Mamiya 645AF - strange artificacts? Flare?

rippo · Jul 22, 2011

I have this recurring problem with my Mamiya 645AF. Every once in awhile I get a light 'arc' on the image, as shown below. I don't know if it always happens with the same lens or not. I primarily shoot with my 80mm f/2.8 lens, usually wide open (hey I'm a wedding photographer!). I can't be sure that it's limited to when I use that lens, as I also have a 55mm and a 150mm.

Normal lens flare tends to vary its location depending on where the offending light source is. Not so here. The arc is very consistent. It almost always appears when I'm shooting in the horizontal orientation, although I do have one image I know of with this arc, that was shot vertically. The arc appears always on the same side, and is the same size. I have a vertical version of the last image that does NOT have the arc on it.

I'm pretty sure I've used different film backs, so I don't think it's a back/darkslide reflection or light leak. I don't see anything in the lens that might cause it, and I've had this problem with and without lens shades.

Any idea what could be causing this? It happens frequently enough to be annoying, but not frequently enough to predict. I also have never seen this arc in the viewfinder, FWIW.

brucemuir · Jul 22, 2011

Looks like a possible shutter issue???
Just guessing.
I think the pivot points for the shutter blades are on the opposite site of the frame though.

Does the AF print shutter speeds on the film?
Check the offending frames and see if they all have similar high speeds.

Frank Chambers · Jul 22, 2011

Did you switched orientation of the back before shooting? Even I don't know the 645 but the RZ, it looks somewhat like a light leak of back's orientation switching unit.

MattKing · Jul 22, 2011

Looks to me like a flared reflection off the rim of a filter or lens hood.

rippo · Jul 22, 2011

Bruce, you may be on to something! I don't have the negs back from the lab yet on the images I posted here. So I had to go back and look at some other images. Sure enough, all the images with the arc are shot at 1/2000 or 1/4000. So what does your pivot-point reference mean? Light being leaked in through a sloppy shutter? Something else?

I wish I had the shutter speeds for the mountain images both vertical and horizontal, to see if they're the same. I'll ask my lab to check, as they usually send my negs back to me once a month.

Thanks Frank and Matt. The 645AF doesn't have a revolving back. I haven't ruled out hood reflection but it's unpredictable.

rippo · Jul 22, 2011

Bruce, how about this theory? The pivot points of the shutter are on the same side as the arc, because the image is flipped by the lens. Could it be that light is reflecting off one of the actual pivots? Bouncing from the film to the pivot and then back onto the film, as it arcs across the film plane? I can't explain why it only appears at high speeds though.

Sirius Glass · Jul 22, 2011

Why not take it to a camera repair and ask? There is no obvious answer for the repeated phenomenology.

F/1.4 · Jul 22, 2011

I have something really similar to this I just found on some E100G that I shot off over the last month or so (kept it in a back and just shot one or two pictures on slide for kicks). However instead of my lines being curved, mine are straight and they're through about 3 or 4 frames.

When I get them scanned on Monday, i'll post them up on here so you can see. I use a 645AFD, so they're basically the same camera.

brucemuir · Jul 22, 2011

Rippo,
one theory is the blades are riveted to the control arm that actuates the shutter.
If the rivet wears into the blade at that point it could possibly leak.
IDK this is all speculative but those leaks look very similar to "shutter bounce", a known issue with Canon and probably other cameras.

Shutter bounce is exhibited at the highest speeds but on a Canon they usually run horizontally not vertically. Unfortunately it is a sign of imminent shutter failure.

rippo · Jul 23, 2011

This 645AF body had been ridden hard and put away wet, when I got it. Hotshoe not working, eyepiece flap not working, serial number filed off (yeah i know…). I wouldn't be too surprised if the shutter was near failing too. Yuck.

Ran a roll of film through it this evening, testing it at shutter speeds from 1/1000 to 1/4000, apertures 2.8 to 5.6, with different angles to the sun. Might give me some answers. Leaky rivets are not the answer I'd like.

rippo · Jul 23, 2011

F/1.4 yes please, I'd love to see your scans and see if it's related. Thanks!

brucemuir · Jul 23, 2011

The rivet idea is just a guess.
What can happen on the Canon (some have 1/8000 top shutter @ 8-10 fps) is one blade becomes loose or out of place.
It leaves an obvious lighter slash through the image but it usually runs horizontal and isn't uniform like yours.

