Stumped by odd flare / light leak / ?

[Dante_Stella]

I bolted my 57/1.2 Hexanon onto my Autoreflex T4 (not a normal combination) and basically screwed around a little re-learning to focus the lens. I have never seen anything like this with a rangefinder, so I must conclude it is some odd and unwholesome characteristic of SLRs.

When I ran the negatives (Ektar 100), I was surprised by what looks like strange flare or light leaks. The marks do not occur in every frame, nor do they bear any relationship to where the sun is in relation to the camera. They occur most often wide-open. Where they crop up, they are always inside the frame by about 1mm. If you were looking at the back of the camera, they would be in the upper right corner.

So far I have eliminated:

• Cartridge light leak (because it would be a red band cutting vertically);
• Negative processing problem (because it would spill out of the frame);
• Camera back light seals (which look fine); and
• Bare metal parts inside the camera.

What am I missing here?! I thought it might be some kind of reflection from the mirror as it swung up, but my eye would have been blocking the viewfinder.

Dante

 

[ChrisN]

Is the flare bound within the edges of the frame, or extend out to the edges of the negative, and across the borders between frames?

 

[Dante_Stella]

Totally inside the frame. So I know it's not an exterior light seal.

 

[Jon Goodman]

From the color, we know it is light striking the front side of the film and not the back side. I'm going to say lens flare or some abnormal reflection within the lens. I have seen this occur with a lens which has been serviced badly and on which was left grease or oil on an internal side of an element (usually smeared when trying to clean). Good luck. Without looking at the lens, it is hard to say where in the haystack the needle might be.
Jon

 

[pvdhaar]

Have you checked the mirror seals? If there's a leak when the mirror's up, light can enter through the finder from behind (the prism makes it bounce around in all directions), and make these kind of streaks.

You could check by dismounting the lens, shining a torch throught the mount, and trip the shutter when on bulb. The finder should completely black out (mirror-up), no light from the mount should peep through the mirror seal into the prism..

 

[pau3]

If the marks are inside the frame, the light is coming from the lens side. Also, the problem looks the same when it appears (which may discard flare, strongly varying with the light direction), and only happens intermitently. I would suggest that is some kind of shutter problem related to a (probably) single faulty speed. You could run a test on all shutter speeds (or the ones you think you use) just to discard my hypothesis.

Pau

 

[alcaraban]

If it is a lens or lens/body issue, I would open the back, put the shutter speed in bulb, place a strong light source in front of the lens and check the image where the film is supposed to be.

From the color, we know it is light striking the front side of the film and not the back side.

Could you elaborate a little? How would it be different?

 

[former member]

I had a similar flare problem with a Contax IIIa. The shutter was not properly capping when advancing the film and cocking the shutter. It only occurred at 1/500 and 1/1250. At first, I thought it was the lens being used wide open- but that was indirectly coupled to using the high speeds.

 

[Muggins]

Light coming through the back of the film will be filtered by the backing, which is usually orangeish. So leaks from the back of the camera will appear orange-red, rather than white.

Adrian

 

[Dante_Stella]

Greg Weber sent me some instructions on how to isolate this; could be the rewind button, viewfinder, or mirror. I'll try to debug it.

Brian, the capping thing is interesting - since the reflection looks like it could be from a mirror that is not all the way up (or down).

It's definitely not grease in the lens (that would be too easy!).

Dante

 

[payasam]

Dante, only the front side of the mirror should be reflective. The back -- the film side -- should be a flat black.

 

[Dante_Stella]

Everything in the mirror box is a dead black. My guess is that light is getting piped along the retracted mirror.

Lens is completely clean and exhibits no reflective metal surfaces.

We'll see with some debugging...

D

Dante, only the front side of the mirror should be reflective. The back -- the film side -- should be a flat black.