Low Reciprocity Failure Film

[Two23]

Last weekend I drove out to the middle of nowhere to photo inside a long abandoned hotel in a forgotten town. Hotel was built in 1910, a three story structure in what was really a 1-story town! The railroad was coming through but never got across the river as planned. The railroad ended up going dormant, the town faded away, the hotel closed forty years ago and is rapidly disintegrating. I took some photos on the first and second floors, using my Chamonix 045n with Dagor 3 5/8 in Compound, and 240mm Dagor also in Compound. Both lenses are from the 1910s. Film was FP4+ @ 125. The light was so dim I was only getting f8 and 15s exposure on my meter. I carefully crept deeper into the hotel's second floor and took a shot of a sagging stairway, but turned back around when my foot went through the floor.* :eek: I considered poking around in the immense basement, but it was black as a coal mine in there, and we all know the worst spooks hole up in the basement during the day. I had about 10,000ws of flash with me but didn't want to haul it in and mess with it. I turned around and left after popping about five sheets.

So anyway, when I got home I looked it up and saw that FP4+ should have about 50s of exposure when the meter says 15s! I allowed another 10s for reciprocity but that might not have been enough! So, I was underexposing by about a stop. My first thought was to order some wonderful Fuji Acros 100 from B&H. But, when I looked, it was gone! No longer available! Crap. So what else is out there with such a low reciprocity failure rate? So far, the other films I checked are similar to FP4+. I guess I better print off an FP4 reciprocity chart? Fifty second exposures, aye yi yi. Might as well start shooting this stuff with one of my pre-Civil War Petzvals.


Kent in SD

*My fear was if I fell through the 2nd floor,
the momentum would carry me through the
rotten 1st floor as well and I'd end up in the
basement with the spooks!

[Alan9940]

Forget what else is out there! Order your Acros through Kumar directly from Japan.

[Drew Wiley]

I can recommend four superb film choices: ACROS, ACROS, ACROS, and ACROS. Well, there are four formats I shoot it in. Technically, however, I wouldn't classify
it as a "low reciprocity" issue film, but closer to "spot on", "no issue".

[Leigh]

Hi Kent,

ACROS certainly is available. I shoot it all the time in 4x5 and 120.

Order it from Kumar in Japan. He's a great vendor, super easy to deal with. Shipping is not unreasonable.

You can get it from vendors in the US like Adorama and Freestyle. Both have it in stock. Adorama is cheaper.

- Leigh

[Vaughn]

Your exposures should be fine -- only the deep shadows were unexposed -- mid-tones and highlights will be fine. All you will get is a little extra contrast to balance nicely with those Dagors. Perhaps some nice deep Brett-blacks!

But then, my "One Ansel Adams, Two Ansel Adams..." tend to be on the slow side.

My son brought me back 3 boxes of 8x10 Acros from his last Japan trip -- but at not much better price than you can get via Kumar.

[Leigh]

ACROS requires virtually no reciprocity correction.

Metered exposures out to 120 seconds use times as indicated.

From 120 out to 1000 seconds requires only 1/2 stop additional exposure. That's pretty trivial.

- Leigh

[Bruce Watson]

So what else is out there with such a low reciprocity failure rate?

I hate that phrase. It's not really a failure -- it's just that you didn't give the shadows enough photons to generate a latent image. That's more user error than a film failure. Just sayin'.

That said, I do like a film that behaves linearly. Especially with the exposures we normal end up with in LF. For this kind of low light photography, Acros is probably the best. But t-grain films will always outperform cubic grain films in low light, so don't dismiss Delta or Tmax (100, but 400 is surprisingly good in low light).

If you've gotta have Acros, order it from Japan.

Whatever you do, this situation just reinforces what I've always believed. Use the best film you can get, regardless of price. Which is why my only B&W film has been TMY-2 since I first tried it. Yeah, it's expensive, but it's practically free compared to a trip across the country to Joshua Tree. What kind of economy is it to spend all that money on a trip and come home and develop a lot of film that's unprintable?

