Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,895   Posts: 1,520,917   Online: 968
      
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 34

Thread: Flashing Paper

  1. #21

    Join Date
    Dec 2002
    Shooter
    Large Format
    Posts
    6,242
    Quote Originally Posted by glbeas
    I can see the reasoning behind the low contrast flash. What I was thinking concerning the high contrast flash was to bring highlight local contrast up. I suspect the threshold exposure for each emulsion layer is going to be different and differing contrast filters will give a different tonal separation in the highlights. This is all just theory right now and the reality may be miles away but I think it's worth looking into.
    I understand what you are wanting to do. I would mention, however, that preflashing of paper is inherently working against highlight tonal separation. It is by nature compressing highlight tonal values downward off the shoulder of the paper's curve into the upper midtone regions.

    The other way to increase local contrast in the midtone and highlight tonal range and not exceed the paper's exposure scale is through unsharp masking. Since this is proportional to camera negative density, it tends to bring shadow density upward and tend to leave highlight density as it exists. The mask film base plus fog as it affects highlight density can be ignored in this instance since it is a constant throughout the mask.

    An unsharp mask does not require extensive enlarger capabilities (such as a registration system). It can be produced very easily in the darkroom using ortho lith film and it produces repeatable results. Typical peak density on an unsharp mask will be in the .15-.35 range. This allows us to then print the mask-negative sandwich at a higher contrast range or paper grade then the negative itself would normally be printed. This has the effect of increasing local contrast while maintaining overall contrast.

    I personally think that, considering human visual tendencies, we are accustomed to seeing more separation in highlights then in shadows. For that reason, when we view a print, the effects of shadow compression are less troublesome then compression of the highlight values through preflashing of the paper. However, I would go on to say, that no blanket assessment can be made in all cases. Since each image must be evaluated on it's own merits.

    There is no "free ride" in any of the these manipulations of the paper exposure scale. Since that would indicate an ability to depart from the laws of sensitometry. We can, however, affect the scale so long as the overall scale is not exceeded.

  2. #22
    Les McLean's Avatar
    Join Date
    Oct 2002
    Location
    Northern England on the Scottish border
    Shooter
    Multi Format
    Posts
    1,610
    glbeas wrote:
    Les and Don, I have a question about flashing VC paper.
    What are the qualitative difference between flashing with the 3 filter or no filter, just the 5 filter or just the 0 filter? I've seen little mention of any testing on this aspect and was curious of any results gotten so far before I start experimenting myself. I seem to have so little time in the darkroom lately it's going to be a while before I have a complete set of results on the paper I want to use.

    I have tested flashing VC paper with different filters and my conclusion is that there are no benefits and this has been confirmed by Richard Ross of RH Designs. My tests were assessed by my eyes and personal judgement which is the way that I make my prints, Richards were much more scientific for he is a Dr of Electronics as well as a fine photographer and his tests agreed with mine.[/quote]

  3. #23
    glbeas's Avatar
    Join Date
    Sep 2002
    Location
    Roswell, Ga. USA
    Shooter
    Multi Format
    Posts
    3,307
    Images
    109
    Quote Originally Posted by Les McLean
    I have tested flashing VC paper with different filters and my conclusion is that there are no benefits and this has been confirmed by Richard Ross of RH Designs. My tests were assessed by my eyes and personal judgement which is the way that I make my prints, Richards were much more scientific for he is a Dr of Electronics as well as a fine photographer and his tests agreed with mine.
    That's quite interesting Les. Any idea why this happens to be so?

  4. #24
    mobtown_4x5's Avatar
    Join Date
    Feb 2004
    Location
    Baltimore
    Shooter
    4x5 Format
    Posts
    244
    The other way to increase local contrast in the midtone and highlight tonal range and not exceed the paper's exposure scale is through unsharp masking. Since this is proportional to camera negative density, it tends to bring shadow density upward and tend to leave highlight density as it exists.
    I find the "unsharp mask" interesting, but I don't understand exactly how it works, or how noticable the effect/improvement is in practice.

    Does anyone have a gallery image example where an unsharp mask was used? And/or even better, a masked/unmasked set for comparison?

    Matt

  5. #25

    Join Date
    Dec 2002
    Shooter
    Large Format
    Posts
    6,242
    Unsharp masking is a technique in that an unsharp low contrast and low density positive is made of the camera film negative.The compression of the original camera negative density scale is directly proportional to the peak density of the mask.

