[pinhole-discussion] camera obscura aperture formula
Hello group, I am wanting to make a large box size camera obscura and I wanted to know about the formula to use for the correct aperture size compared to the focal length as it seems that the traditional pinhole formulas would render the hole too small. My idea is to have a box with the aperture at one end that would bring the image in to a mirror installed at a 45 degree angle opposite it that would in turn reflect the image up to a viewing area on the top of the box. The mirror I plan to use measures 437mm x 250mm and would be situated along a path in the box to allow for the mirror to be in the longest dimension from side to side in the box (what could be considered a landscape mode, or the width would be longer than the height). I have not found any real equations for such a design except just the mention of it being done this way so I am not sure how big I should in fact make the aperture in order to allow enough light in so that it can be viewed with a reasonable amount projection onto ground glass or the like. If anyone has any suggestions they would be greatly appreciated and I would share the final structural information after I complete it to anyone interested in the group. Thanks, Eric
[pinhole-discussion] Brownie pinhole question
I have a Brownie Target Six-20 (among several other Brownies) that I want to convert to a pinhole. The only problem is that with the Six-20 models, as well as some of the others, the lens seems to be fixed in place and cannot easily be removed. On top of that, the light box that the lense is in is riveted so as to not easily be taken apart. I was wondering if anyone else has converted some of their Brownies to pinhole cameras and what is the work around for this riveting in order to get to the lense and remove it. The easiest one would be the Brownie 2, as the lense in that is easily removed by simply bending up a few tabs, but I do not want to sacrifice that one as I use it to take pictures with as well still. Any advice? Eric
[pinhole-discussion] polaroid pinhole question
I have a Polaroid Land Camera that I took off the lense housing and replaced it with a board to size fitted with a pinhole in the middle. It is one of the older Memory Maker versoins of the land camera. The first few pictures I took with it were fine using the newer Fuji FP-100c film, but when I was using it yesterday, every picture I attempted came out brown and the negative side was black. I am curious, as I have not really worked with polaroid type pinhole very much, nor polaroid in itself that much, either, whether or not the film is messed up or if I am just not exposing for the correct amount of time? This is daylight film at ISO 100 and color. Any suggestions would be apprectiated. Eric
[pinhole-discussion] funnel pinhole camera
I was thinking recently about the idea of a funnel shaped pinhole camera, in regards to a modification to a tube one. Such as when you have a tube camera with the pinhole at the end of the tube you can get 360 degrees of view, or 720 with a hole at each end, why not make one that is shaped as a funnel with the hole being at the end where the film is at its widest area (opposite the narrow end of the funnel. I figured this would make some interesting distortion effects on the picture and compensate for loss of light at the narrow end. I have not actually built a test one yet, but was curious if anyone else had done so and what where the results if you have? Just curious to see how it would all turn out. And considering the nature of its design, I would most likely only use it with print film instead of a negative. Any comments? Aeryck
Re: [pinhole-discussion] re: Pinhole Camera Instructions... f/stops and needles
You can also find them in Wal Mart in the craft section. They usually come in a package of several different sizes ranging from 5 -10, etc. They will have the larger diameter (smaller number) and then a smaller diameter (larger number) separated by a slash such as 5/10. The #10 usually does correspond to the 0.018 diameter as I have used these and tested the holes that they make and measured them and they are accurate enough. Just remember that the smaller the needle number, the larger is the diameter of the needle. ive only been able to find sewing machine replacement needles with numbers but these are larger than what the mm size given in renners pinhole photography book (p 118, figure 5.21a) where can i get a #10 (0.46 mm/0.018 in) needle? thanks!
