Discovery of Flashing

[davidkachel]

I doubt there will be a factual answer with respect to who first put non-image exposure to practical use. It could have been anybody and wouldn't have been documented. Some guy saw another guy do it, who learnt it from his teacher who saw someone do it, etc.

You're probably right, but it would have been nice to give credit where credit is due.

 

[Vaughn]

NP. But I never said it was used for contrast control. Though it does reduce contrast in the areas effected, it is a second-rate choice for that particular purpose.

Sorry -- the part about contrast control was a general comment, not directed at you specifically...I was unclear in my post. As long as people reading this thread and who may be thinking of using flashing to lower contrast realize that flashing will not make a Grade 3 paper into a Grade 2 paper -- or anything like it (all other variables kept constant) -- all is good.

 

[davidkachel]

Sorry -- the part about contrast control was a general comment, not directed at you specifically...I was unclear in my post. As long as people reading this thread and who may be thinking of using flashing to lower contrast realize that flashing will not make a Grade 3 paper into a Grade 2 paper -- or anything like it (all other variables kept constant) -- all is good.

Apologies. It is hard to keep track of what is going on with so much being posted that has nothing to do with the very simple topic.

Frankly, I seldom (only every few years) resort to APUG precisely because of the handful of people who insist on jumping into a discussion and immediately changing the topic entirely, or in making unjustified rude remarks.

The last time I resorted to APUG the very same person immediately began explaining to me how my own inventions worked; and of course, he had it entirely wrong. Nonetheless he went on for pages and pages, trying to convince everyone he was right.

 

[Vaughn]

If ones question is not answered within the first few posts, or pages at least, then chances are no one knows for sure. But having posts added to it that may not fit the OP's original intent might eventually bring it to the attention of someone who does know...ya never know.

But if someone wants to know about flashing in the future and does a search, this thread will pop up in the search. Might as well have useful information in it! As an archive of useful information, my opinion is that the OP does not 'own' the thread they start -- the OP might be long gone when someone opens up an old thread -- it is community property.

 

[Bob Carnie]

Not at all, I just think I remember this type of discussion year ago. thicker skin required I think.

"Somehow the OP reminds me of a person who claimed to have actually discovered this only to be told it happened much before his time.. I may be wrong but this whole conversation is a DeJeVue moment for me."

Am I misinterpreting, or did you just decide to insult me, out of the blue, by accusing me of trying to take credit for someone else's discovery?!

 

[davidkachel]

Not at all, I just think I remember this type of discussion year ago. thicker skin required I think.

Applying skin thickener, as we speak.

 

[Vaughn]

If you have done sensitometry tests, then you know more than me and I will defer to your knowledge and testing.

I was only using reason and deduction, in that if flashing only affects the highlights and does not affect the response to light of the rest of the tones (since proportionally so little light has been added to them), the paper's response to light in all but the highlights should remain the same -- that is, contrast remains the same between the mid-tones and shadows. Only the highlights have gotten darker. A different grade of the same paper, with the same negative and processed the same way (w/o flashing) would/should have a different contrast in the mid-tones to shadows tones...that is why it is a different grade.

So far you have not backed up your argument with any reasoning or explanation. I would appreciate knowing what fact(s) I am missing or have incorrect in my reasoning...really I do. My reason and deduction aint worth shinola if my facts are wrong.

 

[Andrew O'Neill]

David, it may be one of the great mysteries of photography and we'll never know. In all the reading I've done over the years, I don't ever recall credit given.
Glad you're here, by the way. Check in more often!

 

[Bill Burk]

"Who discovered its practical use for working photographers?"

I would check into the history of halftones in the graphic arts industry.

Because "Flash" exposure is terminology taken from printing.

Here is a calculator used to determine the "Flash" exposure.

