Just made a pinhole camera! Have a few questions.
Okay. I made a very simple pinhole camera. Am I right in thinking that a smaller hole will make a sharper image? I didn't find the smallest needle I have so will search for a real tiny one!
The negatives were really light so I'll have to leave the pinhole open longer?
Fun to make. I think that this will be a great project for my photography kids. I'll just have to practice a bit to make sure I can get a good image before I show them.
To a point the smaller hole produces a sharper image, but eventually the sharpness becomes diffraction limited. Probably equally significant is the quality of the pinhole itself. A perfectly round, knife-edged hole is the best. Pushing a needle through something creates all sorts of turned and ragged edges. One classic method just uses the needle to raise a small pimple, then that is sanded off very carefully to open a hole. With that method, the needle diameter isn't particularly important.
There are some calculators and resource pages on the web you might find useful.
Sounds as though you need longer exposures. With some films, the reciprocity effects become extremely severe, needing 3 or 4 times (or more) exposure beyond what the exposure computed from the f-stop might predict.
It's fun stuff.
I've learnt to think of my pinhole images in terms of softness. It's like learning to see what will work in B&W. You can talk about pinholes and sharpness, it's all relative but not really worth the effort. I mean if you want sharp, use a lens. Pinhole excels at softness, you can have more or less softness but that is what you are working with. Accept the softness and you can start to consider the qualities of softness and what they offer. So the method described by DWThomas, sanding the pimple, gives a much sweeter quality than popping a hole into tinfoil. Actually, for sharpness you want to be using a laser. There are other variables to consider too, reciprocity is definitely a factor in pinhole but also there is a great difference between a paper negative and a film negative. It's all good. I think pinhole, zoneplates and the whole raft of lenseless photographic methods is a delight and I would only encourage you to do it.
Thanks everyone! It is a lot of fun! Something that was just a few pieces of cardboard and an aluminum can yesterday is a camera today! I'll try to just sand the dimple made by the pin. I sanded the hole after I made it but the hole is probably not perfectly round. I just love the look of pinhole photos. Mine were just extremely fuzzy. I think that I just need to keep it stiller! I already have 2 kids that want to make cameras for a project. Should be fun! We are just using paper so I just need to increase my time that the pinhole is open. Was my first contact print today too! Fun, Fun!
My matchbox PH's shoot at about f/90. Aperture can make a difference to a point. I think the quality in the hole edges make much more difference. If the light enters the camera through a smooth-edged hole it takes a more direct path to the film and creates a 'sharper image'. So I wouldn't worry too much about the size of the hole unless you want to know what aperture you're shooting at. But why make this thing technical, right? Kinda defeats the purpose, in my mind.
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While your going to get information to your posted questions here, pop over to http://www.f295.org and go to the forums. Lot of information just waiting to be read. Good thing about PH is you can be as technical or non technical as you like and still get great and interesting results. But knowing something about the science helps get those images quicker, specially the relationship of pinhole diameter to f-stop for exposure calculations.
Here's a link for you: http://www.mrpinhole.com/calcpinh.php
With this, your exposures will be a little less guessing and a little more knowing. Photographic Paper can be assumed to have a sensitivity of about 5ASA.
Btw, I love your camera... everybody can take photos with an old shoe box, but using a little truck with the license plate as shutter? That's bordering on genius
Poking a hole directly into the metal will always give you such soft pictures. The smaller the hole, the sharper the picture (until a certain limit, see "optimal pinhole diameter") and your's was way too big and the edges are probably to uneven. The calculator can help finding out, what's best for your needs.
Using a small piece of aluminium foil or other very thin metal sheet is the usual practice for making small pinholes. Most people don't push the needle right through but use it to make a tiny dent which is then filed off. That way, you get very small and even holes. I usually just take a sewing needle, place it onto the aluminium foil with very little pressure and turn it around while placing my index finger on top (not pressing hard, just adding a little weight) and repeat that from the other side to smooth the rim... i can usually get almost perfectly round holes from 0,15 to 0,6mm in diameter that way.
As for your problem with the half-overexposed picture: It's either uneven developement (ruled out by multiple tests, I guess) or a light leak on the top of the camera, close to the film plane. Try putting a small flashlight into the box and taking it into a dark room. Does any light get out, apart from the pinhole? Then you've got a light leak that should be fixed with duct tape, a few drops of black paint or whatever you happen to have around.
I *almost* have the light leak fixed. *almost* I'm still trying to get the whole leak - and I'm using electricians tape right now. It seems to be working. The nail hole has a bit of tin foil behind it, covered for the most part, again, with electricians tape. *rolls eyes* My husband suggested duct tape but our local store doesn't carry any black duct tape. I made the pinhole with one of my sewing needles - so the picture is more clear and less soft looking. As for the uneven development, I tried out five tests and it did the same thing each time...so back to a very dark room with a flashlight! My kids think I'm nuts. (Wait...I am...but I'm not telling them that.)
As for the truck, thanks! I didn't realize I had it until I was cleaning out the basement one day.
There it is in the negative form - a 15 second exposure. I think some of that is just shadow from my front porch...and some of it may still be a light leak. I've another test or two to run just in case. The pinhole is still too big I think.
And a view of the newer, but still too big pinhole. :/ (That's one of my bjd's discovering the truck is now a camera. I've a photo shoot planned in the future of him taking a picture with it, me taking a picture with my old Brownie 2A and the two of us having our picture taken with my digital on a tripod!)
Thanks for the link and the reply! I appreciate all the help I can get because even though I took Photog. 101 in college (20 years ago), I'm just now getting back into my darkroom mode. I prefer working in darkroom (okay, the bathroom in the basement). No enlarger, yet. I'm hoping that maybe I can talk my husband into ordering one for me here in a few months.
Have you checked the f295 forum?
Proud member of the League of Upper Midwest Pinholers & f295
"I think, therefore, I photograph."