[Two23]

Whatever you do, this situation just reinforces what I've always believed. Use the best film you can get, regardless of price. Which is why my only B&W film has been TMY-2 since I first tried it. Yeah, it's expensive, but it's practically free compared to a trip across the country to Joshua Tree. What kind of economy is it to spend all that money on a trip and come home and develop a lot of film that's unprintable?


Well, yeah. In the end, the film is the cheapest part of photography. The trip out to Geddes, SD (Padley Hotel) was ~250 miles, or $25 in gas. Five sheets of FP4+ cost $8.65, and I spent ten bucks on snacks & Burger King.


Kent in SD

[Kirk Gittings]

If you carry a smartphone get the Reciprocity Timer app. I just checked it for FP4+ at 15 seconds and it says 51 seconds.
I only shoot FP4+ and have never gotten into trouble using the app.

[tgtaylor]

Kirk beat me to it. I shoot both Delta 100 and Fp4+ and always have a copy of the reciprocity curve with me. For a meter reading of 50 seconds I read the curve at 55 seconds.

Thomas

[Two23]

Kirk beat me to it. I shoot both Delta 100 and Fp4+ and always have a copy of the reciprocity curve with me. For a meter reading of 50 seconds I read the curve at 55 seconds.




Dang, you're making it harder to decide. Should I go with 55s, or 51s? Or maybe split the difference and go with 53s? Too complicated. :D


Kent in SD

[Leigh]

For a meter reading of 50 seconds I read the curve at 55 seconds.
For which film?

- Leigh

[Two23]

I'm kidding around. A few seconds won't matter either way.;)


Kent in SD

[Doremus Scudder]

I hate that phrase. It's not really a failure ...

Actually, it is... For photographic materials, "reciprocity" is the inverse relationship between the intensity (aperture) and duration (shutter speed) of light that gives the same density. As shutter speeds get longer, this relationship "fails" to predict the density; extra exposure is needed to achieve the target density. I'm not sure if the number of photons needed is thus increased or not, but it seems so :)

Best,

Doremus

[Bruce Watson]

I apologize for not being particularly articulate. But then again, I seldom am. If I could express myself well verbally, I wouldn't need photography so much. Sigh....

When I say that "reciprocity failure" isn't really a failure, what I'm talking about is the non-linearity of the film under low light conditions. That is, you're working in the toe of the film. And the film's response there isn't linear by definition. If you increase exposure to increase the number of photons (sufficient to make a latent image) hitting the shadow areas, you overexpose the areas of the film that aren't "in reciprocity" (that is, the parts that are on the linear part of the response curve). So... under develop for the highlights, yes?

Except that the old saw of "expose for the shadows and develop for the highlights" doesn't work so well here. Because the film response isn't linear here. So what you get is shadow detail, good highlight density, but what I call "mid range suck out" because the mids are under density. The resulting tonality isn't right, and it's also not in the right place.

I've never had good results printing film that's been treated this way, but it's not for lack of trying. I spent quite a lot of darkroom time trying to figure this out, and later when I was scanning found that it's still a problem -- thin mids are always going to look a little off even after correction. I don't know why, they just do. It's weird and sort of eerie.

This is the main reason I left Tri-X and went with TMY-2. I could finally work only in the linear part of the curve while still getting the texture and detail from the shadows under that rock in the river in full sunlight. That shadow was in the reciprocity region despite my 1/8 shutter speed, while the vast majority of the frame (98%?) was perfectly exposed. It wasn't until I made the trip back and exposed that same shot again, once with Tri-X, and again with TMY-2, both of which I'd dialed in (Zone System), and both of which I developed to their own individual N-1 development times, that I could understand exactly what was happening -- why I had to struggle so long and hard to get results I just wasn't happy with from Tri-X, while the TMY-2 print just leaped out of the paper with hardly any work at all.

