First Test of 16x20 Hyperfocal Cardboard Camera

Hello! I've taken my first test pictures of a hyperfocal 16x20 Cardboard ULF camera. The lens is the 28 inch element of a Gundlach triple convertible, and it covers fine. The glass is only OK. Since I'll be using this at f128 (maybe f64), I bought an inexpensive shutter and glued it to the back of the lens. No turning back now, but for $50 total, it's worth a try.
I debated using foamcore and Styrofoam, then I figured why not just use cardboard since I don't need focusing. It's a one shot design. I'll load it in the dark and then develop so I don't need film holders. The back is 24x24 inches and the front 10x10 inches. The conical shape gives it a fair amount of rigidity.
When I measured the focal length of the lens using a telescope eyepiece at infinity, I got 26 1/2 inches from the center of the elements instead of 28. Using a CoC of 0.3mm, I obtained a hyperfocal distance of 38.2 feet and this was 28 inches from the center of the elements when I used a telescope eyepiece focused to 38.2 feet.
For this test, I taped 4x5 TMax 400 to the center of the back. It was dusk, so the exposure was 75 seconds at f128. For comparison, I moved up and shot 4x5 TMax400with a 90mm SuperAngulon at f64 at 5 seconds. This was taken 45 minutes before the hyperfocal camera, so its exposure was shorter. I focused the 90mm at 38 feet.
Unfortunately, I missed the fence I was aiming for with the hyperfocal camera, but the foot of the fence at 35 feet is visible as are several leaves at 22 feet. The leaves are 14 feet from the 90mm.
I scanned the hyperfocal negative at 300 spi and the 90mm negative at 1200spi, though I had to crop about 1:5 or 6 instead of 1:4 in order to obtain similar distances between the leaves.
Interestingly, to my eye, the leaves look sharper in the 90mm negative on the right, but the fence post looks sharper in the hyperfocal negative on the left when I enlarged them for easier viewing.
The next step is to try a 16x20 paper negative. Best regards.

Mike

Hello! I shot a paper 11:00 AM, ASA of 6, at f128 giving 75 seconds exposure. Here is a scan of 1/4 of the 16 x 20 paper negative scanned area scanned at 300 spi and an enlargement of the barbecue area under the shade. For a high quality lens comparison (hopefully), enclosed is the same SuperAngulon 90mm with a TMax 400 negative as yesterday, but cropped for a similar view of the yard and barbecue area, but scanned this time at 1600 spi.
I'll take it out and try a landscape shot in the future. I don't have a 150mm lens, but I'll try my 210mm and see how they compare.
How does the lens seem to folks? Best regards.

Mike

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Originally Posted by Michael Heald

Hello! I've taken my first test pictures of a hyperfocal 16x20 Cardboard ULF camera. The lens is the 28 inch element of a Gundlach triple convertible, and it covers fine. The glass is only OK. Since I'll be using this at f128 (maybe f64), I bought an inexpensive shutter and glued it to the back of the lens. No turning back now, but for $50 total, it's worth a try.
I debated using foamcore and Styrofoam, then I figured why not just use cardboard since I don't need focusing. It's a one shot design. I'll load it in the dark and then develop so I don't need film holders. The back is 24x24 inches and the front 10x10 inches. The conical shape gives it a fair amount of rigidity.
When I measured the focal length of the lens using a telescope eyepiece at infinity, I got 26 1/2 inches from the center of the elements instead of 28. Using a CoC of 0.3mm, I obtained a hyperfocal distance of 38.2 feet and this was 28 inches from the center of the elements when I used a telescope eyepiece focused to 38.2 feet.
For this test, I taped 4x5 TMax 400 to the center of the back. It was dusk, so the exposure was 75 seconds at f128. For comparison, I moved up and shot 4x5 TMax400with a 90mm SuperAngulon at f64 at 5 seconds. This was taken 45 minutes before the hyperfocal camera, so its exposure was shorter. I focused the 90mm at 38 feet.
Unfortunately, I missed the fence I was aiming for with the hyperfocal camera, but the foot of the fence at 35 feet is visible as are several leaves at 22 feet. The leaves are 14 feet from the 90mm.
I scanned the hyperfocal negative at 300 spi and the 90mm negative at 1200spi, though I had to crop about 1:5 or 6 instead of 1:4 in order to obtain similar distances between the leaves.
Interestingly, to my eye, the leaves look sharper in the 90mm negative on the right, but the fence post looks sharper in the hyperfocal negative on the left when I enlarged them for easier viewing.
The next step is to try a 16x20 paper negative. Best regards.

Mike

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Michael,

Neat! :) :) At least, having constructed it from cardboard makes it a light(er) camera than otherwise! :)

It wouldn't be all that difficult to mount a holder system to it, would it? It'd certainly give you more options than the one-shot route.

We'll look forward to seeing more images from it.

Cheers

I'd say you have some flare in the hyperfocal camera; it's likely that a carefully sized and positioned baffle behind the lens would trap stray light that's currently (it seems) being scattered onto the film/paper. Beyond that, it looks like f/128 is none too small an aperture for DOF with that focal length; it's tempting to suggest testing at f/180 if your aperture will close down another stop.

Still, nice *CHEAP* way into ULF. Holders? You'd have to pawn your car to get two in that size, and you'll already be hocking the kids to get a box of film; I'd say don't bother, unless you can design one to build from foam core or matt board.

BTW, a telescope eyepiece isn't the best way to check for focus, unless you have a reference object (like a crosshair or similar) at the focal point of the eyepiece itself; otherwise, your eye will accommodate the adjust the image into focus over a fairly broad range of incorrect positions. OTOH, you seem to have gotten the plane of best focus about where you want it, so probably no big deal.

Do you have any photos of the camera itself? It sounds interesting & fun.

~Ted

Michael,

as a builder of "alternative" cameras, I can appreciate your enthusiasm. The temptation to take myself too seriously is easily avoided when using a camera I made from foamcore and gaffer's tape, and the quality of the images produced can make me laugh outloud. More fun than I have a right to. If I can make a few suggestion; you might consider constructing a set of internal baffles from black cardboard, that will do the job a proper bellows does (regarding internal flare), but even better than a bellows does it, and if you don't have one, make a good lens shade from the same black cardboard. These two additions can make an enormous difference in contrast and sharpness, especially when using uncoated lenses. Have fun, and thanks for posting.

Jay

Hello! It has been fun to make and play with so far. Cheap too.

I'll get a picture up; it looks like a brown rectangular pyramide wit the lens on top.

I painted the inside flat black and I took the 11:00 A.M. image with the camera in the shade. I wonder if the blown highlights are due to the high contrast of the time of day, since using VC paper will blow sky and other blue highlights. Would a lens shade help even though the picture was taken with the camera in shade? Best regards.

Mike

Michael,
When I was doing paper negatives and tested the grade-equivalent contrast with a step-wedge, I found that the grades of paper seemed to be additive. That is, if I used a grade 1 paper for the negative, and a grade 1 paper for the print, I got a "grade two" print. The last time I made a camera, I made a foamcore 8x10 as a demonstration for a HS science class and used rc multigrade paper with no filter for the negative and a number 1 filter for the light when making a contact print. The tonal scale was still a little harsh. I also learned that wetting the neg paper and the print paper and squeegeeing them together gives great contact and can help shorten exposure time somewhat. It is also easy to handle the allignment and eliminates the need to dry the negative before printing. Just wet, squeegee in the bottom of a tray, and expose. I also look forward to your experiences and photos. Thanks for sharing.
Michael