Thanks for the messages - had a go preflashing last night and got the result I was after. I'd tried burning in the sky, but the horizon was uneven with tufty grass areas and I couldn't really do much without getting a halo effect. Last night's print had decent exposure & contrast in foreground, and an even light grey sky.
The whole film (HP5) was overdeveloped in rodinal, so I've got a few more frames to work on.
I've been meaning to try flashing for a while (since I got the second enlarger), but I guess this thread was in my head tonight, cause I finally got round to tryingit. I had a portrait shot against a great sky, but the skin tones were buried way too dark.
Rather than aiming for good blacks and whites, I worked the print to get the blacks and mid-tones where I wanted, ignoring the highlights which rapadly became burnt out, as I brought the mid tones up.
I then put a bit of milk carton in the negative carrier of the spare enlarger, racked it up to full hight, and ran a test strip which gave me the timeI coudl flash without effecting the paper visibly.
I then flashed the paper, and repeated the previous exposure - absolutly on cue, all the highlight detail came back!
I guess I could have tried to burn in the sky, but even for a first attempt at the technique, this was probably faster, and certainly easier (and more repeatable). It's pretty much foolproof, as once you've got the correct flash time for the paper it's virtually impossible to get a blown highlight.
Definatly be using this trick again.
one thing you will find is that flashing reduces the overall contrast of the image,
so start by using a contrast grade that is about 1 1/2 to 2 grades over what would
be normal. I personally take the neg out to flash.If you have it right, the image should
have normal contrast and a perfect 5 percent tone in the sky.
Flashing is not like simply adding light. The duration and color of the flash is important. It is truly non-intuitive. If you like, I can refer you to what is (imho) a definitive source of authority that's at my fingertips. My office is in a university library (gosh help me.)
Don't ask me about flashing with VC paper with various colors. I only have a hunch that there is another whole book in that point.
I've one a fair amount of Pre-flashing in color printing. A *very* effective method of reducing contrast without adversely affecting color balance.
The process: Analyze the image of a grey card, uniformy covering the negative frame, balancing for color and exposure. Pre-flash by exposing the paper for 10% to 20% of the analyzed time. Place the negative to be printed in the enlarger and analyze as usual. Print on the pre-flashed paper for the remaining 80% - 90% of the indicated time.
I have a photograph taken in *bright* noonday sunlight of a group of girls wearing white evening gowns. Absolutely "blown" highlights - and truly featureless black shadows -- saved wonderfully through pre-flashing.
Ed Sukach, FFP.
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If you have some Potassium Ferricyanide you could bleach the latent image. You will get highlight rendition according to your filter. You will be able to get shadows at just about any contrast level lower that you want. It is an extremely potent technique. Lets say that you wanted a highlight rendition from a grade 3 filter. Lets say that you wanted the contrast level for the blacks to be about what you would get with a number 1 filter. Here is what you would do.
Prepare a tray with 4 liters of water. Put in 1 teaspoon of Potassium Ferricyanide and mix together...as easy as pie. Insert your # 3 filter into the enlarger. Make an exposure that will render the highlights as you wish.
Insert the exposed paper into the PF bleach and agigtate for 2 minutes, allow it to drip for 5 seconds and develop normally.
Examine your finished print after fixing. If the contrast of your highlights is not correct you will need to expose another piece of paper with a different filter. Look at your shadows and dark tones. If the shadows are slightly darker than you wish Increase your PF bleach time to 4 minutes on your next print. If they are slightly light try a bleach time of 75 seconds on your next test. If your shadows are way too dark or way too light you need to modify your bleach concentration. If way too dark add 2 teaspoons of PF and process another print. If the shadows are way too light pour out 2/3 of the bleach and replace with water.
Make a new test and reevaluate.
This works like a MIRACLE and does not grey down your highlights. It is EXTREMELY flexible.
Claire (Ms Anne Thrope is in the darkroom)
I find the technique of flashing very easy and useful... I have a piece of frosted plastic (with no pattern) that I hold under the enlarger lens after my exposure. I leave my negative in, and my aperture the same as the print ... start with a flashing exposure of about 10% of my original exposure.
I have this tool and could not now live without it. Highly recommended,
If all else fails and you are still getting blocky highlights, even with flashing, and without having to resort to fogging your image, there is always split-diffusion. Using a piece of glass with a film of petroleum jelly evenly spread across it, try diffusing for approximately 25-30% of your total exposure time. This will still preserve your high values in some areas but will spread value in some of the blocky areas to make it appear to have separation. It can be utilized so as not to appear overtly manipulated.
I used to do the same when I was making a couple of thousand custom B&W prints a month from sometimes awful negs. I used a double thickness of spaced milky plex (the pre-exposure with filtration device in the A. Adams books), and gave about 20% of the print exposure with negative in place and f-stop the same as the print. My experience would suggest that you just need to find a percentage time of the main exposure that works for your particular diffuser and go with that.
Originally Posted by Julian Ferreira
The words that most often escaped my lips in that job (after being asked too many times to include shadow detail that wasn't in the negative and bring down uncontrolled highlights): "tell 'em if they want it printed that way, they should shoot it that way." I had the lab manager prominently post the section of the (then new) TMZ technical bulletin that basically says "P3200 is really 800 ASA. Any higher rating is pushing it."
Back on topic: one of my back burner projects is to make my own flasher like the commercial version lee\c points to, but with two LED light sources, green and blue, so that I can try controlling the relative amount of flashing in the low and high contrast emulsions of VC papers.