Discovery of Flashing

[Ian Grant]

My copy of LP Clerc, Photography, Theory and Practice is the 1937 Second Edition in English, edited by the late George Brown, a chemist and editor of the BJP with a very deep knowledge of photography and with impeccable contacts throughout the trade. He new Mees when he was still at Wratten & Wainright

However I have a later "Positive Materials" 1970/71 Revised edition, this was Clerc's book split into individual sections, the editor was DA Spencer a Director of Kodak Ltd who wrote a companion volume on Colour Photography. Guess what I'm right 761 the Herschel effect can be used to control contrast in Printing from Hard negatives. I must have read that last not long after the book was published, I have experienced the Herschel effect with Multigrade papers in a small darkroom where the Paterson red/orange safe light prevented me achieving more than Grade 3.5, changing to a VC brown safe light cured the problem.

This 70/71 edition of Clerc includes pre-flashing 759, and also mentions use of the Herschel effect with direct positive materials 924 stating that most materials were chemically pre-fogged.

Clerc's books are extremely thorough so it would appear that pre-flashing for contrast control wasn't in use (or common use) in 1937 but had been in use for some time for Hypersensitisation. My gut instinct is the research was done for commercial D&P printers which used semi automatic pre flashing to control contrast. I don't think it would have been as useful with the older films and papers available before the war when all lenses were uncoated.

One comment I'd amke was the prints made on the printers with pre-flashing were consistently mediocre, I remember that from my mothers prints from the late 50's and through the 60's until she began using colour films.

Ian

 

[davidkachel]

Vaughn,

Thanks, but a description of what flashing does is not what was requested. My original concern was simply, who and when, for a new book?
I prefer to give credit where it is possible and flashing has been stubborn on that point. Any ideas?

 

[davidkachel]

Bill,
I am sure flashing was around prior to Todd and Zakia and I too found no mention in Mees, though of course, with Mees and James, the particular edition always played a role.
I had 1966. What edition did you not find it in?
I also agree that Mees et al would probably have not found it relevant to their subject matter.

 

[cliveh]

The two effects are very closely related and more importantly Herschell experimented with light of different wavelengths and concluded that what is now termed the "Herschell effect" occurs with exposure to red light and particularly infra-red. The Herschell effect works pre or post exposure, (like flashing) it's the basis of Direct Positive emulsions, although at the time Herschel was interested in post exposure latent image bleaching.

The only differences between flashing and the Herschell effect are that the secondary exposure adds inertia at the wavelengths the emulsion is sensitive too (ie flashing) and the reverse Herschell effect destroys the latent image when that exposure is by Red or Infra-red light.

My point is though that unlike Fox Talbot Herschel took a more scientific approach to photography and experimented with the effects of post exposure of emulsions to various wavelengths of light and at different intensities and exposure times so would have in effect been flashing the materials. He would have been fullyaware of the effects we now term "flashing" but was more interested when the effect reverses and latent image is destroyed and not added to,

Ian

Ian, the thread is about flashing, not a biography of Herschell's experiments.

 

[davidkachel]

Bill,
It doesn't matter whether film or paper, pre or post. Flashing is the vernacular used to describe the process as employed by practical photographers today and as such, there is only one kind. Both "hypersensitization" and "latensification" might be more 'correct' to some, though I don't think flashing really qualifies as either. It is simply a low-level fogging exposure.
I guess it might be more appropriate to ask, "Who discovered its practical use for working photographers?" A lot of things were known to scientists decades before working photographers found a use for them.

 

[davidkachel]

I want you all to note that I took the high road and made no mention of overcoats/raincoats!
;-)

 

[Bob Carnie]

I know I was using flashing techniques in 1973 , taught to me by my tech guides at school, they worked in the photo printing industry in the late 50's and 60's so I can say for certain practical flashing of paper is at least 40 years old
we were also taught red coccine treatment of negatives to improve shadows , this I know goes back to the late 30's Germany.

 

[cliveh]

I know I was using flashing techniques in 1973 , taught to me by my tech guides at school, they worked in the photo printing industry in the late 50's and 60's so I can say for certain practical flashing of paper is at least 40 years old
we were also taught red coccine treatment of negatives to improve shadows , this I know goes back to the late 30's Germany.

As William Henry Fox Talbot used low level candle light in his darkroom, I would have thought flashing is somewhat older than 40 years.

 

[Bob Carnie]

David was asking practical use of it of us.. that's about as far back as I can go.
My first portrait studio gig , the owner retouched in a Berlin Photography Studio in the late 30's and learned red coccine there.

QUOTE=cliveh;1953767682]As William Henry Fox Talbot used low level candle light in his darkroom, I would have thought flashing is somewhat older than 40 years.[/QUOTE]

 

[davidkachel]

"One comment I'd make was the prints made on the printers with pre-flashing were consistently mediocre"

Ian, the reason for that is mildly interesting.
Technically, what those mass-production printers were doing was not flashing, IF we stick to the correct definition of flashing as being a sub-latent exposure.
But these guys didn't care about hair splitting, just making a lot of prints fast. The papers they used were of course single grade, and so they used flashing as a form of contrast control and had no problems giving fogging exposures WAAAY above threshold. That's why those prints looked so muddy in the highlights. They were purposely fogged.
Even today, if you research "flashing" you will see some authors define it as exposure above threshold; some even recommending exposures as high as Zone III or IV.

