Pre-flashing question

[markbau]

I'm currently mentoring a young lady who has shot film for quite a while but then had it scanned. I am now introducing her to the darkroom. Today I showed her about pre-flashing whilst trying to print a very contrasty neg of hers. I've always pre-flashed without a contrast filter but she asked, "if we are printing it with a 2/12 filter shouldn't we pre-flash with a 2 1/2 filter?" I had no idea how to answer her so we tried both ways (with necessary exposure changes of course) I couldn't really see a difference but I was wondering what the brains trust in here has to say about it? I might add that I'm not a fan of pre-flashing but I know that sometimes an impossibly contrasty neg can only be printed this way. Two of my heroes, AA and Tim Rudman had very different views on pre-flashing! (AA considered it a technique of last resort)

 

[tezzasmall]

Here's two links that are worth reading:

https://www.lesmcleanphotography.com/articles.php?page=full&article=27

https://www.photrio.com/forum/threads/paper-flashing.33739/

And a link to a (depending upon who you ask)) useful, paper flashing unit:

http://rhdesigns.co.uk/product/paper-flasher-ii/

Terry S

 

[M Carter]

I'm currently mentoring a young lady who has shot film for quite a while but then had it scanned. I am now introducing her to the darkroom. Today I showed her about pre-flashing whilst trying to print a very contrasty neg of hers. I've always pre-flashed without a contrast filter but she asked, "if we are printing it with a 2/12 filter shouldn't we pre-flash with a 2 1/2 filter?" I had no idea how to answer her so we tried both ways (with necessary exposure changes of course) I couldn't really see a difference but I was wondering what the brains trust in here has to say about it? I might add that I'm not a fan of pre-flashing but I know that sometimes an impossibly contrasty neg can only be printed this way. Two of my heroes, AA and Tim Rudman had very different views on pre-flashing! (AA considered it a technique of last resort)

A late reply, but I've never found the grade to matter when flashing, though I often do lith prints. I imagine flashing at grade V could be ineffective, but a test would tell you pretty quickly.

All you need to test flashing is a scrap or strip of paper with some lines drawn on it, so you could suss this out in minutes. (With lith prints, filters generally aren't used when printing). It is an interesting question, I may try it with grades 00 and 5 and no filter next time I'm in there.

I really don't get the "don't flash with the same enlarger" discussed in the above links - flashing times are very short, it's non-image-forming exposure, so simply diffusing the negative projection will work fine. And pulling the neg is no big deal (I use a masking carrier so the damn thing is in and out 5 or 6 times for some of my prints). The real issue is being able to repeat it for an edition of prints or when dialing in a print, do the same thing each time!

Though Ansel considered it a last resort, I've found it's often very useful, but I like clouds and skies! And man, if you use variable sepia in the yellow range, flashing to the point of the faintest fog makes it easier to get all your highlights back in redevelopment. (For the Guardians of Semantics, yes I know that means "fogging" but the procedure and testing is the same as flashing).

I guess a dedicated paper flasher with data for all your papers could be cool, but seeing how testing flashing once you have a print getting dialed in takes maybe 60 seconds, it doesn't bother me. And with lith prints I find flashing is dependent upon the exposure and development that the print demands; your basic print needs to be dialed in a bit before you assess flashing time anyway.

 

[cliveh]

Have you asked why she needs to do pre-flashing? Why not teach her to expose and develop correctly?

 

[Nicholas Lindan]

For grades #00-#3.5 the highlights of the image are almost entirely the domain of the 'green sensitive' layer - the filter you flash with (or just using white light) will make little difference. You would only need to flash with a contrast filter when printing at grades #4-#5 - but you rarely need/want to flash when printing very low contrast negatives so the point is moot.

 

[Pieter12]

I'm currently mentoring a young lady who has shot film for quite a while but then had it scanned. I am now introducing her to the darkroom. Today I showed her about pre-flashing whilst trying to print a very contrasty neg of hers. I've always pre-flashed without a contrast filter but she asked, "if we are printing it with a 2/12 filter shouldn't we pre-flash with a 2 1/2 filter?" I had no idea how to answer her so we tried both ways (with necessary exposure changes of course) I couldn't really see a difference but I was wondering what the brains trust in here has to say about it? I might add that I'm not a fan of pre-flashing but I know that sometimes an impossibly contrasty neg can only be printed this way. Two of my heroes, AA and Tim Rudman had very different views on pre-flashing! (AA considered it a technique of last resort)

How contrasty could the neg be if you're printing at grade 2-1/2?

 

[markbau]

I am trying to teach her the foundational techniques. pre-flashing is a not a technique I would use but many great printers do use it so I believe it needs to be taught as another tool in the toolbox. In one of Tim Rudman's books he has an image that was exposed and developed correctly of an extremely contrasty scene. Pre-flashing made the neg printable. In the same vein, I'm not an advocate of split contrast printing but I have said that she needs to watch a few YouTube videos on the subject. Being a teacher doesn't mean just teaching the ways the teacher likes.

Grade 2 1/2 was a figure I plucked out of the air. The question was actually, why wouldn't you pre-flash with the same filter that you are printing with?

 

[Nicholas Lindan]

The question was actually, why wouldn't you pre-flash with the same filter that you are printing with?

No reason at all, and what the heck, it saves you from changing filters.

You might want to try a flash with a lower contrast filter if the print is being made at grades #4-#5, giving you a bit more control over the highlights. For normal grade prints the filter you use for flashing will make no difference to the look of the print.

You may have your student read http://www.darkroomautomation.com/support/appnotevcworkings.pdf - referring to the graphs on page 2, where you can see that the highlights are controlled entirely by the green sensitive emulsion until you get to the higher contrast grades.

You are, I hope, teaching f-stop timing. The charts published by Ralph Lambrecht in Beyond Monochrome or the various f-stop dials for GraLab timers can serve as a low-cost introduction.