It took me another couple of months of work to be sure of what I was seeing. But indeed, it was because of that dip in the low mids in this case because of working in the toe of the Tri-X curve. Those parts of the image, few as they might be, and scattered about in no reasonable pattern, just drove me crazy. And with TMY-2, they didn't, because they weren't in the toe anymore, and gave a linear response. The resulting tonality from the TMY-2 negative was just spot on.

Probably I'm one of the only people on this board to be bothered by this, or to have worked to figure out just what the heck was driving me bonkers. So it probably just doesn't matter to most of you. Fine, so be it. But just because it doesn't matter to you, doesn't mean it doesn't happen.

So my message is, if you're working in low light conditions, consider the implications this has on film response, even if you "correctly" compensate for both exposure (shadows) and development (highlights). And that is: you can correct for the two end points, but you can't correct for what happens in the mids. You can't alter the film's response curve; that's a decision made by the film designers and baked in during manufacturing. The only way out of this situation is to use a film that lets you work in the linear part of the response curve, at the light levels you have available.

[Kirk Gittings]

So my message is, if you're working in low light conditions, consider the implications this has on film response, even if you "correctly" compensate for both exposure (shadows) and development (highlights). And that is: you can correct for the two end points, but you can't correct for what happens in the mids. You can't alter the film's response curve; that's a decision made by the film designers and baked in during manufacturing. The only way out of this situation is to use a film that lets you work in the linear part of the response curve, at the light levels you have available.

All true and I get the point unless and until you scan the film.

[Drew Wiley]

Not really, Kirk. If something isn't on the film to begin with, adjusting the curve in PS won't change that. Besides, there were ways of doing that long before PS,
albeit rather tedious. It things are a little bit off, that's one matter; if the film choice is simply out of its league to begin with, that's another. Or by salvaging the curve, some other property might be compromised. Kinda like having a temporary spare on the car - yeah, you'll get down the road, but how far? What makes
reciprocity failure itself even more complicated is that spectral sensitivity and hence contrast filter factors can change dramatically at long exposures versus normal ones. This fact might not matter to some, but might to others. The only way to really know what is going on is to test, test, test, because there are darn
few if any printed references that tell you much about such sensitivity shifts.

[Michael R]

Bear in mind flare can be an important variable since it affects where the lower exposures fall on the film curve. Flare both raises the lower exposure values, and flattens local contrast - ie the very opposite effects of low intensity reciprocity failure.

You can't know what you're getting with any kind of precision.

[Bruce Watson]

All true and I get the point unless and until you scan the film.

I mostly scan my film. Do my own drum scanning. And I can't get it to work to the point I'm satisfied with the final print. So I'll have to disagree with you on this.

At least two things happen when you force the image into the nonlinear part of the response curve (and try to correct for it with exposure and development). First is the pushing of the mids into the lower mids and upper shadows. Building masks in a photoeditor to find all this is, well... problematic. And then, it's not a linear push. It's following the nonlinearity of the toe of the response curve. So you can break it up into lots of masks and move them each by somewhat different amounts depending on where they are in the curve. "That way madness lies" -- Shakespeare

Second, there's some compression of those tones that takes place. If sufficient compression takes place, it may be difficult to impossible to uncompress them. And that uncompression has to take place in conjunction with moving them back to where they should be (overlaps, feathering, etc.).

So while digital "recovery" in post might be theoretically possible, it's not easy (but maybe there's some nice algorithms out there by now that can do this, IDK), and for me at least it's not practical. It's way more work than just using a film that you can keep in the linear range of the response curve in the first place.

I guess I'm making an argument for knowing your craft, rather than fix it in post. I just wish 1) someone had told me, or 2) I had figured it out much sooner. I wasted way too much time chasing my tail trying to make my "favorite film" do what I needed it to do, when in fact that wasn't even possible.

[Andrew O'Neill]

For me, with FP4+, an indicated exposure of 15s should be increased to 32s from data that I generated several years ago. Manufacturers' data is usually a bit over the top. Acros is the king, followed by TMY-2. I'll be picking up a few boxes of Acros when I'm in Japan in March.
By the way, I'd love to see the photos of the old hotel, Kent!

