Lenscap Pinhole for 35mm

[paladin1420]

I have played with a pinhole in a body cap for my Argus slr (pentax m42 mount). It works pretty well, but I'm hoping to get more of the whole image circle into the frame. I think the pinhole is too far from the film.

I was wondering if it would work better using a rangefinder camera with a focal plane shutter. I think that the distance from the body cap to the film would be less but, since I don't have a rangefinder right now I'm only guessing.

Has anyone ever done this and would the difference between an slr and rangefinder be noticeable with a body cap pinhole?


Thanks

 

[Jim Jones]

A recessed body cap pinhole could be improvised to work with mirror lockup on an SLE to give a somewhat wider view. A rangefinder camera might be a bit better. The once ubiquitous Argus C-3 would be a good candidate for this

 

[rwyoung]

Making one is fun but if you are feeling lazy, pinholebilly over on Ebay does a nice job. I can't remember if he specifically has an M42 cap available but he does say that custom products can be made. Also try him at www.pinholeedun.com

Not a paid advertisement, just happy with the product...

 

[removed account4]

i bought my pinholes from him years ago.
really nice guy.

john

 

[paladin1420]

I already have a M42 pinhole cap. My problem is that I don't have mirror lock (at least I think I don't) on my SLR, so a recessed pinhole is a problem.

 

[paladin1420]

A recessed body cap pinhole could be improvised to work with mirror lockup on an SLE to give a somewhat wider view. A rangefinder camera might be a bit better. The once ubiquitous Argus C-3 would be a good candidate for this

I have an old argus C2, but the shutter is part of the lens. Is it the same with the c3 or did the c3 have a focal plane shutter.

Thanks

 

[Murray@uptowngallery]

C-3 has a leaf shutter, somewhat in front of the focal plane. I am not at home with a C3 to measure

I mounted a pinhole on a Deckel mount from a broken Kodak Retina Reflex lens and installed it like a lens. I think it was 41.5 mm in my case (ended up slightly recessed, I guess). The camera flange distance is 44.7 mm. Coverage and angle of view were 'normal', and I never noticed (nor expected) light falloff at that distance. The problem with this configuration is that I could never do a wide angle. The mirror was not a problem in the 'mount in front of shutter' configuration.

See the link below for others.

Dead Link Removed

Maybe I misunderstood your comment on distance from the film plane.

Nearly all SLR lenses are 'retrofocus' so, for example, a 200 mm lens need not be 200 mm from the film plane at infinity focus (as it need be in a view camera with a non-zoom lens).

I would assume the standard 50 mm lens on a C3 is not retrofocus. I don't know the lens flange distance but would assume it is 50 mm minus the distance from the flange mount to the relevant lens node (1. I don't know which one is important 2. Far easier to just measure the flange to film plane distance and note that it is probably less than the lens f.l.). Actually, looking at the referenced link above, there are some flange distances on some RF's that are shorter than typical SLR's.

Contax RF is 34.85 mm
Canon screw mount 28.8
Leica screw mount 28.8
Narcissus (here's lookin' at you) 28.8

So if Argus was thinking at all like everyone else, it may be on the order of 29 mm.

You could possibly (probably) accomplish a wide angle camera construction with a short flange distance RF, depending on the location of the pinhole vs. the shutter.

I once converted a Kodak 35 RF with a bad lens. When I was done I had a bad shutter too. I used aggressive double stick tape and slipped and got some on the shutter. Initially I left the lens body intact for looks, but it created a round image. I later took the lens barrel off and used a refrigerator magnet for a shutter after gluing a metal ring on the camera.

 

[paladin1420]

C-3 has a leaf shutter, somewhat in front of the focal plane. I am not at home with a C3 to measure

I mounted a pinhole on a Deckel mount from a broken Kodak Retina Reflex lens and installed it like a lens. I think it was 41.5 mm in my case (ended up slightly recessed, I guess). The camera flange distance is 44.7 mm. Coverage and angle of view were 'normal', and I never noticed (nor expected) light falloff at that distance. The problem with this configuration is that I could never do a wide angle. The mirror was not a problem in the 'mount in front of shutter' configuration.

