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View Full Version : Converting a Walgreen's Studio 35 Camera



ChowYummyPhat
01-11-2006, 05:58 PM
Howdy, all! BRAND spanking new to the pinhole scene.

I was going to buy a pre-made pinhole Holga at www.holgamods.com , but then I thought "Why spend money on what is supposed to be cheap in the first place?" I'm still getting a regular modded Holga, but I want to make my own pinhole.

To that end, my daughter (she goes on photography trips with me) has two of the Walgreens $10US one-piece 35mm instamatics. A piece of plastic with a small piece of glass stuck in the front of it...

I'm thinking: 1. remove the shutter. 2. remove the lens. 3. replace lens with a small piece of something with a pinhole in it. or maybe even an adapter that can take different pinhole sizes?

I understand size of hole and distance from film are the key issues. Obviously, distance from film is pre-set on this unit. How do I determine what size hole to punch, and can I buy small round bits of metal with nice clean holes of known sizes already punched in them? I have a drill and a Dremel tool, but have no clue where to begin...

Thanks!

- Chow Yummy Phat

ImageMaker
01-11-2006, 08:01 PM
That lens is most likely plastic, too.

Look around here and you'll find my article (http://f295.tompersinger.com/cgi-bin/Blah/Blah.pl?b-cm/m-1129667381/) on converting one of those using the original shutter, converted to B operation, but if you have one with a sliding lens cover, it's *much* simpler to just remove the lens and shutter (leaving enough shutter mechanism to release the film advance, of course) and use the sliding cover as your shutter.

The down side of doing it the simple way is you can't use a cable release. OTOH, those cameras don't have cable release sockets anyway; if you want to use one you have to install or improvise a socket for the cable. Likewise, they probably don't have tripod sockets, so loading slower film than I normally like and using the slide cover might be the preferred way to go.

ChowYummyPhat
01-11-2006, 10:16 PM
Excellent article!

I have not cracked or drilled mine, as I still have 12 shots left on it in boring ol' 35mm mode. Therefore, if I do things right, I won't have to repair the shutter. Mine doesn't have the slide cover either. :-( Wish I still had my Samsung Advantix 35mm - it had an awesome slide cover. But I digress.

I'm noticing that everyone uses brass for the pinhole material. I assume that this is because brass is soft enough to "give" rather than "tear" during machining, thus resulting in a more round hole with less jags? I also assume that it quickly tarnishes itself and thus loses light reflection...

How are you determining this part:

End result: 28 mm projection distance, 0.23 mm pinhole giving about f/120 (I meter for f/128)

It seems to me that everyone has some chart I don't have, as well as knowledge on the basic physics I don't seem to have. For that matter, how in the heck do you know your pinhole is .023? Can I get a drill bit that small? Is it a machine punch?

Last question - what's the best material to use to affix the brass to (what appears to be) the inside of the front cover once I've removed the plastic lens?

earlj
01-11-2006, 11:01 PM
CYP - I know that several of us on this site use hobby drill bits to make the holes. I have a pin vise, and I have used #74 through #80 hobby drills to make holes in Coke can aluminum. The #80 drill is .343 mm, which is a bit big for the optimal size for most 35 mm cameras, but it is plenty good enough. The nice thing about using a drill bit is that you don't have to measure the pinhole - you pretty much know what the diameter is.

For the chart, download the Pinhole Designer from http://www.pinhole.cz Then you can save a chart (in Excel format) for any aperture/focal distance combination; it can also include reciprocity failure correction for many common films.

derevaun
01-12-2006, 01:59 AM
Thrift stores usually have a few plastic P&S that make good candidates. I converted a Bell & Howell camera and found the ubiquitous Vivitar PN2011 to be nearly identical inside. Chances are the Walgreens is similar.

On the B & H I pried off the lens plate to reveal the padddle shutter; I couldn't figure out the shutter action so I just cut the paddle of the shutter off so the shutter button still releases the film to wind on to the next shot. I removed the lens and mounted the lens at the front of the lens keeper barrel (all these terms are totally made up).

The other day I saw a little P&S in Goodwill with a cable release shutter button. Seems like it could replace the standard plastic button (it's rolling around on the floor anyway) on most mods with a little trimming or padding. It was marked at $5 and I didn't have the energy to supress the ethical disinclination toward switching tags with the I-zone next to it. But tomorrow is another day....

I use the sliding cover as a shutter. Actually I'm in the habit of holding a finger over the opening, sliding the cover open, positioning the camera, then using my finger as the effective shutter. Prolly some finger crud clogging issues, but so far so good!