[Drew Wiley]

The curve characteristics and general speed of ACROS are similar to FP4. The recip characteristics are dramatically better, while the grain if finer, and the spectral
sensitivity distinctly different from most films (orthopan rather than typical panchromatic). Either film will dig down into the shadows better than the Delta 100,
but not as far as TMax films. They're all superb products, just with different personalities.

[tgtaylor]

Below is a link to a night shot on Ilford Delta 100. Keep in mind that it is a, and not very good I'm afraid, P&S shot of the mounted salt paper print hanging on the wall and in person is far better than in this picture: For example "Port of San Francisco" is clearly legible across the top of the port and looking through some of the office windows in the tall office building behind the port the outlines of what is clearly mounted art work is visible on some of the walls.

http://spiritsofsilver.com/yahoo_site_admin/assets/images/Port.58223548_large.jpg

The idea was to to have a silver reflection from the shoreline in the black waters of the bay and the clock and lighted portions of the Port well lit along with the office windows in the background. If I recall correctly the brightest reflection in the water metered at 4 EI and diminished as it got closer to me and I wanted the clock, etc., at around an EI of 7 or 8 with a Pentax Digital spot meter. Anyway, the overall exposure came to 30 seconds at F8 or F16 and from the printed Ilford reciprocity curve I used 160 seconds (2'40") which is maybe 4 or 5 seconds overexposure. As you can see following the printed curve resulted in a good negative and print.

Thomas

[koraks]

That said, I do like a film that behaves linearly. Especially with the exposures we normal end up with in LF. For this kind of low light photography, Acros is probably the best. But t-grain films will always outperform cubic grain films in low light, so don't dismiss Delta or Tmax (100, but 400 is surprisingly good in low light).
I have good experiences with TMAX100 in this respect. I find it performs well enough for exposures up to several minutes; I give about a stop extra for exposures of a few minutes and don't bother with adjusting development. Not as good as Acros, but very usable in practice for low-light situations.

[Two23]

By the way, I'd love to see the photos of the old hotel, Kent!


Will post here when I get the film back, assuming I got anything. (Old lenses, challenging conditions, scatter brain photographer.) There is quite a history to the hotel starting with it's earliest days. It's linked to a prostitution scandal, a missing doctor, and a hidden speakeasy in the 1920s! It was a white elephant from the start, and sort of slipped away with barely a whimper. I talked quite awhile with the good old boys at the nearby bar. I enjoy dressing up in my old "farmer clothes", driving out to an isolated fading prairie town, and swapping tales with the good old boys sitting around at a bar or bait shop. They seem to understand I'm a bit eccentric but harmless. Everyone enjoys a good story out here.


Kent in SD

[stawastawa]

Bruce,
Yes, generally only two points can be fixed with exposure and Development compensation. But what about some Developers altering curve shape based on development method?
I have heard (havn't generated enough data myself though) That Rodinal can be linear, or create a concave on convex curve based on the combination of agitation, dilution, duration . . .

Anyone have a reference to a procedure for testing Reciprocity characteristics?

[Leigh]

Anyone have a reference to a procedure for testing Reciprocity characteristics?
That's probably one of the easiest tests to perform.

You set up a target and pick an exposure, then walk the exposure up and down with shutter speed.
Of course the aperture must be changed for each speed to maintain the same exposure (theoretically).

There are some gotchas.
The aperture markings on the shutter may not be very accurate. I know of no spec for this.
Worse than that, standard tolerance on slow mechanical shutter speeds is +/- 20% (fast speeds are +/- 30%).

- Leigh

[Drew Wiley]

Curves can be somewhat modified by choice of developer. It's like nutrition; better food might make you grow taller, but not by much if the DNA you inherited all
came from short people to begin with. Let's take extremes. Pan F is basically a Zone III to Zone VII film. There are ways to squeeze in another stop or so; but it
will never ever be capable of 12-stop ranges like good ole Super-XX, which had a straight line that went from Bolivia to Boise. "Compensating" or "minus" development won't change the inherent characteristic curve, but simply squashes the whole range like an overstuffed sandwich that somebody stomped on, at the expense of intermediate tonal differentiation. Development flexibility itself differs film to film.

[Jody_S]

You can use film choice and technique to defeat reciprocity failure and obtain a linear curve, or you can use the characteristics of the film and equipment you have to compose your images. Not really an either/or choice.

I create a digital post-it note in my phone for every film I shoot. If I didn't have the phone, I could just as easily carry it in a notebook in my camera bag.

[Doremus Scudder]

I apologize for not being particularly articulate. But then again, I seldom am. If I could express myself well verbally, I wouldn't need photography so much. Sigh....

When I say that "reciprocity failure" isn't really a failure, what I'm talking about is the non-linearity of the film under low light conditions...

Bruce,

I'd say you are abundantly articulate; your post more than proves it!

I didn't mean to be nit-picky about the reciprocity failure, but a lot of people don't understand where the term comes from. However, note that the method for referencing reciprocity failure as well as Leigh's method of testing for it deal with only one density, not the entire density range of a film along the curve.

I well understand what you are dealing with using TXP and long exposures. 320Tri-X is one of my go-to films, but I shoot a lot of TMY as well, just for the difference in the toe curve. I've found that Tri-X works well with long exposures if you give enough extra exposure to get the important shadows up off the long toe curve. For me, this is 1-2 extra stops. I have a lot of negatives made this way and I like the look, especially for low-contrast subjects. I sometimes will use an ND filter and reciprocity correction on a low-contrast subject instead of increased development just to get this effect. However, if you get the mid-tones all bunched up down on the toe, then it's no fun. Hence making sure you expose adequately for the separation you want... or, use TMY.

Best,

Doremus

[Pere Casals]

Bruce,
Yes, generally only two points can be fixed with exposure and Development compensation. But what about some Developers altering curve shape based on development method?
I have heard (havn't generated enough data myself though) That Rodinal can be linear, or create a concave on convex curve based on the combination of agitation, dilution, duration . . .

Anyone have a reference to a procedure for testing Reciprocity characteristics?


I'm planning to do these tests as part of a extensive personal process calibration I'm preparing . IMHO to take command of night photography film calibration has to be done to match shooting conditions.

If doing usual film calibration (contact copy of Stouffer wedge under enlarger) usally 1s exposures are recommended, as if shorter there is the effect of lamp filament warming, and if longuer repciprocity failure can happen.

But if we are to shot with long exposures (night or river/sea to smoothen water) then the film has to be calibrated with exposures under enlarger with 10s, 30s or what exposure we are to use. Very straight, and this will deliver clear facts, transparent truth.

We also can guess it from manufacturer's reciprocity curves (ilford) or tables (kodak), but I suspect that developer and agitation has its impact.


Also these tests should be repeated with different compensating development procedures: developer dilution, reduced agitation... and even with water bath or Diafine . So cooking a night photography negative may require reduced agitation (every 3 min), semistand or stand, to allow developer exhaustion in highlight areas.

In such low agitation development trays are a good advice, with sheet horizontal it happens that bromide streaks don't have help from gravity.


So test for say 30s exposure may consist in measuring lux under enlarger and adjusting light power to the higher lux·second we want to consider, making some 3 contact copies of the Stouffer, and developing it under some 3 development ways. And then... a plot is there.


There is another option: neopan acros, and no problem. TMY is not as good for that, by far.


I ask myself if Acros' near null reciprocity failure comes from much higher dye sensitization.

[Pere Casals]

I've found that Tri-X works well with long exposures if you give enough extra exposure to get the important shadows up off the long toe curve.



I also think that by allowing extra exposure we can get the shadow detail we want (in my case with HP5). Just development has to control highlights. If negative is to be scanned no problem is there, but we can get a negative that is difficult to print optically, and it may require CRM/SCIM to get a sound print.

I had this accident, that at the end was good because I discovered CRM/SCIM :) as no contrast grade delivered a good print. Still burning with different grade improved the result, but CRM/SCIM was really useful.

158400

https://www.flickr.com/photos/125592977@N05/28693688313/in/dateposted-public/

[tonyowen]

I discovered CRM/SCIM

what is CRM/SCIM ??????
regards
Tony

[Pere Casals]

what is CRM/SCIM ??????
regards
Tony

CRM = contrast reduction mask

You make a contact copy of a negative on another film sheet, when developed you have also a positive image, usually it is exposed/developed to have thin positive image. If you stack that positive image on the original negative you can consider it a new negative that is less contrasty. Similar process is also used to render a sharper looking image, in optical darkroom prints, enlarged or contact (unsharp masking).

SCIM = Shadow contrast increase maks. Used to increase contrast in shadows...



http://www.maskingkits.com/maskingexamples.htm

http://www.largeformatphotography.info/unsharp/

http://www.alanrossphotography.com/tag/selective-masking/



Then... instead using photographic film to make the mask, it is also possible to make those masks with a bare laser printer by using a transparent sheet.

This is an exciting technology crossover that allows darkroom + Photoshop combination, still requires a high amount of traditional skills like calibration, but one can print HQ and also cheap, if we don't account manpower. So, also ideal for enthusiasts, IMHO.


Regards


PD: This solution was first pointed to me by "interneg" user a couple of months ago...

[Leigh]

Leigh's method of testing for it deal with only one density, not the entire density range of a film along the curve.
Sorry, Doremus...

Not true.

I said to set up a "target", which you always need for any kind of test, without specifying what that target is.

If you want to evaluate a range of densities, use a gray scale as a target, with exposure set for the middle gray.

- Leigh

[Doremus Scudder]

Sorry, Doremus...

Not true.

I said to set up a "target", which you always need for any kind of test, without specifying what that target is.

If you want to evaluate a range of densities, use a gray scale as a target, with exposure set for the middle gray.

- Leigh

My apologies, Leigh,

I misunderstood your post, assuming your target was supposed to be a monotone gray card, etc.

I think it's a good idea to test with a full range of tones when doing reciprocity tests. I find that real-life subjects work well too and sometimes make a range of negatives at different exposures to check/confirm the compensation I'm using.

As Bruce points out, the relations of the zones changes with long exposures and it's good to kind of know what to expect. Keeping extra-careful notes of the different luminance zones in the subject and comparing these with the final print is enlightening. I imagine one could do a lot of quantification with a gray scale and a densitometer and come up with real substantive data. Personally, I just don't have the time nor the drive (nor the densitometer) to do such tests and tend to rely on visual methods, my experience and empirical evidence to gain an understanding of what happens when compensating for reciprocity failure.

It would be really interesting to me to see such data if anyone has done such tests.

Best,

Doremus

[Michael R]

Howard Bond did a series of tests, but he aimed for a constant Zone III density rather than a constant speed point.

Using a target with a full range of greys will introduce flare, which counteracts the effects of reciprocity failure.

I would not suggest wasting too much time testing. This is actually quite difficult and complicated to test for, and really requires at least a sensitometer with a known intensity, since reciprocity failure is all about intensity. Approximating is the best you can realistically do, using manufacturer data (which tends to be conservative, and generic at least in the case of Ilford's current data, although Ilford is working on revised data).

[Pere Casals]

Howard Bond did a series of tests, but he aimed for a constant Zone III density rather than a constant speed point.

Using a target with a full range of greys will introduce flare, which counteracts the effects of reciprocity failure.

I would not suggest wasting too much time testing. This is actually quite difficult and complicated to test for, and really requires at least a sensitometer with a known intensity, since reciprocity failure is all about intensity. Approximating is the best you can realistically do, using manufacturer data (which tends to be conservative, and generic at least in the case of Ilford's current data, although Ilford is working on revised data).