See the link below for others.

Dead Link Removed

Maybe I misunderstood your comment on distance from the film plane.

Nearly all SLR lenses are 'retrofocus' so, for example, a 200 mm lens need not be 200 mm from the film plane at infinity focus (as it need be in a view camera with a non-zoom lens).

I would assume the standard 50 mm lens on a C3 is not retrofocus. I don't know the lens flange distance but would assume it is 50 mm minus the distance from the flange mount to the relevant lens node (1. I don't know which one is important 2. Far easier to just measure the flange to film plane distance and note that it is probably less than the lens f.l.). Actually, looking at the referenced link above, there are some flange distances on some RF's that are shorter than typical SLR's.

Contax RF is 34.85 mm
Canon screw mount 28.8
Leica screw mount 28.8
Narcissus (here's lookin' at you) 28.8

So if Argus was thinking at all like everyone else, it may be on the order of 29 mm.

You could possibly (probably) accomplish a wide angle camera construction with a short flange distance RF, depending on the location of the pinhole vs. the shutter.

I once converted a Kodak 35 RF with a bad lens. When I was done I had a bad shutter too. I used aggressive double stick tape and slipped and got some on the shutter. Initially I left the lens body intact for looks, but it created a round image. I later took the lens barrel off and used a refrigerator magnet for a shutter after gluing a metal ring on the camera.

Murray,

That's a bunch of info, thanks. Pardon my ignorance, but what's a Deckel mount?


I guess first I should try to figure out how close the pinhole needs to be to the film so that the image circle is just about the diameter of a frame.

Next, I realize that in my original post I claimed to not own a rangefinder, then went ahead in my next post and mentioned the c2. To clarify, I meant that I didn't own a rangefinder with interchangable lenses. The c2 has a fixed lens, although I have taken it off so I suppose it is a candidate.

On my Argus STL 1000 (the slr) the front of the body where the body cap sits, is about 47-48mm from the film plane. The mirror swings to within 10 mm of the front, so I guess I could get a recessed body cap pinhole to about 38mm from the film without interfering with the mirror. Would that get the image circle where I want it? I have to look up that calculation.

On the argus c2, it looks like the shutter is about 35-37mm from the film plane. I got the glass part of the lens off, but I can't see how to take out the inner threaded piece or the ring that connects to the range wheel. I suppose I could do something recessed, if I could figure out what the inside thread measurement was. Is that a good direction to go in?

(all measurements are approximate, I was trying not to poke the ruler through any shutters)


Thanks

 

[Murray@uptowngallery]

Deckel mount:

Well, maybe I didn't even need to bring it up, but since I did,
it's the bayonet mount on the Kodak Retina Reflex S.

I don't know if there was ever a body cap for that camera, and I don't want to spend more money on it at this time, and I had previously considered hacking a Japanese zoom lens onto that lens mount. It was the easiest removeable way to switch between pinhole & lens for me.

Nagel made the German-made Kodak Retinas and Deckel is who developed the mount. It's apparently used in slightly modified form on some other Geman cameras (Contax maybe?)

 

[Murray@uptowngallery]

People call the C-3 ubiquitous (found everywhere).

I have three and can't find ANY right now. (Another 3 victims of my basement). I was going to measure.

Using the nominal 24x36 mm frame dimensions, not knowing if they are actual, I get 43.3 mm diagonal. That's why my 41.5 mm distance looked so 'normal'.

Some people get tired of the very wide angle camera constructions, but I like them (say, an f.l. less than half the diagonal length) because they look so different from 'normal' angle of view.

I have to break the habit of shooting 'normal' subject matter in a 'normal' angle of view pinhole camera. Due to my choice of subject matter, I get what look like blurry normal camrea pics. Very wide angle solves some that for me (called gimmickery by some, however).

