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Thread: Preflashing

  1. #1
    bvy
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    Preflashing

    Iím hoping Joe Van Cleave, the prophet of preflashing, will stop by, but anyone who has an opinion or some experience on the matter, Iíll be happy to hear from.

    Iím working with a cylindrical pinhole camera (think Quaker Oats), f/226, using Ilford grade 2 RC paper (satin) and developing in Ilford chemicals (PQ 1 min, water/vinegar 20 sec, rapid fix 1 min). I get mostly good results, except my shadows are often a little (or a lot) lacking in details.

    Iíve read that preflashing the paper is one solution, but Iíve also read of some pretty elaborate schemes. I really donít want to build anything in terms of a special light or some other contraption Ė at least not right away. Is there some quick and dirty, MacGyver-style approach to preflashing that I can try just to get a taste of it? If I see that it works for me, then I might look into something more elaborate.

    Thanks!

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    Andrew Moxom's Avatar
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    It's a trial and error process for flashing paper and is something that you could do with an enlarger with no neg in the carrier. Stop down your lens and make a test print on the paper you are going to use and do like you would do for a regular test print while printing a neg. then process in paper dev and stop/fix as normal and then look for the time when the paper just starts to show a tone/fog. Then back off to the previous expsoure that gave you that tone. you have now pushed the papers response just up to the inertia point. Then you can use as you normally would in your pinhole camera.

    Your mileage may vary, but it's a starting point at least. If you find your resulting work still looks muddy, then continue to back off on the flashing expsoure until you get the tones and density you want.

    Long term, I would invest in a RH designs paper flasher that can be mounted to your enlarger next to the lens stage and flash your paper that way.
    Please check out my website www.amoxomphotography.com and APUG Portfolio .....

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    BetterSense's Avatar
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    I just put the paper on my enlarger and expose it without the negative carrier installed. I expose it just enough to put a faint amount of tone if you develop the paper right then. This doesn't harm my pictures to have this faint amount of "base fog" present. Preflashing definietly helps tame contrast.

    I wonder what difference you could make if you preflashed with different Multigrade filters in place?
    f/22 and be there.

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    bvy
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    Thanks so far for the responses. No enlarger at the moment unfortunately. I'm only developing paper negatives and scanning (sorry!) film. I will refer back though, as I hope to start making prints, probably next year. Any other ideas?

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    BetterSense's Avatar
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    My next idea would be to shoot a grey card held in front of the camera (and maybe moved around) for a certain amount of time before making your normal exposure. Say, 3-5 stops less than you judge for your regular exposure.

    I've been thinking about this myself for when I need to be far away from home.
    f/22 and be there.

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    RalphLambrecht's Avatar
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    Quote Originally Posted by bvy View Post
    Iím hoping Joe Van Cleave, the prophet of preflashing, will stop by, but anyone who has an opinion or some experience on the matter, Iíll be happy to hear from.

    Iím working with a cylindrical pinhole camera (think Quaker Oats), f/226, using Ilford grade 2 RC paper (satin) and developing in Ilford chemicals (PQ 1 min, water/vinegar 20 sec, rapid fix 1 min). I get mostly good results, except my shadows are often a little (or a lot) lacking in details.

    Iíve read that preflashing the paper is one solution, but Iíve also read of some pretty elaborate schemes. I really donít want to build anything in terms of a special light or some other contraption Ė at least not right away. Is there some quick and dirty, MacGyver-style approach to preflashing that I can try just to get a taste of it? If I see that it works for me, then I might look into something more elaborate.

    Thanks!
    Photographic paper is not made for daylight exposures and reacts to the 'blue' light with high-contrast. The best way to make paper negatives (I'm a fan) is to use a yellow filter during the exposure and use half-strength paper developer. It will lengthen the exposure and processing time but does wonders to paper-negative shadow detail and make them a breeze to print. attached are some before and after negatives.
    Attached Thumbnails Attached Thumbnails NoFilter.jpg   YellowFilter.jpg   Dektol1+4.jpg  
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  7. #7
    SMBooth's Avatar
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    Regarding the light I used a 15watt lamp on a dimmer turned pretty much all the way down and diffused it through a plastic milkbottle. Cannot remember the time but easy to test. Held it about 600mm above the paper.

  8. #8
    Joe VanCleave's Avatar
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    The grade 2 paper that I use (Freestyle's Arista) I usually develop for closer to 2-3 minutes; inadequate development can sometimes cause you to miss shadow details.

    In the past I've rated this paper around EI=3; but doing more controlled development tests this summer revealed that with the developer mixed fresh, and its temperature maintained close to 68f, I found EI=12 to be pretty good. FYI I've used both Neutol WA and Ilford's Universal liquid paper developer; both I dilute around 1+15.

    Regarding the preflashing, my setup uses a type S11 bulb, which is a white frosted round globe, about the size of a golfball, in standard household socket base, built into a soup can housing with a 3mm exit hole; the lamp is suspended about 30 inches above the paper when preflashing. I've found 10 seconds a good preflash time with my light, paper choice, EI rating and developer methodology.

    For your setup, you'd want to get a dim enough light source such that the preflash exposure times can be accurately timed; I time mine by a standard Graylab darkroom timer that doesn't permit sub-1 second exposures, so getting the light intensity low enough to permit exposure times in the 5-10 second range is important for accuracy.

    I know you don't want to build your own light source. You could try a light dimmer to reduce the intensity; but the problem is that this changes the color temperature of the lamp with changes in voltage. You end up chasing your tail with calibration tests using a light dimmer, since the spectal response of the paper is not linear with wavelength, trust me! Spend a bit of time to make a reliable light source, then do some calibration tests to get your prefered preflash time down. I prefer to preflash such that an otherwise unexposed negative, when developed, yields a faint light-gray tone.

    The idea with a paper negative is to fit all of the scene's brightness range onto the limited tones of the paper. So you don't want a paper negative to have the wide contrast range of a finished print; you want the tonal scale compressed, but maintaining detail in both shadows and highlights (ideally; sometimes this isn't possible, in which case you pick which is more important). Then, when you contact print (or scan and tweak in PS), you can extract the scene's full tonal range into the finished print.

    ~Joe

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    bvy
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    Joe, thanks so much for responding. So you think I might also be underdeveloping? It's something I should experiment with, I suppose. I'll experiment with a "proper" light source for preflashing. I like your ideas.

    Ralph, I'm intrigued by the yellow filter suggestion. Silly question maybe, but do you just hold the filter in front of the pinhole? The results look good.

  10. #10
    RalphLambrecht's Avatar
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    Quote Originally Posted by bvy View Post
    Joe, thanks so much for responding. So you think I might also be underdeveloping? It's something I should experiment with, I suppose. I'll experiment with a "proper" light source for preflashing. I like your ideas.

    Ralph, I'm intrigued by the yellow filter suggestion. Silly question maybe, but do you just hold the filter in front of the pinhole? The results look good.
    For pinhole photography, it's held from underneath on the lens plate by a lump of blue-tack. But I also make paper-negatives with lens-based photography. I rate the filter/paper combo as ASA 3 for MG-IV paper. It gives me a beautiful tonality and easy-to-print negatives.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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