For future reference it is a Kodak Graphic Arts Exposure Computer, a dial-type reference card which calculates the Flash exposure required when using Kodak contact screens.

http://www.ebay.com/itm/KODAK-GRAPHIC-ARTS-EXPOSURE-COMPUTER-GOOD-CONDITION-/171838237372?pt=LH_DefaultDomain_0&hash=item28025b6abc

 

[davidkachel]

I would check into the history of halftones in the graphic arts industry.

Because "Flash" exposure is terminology taken from printing.

Here is a calculator used to determine the "Flash" exposure.

For future reference it is a Kodak Graphic Arts Exposure Computer, a dial-type reference card which calculates the Flash exposure required when using Kodak contact screens.

http://www.ebay.com/itm/KODAK-GRAPHIC-ARTS-EXPOSURE-COMPUTER-GOOD-CONDITION-/171838237372?pt=LH_DefaultDomain_0&hash=item28025b6abc

Bill,
I had completely forgotten that flashing was used in graphic arts, too.
That might help explain some things. Different industry, different terminology.

Thanks. I'll look into it.

dk

 

[Bill Burk]

The interesting thing is... in graphic arts the "Flash" that the dial above calculates, is needed to open up the shadows. This is practically the same concept you are researching.

 

[Xmas]

One problem is the term "Flashing" is relatively recent name for the pre/post exposure of films or papers, it was used commercially in printers used in the B&W D & P trade for a number of years to control contrast. Somewhere I have an article or short piece on the use of flashing in the D&P trade. The term isn't in pre-WWII books.

All the early references to pre/post exposure are for increasing the speed of emulsions, rather than contrast control, and it's s technique used primarily in astro-photography. This was Herschel's main field and he discovered the use of Mercury intensifiers to boost negative contrast.

Ian

https://en.m.wikipedia.org/wiki/Robert_Cornelius

Even the USA "got into" Hg sensitization although Wiki does not mention...

 

[Ian Grant]

Did you find a reference that states that?
Or are you still talking about the Herschel effect, which is utterly unrelated to the topic at hand?

The Herschel effect isn't unrelated at all, we'll just have to disagree on that,, just like flashing it's a secondary exposure to light, the difference is it's causing latent image bleaching rather than fogging. Flashing can be done pre or post the film or negatives exposure although it's mainly done first.

We don't know now, unless we read Herschel's papers, what he was actually looking at or for in his experiments which resulted in him finding the "Herschell effect", What we do know though is he experimented with different wave lengths of light and different times and intensities. There's a point as you move from the infra red and red end of the spectrum in the wave length of the light being used when it isn't causing the Herschel effect and is giving a secondary fogging exposure. That's the area of flashing.

At the moment the earliest reference I've found to pre-exposure (flashing) is in a 1931 BJPA which is a précis of an article in Amer. Phot., 1929, May, but it's not claiming it as a new technique, the article is on Night Photography and just states pre-exposure can be used and gives an example exposure using a Wratten 54 filter.

I agree with Bill Burk that pre-exposure (flashing) was an applied photography technique originally and I'm certain the earliest uses were in astro-photography to increase film speed, Bill may well be right that the printing trade may be the earliest use of flashing for contrast control.

Ian

 

[Bob Carnie]

From a very practical point of view -

When I use pre flash of paper I am using 0 balanced filters on Deveere which I believe is close to a grade 2, if I am using condenser enlarger no filter which I also assume is about a grade 2.

I test strip until I see the steps , usually a three second blast and I adjust the the aperture so I get a 7- 10 second time where I can just start seeing density.
I make sure I jiggle the paper as I hit the exposure so I do not get any dust laying on paper.

Much like solarization printing, this flash helps control contrast and I am always amazed that even though I am putting down tone overall, I still can get a full range print with Dmax to percieved specular highlights.
Most of the effect is in the highlight region even though I know the flash is everywhere..

