Large Format Pinhole

As I mentioned in the "welcome" thread, I have a pinhole "lens"

mounted in an original shutter for one of my plate cameras. This lets

me make 9x12 cm large format negatives with a pinhole, and produces

some interesting images (though I've been disappointed with the

sharpness; I had expected a negative this large to be sharper when

reduced for web viewing than what I'm seeing -- perhaps I should try

some unsharp masking).

 

There are, I know, a bunch of large format pinhole cameras made to use

standard 4x5 holders; some can even take a Polaroid 405, 500 or 545

holder. I've seen a few that went to 8x10...

 

Who else is shooting pinholes in large format, and what kind of

results are you getting?<div></div>

I shoot some LF pinhole now and then. Here's an 8x10, shot in a Leonardo that's 6" deep. I

think the pinhole comes out to f360.

 

I also have a few 4x5s, one handmade by a buddy of mine, it is 7" FL. And a couple of

cams made out of metal lunch boxes. I'm working on a 4x10 made out of a "Last Supper"

lunch box, thinking of off setting the hole so that I can use it as "rise" for building shots.

 

Nice to see this new forum.<div></div>

Larry, that shot is beautiful. Pinhole might be something to strive for once the winter's here and all the insects are gone.

Hi Donald ... I have always understood that scanning necessarily requires at least one pass of the sharpener, by virtue of the nature of consumer scanners (reflective or transparency).

<p>Some day soon I'll pick up an 8x10 DDS and build something onto it. I've already got some 8x10 paper. What would you suggest as the ideal focal length for an 8x10 portrait pinhole? (full/wide portrait, rather than close up).

Sandeha, I haven't always found sharpening to be necessary -- when I get a negative that scans with single-pixel sharpness at 2400 ppi, I never find it necessary to sharpen when I downsize it for the web, much less for printing at Costco.

 

Contrariwise, in fact, a simple sharpening filter (which works by emphasizing microcontrast) will tend to exaggerate blur, which is present on all edges in a pinhole photo. The only thing that will help is unsharp masking with careful selection of radius, threshold, and amount -- and even then, there's a strong tendency for the result to look very unnatural long before it looks sharp.

 

Perhaps the real trick is to simply make a larger camera. I can get J&C Pro 100 in 8x10 (the largest my scanner will handle) at quite reasonable prices, and it ought to cost about $10 to build an 8x10 pinhole camera, plus a couple dollars each for foamcore film holders to avoid having to run back to the darkroom between exposures. Of course, something like that probably won't fit in my changing bag, so may have to wait until I get the light seals in my bathroom.

 

And in 8x10, I can make much nicer cyanotypes, too...

Donald, your photo doesn't look bad to me. Pretty doggone good, I'd say. I have several pinhole cameras, from an Argus C-3 to 5X7. As always, I just need to get out there and use them.

I have a pinhole that I use with my Speed Graphic (4x5) on occasion. It is 0.0138" and used at ~60 mm (f=171). I am actually surprised at how sharp the pictures turn out. One of these days, I want to try a laser drilled pinhole to see if it is any sharper than the hand-drilled one that i'm using.

 

The attached picture is the one that I submitted for world pinhole day this year. The 500 pixel limit doesn't do justice to the picture. You can pick out individual blades of grass most of the way to the church on the original chrome.<div></div>

Whoa, another NC denizen... ;)

 

Well, yeah, okay, the shot of the dining room isn't *that* fuzzy, for a pinhole shot. But I keep seeing these shots made with one model or another of Zero Image camera that look almost like classic lensed large format -- that is, everything in frame is sharp -- and my pinhole shots (with hand drilled pinhole) never look anything like that good. From 35 mm, I expect that -- but by the time the display image on screen is smaller than the original negative, the circle of confusion from the pinhole is down to a couple pixels and I tend to think they should look better than they do. Maybe I'm just expecting too much (again) and simply need to "go shoot more film!", as Daryl Duckworth says over on f295.

 

BTW, you've got more nerve than I do if you shoot 4x5 chromes with a pinhole -- or a lot bigger budget. I'd have to save up for months just to afford a box of Ektachrome (assuming I had a camera that held 4x5), and then the processing cost would limit me to a few sheets per month. At least with B&W in 4x5 or 9x12 cm, I can get a box of film for around fifty cents a sheet and process it myself for about that much again.

 

Hmm. Blades of grass... I guess my negatives aren't as bad as all that...<div></div>

The classic pinhole dilema - the images just won't stand much enlargement. That's why I have built a couple of large format cameras. The 5X7 will be great for contact prints. IF I made the hole the right size. My rather crude measuring devices aren't very accurate.

Well, Glenn, some take more enlargement than others. I've got some images shot with a body cap on 35 mm SLR that look just fine on the screen, even though the screen image is 2x up from the negative. In fact, they look about as good (to my eye) as the stuff I've done with 9x12 cm, which is 1x on the screen.

 

Still, I'm just working with my second handmade hole to date -- maybe they'll improve with practice...

