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Thread: Homemade 8x10 with copy lens

  1. #1

    Homemade 8x10 with copy lens

    Further testing of my homemade 8x10 camera, based on Allan Greene's "Primitive Photography" book. I've graduated from a pinhole 'lens', and have installed a copy lens inside a lens-tube to hold it. The lens is a little short, around 200mm focal length. My minimum extension on the camera is about 250mm. So the lens is recessed a few inches inside the camera, and vignetting results. No big deal, just trim the negative.

    I also switched to grade 1 paper rather than 2, which seems to do a great job in retaining range. However this lens is too fast, f/4.5 to f/16 only, and I don't have a shutter. Trying to get 1/4 and 1/2 second exposures is tricky, although I managed it. This was a 1/2 second exposure, paper having a rough ASA of 8. Subject matter was in open shade, on a bright sunny day. f-stop set to f/8, and I focused on spongebob's eyes.


    http://farm1.static.flickr.com/140/400501610_69bab31aac.jpg

  2. #2

    Homemade 8x10 with copy lens

    This is a great example of what I love about improvised lens cameras with paper negatives. Outstanding results in terms of tonal range and sharpness, at least as viewed via the web. I would imagine the contact print could be quite nice.

    Great job!

  3. #3

    Homemade 8x10 with copy lens

    i think ths exposure is probably better for scanning, and i'd want to rate the paper at ASA 4 for contact printing. although i haven't tried contact printing one of these grade-1 papers yet, so i could be wrong. it just looks a little thin to me, but ultimately scanned very well.

    and man it's sharp! i think i might enjoy this large format photography.... mind you, i'm next going to build some homemade lenses, and the sharpness thing will probably go out the window again.

  4. #4

    Homemade 8x10 with copy lens

    Cool...what kind of copy lens was it? Nice find, one with adjustable iris.

    I have three that are all fixed iris. One will fit on an Ilex #1 electronic shutter.

  5. #5

    Homemade 8x10 with copy lens

    it's a bausch and lomb. says "8 1/4" f/4.5 1:1 mag" on it, as well as a stamp that says "+3" and "Apr 28, 1964"

    i wouldn't know a copy lens if it snuck up behind me in an alley and hit me over the head with a hasselblad. so i didn't know i'd struck gold with a variable aperture. i may resort to sticking a homemade stop in front of it anyway, which would negate the coolness of it. although my bowler-hat moves seem to be working for shady areas at f/8, so perhaps not.

    what i can't quite figure out is why the vignetting is oval-shaped rather than circular. it seems to conform to the paper size, which it shouldn't. i'm wondering if this is a function of lens cap removal/replacement. i'm left handed, would have pulled from the left, and since everything's inverted, the left side is darker than the right. perhaps that's entering into the problem.

    time to build a guillotine shutter or something similar.

    or move from southern california, to a place with less contrast and longer exposure times.

  6. #6

    Homemade 8x10 with copy lens

    Process lenses usually start at f/8 or f/9 and go to high numbers, minimum 45, typ. 64, sometimes 90 or 128, occasionally 256 on older ones. Really long f.l. process lenses may be f/11, f/12, f14 and up.

    The 4.5 and 1:1 is probably a key clue to a copy lens, although so is the sometimes-present label identifying it :O).

    I looked up patents on my Ednalite ones and found that they were optimized for a particular type of lamp...basically closer to monochromatic than color-corrected...probably good for paper negs...color film debatable.

    OTOH, after concentrating on Pinhole for so long, I'll bet any LF neg with a copy lens would look good to me. I'm not too fussy.

  7. #7

    Homemade 8x10 with copy lens

    so what was/is a process lens used for? i assume a copy lens is for copying documents and such onto film. what's a process lens?

  8. #8

    Homemade 8x10 with copy lens

    That is probably the best looking paper negavtive I have seen yet. I has a better feel to it than any I have ever shot. I haven't seen all joe's yet so I can't say anything about his but mine never look this good. Even my five by seven never looked so good.

    The one thing I like about paper negs is usually I dont really need the shutter at all. pull the dark slide and then replace the dark slide ten minutes of so later..

    Nice job

  9. #9

    Homemade 8x10 with copy lens

    thanks retroshooter. i should probably reiterate that this is with a copy lens installed...it's not a pinhole. your comments lead me to believe you might be thinking it's a pinhole.

    i'm finding that the grade 1 paper i've switched to makes a big difference. i had started with grade 2, but it was just too contrasty for outdoor scenes. it didn't scan well at all, although i never tried much contact printing with it.

    i really should shoot some more with this camera, but other projects have gotten in the way (like a 2x3 press camera, and more recently a 'proper' 4x5). even my four year old son over the weekend asked me why i hadn't used it! so i shall have to enlist his help soon. it would probably be more convenient if i finished the tripod mount so i didn't have to shoot scenes from picnic tables.

  10. #10

    Homemade 8x10 with copy lens

    I seldom shoot a pinhole camera at all these days. I do shoot a few paper negs though. Mine seldom have that particular sharpness at any point.

    I shot a five by seven home made camera for a while and it was never that sharp but i was using half of a rectiliner lens so I guess that might have been a drawback. I shoot paper in my 4x5 graflex with a mint 3a lens and it looks really nice but I doubt that it is that sharp.

    I guess the optar lens might be but I'm not sure about that either. I have a desire to build a tripod but havent found the right set of plans or the proper incentive yet.

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