Pinhole passes clown test

Way too hot to do anything outside lately. I've passed the time

trying to make a better pinhole. I got some very thin brass sheet at

the hardware, and picked up some #12 needles and a pin vise to hold

them. I tried out all the recommended procedures without a lot of

success. The best result was obtained by sandwiching the brass

between a couple layers of aluminum, and then drilling through,

followed by very light sanding. Still have a way to go. I've ordered

a dozen drilled pinholes from a guy on ebay, so will be interested to

see how they compare to my efforts. Also want to try something with

around a 35mm focal length.<div></div>

That is good. The stitchwork on the ruff comes across very well, and (apart from the "ladder" shot which I really liked) the contrast seems an improvement on the earlier ones taken with the Tower. USM, or not?

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Didn't you once say you had a Speed Graphic, or similar?

I did my usual routine of sharpen/sharpen after resizing for the web. I'll attach a 100% detail crop with no sharpening. I did once have a Speed Graphic, but it is long gone. Something like that seems like it would be the ideal platform for pinhole experimentation. I should probably trade in part of my over-large 35mm collection for a Graphic or some other LF camera.<div></div>

I think that looks very good Mike.

 

A while back I was researching pinholes on the net and found a method that works well for me. Use your needle to press a dimple into the brass, then sand with very fine (400) sandpaper until smooth, and repeat until you see the hole appear. When I have my hole, I measure it with my flatbed scanner. I make two pencil marks on the brass a measured distance apart and then count (with photoshop) the pixel size of your hole and the pixel size between your marks and do the math. Pretty accurate.

Here's one of my early tests. If I remember correctly, the two pencil marks at right are 30mm apart.<div></div>

Hah! Very smart John.

The SilverFast software I use with my flatbed gives me a direct readout of the width of a cropped image of the pinhole based on the chosen resolution.

I was surprised to find that the "precision drilled pinhole" I purchased from the fellow on ebay did not give me images sharper than the one I had made myself. His pinhole was drilled into stainless steel and lightly buffed on each side. It looked good under the loupe, but I don't see any more detail in the image from it than from mine which was done with a #12 needle in thin brass sheet. I would like to see a 100mm focal length laser drilled pinhole image for comparison. I'm also looking forward to trying a shorter length setup - maybe around 35mm. I've made <a href="http://www.photo.net/photodb/folder.tcl?folder_id=508477">a new folder</a> for my pinhole shots. The jack-in-the-box was shot with my pin-drilled brass aperture; the others are all with the purchased pinhole.

The optimum pinhole size acrording to Kingslake in 1951 is where the pinhole diameter is equal to the diffraction spot. This is 0.006 inch; times the square root of the "focal length/box size". Thus for a 4 inch box; we have dia= 0.006 * sqrt (4) = 0.012 inch. It is far cheaper to make you own pinholes; and measure them; then buy them. <BR><BR>

It's hard to know what to go by, without ending up with Leica-like discussions of Pinhole Resolution and (God forbid) Pinhole Bokeh. However, the Canal Gate shot looks crisp, the bouquet looks pleasantly soft, and the jack-in-the-box encompasses both effects. I suspect this means that the homemade pinhole is really just as good as the shop-bought !

I tore apart a Billy Record today with the intent of making a short focal length pinhole camera. I think the pinhole to film distance will turn out to be about 35mm; that will mean I can probably use the viewfinder off my Kiev. I'll try one of my pinholes and one of those I purchased, and may also try to find an affordable laser drilled example.