QUOTE - BTW, you've got more nerve than I do if you shoot 4x5 chromes with a pinhole -- or a lot bigger budget. - Unquote

 

Between the film, flashbulbs, and vintage cameras, my wife might complain that the latter is true. But, the film came cheap from eBay and I did a test exposure with cheap Polaroid film first. Unfortunately, I don't shoot as much 4x5 as I'd like. I get the camera out a few times a year, then save the film until I have enough to send it out economically.

 

I've attached an enlargement of the cupola that shows some of the detail that is possible with a pinhole. It is still a bit soft, but I was pleasantly surprised when the film came back. (I will have to admit that I took the easy way out and bought a set of pre-drilled pinholes. But I have installed them in several different camera bodies and have been quite pleased with the outcome. If I only had as much time to pursue photography as I would like!)<div></div>

Well, and there you go -- every time I see a pinhole photo that's really sharp, in any format, it turns out it was made with a commercially purchased, laser drilled hole. My problem is that a small pack of assorted size laser drilled holes costs as much as 15-20 rolls of film or a full box of Fomapan 100 9x12. I just need to improve my technique, and find a better method of sanding off the burrs around the hole. I do think getting .001" shim stock instead of the .005" I used for my first hole has helped a good bit, though.

 

Maybe I should work out the details for the electric discharge hole making technique I read about a while back -- a small battery (or, better, a lab power supply) and capacitor, needle, and aluminum foil, with the needle and foil forming a circuit; the capacitor discharging through the foil each time the circuit closes is said to produce tiny, perfectly round holes, with the voltage controlling hole size. Capacitors are cheap, but regulated power supplies aren't... Hmmm...

Donald;

 

Its pretty easy to routinely get nicely uniform pinholes. The secret is the technique.

 

I use .002" sheet brass. Make a uniform dimple, using a dull brad. Then drill down into the dimple with a needle, but don't break through with the pinpoint. You're just making the peak of the resulting dimple a bit sharper and thinner.

 

Next, place the sheet brass, dimple side down, on a sheet of 600 grit emory paper. Press your finger onto the dimple and sand it down using uniform circular motion.

 

Examine the results periodically using a magnifier. Stop when the aperture is of the required size. This method makes the pinhole aperture using the circular sanding action against the peak of the dimple, rather than tearing through the thin metal with a needle. The result is no burrs, and a clean, circular aperture.

 

Although there are nice laser driller pinholes available, I feel it to be against my personal "pinhole ethic" to purchase one.

 

Regarding sharpness, my 8x8 box camera, f/456, makes really sharp landscape images. I typically use paper negatives. Graded paper is best for controlling contrast in high-contrast light. I like grade 2.

 

I also do some pre-flashing of the paper negatives under my enlarger, lens set at f/32 for about 1-2 seconds. The deal with pre-flashing is it helps fill in the shadow detail in high-contrast light. Otherwise, you'd have to overexpose the highlights to get any shadow detail at all. I find typically I shoot at 1/2 my normal exposure time without pre-flashing.

 

For scanning paper negatives, I almost always use unsharp masking, after inverting, curves and cleaning up any spots, etc. I'll try to post an image soon.

Although my pinholes were purchased, they were not laser drilled - and they weren't that expensive (though at a buck or two a roll for short or just past date film, I guess you could buy a dozen or so rolls of film for what they cost. The seller I picked them up from currently has a set up at auction:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=7523279894&ssPageName=STRK:MEWA:IT (Standard disclaimer: I have no stake in the auction, but was pleased with my purchase.)

 

I guess I could make my own, and I may try someday. But, I was looking for the shortest path to playing with pinholes. I especially enjoy working at short focal lengths - it's an easy path to very wide angle photography. I'm currently trying to decide on a folder to change into a short focal length pinhole camera.

Joe, I'll have to practice some more -- I haven't reached the stage where I can make the hole without actually pushing the needle through the stock. I'm using .001" brass shim stock at this time (found .005" was too stiff). Maybe I should start with the dull end of the needle (or grind a flat or round point on a brad, heaven knows I have some of those around). I'm surprised you can get good results with 600; I've read from other sources that 1200 was needed to get a smooth edge on the hole (but then, those folks were also teaching me to push the needle through to a set depth to make the hole the right diameter, then sand off the resulting burr).

 

I have a scanner that does a fine job of measuring the holes, I just need better technique for gettin them round and smooth. Your method looks promising. Good project for this coming week...

In another thread about "Haze" I mentioned that I used a slide projector for measuring, but I'm interested to hear about your scanning technique. What do you measure against, or by what calculation do you arrive at the actual size of the pinhole?

My scanner (and yours, and everone else's) has a known scanning resolution. I scan the hole as a transparency or negative at the highest possible resolution, crop the resulting image to the edges of the hole in both directions, and read the hole size directly, in pixels, from the editing software. Since my scanner operates at 2400 ppi, I can simply divide by 2.4 to get the diameter in thousandths of an inch.

Thanks, Donald.