What's Optimal About Optimal?

aaronmichael said:

I'm just a newbie into pinhole photography but as for the shape of my pinhole, I've tried to get it as round as possible using a needle. For the material, I use the metal from soda cans and sand it down with an electrical orbital sander using 60 grit sand paper. This gets it pretty thin pretty fast. As for the color of the material, I usually paint both sides black. Below is probably the best shot I've done using the methods described.

http://www.flickr.com/photos/aaronmichael/5256810534/in/set-72157625595921944/

Referring to the second image with the tree.

The focal length for the camera it was taken with is 125mm and my new 8x10 camera that I built has a focal length of 190mm - which is what sparked the thread. Wanted to know if there was a reason why making a larger pinhole for the longer focal length would be beneficial. I think the pinhole diameter for the above shot was .46mm.

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aaronmichael said:

I spent a while myself trying to figure out what that was - hahah. My pinhole camera is made out of half inch thick plywood and the hole that was cut out in the wood on the front for the pinhole to go behind was too small at first. The hole being too small resulted in light bouncing off of the wood and framing the image. After I finally realized this I made the hole larger and you can see with the bricks and door image that I almost completely fixed the problem. After that photo, I made it even larger but haven't had a chance to try it out yet.

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aaronmichael said:

I spent a while myself trying to figure out what that was - hahah. My pinhole camera is made out of half inch thick plywood and the hole that was cut out in the wood on the front for the pinhole to go behind was too small at first. The hole being too small resulted in light bouncing off of the wood and framing the image. After I finally realized this I made the hole larger and you can see with the bricks and door image that I almost completely fixed the problem. After that photo, I made it even larger but haven't had a chance to try it out yet.

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michaelbsc said:

Ok. In essence your original hole formed a mechanical vignette hood?

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aaronmichael said:

Haha - exactly. Sorry for the crappy quality of this photo (it was taken with my phone), but this was the hole before I widened it out.

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And this is it after making it larger.

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