First hand-made pinhole :)

[mentos_007]

Please, all you analog guys don't beat me :-) I "altered" my Canon Rebel to become a pinhole camera. This is my very first attempt and please let me know what is the mathematical relation between sharpness of the photo and the diameter of the pinhole. I noticed, that the smaller the hole, the sharper the images are. But then, I made such a small hole that I had no idea how to make it smaller, and the image was still not sharp...
http://www.amietus.nets.pl/images/20110809193814_img_1727b_sm.jpg

[Terri]

Hey Mentos, I think you did just fine, especially for a hand-made pinhole!

I'm not the one who can give you the math...we do have a poster on this forum who does a lot of pinhole, JamesD. He's on and off depending on his work/travel schedule, but he will eventually see this. Hopefully someone else might be able to chime in here.

The only pinhole I have is in a lens cap for one of my older cameras, and I've only used it once. It was a manufactured pinhole, so I got pretty good sharpness in the detail.

But I like this. :cheer: Keep it up!

[mentos_007]

Thanks Terri! I think that there must be a connection between size of the sensor/distnace from the obejct and the pinhole size and shape... I am not yet sure how it all works but I am going to give it more tries :D

[Walter]

I've always liked the effect--How did you make the pinhole?

[mentos_007]

ok, I was afraid that someone might ask this question... :)
I took a black, rubber-like duct tape. I took of the lens from my camera, and precisely put the tape covering the "hole" after removing the lens :) you have to be careful there because duct tape is elastic so you need to avoid stretching. When it was precisely aligned to the camera I took...a needle :) the smallest one I had...well from my calculations it seemed that the hole should be of about 1/3rd of a milimeter (it's diameter)
the main drawback was that I didn't accurately hit the center of the hole. Then the hole was not precisely round.

[Walter]

Thanks- I'd like to try that sometime. It seems the tape would distort and be fiberous at such a minute scale. Hear of any other materials that could be used?

[mentos_007]

Yes, I saw some really great examples of using the cap which came along with your camera's body (the one that protects your "hole" after removing the lens. But then it is the way to do it when you precisely know how big the hole should be :) you can make it only once :)

I tried again with a card board and duct tape - this was much more convenient because the card board was not so elastic like duct tape and it didn't move. however the "hole" was not flat then - I had some sticking fibers of paper around it so they could also have distorted the image.

[Walter]

I've been trying to think of what would be good to use instead of a cover--it just seems that it'd be too thick anyhow. Aluminum foil? something similar to a credit card? I've probably taken too much of your time already when you could be out having some fun, thank you. What you have works until you can refine it. Looking forward to seeing more.

[mentos_007]

you took too much of my time? Oh come on :) I didn't go out yesterday because it was raining heavily! Crap summer...I hoped it would be sunny and warm and it is definitely not...

I'll try with a credit card :)

I've been trying to think of what would be good to use instead of a cover--it just seems that it'd be too thick anyhow. Aluminum foil? something similar to a credit card? I've probably taken too much of your time already when you could be out having some fun, thank you. What you have works until you can refine it. Looking forward to seeing more.

[Alex]

Aluminum foil?

... that should be the way to go there ... !

Used that sort of foil for my first pinhole as well ... loooong time ago.

As for the optics:
If light would follow the simple rules of geometrical optics, things would be easy and you were right saying that the smaller the diameter of the pinhole, the sharper the image.

However, there is always diffraction (light bending) at the edge of the aperture (hey, light after all is to be described as waves, not as beams ;) ) ... this effect you would nor realise if the aperture is not too small (and the distance between the hole and the sensor is not too large) since most light travelling through the aperture does indeed follow the simple geometric straight line away from the edge.

If you reduce the size of the hole, the effect becomes visible though at some point, and then it gets only worse if the hole gets smaller.

Do not ask me what the optimum diameter is . I am sure someone did calculate this and post it on the internet ;)