    The method that I use is to place a sheet of ortho lith film (Freestyle or Photo Warehouse) emulsion side down on a sheet of black paper. (this is important since this film has no antihalation coating). On top of this sheet of lith film I lay a sheet of fixed and unexposed film or clear acetate. On top of the acetate I lay the camera negative emulsion side up. On top of this is placed a sheet of Duratrans or similar untextured diffusion material. This is then exposed with the enlarger. Typically with my Saunders 4550 VCCE with the enlarger head at 8X10 enlargement the times will be about 16-20 seconds at F16. The lith film is developed in Dektol 1-30 for 2 1/2 to 3 minutes, fixed and washed. The mask peak density should be .15 to .35 This mask is best evaluated by laying it on a sheet of white paper. To evaluate it by light transmission does not work well since the density of the mask is so low. If one does not have a densitometer the density can be evaluated by comparison to a .30 ND filter.

    The effect is obtained by printing the mask in registration with the camera negative. The registration is not ultra critical since the mask is unsharp.

    Because the overall camera negative density range will be compressed by the amount of the peak density of the mask, the contrast grade of the paper/filtration can be increased without exceeding the papers exposure scale. This has the effect of increasing local contrast and hence a greater "glow" from the image. Another benefit of an unsharp mask is that it increases apparent sharpness due to edge effects.

    I don't have anything currently posted depicting the effects of this practice. I have had images posted in the past that have had unsharp and also sharp masking utilized.

  6. #26

    Join Date
    May 2003
    Posts
    336
    I concur with less. I have tried flashing variable contrast papers and films with various colors and the only difference will be the flashing exposure time. Otherwise, as with Les, my unscientific but usual method of evaluation notes no end difference.
    Embrace **it! **it. . .just another name for fertilizer. . . Grow baby Grow!

  7. #27
    Les McLean's Avatar
    Join Date
    Oct 2002
    Location
    Northern England on the Scottish border
    Shooter
    Multi Format
    Posts
    1,610
    glbeas wrote:
    That's quite interesting Les. Any idea why this happens to be so?


    The object of flashing is to sensitize the paper so it seems to me that the "grade" of the light source is irrelevant just so long as it is consistent.

  8. #28

    Join Date
    May 2003
    Posts
    336
    As I was drifting off to sleep, it occured to me that with VC paper, I often do a form of what I think you all call "split filitering" with different contrast and color filters, also I have often dodged with a color filter to control contrast in just one area. But as Les once again has commented, once you take away the negative, it becomes simply a matter of how dark the flash will be.

  9. #29
    Flotsam's Avatar
    Join Date
    Sep 2002
    Location
    S.E. New York State
    Posts
    3,221
    Images
    13
    I have seen this thread topic but haven't been following the posts until today.
    Last night I was working on a negative that happened to be perfect for this technique. It is a shot taken straight up through the branches of a Magnolia tree. The branches and flowers were backlit and, on a #2 grade, the sky was paper white. A brief flash added an even, grainless, minimal density to the sky, vastly improving the print. I used the, "just yank out the carrier" method. This is a good technique to keep handy in a printer's toolbox.
    That is called grain. It is supposed to be there.
    =Neal W.=

  10. #30
    Alex Hawley's Avatar
    Join Date
    Jul 2003
    Location
    Kansas, USA
    Shooter
    Large Format
    Posts
    2,895
    Images
    63
    Quote Originally Posted by glbeas
    Les and Don, I have a question about flashing VC paper.
    What are the qualitative difference between flashing with the 3 filter or no filter, just the 5 filter or just the 0 filter?
    OOPS! I did my first pre-flashing with VC paper and it worked. Many thanks to Les for sharing his knowledge with me. I guess I didn't pick up on using the technique with only graded paper.

    I can attest to the fact that the filter grade makes no difference. I tried it it with 0, 2, 4, 5, and no filter. Tried split filtering on the same print with pre-flashing but saw no improvement.

    Here's the one I tried all this with. In the final outcome, I pre-flashed for a couple seconds then exposed with a #1 filter.

    http://www.apug.org/site/main/album_...hp?pic_id=2536

Page 3 of 4 FirstFirst 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin