Is pre-exposing negs a useful tool or a complete waste of time?

Bruce Robbins · Apr 24, 2015

I've written a post about this on my blog, The Online Darkroom, hoping to start a bit of a debate to see if we could get a definitive answer. Bruce Barnbaum in his book The Art of Photography says it doesn't work. Others, including Ansel Adams and Barry Thornton, were adamant it did. I've explained some of the background at this link Barnbaum v Thornton: Who's Right?.

I'm sure there must be someone out there technically inclined who's done the testing and can show whether or not pre-exposure is valuable. If so, please feel encouraged to add a comment at the end of my post or add something here that I can copy and paste. Pre-exposure seems an unlikely procedure to be in some doubt.

Keith Tapscott. · Apr 24, 2015

Bruce Robbins said:
I've written a post about this on my blog, The Online Darkroom, hoping to start a bit of a debate to see if we could get a definitive answer. Bruce Barnbaum in his book The Art of Photography says it doesn't work. Others, including Ansel Adams and Barry Thornton, were adamant it did. I've explained some of the background at this link Barnbaum v Thornton: Who's Right?.

I'm sure there must be someone out there technically inclined who's done the testing and can show whether or not pre-exposure is valuable.

Whether it is of any use, I honestly couldn't say, but I doubt very much that there would be many people who would be interested or want to try it.

Simon R Galley · Apr 24, 2015

Dear Bruce,

With negatives I have never done it, I have never felt technically any reason to do it with the modern emulsions available to us and cannot see
personally any aesthetic for doing it. BUT as with other techniques that apply to all areas of photo 'science' if you do it, it works for you, and it forms part of your discipline then do it. If we all did the same thing it would be pretty boring, we would not experiment and experimentation at many levels can bring additional satisfaction or expression to your photography and printing and that has to be a good thing.

Simon ILFORD Photo / HARMAN technology Limited :

Simon ILFORD photo / HARMAN technology Limited

Xmas · Apr 24, 2015

There are people on the forum who do it, maybe the search function has broken again?

Athiril · Apr 24, 2015

It's incredibly useful if you push the film hard and are seeking speed.

I haven't done it much, so my only example is on Superia 800 pushed hard in C-41, but the principle applies to B&W as well.

Superia 800 @ 12800 no-preflash

Superia 800 @ 12800 no preflash by athiril, on Flickr

Superia 800 @ 12800 with the right amount of preflash

Superia 800 @ 12800 Zone 3 preflash by athiril, on Flickr

RobC · Apr 24, 2015

I've used it only once as a technical exercise.

The thing is that you really need to have absolutely nailed yor exposure and development to very precise levels to know exactly what your pre-flash is going to achieve.
In zone system terms I wouldn't ever want to pre-flash at more than zone 1 and probably only on zone 0. The need to do it implies you are exposing for the highlights and not the shadows and know that there are shadows which are not going to register on the negative. The simplest solution to this is to expose for the shadows and then deal with the highlights in development and/or printing.
With pre-flash you get only one try at it. If you over do it you ruin the negative. If you under do it you achieve nothing. The process itself is finicky.
Since modern B&W films ae capable of maybe 14 or more stops on the straight line you can usually get it all on the neg without pre-flashing so it seems to me to be an unecessary procedure which is highly risky. Using compensating development to control the development is what most people would do or simply use fill flash rather than film pre-flash.

I haven't tried with colour films so will defer to others for their thoughts on that.

RalphLambrecht · Apr 24, 2015

Bruce Robbins said:
I've written a post about this on my blog, The Online Darkroom, hoping to start a bit of a debate to see if we could get a definitive answer. Bruce Barnbaum in his book The Art of Photography says it doesn't work. Others, including Ansel Adams and Barry Thornton, were adamant it did. I've explained some of the background at this link Barnbaum v Thornton: Who's Right?.

I'm sure there must be someone out there technically inclined who's done the testing and can show whether or not pre-exposure is valuable. If so, please feel encouraged to add a comment at the end of my post or add something here that I can copy and paste. Pre-exposure seems an unlikely procedure to be in some doubt.

itdefinately works!it adds more density to the shadows but it unfortunately reduces contrast at the same timecreating a muddy image.I prefer to overexpose and dodge where necessary.

gone · Apr 24, 2015

I think Ralph nailed it, but that's for my tastes and my style of photography. Yours is surely different. There's only way to find out for sure, yes? Like most people here, I'm a big fan of trying things out myself to see what happens. Sort of like the old joke....who you gonna believe, me or your own two eyes? I know it works in the print stage, so maybe if you're using paper negatives it will work fine.

wildbill · Apr 24, 2015

completely useless waste of tool
I've used it and it works.

RobC · Apr 24, 2015

RalphLambrecht said:
itdefinately works!it adds more density to the shadows but it unfortunately reduces contrast at the same timecreating a muddy image.I prefer to overexpose and dodge where necessary.

Reducing contrast is the whole point of using it.

removed account4 · Apr 24, 2015

this thread might be of some help

(there was a url link here which no longer exists)

Xmas · Apr 24, 2015

wildbill said:
completely useless waste of tool
I've used it and it works.

Yes it works in theory and in practice.

Duping transparencies even on to duping film you needed to flash to control contrast.

Deciding on a practical process is difficult.
Mine is very simple-
For flat cloudy days I use multi coated lenses
For bright sunny days I use single coated lenses
the single coated lenses spill highlights into shadows and reduce contrast adaptively dependent on scene brightness range - I use deep hoods to keep the dependency in scene.

I can still burn highlights.

RobC · Apr 24, 2015

Having read your article in your blog I would just coment that Adams and Thornton and I think Barnbaum all advocate exposing for the shadows and developing for the highlights.
So why are they all espousing a technique which is exposing for the highlights and then trying to fix the shadows by pre-flashing film?

I think the trouble with writing photography books is that the essentials really require very little explanation and therefore few pages. So it has to be padded out with all sorts of little techniques which are rarely if ever actually needed but make a 50 page page book into a 200 page book. :confused:

Jim Jones · Apr 24, 2015

Flashing film works for bringing up a little detail in shadows just as flashing paper works on highlights.

Athiril · Apr 24, 2015

If you're pushing from the time I tried, it adds contrast, shadow detail that otherwise is simply not on the neg, and reduces muddiness of the image.

Jim Noel · Apr 24, 2015

Bruce Robbins said:
I've written a post about this on my blog, The Online Darkroom, hoping to start a bit of a debate to see if we could get a definitive answer. Bruce Barnbaum in his book The Art of Photography says it doesn't work. Others, including Ansel Adams and Barry Thornton, were adamant it did. I've explained some of the background at this link Barnbaum v Thornton: Who's Right?.

I'm sure there must be someone out there technically inclined who's done the testing and can show whether or not pre-exposure is valuable. If so, please feel encouraged to add a comment at the end of my post or add something here that I can copy and paste. Pre-exposure seems an unlikely procedure to be in some doubt.

Just another case of Barnbaum being wrong.
There is nothing easier or more effective in bringing down excessive contrast in some situations. A good example is in a dark forest area with very bright sunlit spots and backlit trees. a 1 or 2 zone pre-exposure opens up the shadows beautifully. It is so easy and quick to do it seems ridiculous to not use the tool when needed.

ic-racer · Apr 24, 2015

I think that my prediction that we are entering a new 'Dark Ages' is coming true.

No one has access to the scientific literature on the subject from the last 75 years??

J. H. Webb, J. O. S. A, 25; 4. 1935
G. C Farnell, Phil. Mag., 43 289, 1952
J. H. Webb and C. H. Evans, J. O. S. A., 28, 431, 1938
J. H. Webb, J. O. S. A., 40, 3, 1950
M. Blitz , J. O. S. A., 42 898, 1952
i. s. Bowen and L. T Clark, J. O. S. A., 30 508, 1940

Xmas · Apr 24, 2015

ic-racer said:
I think that my prediction that we are entering a new 'Dark Ages' is coming true.

No one has access to the scientific literature on the subject from the last 75 years??

J. H. Webb, J. O. S. A, 25; 4. 1935
G. C Farnell, Phil. Mag., 43 289, 1952
J. H. Webb and C. H. Evans, J. O. S. A., 28, 431, 1938
J. H. Webb, J. O. S. A., 40, 3, 1950
M. Blitz , J. O. S. A., 42 898, 1952
i. s. Bowen and L. T Clark, J. O. S. A., 30 508, 1940

It is easier just fitting single coated lens.

Lamar · Apr 24, 2015

My tries at pre-flashing B&W. I'm still undecided about it. It appears to add just a bit of shadow detail. I think I still need to find the best development method to use in combination with the pre-flash.

Dead Link Removed

Gerald C Koch · Apr 24, 2015

All that pre-flashing does is to move the image further up the characteristic curve. Is this useful, depends on what you are trying to do. As a general purpose tool it is a waste of time. Can it improve shadow detail, no. Shadow detail depends on exposure. You cannot "trick" the emulsion into registering what is not there. I cannot get to my copy but what does Dr Henry say on the subject in his book?

Bruce Osgood · Apr 24, 2015

I learned of pre-flashing film more than 10 years ago. Thought it was a great/profound idea. Carried a translucent coffee can lid in my bag to cover the lens and am still waiting for the opportunity to need it. I think Ralph has summed it up and ic racer added the frosting.

DREW WILEY · Apr 24, 2015

There is no definitive answer. It's just another tool potentially in your tool kit, with a few pros and a lot of cons. It all depends how you use it. Pre-flashing has to be done very carefully or it simply produces mud in the shadows. I consider it one of the least desirable methods for
controlling contrast range in black and white work, either with film in the field or with paper in the darkroom. Where I do still sometimes use it for correcting color casts in deep shadow with color neg film, without altering the overall color balance of the entire scene. In other words, I pre-expose the film using a flashing diffuser containing a warming filter aimed at a big neutral gray card, but with just enough exposure to affect those deeper shadows themselves and not even the lower midtones. The concept is easy in principle but finicky in the
details. It never worked well for chrome (slide) films because, with their limited latitude, there is almost no way to flash the shadows without affecting midtones and messing up detail and color there. But color negs have a range. It's a tool you want to employ gently, circumspectly. And test, test, test first.

DREW WILEY · Apr 24, 2015

Per a post way back. Flashing for making dupes was the lazy way to do that, and the wrong way. That's just one of the reasons commercial
dupes routinely had a bad rap. But they used those damn automated slide duping systems becuase they had to do it fast and economically.
To do it well the chrome has to be unsharp masked and mounted in a precise glass carrier. But at this point in history this has become academic, since probably nobody is making dupes commercially except via film recorders.

Ian Grant · Apr 24, 2015

In around 50 years I've never pre-flashed film wxcept a few times with a slide copier but then it was to reduce contrast duping Kodachromes onto Kodachrome and controlled by the copier, it worked well.

I can see the point in Athrils push process example it may have been a way to tame push processed HP5 but XP1/2 were my saviour. It's far more important in the printing stage it gave control of Cibachrome and is very useful in B&W printing.

Ian

Andrew O'Neill · Apr 24, 2015

I have used it for B/W. It works and it's useful. Usually on zone I, but occassionally on zone II. I prefer to pre-expose in the field, through a translucent piece of plexi which slips into my filter holder. During Spring Break, I pre-exposed a sheet of x-ray whilst photographing under a bridge. Worked very well.

Is pre-exposing negs a useful tool or a complete waste of time?

Bruce Robbins

Keith Tapscott.

Simon R Galley

Xmas

Athiril

RobC

RalphLambrecht

gone

wildbill

RobC

removed account4

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RobC

Jim Jones

Athiril

Jim Noel

ic-racer

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Lamar

Gerald C Koch

Bruce Osgood

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