Broken SLR for pinhole project advise please

[BADGER.BRAD]

I had the intention of building a pinhole camera in the future then suddenly realized I had a 35mm Zenit SLR with a broken Mirror mechanism which I could use + it is also stuck on B. I was going to put a hole in the body cap but as this gives me quite a low f number due to short focal length this would make it really hard to time exposure. My possible solution was to attach a plastic tube to where the lens mounted to give me a longer focal length vus higher F number, I could then taylor this length to give me a 1 second exposure for sunny days. Does this make sense ? Do you think this would this cause me to have rounded photos ? I'm thinking off looking down a tube and the affect you get !

Thanks all

 

[dmr]

Some time ago I got a laser-drilled .3mm pinhole "lens" with an M42 thread for a few $ at a camera show. It was dirt cheap and an impulse buy. I've tried it a few times, but I can't find any images handy. The best were still life type shots, Fuji 1600 film with several seconds of exposure. The viewfinder is almost useless as you can barely see an image except in very bright light.

Something like this would screw right in to your Zenit. I'm sure you can find these on Ebay.

 

[BADGER.BRAD]

Thanks I'll have a look

 

[Jim Jones]

The image blur with an ideally sized pinhole is proportional to the pinhole diameter. That ideal diameter (and the image blur) slowly increases as the focal length increases. This might not matter for many pinhole images, but should be considered when maximum detail is preferred. A filter to increase exposure time is another option.

 

[Chan Tran]

I was about doing that but then I read the article from Ralph and it said you get better result with large format.

 

[OptiKen]

I picked up a pinhole drilled camera cap for my Zorki from eBay.
Just search pinhole and the mount and you should have lots of offerings on eBay

 

[ransel]

If your exposures are not going to be long enough, like 1/2 second or longer, I have used ND filters - helps so that you don't have to rush the shutter speed / exposure speed.

 

[dmr]

Am I missing something here? You people are talking about ND filters and such, as in LESS exposure.

I haven't played with my pinhole lens for a long time, but I would think we would want faster shutter speeds. I could not get a good image (terribly underexposed) at 1/15, the slowest I can reliably hand-hold. The best ones were indoor still life type shots in bright room light, a few seconds at least, with the tripod, of course.

 

[ransel]

Am I missing something here? You people are talking about ND filters and such, as in LESS exposure....I haven't played with my pinhole lens for a long time, but I would think we would want faster shutter speeds.

I think his shutter speed on the camera was stuck on "B". It would be very difficult out-doors in bright daylight to get an accurate shutter speed (by manually tipping the shutter on "B" mode with finger or cable release) of less than 1/2 second. The neutral density filter would enable him to shoot for longer shutter speeds, like 1, 2, 4, 8 seconds, depending on the ND filter...am I incorrect? Am I misunderstanding his quandary?

 

[BADGER.BRAD]

You got it right ransel very difficult to judge speed of less than a second with just a quick press of the shutter button.

 

[ciniframe]

Curious why you want to use a broken 35mm SLR for pinhole. Any working, mechanical SLR can be used for pinhole. Just obtain a plastic body cap, order up a .2mm pinhole, (there is a supplier in France who sells them for $7 shipped, worldwide) Drill a 1/4 in hole in the plastic body cap, and mount the pinhole with tape on the inside of the cap. The f stop will be around f225 if the pinhole is 45mm from the film. With ISO 100 in bright sunlight exposure would be about 2.5 seconds. Or order a .3mm pinhole for about a 1 second exposure working at f150

 

[Chan Tran]

I think his shutter speed on the camera was stuck on "B". It would be very difficult out-doors in bright daylight to get an accurate shutter speed (by manually tipping the shutter on "B" mode with finger or cable release) of less than 1/2 second. The neutral density filter would enable him to shoot for longer shutter speeds, like 1, 2, 4, 8 seconds, depending on the ND filter...am I incorrect? Am I misunderstanding his quandary?

That's no problem for pinhole photography as exposure requires generally are many seconds so really shutter speed from 1 to 1/8000 are not needed. What he needs are shutter speed of 1 seconds and longer could be in minutes. For that B works just fine. And no definitely you don't want ND filter as typical aperture of the pin hole is f/128 or so and smaller.