 

[paladin1420]

People call the C-3 ubiquitous (found everywhere).

I have three and can't find ANY right now. (Another 3 victims of my basement). I was going to measure.

Using the nominal 24x36 mm frame dimensions, not knowing if they are actual, I get 43.3 mm diagonal. That's why my 41.5 mm distance looked so 'normal'.

Some people get tired of the very wide angle camera constructions, but I like them (say, an f.l. less than half the diagonal length) because they look so different from 'normal' angle of view.

I have to break the habit of shooting 'normal' subject matter in a 'normal' angle of view pinhole camera. Due to my choice of subject matter, I get what look like blurry normal camrea pics. Very wide angle solves some that for me (called gimmickery by some, however).

That's exactly how I got into this to begin with. The pictures from the bodycap pinhole - just about normal focal length for 35mm - look, well, normal. Like they were taken with a crummy glass lens. I guess I was expecting some distortion or vignetting. That's why I want to get the pinhole closer.

If I was going to attempt this with the C2, do I have to remove the whole lens assembly, or should I try to get something to screw into the inside threaded tube that the lens fits into?

Thanks,

 

[jolefler]

Related, but slightly off topic.

My scenario may provide additional input for the OP.

I used an Argus C4 for the pinhole I'm casually working on currently. It measured 29mm from the pinhole to the film plane. I also hogged out the 24X36mm frame in the body to 24X52mm for a more panaramic format.

My first tests showed complete coverage of the new frame, but the center of the frame showed overexposure (more like fogging) when compared to the edges....would this be attributed to too large a pinhole diameter? The correct exposure from the film test indicated about 2 seconds in sunny but high, light cloud cover conditions with ASA 400 speed film.

The other problem I have is with the film advance. I measured 2 1/2 turns of the winder to give me spacing on the first frame. I thought as the diameter of the take up spool increases, I'd have larger frame spacing....but quite the opposite happened.

Thanks for your replies, in advance.

 

[Pitxu]

Hi jolefler. I think your film being over exposed in the middle part is quite normal. The distance from the pinhole and the middle partof the film being 29mm, but from the pinhole to the edges of the film will be much longer, in fact you've exgagerrated the effect by having opened out your body to a more panoramic format. For this type of format a curved film back is used in order to obtain a pinhole to film distance uniform. You ask if your problem could be that the pinhole was too big, I would say no. The size of the pinhole is governed by the focal length, that is, there is an "ideal" pinhole size for every pinhole focal length. There is a table here showing focal length, pinhole size and f numbers:http://cgi.ebay.de/Lochblende-fuer-...82690352QQihZ007QQcategoryZ8281QQcmdZViewItem

This guys pinholes are very good, I use one on my rangefinder cameras.

 

[jolefler]

Many thanks for that, Pitxu! It makes much sense. This is such a new project and interest for me I haven't aquired the knowledge to measure the pinhole. I did guesstimate from a similar table that the diameter needed to be about half the diameter of the smallest sewing needle made....I used a sewing straight pin. It's fun for me, I sweat the small stuff too much in my other photographic endeavors, I'm hoping it won't be like that using the guts of a $5 Agfa! But now.....if I can just curve that filmplane :rolleyes:

Jo

 

[Pitxu]

jolefler,
I've been thinking more about this distance thing, I don't know how they do it , but some guys use pinholes equivalent to very wide-angles on large format cameras where the distances are greater, but still keeping the film plane "flat".

It must be more complicated than I thought:confused:



Pitxu.

 

[jolefler]

In case you were following....

The "over-exposed center" of my pano-pinhole has been solved. Apparently rough edges of the pinhole were to blame.

I was chatting with my 83 year old ex-wedding shooter Dad, and he came up with that explaination of what was happening. Sure enough, cleaning and reaming the opposite side from where it was punched has yielded even exposures across the 24 X 52mm frame.

Lesson of the week....don't dismiss the advice of the aging, even should they be strickened with Alzheimer's disease. Thanks, Dad!

Jo