A Jim of All Trades

1st Roll With the SLR Pinhole: Failure

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I am very disappointed and sorry to report that the first roll of film did not turn out well with the pinhole lens I made for my SLR. You can vaguely make out what the images are, but they are all dark (appear to be under exposed) and are not in focus/not sharp. Considering pinholes are supposed to focus to infinity, this was troublesome. I did not bother to scan any of them in, there truly was little to no point.

When shooting, I shot multiple shots from the same position, varying the shutter speed from one to another, because I wasn’t sure which exposures would work best and wanted to compare results. Some turned out better than others exposure wise, and having shot a few rolls with my other pinhole camera I’m somewhat confident in my ability to choose exposure times, but all, no matter what, were out of focus.

So, I did some more research. My assumption is that focal length is the issue, and though it is too early to tell (haven’t taken any new pictures yet), after the research I do indeed believe that focal length is the problem.

I will only touch on focal length at a high level here, hopefully it’ll be enough info to make sense and help anyone out that is trying to do the same thing.

In the following paragraph I’m going to be quoting/paraphrasing from the book Adventures with Pinhole and Homemade Cameras by John Evans. It’s my main source of info and a very informative book.

For pinhole cameras, the distance from the hole to the image plane (film or a sensor) equates to the focal length of a lens. There is an optimum pinhole diameter for each focal length that will give the sharpest images possible. There are formulas and ways of figuring out what size pinhole you need, but simply put, if the hole size is too big the image becomes brighter and less sharp, and if the hole size is too small the photos become fainter and less sharp.

I wouldn’t say that my images are “faint,” they’re more just dark, but “sharp” they most definitely aren’t. The darkness also hints at too small a hole; think in terms of lens aperture and how an image will be too dark if the lens isn’t open wide enough, assuming shutter speed couldn’t be adjusted. I can compensate for the darkness by adjusting my exposure times, but nothing I can do would help with the sharpness when using a pinhole.

Long story short, I [think I] need a bigger pinhole.

Here is another area where I won’t go into too much detail, but I actually did measure the focal length of my camera as best I can and determined what size hole I need. Problem is, I can’t measure a pinhole; they’re way too small. Well, technically I could; the book gives very good instructions on how to do it, but it requires a bit of setup and extra steps that I’m not ready to commit too. So, I simply made one and by holding it right against my eye and staring at a light bulb, then doing the same with the old pinhole, I got it to the point where I feel the new one is bigger.  This is a very unscientific approach and I am fearful that I’ll blow another roll of film and will end up doing the whole measuring routine anyway. I’ll gamble and try my home-made pinhole first though.

One thing I did learn though, was, don’t waste a whole roll of film on a pinhole you don’t know will work. DSLR folk won’t have this problem, they can tell shot by shot how the images are turning out, and depending on the results can make adjustments or other pinholes as needed. For film users though, if you’re doing this on a SLR, I’d recommend making a few different size pinholes and only shooting a handful of shots with each of the exact same subject from the exact same position. Carefully record your exposure times and which pinhole you used for each. Then when you get your first roll of film developed you can compare the photos with your notes, determine which hole worked best, and you’ll be good to go moving forward! I plan to do as much with the next roll I shoot; I’ll use at least one more pinhole and determine which works best with the camera. That’s the plan anyway.

Hopefully the next time I update it will be to share my success and show some photos that turned out good. With any luck, this is just a bump in the road! If it doesn’t work out again, don’t expect another post about this until I get it right.

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Written by Jim

May 2, 2012 at 6:15 am

Posted in Photography

Tagged with , , ,

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