 

[Chan Tran]

Curious why you want to use a broken 35mm SLR for pinhole. Any working, mechanical SLR can be used for pinhole. Just obtain a plastic body cap, order up a .2mm pinhole, (there is a supplier in France who sells them for $7 shipped, worldwide) Drill a 1/4 in hole in the plastic body cap, and mount the pinhole with tape on the inside of the cap. The f stop will be around f225 if the pinhole is 45mm from the film. With ISO 100 in bright sunlight exposure would be about 2.5 seconds. Or order a .3mm pinhole for about a 1 second exposure working at f150

I think since his broken camera with 1 shutter speed B is useless in most application but would work fine for pinhole.

 

[ransel]

And no definitely you don't want ND filter as typical aperture of the pin hole is f/128 or so and smaller.

My pinhole for my 35mm camera is .25mm with a F/L of 35mm, giving it an aperture of f/140, which is about 6 stops past f/16.

~ now ~

If I were shooting in bright sun light at ISO 100, my normal exposure reading would likely be 1/125 sec @ f/16.

~ now ~

I need to give 6 stops more time to the pin hole exposure, which would come to about a 1/2 second exposure. If I were shooting ISO 400 film, were looking at 1/8 second exposure in bright sun.

I personally find it easier to get an accurate timed exposure (If the exposure time is dependent on my thumb on the cable release for accuracy) if I shoot at least one second - an that is where a ND filter comes in handy.

 

[RalphLambrecht]

I had the intention of building a pinhole camera in the future then suddenly realized I had a 35mm Zenit SLR with a broken Mirror mechanism which I could use + it is also stuck on B. I was going to put a hole in the body cap but as this gives me quite a low f number due to short focal length this would make it really hard to time exposure. My possible solution was to attach a plastic tube to where the lens mounted to give me a longer focal length vus higher F number, I could then taylor this length to give me a 1 second exposure for sunny days. Does this make sense ? Do you think this would this cause me to have rounded photos ? I'm thinking off looking down a tube and the affect you get !

Thanks all

with pinhole cameras, you control the aperture or f number wiyh your pinhole diameter;Why change the focal length? BTW I finfind f/180 or f/256 very handy for pinhole cameras because they are an easy conversion from what a hand-hrld meter will suggest.

 

[BADGER.BRAD]

This was purely down to being able to control exposure time to something I could count and have an aperture I could make myself with easily available drills of a known diameter to make f number calculation easier Ralph.With such a short focal length (38MM) I couldn't find a drill small enough to give a longish exposure time.

 

[Jim Jones]

This was purely down to being able to control exposure time to something I could count and have an aperture I could make myself with easily available drills of a known diameter to make f number calculation easier Ralph.With such a short focal length (38MM) I couldn't find a drill small enough to give a longish exposure time.

That's true. Perhaps one could make a spade bit from a length of .008 inch spring wire, but it is easier to do the dimple method on thin shim brass. One technique for such small pinholes is to use sewing pins instead of needles. Punch the pin through the shim stock and hone down the pin's tip together with the bur on the pinhole. Removing the pin will help clean up much of the burs on the pinhole. If the hole is still too small, hone off any burs from the pin's tip, insert it slightly further into the pinhole, and repeat the process. If you overshoot the size of the pinhole, mark its diameter and save it for any future use.

 

[ransel]

I just made a pinhole adapter (from a spare plastic body cap) for my digital SLR:

F/L - 35mm
Pinhole diameter - .25mm
Aperture - f/140

I used some very thin copper sheeting, very small sewing needle, and some very fine jewelers "sand paper", like about 600 grit or higher.
Just takes a very gentle hand to poke a small hole in the copper, twisting it as you apply slight pressure, then checking with a ruler that has a mm scale - I use a very inexpensive clear plastic ruler and lens for magnifying so I can get an idea of the hole I have made.
If I am close, I just polish both sides to get rid of any bur I made with the pin. When I am satisfied I blow the hole clean and check with the magnifier. I blacken the inside with either a black sharpy marker, flat black spray paint, or hold it close to a candle flame with tweezers so the soot collects on the metal. This last one I used spray paint, then when mostly dry I gently insert the needle in the hole to clean it if any stray paint or microscopic dust particles.
Note - I usually don't use aluminum can because I have found it difficult to get a good round hole - seems it always tears, making it more oblong in shape.