the camera without lens, at the bottom of the lens mount, there is a lever that sits to the subject's right, holding the aperture open for viewing. When you fire the shutter or press the DOF preview button, this lever should move all the way over to the left (subject's left, photographer's right), allowing the lens to stop down fully.

My guess is that one or more linkages are bent or restricted after dropping, resulting in incorrect metering and the body not allowing the lens to stop down fully. It would help to see pictures of the body's lens mount.

Click to expand...

Hi, Thanks for the info! I've attached some photos:
50mm f1.4 at F1.4 off camera

50mm f1.4 at F16 off camera

SLR mount
SLR mount when fired (bulb)

I did notice the level on the body didn't go all the way to the left when fired, it looks like it's stopping in the middle? and I did encounter a problem with the DOF preview button before, when I pressed the DOF button it got stuck and it took me a while to wiggle it out so I never pressed it again.

Please let me know what you think, really appriciate it!

The photos are helpful, but I get a permissions error if I try to click on them to enlarge. Either they are too small or you have some Photrio access permission set that doesn't allow people to see your attachments. The files all have names like "wechat-image-something", try uploading the photos taken with the camera app, not sent through Wechat.

But anyway, from the last photo on "B," I can tell that the stop-down lever is not moving far enough to the left. It should move all the way left, to a point behind the bayonet flange. I don't know if the lever is bent, or if there's something wrong with the DOF preview mechanism that is fouling it, and from the small photo one can't say more. (BTW, it doesn't look like the upper aperture sensing lever for the meter is out of position. It should move from that position if you push it to the right, and then spring back.)

This is what a Yashica FR I looks like fired on bulb, so you can see where the lever ought to be.

reddesert said:

The photos are helpful, but I get a permissions error if I try to click on them to enlarge. Either they are too small or you have some Photrio access permission set that doesn't allow people to see your attachments. The files all have names like "wechat-image-something", try uploading the photos taken with the camera app, not sent through Wechat.

But anyway, from the last photo on "B," I can tell that the stop-down lever is not moving far enough to the left. It should move all the way left, to a point behind the bayonet flange. I don't know if the lever is bent, or if there's something wrong with the DOF preview mechanism that is fouling it, and from the small photo one can't say more. (BTW, it doesn't look like the upper aperture sensing lever for the meter is out of position. It should move from that position if you push it to the right, and then spring back.)

This is what a Yashica FR I looks like fired on bulb, so you can see where the lever ought to be.

View attachment 340367

Click to expand...

Hi, Thanks for showing me this, yes the bottom level on my body only moves to the middle. Do you have any idea how this could be fixed?

Qiuhong said:

Hi, Thanks for showing me this, yes the bottom level on my body only moves to the middle. Do you have any idea how this could be fixed?

Click to expand...

I imagine that it could be fixed, by a trip to a capable repair shop, but I can't say how quickly or easily or costly. There's no way to tell from the tiny picture you uploaded what could be wrong. It could be something like the lever is bent from getting caught on the lens linkage by a clumsy lens dismount (this happened to me with my second SLR; IIRC the shop fixed the lens right away with a pair of pliers and I paid them to fix the body, or the other way around). Or it could be that the DOF preview mechanism is jammed, since you had a problem with that earlier. Or there could be something out of position at the lever pivot, which is under the mirror box I think.

Anyway, I think the simplest thing you could do to get photographing again would be to find a compatible and working Contax or Yashica body (there are a zillion Yashicas out there that are pretty inexpensive), while you figure out what to do with this one, plus that should get you a working light meter. That would be more productive than obsessing over which Zeiss lens is the best (I'm sure they're all good).