Hoping to get some interest in this aspect of photography, and following the demise of that excellent site f295, I thought I’d set the ball rolling by describing in more detail how I went about building a camera which I recently mentioned here: http://www.largeformatphotography.in...amera!/page324
A friend on this forum happened to throw in a box of 5x12 x-ray film in a parts swap we did and that got me thinking about a panoramic pinhole camera in this format. The result here followed months of trial and error:
The camera has front rise and fall of +/- 15mm to allow it to be used level and yet ensuring that the horizon remains straight, since the horizon will be curved in a curved film-plane camera if it is tilted up or down. As it turned out I could only find 15mm as I’d made the frame for the front too wide top and bottom. I haven’t yet tested whether this is enough. The camera has a bubble level in the top and sighting dots made from 1” painted nails to aid composition.
The first hurdle to overcome was bending the plywood back. This was eventually achieved by scoring the inside surface with vertical Vs spaced at 1cm intervals using a router, then soaking and careful progressive bending over several days, using clamps and weights, then eventually gluing top and bottom to hold it all together. It was a hair-raising experience and I felt several times that I came very close to splitting the wood. In retrospect, Vs at 5mm spacing may have made the bending easier.
I used a 0.5mm EMS (electron microscope) aperture for the pinhole. These are truly excellent - laser drilled precision. I’ve used them before on other cameras with great success. I’d never think of making my own now. They’re available from a guy on f295 at $1 apiece posted. If anyone has contact with Earl, would you mind seeing if he’s interested in posting here?
Mounting these pinholes is tricky, since they’re very small. Some folk use tape with a 1.5mm hole punched in it to grab the pinhole; the pinhole is then taped to the camera front. I don’t yet have a punch to allow me to do it this way, but I’ve ordered a couple from China. Meantime I mount my pinholes in a small brass washer, using a couple of blobs of black paint that find their way by capillary action. The pinhole on its washer is then mounted into a recess drilled into the plate (more black paint).
As per my previous post (above) I found vignetting on my first test shot, which I immediately thought was an image circle issue. I thought that I may have to mount the pinhole further forward to fix this. However a member (NedL) was right when he suggested that it was obstruction. Sure enough, although I’d beveled the exit hole in the rear of the plate, there was still a definite ridge, which I’m sure was responsible. I’ve since ground this down, but have not yet tested it as I have a scratching issue with my developing trays and have to get some glass cut to remedy this. The next pic shows the rear of the plate and also a view of the front showing the clearance needed for rise/fall and horizontal field.
The 0.5mm pinhole is mounted 135mm from the film plane. I had intended it to be 127mm (5”), the radius of the film curve, but things don’t always turn out as hoped. Fortunately pinhole is very forgiving, and I don’t think any unevenness in exposure will show up. At 135mm the speed is f/270. The one test I’ve done suggests that the image is a little soft. I’ll do a few more tests after I sort out my developing issues, and may yet go down to 0.4mm and f/340.
A note on bits and pieces: I now get everything from China via eBay. No doubt about it. Over the years I’ve scoured the country from engineering suppliers to model shops and found sourcing small screws and knobs etc, the type of things so vital to DIY photography, next to impossible. For me eBay is the answer, and knowing how to search is very helpful. Terms like M3 screws for 3mm metric, or knurled knobs, case clips etc usually turn up direct hits or lead to further search clues. The two brass pieces in the last two pics are known in eBay speak as "M3 / M4 Brass Knurled Nuts Insert Embedded Nuts"; I used these as nuts to secure the front panel and as embedded nuts held with epoxy for the front panel to bolt into.
So how about it LF Pinholers? I'm sure there would be much interest in your own pinhole camera building achievements. There is certainly interest in pinhole photography here, as evidenced by the many favourable responses to pinhole images posted here. Love to hear from you.
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