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  1. #11
    Marco B's Avatar
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    Quote Originally Posted by ath View Post
    Maybe I just simply don't understand this - I always had the understanding that preflashing reduces the contrast in the highlights and adds more detail (bringing back blown out highlights by reduced contrast).
    If your highlights don't print at all, which is the situation I was referring too, there is no "highlight contrast" , so if the pre-flashing helps in getting highlights in some parts of the print, it actually increases the contrast there...

    I think it is better to say that pre-flashing reduces or influences the overall contrast of the entire print.
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    "The nineteenth century began by believing that what was reasonable was true, and it wound up by believing that what it saw a photograph of, was true." - William M. Ivins Jr.

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  2. #12
    RH Designs's Avatar
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    If your highlights don't print at all, your overall exposure is too short. That's exactly akin to insufficient negative exposure resulting in irretrievably blank shadows. As you're split-printing I suggest you establish the soft exposure first based only on the highlights, then use the hard exposure to get the midtones and shadows how you want them. Occasionally if I'm having trouble with a negative with soft highlights I find a preflash followed by a grade 5 exposure only works quite well at adding detail to the highlights without the muddiness that can occur by simply increasing exposure. Flashing certainly does influence the overall print contrast and the best way to establish the right balance of flash and image-forming exposures is by a test strip. Well, several test strips probably! Use white light or a soft filter when flashing VC paper, a hard filter will not work - it just adds overall exposure.
    Regards,
    Richard.

    RH Designs - My Photography

  3. #13
    Marco B's Avatar
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    Quote Originally Posted by RH Designs View Post
    If your highlights don't print at all, your overall exposure is too short.
    Quote Originally Posted by RH Designs View Post
    Occasionally if I'm having trouble with a negative with soft highlights I find a preflash followed by a grade 5 exposure only works quite well at adding detail to the highlights without the muddiness that can occur by simply increasing exposure.
    Richard, I think these two quotes are slightly contradictory. I don't agree the overall exposure is necessarily to short, and your second remark seems to confirm this, as you state a simple increase of exposure can cause overall muddiness.

    In addition, as I stated with my recent RC / FB experience, sometimes the RC prints proper overall including highlights, while the FB has good midtones and shadows, but fails to print the really dense parts of the negative. Please note that I am talking very dense parts, that usually require some additional burning in as well.

    Flashing can help make these highlights more printable, without altering the overall midtone and shadow appearance to much in my experience.
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    "The nineteenth century began by believing that what was reasonable was true, and it wound up by believing that what it saw a photograph of, was true." - William M. Ivins Jr.

    "I don't know, maybe we should disinvent color, and we could just shoot Black & White." - David Burnett in 1978

    "Analog is chemistry + physics, digital is physics + math, which ones did you like most?"

  4. #14
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    ath: in my theoretical understanding, preflashing reduces the total dynamic range of the print without changing the slope of the characteristic curve. Some people refer to the total DR as "contrast" and as such it is a reduction thereof. The intention though is to increase contrast (slope of the curve) without increasing DR and thereby blowing highlights. The alternative to preflashing is using a softer filter, which reduces print DR by flattening the curve.

    Yes, it could be my negs. Some in particular are probably overexposed by about a stop but most are not and I'm having this issue on all at the moment.

  5. #15
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    What's on the negative in the area in question, can you examine it with a loupe? Is there noticeable density differences in this highlight area so that you should expect it to print with the desired contrast?

  6. #16
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    Quote Originally Posted by polyglot View Post
    ath: in my theoretical understanding, preflashing reduces the total dynamic range of the print without changing the slope of the characteristic curve. Some people refer to the total DR as "contrast" and as such it is a reduction thereof. The intention though is to increase contrast (slope of the curve) without increasing DR and thereby blowing highlights. The alternative to preflashing is using a softer filter, which reduces print DR by flattening the curve.

    Yes, it could be my negs. Some in particular are probably overexposed by about a stop but most are not and I'm having this issue on all at the moment.
    About a stop over exposure is where I aim at for a split grade printing negative. I find contras-tier or expanded negs work better for me with the technique.

  7. #17
    polyglot's Avatar
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    Yep, there is plenty of detail in these highlights: they show up fine in neg scans and if I print at a higher grade and burn them down instead of using a softer filter.

    I should get to the darkroom on Monday (it's 25km away at the camera club) and give the preflashing and yellow-before-magenta a go.

  8. #18
    RH Designs's Avatar
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    Quote Originally Posted by Marco B View Post
    Richard, I think these two quotes are slightly contradictory. I don't agree the overall exposure is necessarily to short, and your second remark seems to confirm this, as you state a simple increase of exposure can cause overall muddiness.
    If there's no tone on the paper in an area where you want some, then the exposure is too short - only exposure to light can put tone on paper. However, because highlights generally fall in the toe of the paper curve contrast will be inherently lower than in light mid tones. So they require a greater exposure increase than would be desirable for the remaining areas. Flashing adds overall exposure, whereas image forming light will add relatively more exposure in less dense areas of the negative. That's what causes the muddiness. A flash exposure sensitises the paper so that even highlight areas start to move out of the toe, increasing contrast, and then a high contrast image-forming exposure is used to produce the mid and dark tones.

    In addition, as I stated with my recent RC / FB experience, sometimes the RC prints proper overall including highlights, while the FB has good midtones and shadows, but fails to print the really dense parts of the negative.
    In your earlier post you said you are using Agfa RC and Kentmere FB papers. That's not really comparing like with like. They are very different animals, and I personally much preferred the results I got with Agfa FB paper to Kentmere.
    Regards,
    Richard.

    RH Designs - My Photography

  9. #19
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    My understanding of pre-flashing is to get the whole material (film or paper) up closer to the threshold of where it will record detail.

    For paper, pre-flash can easily double the total amount of light that the highlight areas receive.

    In the shadows which are heavily exposed the pre-flash may only increase the total exposure 1/2 a percent so the effect is negligible.

    The risk or limit is simply reaching the point where the paper fogs.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  10. #20
    Marco B's Avatar
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    Quote Originally Posted by RH Designs View Post
    In your earlier post you said you are using Agfa RC and Kentmere FB papers. That's not really comparing like with like. They are very different animals, and I personally much preferred the results I got with Agfa FB paper to Kentmere.
    I wasn't suggesting they were anything alike, and AGFA MCC was my preferred paper too before AGFA went bust... (the RC variant was just some left over stock that I used). But even so, I have used Kentmere VC Select too (RC), and Ilford RC and FB papers. Although I haven't tested this properly, my gut feeling tells me I always have had a bit more trouble printing highlights on the FB variants...

    Looking at your last post though and the further explanation, I think we basically agree about the effect and usage of a pre-flash

    Lastly, also taking your own and now Polyglots experience with Kentmere Fineprint VC into account, I think that at least for this specific paper, pre-flashing should be considered in case one has difficulty printing (highlights). My experiences are good with it on Fineprint.
    My website

    "The nineteenth century began by believing that what was reasonable was true, and it wound up by believing that what it saw a photograph of, was true." - William M. Ivins Jr.

    "I don't know, maybe we should disinvent color, and we could just shoot Black & White." - David Burnett in 1978

    "Analog is chemistry + physics, digital is physics + math, which ones did you like most?"

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