crappy lens reccomendation:
I am using a field camera with a 6x7 roll film back. I'm looking for a low-quality lens that will fit on a lens board, but with an image circle that just barely covers the format, and a circle of sharpness that falls off greatly at the corners.....maybe an old barrel lens of some sort? Any suggestions? I realize could accomplish this with Tilts and swings, but I'm looking for something different. If I have to make a special lens board, or even the lens itself for that matter, I would not be afraid to.
I'm not trying to get somebody to sell me a lens here, I'm just looking for some suggestions.
Last edited by Tom Nutter; 10-11-2011 at 11:02 PM. Click to view previous post history.
Early 20th century 35mm Petzval projector lenses are a good bet, but you'd need a short one--maybe 3 or 3.5 inch, if you want to see a lot of craziness in the edges. These lenses are small enough to rig in a medium size shutter, like an Alphax, Betax, or Ilex 4. Short projector Petzvals aren't always easy to find, so you could also look for a simple meniscus lens in a shutter--or buy a positive meniscus lens and rig it in a shutter.
I've played around quite a bit with dollar-store magnifying glasses set in a lensboard. Sharpness definitely falls off on the corners, while giving a nice "sweet spot" in the center. The lenses are very low in contrast, however, so are best suited to contrasty scenes or paper negatives, which inherently have more contrast. This image was taken with just such a lens, using a 5x7 paper negative.
Tom, on Point Pelee, Canada
Ansel Adams had the Zone System... I'm working on the points
system. First I points it here, and then I points it there...
+1 on the magnifying glass idea
Real men use Speed Graphics and flashbulbs.
I think you're going to have trouble finding a petzval for that size film that also offers falloff and aberrations. You're talking about a total image circle of less then 10.8cm, right? So, the lens would need to cover less than that at infinity, then you'd need to do closer shots and push the lens beyond design limits to get what you want. Even the cheapo projection petzvals will probably cover more than that. I've been messing with petzvals for years and years and have never had one with that small of a coverage except one that barely covered anything at all...
For an interesting look, probably skip the petzval and go for a meniscus type lens. You can buy some random meniscus lens at Surplus shed or you could get something like a Scovill if you want 'old stuff' and use the lens without the barrel. They generally go to f6 like that and offer soft scenes and glowing highlights. I can loan you one if you can't find one to buy.
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Magnifying glass idea is definitely in the budget....anybody ever try dismantling a Holga and trying that lens? ....guessing I would need a recessed board for that or some other complication.
Last edited by Tom Nutter; 10-11-2011 at 11:50 PM. Click to view previous post history.
Maybe an old cine lens from a home movie camera.
Okay...so this is what I have come up with so far....I dug out my holga...which incidentally seems to be worth about 250% more than it was when I bought it 10 years ago......but I digress...what I have done so far is this: I'm not sure how many of you know how the "focus" on a holga works, but basically, the lens is screwed to the front of the camera with a little stop inside that keeps it from unscrewing off the body...you force it a little and it snaps right past the stop and comes right off.....so.....
you now have a 60mm F/8 lens with no shutter and a fixed aperture....a pretty wide lens even for 6X7CM. I had a spare flat board for my Toyo, but no recessed board and so to get the lens close-enough, I had to tape it to the BACK of my lens board. I will have to use the darkslide or my hand as the shutter and some slow film, I guess. At this point, I am not willing to put a bunch of sticky tape all over one of my copals, so this will suffice for now.
I predict this will NOT produce the look I am hoping for, but I will shoot something and post an image to my blog in a few days if anybody is interested.
A transplanted Holga lens was exactly what I had in mind. Sticky tape doesn't bother Copal shutters. Just keep it on the outside. You should see what I sometimes do to mine!
Kent in SD
I use an 80(I think)mm lens from an Ansco Speedex Jr. on my 4x5, might do just as well on yours, definite vignetting, full circle image on my negs. Maybe a lens from a thrift shop 35mm p&s, or a disposable, and some duct tape.
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