I usually avoid even looking at my afd shutter too hard but,
maybe you can see something amiss from the lens side?

I did see a guy on the auction site with replacement shutters but bodies aren't too outrageously expensive if you have an investment in glass.
I actually like the afd system. The lenses kick some serious azzz.

Let us know what happens.

rippo · Jul 23, 2011

Can't lift the mirror while the lens is off, so I can't see the inside of the shutter. And everything moves too fast to spot a problem during firing.

Given the other deficiencies of this body, it would make more sense for me to get a new (used) AF than it would have it repaired. Perhaps I should do that before it fails completely. Will wait and see on Monday's film test results. Thanks!

rippo · Jul 25, 2011

Got the test roll back today. I aimed at the sky with the sun on different sides of the camera (to account for hood flare or something like that). I shot at 1/4000, 1/2000 and 1/1000. The mark is there on all 1/4000 shots, much fainter on 1/2000 shots, and not there at 1/1000 shots. So it does not appear to be hood-based or even lens based, but in fact shutter-related. Yuck.

Sirius Glass · Jul 26, 2011

rippo said:
Got the test roll back today. I aimed at the sky with the sun on different sides of the camera (to account for hood flare or something like that). I shot at 1/4000, 1/2000 and 1/1000. The mark is there on all 1/4000 shots, much fainter on 1/2000 shots, and not there at 1/1000 shots. So it does not appear to be hood-based or even lens based, but in fact shutter-related. Yuck.

That was a great way to test the camera, but the results make me shutter shutter shutter!

I hope that you can find a competent repair man to correct the problem. It does sound repairable with the proper cleaning and lubrication.

Steve

rippo · Jul 26, 2011

Sirius: I'm guessing it's not a CLA issue, but would require a new shutter (if that's the problem). That would probably cost me more than I paid for it.

paul ron · Jul 26, 2011

Light leak.

Sirius Glass · Jul 27, 2011

rippo said:
Sirius: I'm guessing it's not a CLA issue, but would require a new shutter (if that's the problem). That would probably cost me more than I paid for it.

I hope that I am right and that you are wrong.

Good luck with it!

paul ron · Jul 27, 2011

I'm looking again at the photo examples and it seems to be in the exact same place in all the frames, top left corner. This tells me a light leak, but I see everyone blaming the shutter or some lose rivit of a blade. The shutter is a verticle blind focal plane if I am correct... why an arc radiating from the lower right corner of the negative when properly oriented in the camera?

To rule out the shutter theory, simply change the lens and try another back one step at a time to see what is leaking.

.

Sirius Glass · Jul 27, 2011

paul ron said:
I'm looking again at the photo examples and it seems to be in the exact same place in all the frames, top left corner. This tells me a light leak, but I see everyone blaming the shutter or some lose rivit of a blade. The shutter is a verticle blind focal plane if I am correct... why an arc radiating from the lower right corner of the negative when properly oriented in the camera?

To rule out the shutter theory, simply change the lens and try another back one step at a time to see what is leaking.

.

OK, back to basics and using Occams Razor.

Occam's Razor is a line of reasoning that says the simplest answer is often correct.

Good idea.

redstarjedi · Aug 31, 2014

Hello. My mamiya 645af just developed this problem. In the bottom left corner i get what looks like a light leak. It's a uniform triangle that cuts across the negative, it's in the shape of those old corner savers you'd put on prints. Most of the frames that i shot at a high shutter speed had this problem, the ones at a low shutter speed didnt. I used only one lens the 45mm f/2.8

rippo · Sep 2, 2014

redstarjedi said:
Hello. My mamiya 645af just developed this problem. In the bottom left corner i get what looks like a light leak. It's a uniform triangle that cuts across the negative, it's in the shape of those old corner savers you'd put on prints. Most of the frames that i shot at a high shutter speed had this problem, the ones at a low shutter speed didnt. I used only one lens the 45mm f/2.8

The artifact I experienced was a pale arc across one side of the image, that only appeared at the very highest shutter speeds. I wouldn't call it triangular, but it's possible that it's still a shutter issue. I ended up selling the body (which was pretty beat up anyway) and buying a replacement body. I've had no problems since then, so it wasn't a back or some other issue related to something other than the body.

rippo · Sep 2, 2014

Do you have examples you can post?

Mamiya 645AF - strange artificacts? Flare?

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