ImageMaker
01-12-2006, 03:29 AM
I'm noticing that everyone uses brass for the pinhole material. I assume that this is because brass is soft enough to "give" rather than "tear" during machining, thus resulting in a more round hole with less jags? I also assume that it quickly tarnishes itself and thus loses light reflection...

How are you determining this part:

End result: 28 mm projection distance, 0.23 mm pinhole giving about f/120 (I meter for f/128)

It seems to me that everyone has some chart I don't have, as well as knowledge on the basic physics I don't seem to have. For that matter, how in the heck do you know your pinhole is .023? Can I get a drill bit that small? Is it a machine punch?

Last question - what's the best material to use to affix the brass to (what appears to be) the inside of the front cover once I've removed the plastic lens?

Brass is handy because you can purchase it, relatively cheaply, at some hardware stores already rolled to a nice, smooth, consistent .001" thickness. I use a sewing needle to dimple the brass, then "sand" through the dimple on a very fine whetstone made for sharpening straight razors; 1200 grit sandpaper used for building plastic models works well, too. I've tried with and without oil, makes little difference but the stone cleans up better with oil. The aluminum from reusable foil pans or the thin part of the side of a beverage can works just about as well; it's a little thicker, and stiffer, but still thin enough for the dimple and sand technique (which, IMO, produces the best holes). I blacken the hole with a Sharpie marker, since oxidation of the brass takes forever (and aluminum never will oxidize black).

The desirable hole size is arrived at by formula, which (if you understand diffraction at the level of wave mechanics) can be derived as the crossover point between diffraction and hole size as sources of image blur. The formula I use is to divide the square root of the projection distance by 25 (all in millimeters). I measure the holes with my scanner -- scan the hole, crop the resulting image to just the hole, and the editing software will tell me the size of the selected region (directly in mm, inches, or in pixels at 2400 to the inch). Projection distance for that camera was arrived at by the low-tech method of sticking a narrow tape measure into the back and measuring to the location where the hole would be stuck.

Daryl uses epoxy for a lot of his hole installations, but I usually use black masking tape (I got a big roll for $8 a while back at a camera store; I've used about half of it, almost all of that in making the light shield for my bathroom window). One advantage of the tape is that I can take it off again later if needed (though you shouldn't depend on it being completely opaque, because it's not).

murrayatuptowngallery
01-12-2006, 04:03 AM
I use RTV silicone rubber. I got some electronics grade (non-acidic curing process) that was being tossed at work. It allows me to reposition the pinhole disc. My first placement is always way off.

underbyte
01-12-2006, 11:34 AM
Imagemaker, excellent post! I like the idea of starting with a sewing machine and I understood your explanation of the math too. That is usually more of a challenge for me. I'm going to save some time next time.

Thanks!

ImageMaker
01-13-2006, 12:02 AM
Imagemaker, excellent post! I like the idea of starting with a sewing machine and I understood your explanation of the math too. That is usually more of a challenge for me. I'm going to save some time next time.

Thanks!

I use a hand sewing needle, actually, not a sewing machine needle (though those would probably also work, since you don't need to poke the needle completely through the metal -- the ball point kind, for knits and synthetics, might be even better, make a nice dimple without tearing the brass or aluminum). I've heard of people using a pencil point, or the tip of a fine point ball pen, or an old phonograph needle (the steel kind) to make the dimple, too.

JoeVanCleave
01-13-2006, 04:18 PM
I use the dimple and sand method, also. I use hand sewing needles, with the eye-end mounted into a small wooden dowel for use as a handle.

I've been using 400 grit emory, but I like ImageMaker's suggestion of the finer 1200 grit cloth.

I also use a magnifying loupe to inspect the hole after sanding, and find that the first attempt usually results in an uneven hole. A blast of canned air, a resanding, and finally a careful reaming with the tappered tip of the needle are how I deal with burrs in the hole, although the reaming is a last resort, as it can waller out the hole size.

I find a really round, smooth hole is at least as important as getting the ideal size exactly correct.

For longer focal length cameras where the hole sizes are at least as big as standard sewing needles, I use a sewing needle pack that lists their diameters. Choosing a diameter close to the ideal, I dimple and sand, then carefully "spin ream" with the needle and resand, until the shank diameter of the needle fits tightly in the hole, and its smooth.

I've also lately been tasked with making matched sets of pinholes. My 9-shot gridcam was a recent example. In that case, I used my first hole as a comparitor. When a subsequent hole was finished, I would view them both, side-by-side under the loupe against a lightbox table, but out of focus. Comparison of the resulting focus blur enables me to get the subsequent holes close to the original size. Again, smoothness is in important factor to good image quality.

Of course, its not as fun as making the pinhole with a .22 rimfire cartridge, after the paper's been loaded in the box. Just don't try that trick at home, unless you live in the country.