Well... modern multicoated lenses deliver lower flare, and it also depends of if the scene has very intense bright points...

But I think that under enlarger tests with the Stouffer are of great value, if test exposure is the same (say 30s) than with real shots we are to take.

Then it comes flare, but this can be measured very well with an SLR. I found that flare is very similar with a Sironar-N 300 than with a Nikon 50mm of the Nikon F5 camera. What I do is using the Nikon F5 as an spot photometer, and that spot measuring will match closely what happens in the LF camera, as the SLR spot metering also includes flare. So in this way we can predict very well what (aproximate) density will have every spot of the scene. At least we'll know what kind of shadow (or highlight) detail we'll have, and if the scene will be easy to print optically.

To get that we need 2 tools: the film calibration with same exposure time we are to use with the LF camera, and one SLR with a prime lens (with spot metering) that has comparable amount of flare.

[Leigh]

My apologies, Leigh,
I misunderstood your post, assuming your target was supposed to be a monotone gray card, etc.
Hi Doremus,

Thanks. No apology needed.

I was intentionally vague regarding the target's characteristics because that can vary based on many factors. The nature of the desired results, the kind of film being tested (b&w or color), and the available test equipment all affect the choice.

A simple gray card or multi-step gray scale are the more obvious and commonly-available options.
But something like a MacBeth card may be more appropriate for some tests.

Use of a multi-element card depends on the size of the film being tested. The size of the individual elements on the negative matters.

- Leigh

[Drew Wiley]

Flare is even easier to control in an enlarger in a darkroom than in a camera outdoors. Most people don't even try - that's the problem.

[Pere Casals]

Flare is even easier to control in an enlarger in a darkroom than in a camera outdoors. Most people don't even try - that's the problem.

Well, I guess that flare may even be benefical in an enlarger, as it acts like a paper pre-flashing... http://www.ilfordphoto.com/aboutus/page.asp?n=125

[Drew Wiley]

Pre-Flashing? Isn't that just another term for veiling fog? At least it is in my dictionary. It's like saying a few bullet holes in your windshield are beneficial to
automotive air conditioning. There are better ways to manage contrast.

[Kirk Gittings]

Pre-Flashing? Isn't that just another term for veiling fog? At least it is in my dictionary. It's like saying a few bullet holes in your windshield are beneficial to
automotive air conditioning. There are better ways to manage contrast.

:)

[Vaughn]

I have never "pre-flashed", but I have flashed photopaper before -- nice technique if handled well. Like most techniques, if it looks like you've used it, you have over-used it.


Well, I guess that flare may even be benefical in an enlarger, as it acts like a paper pre-flashing...
I believe it takes a little more control than that ...:cool:

[Two23]

I sent my negs to Citizen Photo a week ago Monday, Priority Mail. I think they just received them today. The mail is moving very slowly right now.


Kent in SD

[Pere Casals]

Pre-Flashing? Isn't that just another term for veiling fog? At least it is in my dictionary. It's like saying a few bullet holes in your windshield are beneficial to
automotive air conditioning. There are better ways to manage contrast.


I have never "pre-flashed", but I have flashed photopaper before -- nice technique if handled well. Like most techniques, if it looks like you've used it, you have over-used it.


I believe it takes a little more control than that ...:cool:


Well, as a darkroom printing learner that I'm... I've followed Darkroom Cookbook instructions, this is measuring the amount of exposure you have to give to a paper to start building density. Then any amount of shadow detail will be seen.

Also I calculated parasite light in my enlarger with a particular negative. I placed an 1cm2 opaque shield (household alluminium foil) on the negative, then I measured its shadow with a luxometer to substract that exposure of pre-flash. Also Substracting exposure of areas I want in perfect white, to put it out of the paper toe.

I found that accurate procedure renders accurate results. Still it was more a learning exercise than an operative job...