The fastest way to have people take your ideas and head directly over a cliff with them, is to publish them! ;-)

 

[davidkachel]

"David was asking practical use of it of us.."

Bob,
No, I wasn't. I was simply asking, who discovered its practical use and in what year.

 

[Bob Carnie]

Fred Farkle 1958
QUOTE=davidkachel;1953767697]"David was asking practical use of it of us.."

Bob,
No, I wasn't. I was simply asking, who discovered its practical use and in what year.[/QUOTE]

 

[Ian Grant]

Ian, the thread is about flashing, not a biography of Herschell's experiments.

Herschel experimented with what we now call "flashing" short secondary exposure with light of various wavelengths, as well as longer exposures, and also different intensities, so what he published in 1839 is of relevance. The fact that what's termed the Herschel effect works differently is of course important - he was more interested in the strange image bleaching he found and that over shadows the other results.

Because all that's now written about that particular research work by Herschel is about the "Herschel effect" doesn't mean he didn't find other benefits of secondary exposures, we won't know without reading the research papers.. My guess is his work was presented to the Royal Society, that would have been the norm around 1839.

Ian

 

[Bob Carnie]

I learned it from a guy who learned it from a guy.. you are right this one would be very hard to nail.

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.

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.

 

[Ian Grant]

As William Henry Fox Talbot used low level candle light in his darkroom, I would have thought flashing is somewhat older than 40 years.

Candle light is quite safe for some time with early emulsions as there's no blue/green content, so are low wattage tungsten bulbs.

Flashing in terms of Hypersensitising films is a very old technique and it's working exactly the same way as flashing for contrast control, it just wasn't called flashing until after WWII. One problem its earliest uses are in applied photography in the astro-photography field so it's unlikely you'd find much about it in regular photographic publications,

I've too many BJP Almanacs (and later annuals) 60+ to go searching but there's one piece on pre-flashing for D&P work and that was post WWII, I can't remember seeing pre-flashing except for increasing film sensitivity in pre-WWII BJP Almanacs. I'm quite sure I'd have picked up on it if I'd seen it in pre WWII Almanacs, like the 1926 piece on wet mounting films for enlargements (now common with High end scanning), and the Kodak Research Fine Grain developer that pre-dates D76.

Ian

 

[Vaughn]

Vaughn,

Thanks, but a description of what flashing does is not what was requested. My original concern was simply, who and when, for a new book?
I prefer to give credit where it is possible and flashing has been stubborn on that point. Any ideas?

Sorry -- was just trying to help by defining exactly what you were looking for information on...and to see if I am on the right page in the discussion.

And I don't think to call flashing "contrast control" is very fitting, but I see why it might be considered so. I would see it more as highlight control (in photo paper) as it does not significantly affect mid-tones and shadows. It does not change the slope of the curve -- just where the toe starts.

 

[Ian Grant]

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.

Herschel discover non image (secondary) exposure in 1839.

Ian

 

[cliveh]

Candle light is quite safe for some time with early emulsions as there's no blue/green content, so are low wattage tungsten bulbs.

Flashing in terms of Hypersensitising films is a very old technique and it's working exactly the same way as flashing for contrast control, it just wasn't called flashing until after WWII. One problem its earliest uses are in applied photography in the astro-photography field so it's unlikely you'd find much about it in regular photographic publications,

Ian

Ian, I understand and believe this is quite correct.

 

[Ian Grant]

Ian, I understand and believe this is quite correct.

I have an Ensign (Houghtons) candle powered red safelight

Looking at the 1839 date it seems that the use of red safe lights is a trigger for Herschel's work.

Ian

 

[Vaughn]

As I said, I can understand the use of the term 'lowers contrast' in this context...even tho it is different than other uses of the term contrast.

I have used 'contrast' in the same context as you have when describing what I do when giving a negative a light bleaching -- I am affecting primarily the deeper shadows as they bleach out completely quickly without significantly alterating the relationship of the rest of the tones in the negative.

Then I selenium tone the negative, increasing the highlight densities. There is a greater change in the slope of the film's curve than flashing does to paper.

As long as we know what we are trying to communicate, it does not matter what words we use. And since I am bored,

If you flash the whole sheet of paper, you get a lower contrast paper.

could also be written as: Flashing the whole sheet of paper does not change its original contrast, it just creatively fogs the highlights.

 

[Vaughn]

Well I think you are 100% correct, and so am I...

 

[removed account4]

this seems to me to be a technique that
was discovered and put into use along long time ago
who knows, maybe by people who used dry plates ... like the zone system
and over time people used it, adopted it for other things and refined it to be something used by many.
while it would be nice to put the invention into one person's life's work, its probably just one of those thing ...

 

[davidkachel]

"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]

Sorry -- was just trying to help by defining exactly what you were looking for information on...and to see if I am on the right page in the discussion.

And I don't think to call flashing "contrast control" is very fitting, but I see why it might be considered so. I would see it more as highlight control (in photo paper) as it does not significantly affect mid-tones and shadows. It does not change the slope of the curve -- just where the toe starts.

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.

 

[davidkachel]

Herschel discover non image (secondary) exposure in 1839.

Ian

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?