Now I may be subconsiously raising the print contrast by using more 5 filter, and I am dodging during the low filter exposure - at this point I am working on the 1/4 tone area to upper midtone areas to allow more 5 filter to come in on the second exposure . In all cases I am burning in the mid to upper highlight regions one more time with the low filter and of course I will also burn in these same regions with the #5 filter. This #5 burn is IMO the secret of obtaining believable density in highlight regions and helps apply some local contrast or microcontrast in these regions.

Remember the old days of burning in a graded paper to the nthh degree and once one has obtained tone- well it looked mushy and flat. (to offset this problem we would resort to a very complicated highlight protection masks, that was a must in all ciba work but was applicable for negative work. I doubt I could explain the workthrough now on how we made these masks but suffice to say they would take quite a bit of time)

From a practical viewpoint - though all of the above is a printers attempt to camoflauge or create and effect that basically fools the viewers eye when seeing the print on a wall.

Some of it really does not make sense to me but our eye/brain can really fill in blanks. If you do solarization work a lot , this phenomenom will be really striking and your perception of base density plus fog will become warped.

So the question could be , well how much of this is really done in the real world and I would say at least 25% of all prints I do when straight printing employ the above.

 

[Xmas]

Hi Vaughn, your points have validity - I was with you (ie we're both "right") until you said the effect of flashing wouldn't be anything like reducing the paper grade. It isn't entirely straight forward as it depends on how a particular paper's overall curve 'shape' changes (or doesn't), by design, with a grade change in the case of graded paper, or with a change in filtration in the case of a VC paper. In some cases the flashing effect can be far more similar to a grade change than we expect. Richard Henry treats non-image exposure effects fairly extensively in his book, which has some interesting data/results (using Ilford Ilfobrom graded at the time). While I would not go as far as agreeing with his statement that non-image exposure is exactly the same as a grade change, it may or may not be quite similar depending on the paper.

I started a series of experiments on this a while back (because I sometimes use localized flashing and wanted to better understand what was actually happening) but photography interrupted them (thankfully). This discussion has reminded me to go back and finish those tests.

What I always found (visually), was that the contrast reduction effect extended further down than I expected, even into to the low midtones. Of course the effects were greatest in highlight areas, but they were not limited to the highlights, which is why whenever I use flashing, I treat it as a local adjustment (same as if I were burning in). But then this led me to another question - since I use VC paper, if I'm doing a localized flash, is it any different than a localized burn at low contrast? That's what led me to want to test all this.

There might be a dependency on doing the flash with a grade 0 or 5 filter?

 

[Ian Grant]

Some comments for David.

Applied Photography, Focal Press, 1971 lists pre-exposure as a means of contrast control and says it's commonly use with many B&W printing machines. Enlarging, Jacobson, 1940 doesn't mention pre-flashin but it's in Enlarging, Jacobson & Mannheim 24th Impression 1979.

I already mentioned it's listed in Clerc,1937 and I'd guess also the 1930 first edition as \GEorge Brwn the English edior had already included an article in the weekly BJP in Nov 1929, and a précis in the Almanac for 1931 (published late 1930). These references are pre-exposure for increasing film speed.

The BJP from it's early beginnings had writers contributing articles on Applied, Medical and Astro-photography as well as all other areas of photography and the trade, most were experts in their field. The yearly Almanacs where a collection of the more important article, news, new equipment etc from the weekly magazine.

HP Arnold, one of the 3 co-writers of Applied Photography, was the Astro-photography writer for the BJP until quite recently, maybe 10 years ago. As well as reporting on the latest methods and equipment the BJP included historical articles often drawing from their own archives I'm fairly sure it was a BJP article that mentioned pre-exposure as an early technique for increasing film speed. A number of techniques used in that field never really surface in normal photography books, looping colour negative films for example to amplify the image.

If the BJP article was in an Almanac or Annual I'll still have it and I'll try and find it. Meanwhile it would be interesting to see if the 1954 3rd Edition of LP Clerc, Photography - Theory & Practice mentions pre-exposure as a contrast control method for printing. I've no idea where to find a copy.

Ian

 

[Vaughn]

Thanks, Michael!