light defect on picture - what causes it?

[darkosaric]

to tape up every seal with black gaffer tape for this outing

This is what I do with my original Diana F. Duct tape is very important photographic tool .

Often I buy some old cameras on flea markets - play a little and sell them later (usually with no profit ).
What I always do is install new light seals - I got not expensive kit from Micro-tools that is enough for around 50 cameras - I recommend buying this to everybody who likes to play with old cameras.

 

[Truzi]

On my camera, I did fix the leak after figuring out why it wasn't always there (depending on whether leather cover was on or off the camera).

I'm not familiar with your camera, so did a quick Google search to see what it looks like. (The search took less than 3 minutes, let alone reading the thread )
I have a few additional ideas.

Looking at the back of the camera, and where the cartridge sits, I doubt the leak is along the cartridge side, bottom, or top. I suspect the leak is near the take-up spool:
http://oi35.tinypic.com/5bzfif.jpg
(From this page if the link doesn't work: http://tinypic.com/view.php?pic=5bzfif&s=4)

It looks like the leak is in the hinge area. The design of the hinge could let more light in at the hinge area itself than the rest of the seam, possibly giving the triangular shape. Notice the hinges at the far left of this photo:
Dead Link Removed

This link is from a shutter repair page, but I can see a thumb-wheel is used for advance. Being slower to wind than a lever, it may explain the "staggered" leak:
http://www.lomography.com/magazine/tipster/2011/06/13/how-to-repair-smena-8m-shutter-blade
It's not a curtain shutter, so I don't think the leak is from the shutter (though I could be wrong).

From the pictures, I would suspect the bottom hinge area of the back. (It would help to know if you rotated the camera clockwise or counter-clockwise for the photos.)

How I would test this theory (if you feel it's reasonable - remember, I'm mostly guessing):

Load the camera with some cheap/expired film. Take a few pictures - lets say 3 pictures, and make sure the bottom hinge-area of the camera gets exposed to plenty of bright light. Then tape the bottom hinge area (electrical tape or gaffer's tape, something lightproof), and take more pictures, making sure you expose the suspect area to plenty of light. Tape the upper hinge area, take more pictures, etc.

To make sure the area gets light, hold it to the sun before and after taking a picture, or hold it near a bright light bulb. You can even take pictures inside with the lens covered for all it matters, holding the edges of the camera very near a light bulb as stated in the above paragraph - all you really want is to see where the leak is. I bought some cheap expired 800 ISO Walgreen's film just to do this type of thing.

After finding the leak, figure out how you intend to seal it. You could glue-in some wool yarn and/or felt to recreate the seals. This should be relatively cheap.

 

[pbromaghin]

I spent my time reading about a guy with a 4 dollar camera with light leaks, in the spirit of wanting to help.

Then why didn't you?

 

[tkamiya]

I had two thoughts:

I'm wondering if you typically wind your film by moving the winding level in 3 motions. If so, repetitive triangle may be caused by this where as just one when you wind it in one shot.

I had some strange light leak on my old camera. It really wasn't a leak, actually. What was happening was internal reflection causing extra exposure.

On both side of film, there were rollers. When light entered the camera through the lens at certain angle, it would bounce off side of the chamber, hit the area between the roller and the body, then expose edge of the film in this manner.

 

[AgX]

That model has no winding lever but a winding knob.
What can explain that repetitive pattern in the first photo.

 

[shutterfinger]

I found a user manual, in Russian, at http://www.cameramanuals.org/russian_pdf/smena-8-1963.pdf
I found http://www.pentaxforums.com/forums/...91-lomo-smena-8-film-camera-rediscovered.html
by clicking on pictures of a Smena 8 in a google search. https://www.google.com/search?q=Sme...jEMGFogT7o4GgDQ&ved=0CDAQsAQ&biw=1920&bih=951
Both show the back detached from the camera body. Does the back detach?
Both of your light leak samples are in Portrait position while the camera manual and pictures show it in landscape position.
Which way was the camera turned to make the shots, 90° to the right or 90° to the left?

 

[AgX]

There also is a Smena 8M with more modern design.

 

[MartinP]

I bought a Smena 8M from Slovakia out of curiosity. A really simple, moulded-plastic camera with a reasonable triplet lens, 40mm f4, and a leaf shutter giving 1/25 - 1/250 plus B. The results were good enough with 10x15cm prints and could go bigger especially when stopped down a bit. I gather that it was designed as a robust, functional family camera for everyone and it fills (or filled) this role well. There is a simple exposure-guide, based on weather symbols for the shutter-speeds, to give adequate exposure results with negative film.

There are no foam light seals on the camera back, which is hinged at the right side. Light is (or should be) blocked by moulded light-traps around the door, so if any of the moulded channel has been snapped off then you may have found a possible cause of the leak. The only areas where the moulded channels are shallow by design seem to be near the bases of the cassette and the take-up spool. A leak through the shutter button wouldn't enter the film-compartment and a light-leak at the rewind knob looks as though it would be blocked by the knob itself and by the cassette.

The simplest diagnostic test would be the tape idea mentioned by several people. My copy of the camera came in a black plastic "never-ready" case, which looks as though it would already stop leaks from the back of the camera except for the very top of the door. Were you shooting with the camera in the case ? (if so and you still had the light leaks, then maybe try taping the top hinge area).

Edit. The products of Foma, in Hradec Kralove are very well used by many members of Apug. Congratulations for coming from somewhere with a local foto-materials industry, and welcome to Apug!! Somehow I also own a Meopta Flexaret, with a very nice tessar-type lens. Meopta made huge amounts of photographic equipment and I'm sure I'm not the only European still having that gear in their darkroom.