I've a cheap handheld luxometer, but 0.1 Lux precission. I remove the the white dome to have spot reading, it is different but still good as a reference


158669


But now I use my mobile (Sony Z2) as a spot/directional luxometer. Smartphones have a precission luxometer in the front face to auto-regulate screen brightness. This is the App I use:

158670


With diffuse illumination it gives same reading than the handheld one, with directional illumination reading depends a lot on the direction you place it.

But I found the mobile+app it can be a very good relative reference for darkroom tests.

I think that with experience I'll be able to be more straight with less measurements...

Sorry for the off, as usual :)

[Pere Casals]

Then any amount of shadow detail will be seen. should be "amount of highlight detail"

[Two23]

Shots are back. I added them to the Image Sharing--Old Things thread.
http://www.largeformatphotography.info/forum/showthread.php?71352-Old-Things-Farms-Barns-Buildings-Plus/page204


Kent in SD

[Steve Sherman]

Interesting thread, much of the theory of both Reciprocity and the Flashing technique has been discussed and less of the practical application of the terms.

IMHO, I have always thought of Reciprocity as "Reciprocity Success", naturally it is a tongue in cheek phrase. What I mean by that is with the type photography I embrace, I make longer exposures most times when the sun is below the horizon. During those times of day the amount of contrast is considerably reduced and many times lacking enough contrast for Silver Gelatin work. I used to covent that type of light as I knew the mid tone contrast would be exaggerated far beyond what the eye / brain relationship could see. Remembering the old instructions which film manufacturers would include with film told photographers, that if exposures of longer than 1 second occurred then reduced development was in order, they knew the reciprocity phenomenon would inherently increase contrast. In my world I counted on the added contrast and on some occasions even Plus developed the film to increase the contrast gain.

Flashing by definition is allowing a controlled amount of "non image forming light" to fall on the paper, effectively offsetting the threshold portion of the paper so that any light passed through the negative would yield an immediate grey tone, hence reducing the contrast of over developed / exposed negatives. It was a valuable technique back in the graded paper days. Unfortunately, multi-contrast papers have lead Silver printers to believe the technique no longer has merit, especially when MC paper manufacturers suggest any highlight density can be controlled with a much greater success rate than with single graded papers, in theory !! Again, IMHO, based on real world results the more Green (soft contrast) light that any MC print requires to effect detail in the highlights has an adverse effect on mid tone contrast throughout the entire print. I call it "Contrast Killing Green Light" and that is the exact reason that my negative design for today's MC papers is as flat a negative as one can imagine, a negative that requires less green light to affect highlight detail. I have found by reintroducing the Flashing technique I can reduce the amount of Green exposure "Thru the negative" by 25 - 30 % and that is a considerable amount of reduced Contrast Killing Green Light. The area of the print that realizes the biggest gain from less Green exposure is in Mid Tone contrast areas, for me the one relationship most difficult to affect in the Silver print.

Thinking back to the days of Howard Bond and his unsharp masking technique, and even nowadays with some of the modern computer masking techniques, they are all intended to maximize Mid Tone contrast. All of my focus is on maximizing Mid Tone contrast in the final Silver print, however my methods are all done organically and will always appear smoother and more believable. It goes without saying, if there is too much Mid Tone contrast there are any number of techniques to reduce the contrast in the final print.

My observations gathered over years of negative design and Silver printing.

[David Karp]

Thanks Steve. That is really interesting, helpful, and extremely useful!

[Eric Woodbury]

Gas Hypering. It's what the astro-dudes do (or did).

http://www.astropix.com/HTML/I_ASTROP/FILM/HYPERING.HTM

https://en.wikipedia.org/wiki/Photographic_hypersensitization

[Pere Casals]

Reciprocity and the Flashing technique...


Gas Hypering. It's what the astro-dudes do (or did).

http://www.astropix.com/HTML/I_ASTROP/FILM/HYPERING.HTM

https://en.wikipedia.org/wiki/Photographic_hypersensitization


Very interesting/useful information, thanks for sharing it !

Merry Christmas !