I need to develop some 4x5 Tri-X that was a little underexposed. It was a low contrast subject (copies of old b+w prints). I was planning to use Xtol, but i'm nervous about the failures that have occurred. I have ready access to Microphen, Acufine and Rodinal, or I could buy something else. What would be a good alternative to Xtol for this purpose?

-- John Stockdale (jo.sto@bigpond.com), August 30, 2001

Answers

D-76

-- Cem Topdemir (cem-1@softhome.net), August 30, 2001.

What you need is a developer than can build up contrast and can achieve high densities. D76 is relatively soft working. The developer I really can recommend, because the contrast buildup is immense, before the shadows are affected (every developer has a max density and when this is reached only the shadows will be affectes, thus giving you less contrast), is Calbe A49. This is traditional Agfa Atomal FF modified with colour developer. For your purpose use it straight. Atomal achieves finer grain than D76, higher accutance and superior tonal values.

-- Volker Schier (Volker.Schier@fen-net.de), August 31, 2001.

Use the Microphen.

-- Tim Brown (brownt@flash.net), August 31, 2001.

I've used Microphen to rescue underexposed negs. It gives a true speed boost of 1/3 to 2/3 stop with most films for "normal" contrast.

Acufine should be fairly similar but it's been ages since I used it so have no recent information and can't rely on my faulty memory.

-- John Hicks (jbh@magicnet.net), September 01, 2001.

Microphene unfortunately does not give any speed increase. My measurements with a densitometer show that it is hardly possible to change effective film speed with different developer formulations. With a few exeptions the speed will stay about the same when the negs are developed to an equal gamma. That some developers increase effective speed is one of the big urban myths fostered by the manufacturers of photo chemicals obviously to improve sales. In most standard developers the effective speed of most films is about half the speed that is printed on the box, often even less (exception is Efke, which is very close). Especially high speed films are "off" quite a bit. The manufacuters deliberately accept loss of shadow detail and many photographers accept this loss as desired "look" of a specific film. Examples for this are Ilford HP5, which -- according to ISO specifications -- would have to be rated around ISO 320 in many developers. Microphene will not alter this speed rating at all. The higher the film speed, the more "off" films are as a rule of thumb. The developing times stated on the box take this into account and what you do when you develop the film is already push processing in many instances: The developing times were adjusted according to midtones, not according to overal contrast and not according to shadow densities, which affect film speed. Since high speed films are generally softer than low and medium speed films they take a little more abuse in exposure but still the overal contrast rendition will suffer from this. The film will generally be "harder" than it ought to. This brings us back to underexposed negs. If the film was shot -- lets say -- with ISO 800, although the box says ISO 400 than we have an effective underexposure of 2 f-stops, not one. There is no way of compensating for this with maintaining full shadow detail. Shadows inevitably will have to go when the midrange contrast is being built up. There are two differing strategies now: (1) Active developer that can achieve high densities. I had suggested A49 for this before. A49 will easily push the midrange densities back into place, but the contrast will (as always in push processing) be much higher. People often underestimate this phenomenon. If the gamma was 0.7 using "normal" development (to use this as example), than a one f-stop push will get you into the 0.8s or 0.9s and a two stop will get you in a gamma range of 1.x and higher. There is no paper grade that will print this neg with full spectrum if a scene with average contrast was recorded. If the scene recorded was low contrast A49 still is an excellent solution. (2) The second strategy is to build up midtone contrast and somehow restrict the overal contrast buildup especially in the highlights. 2-part developers can limit the highlight contrast effectivly. There are better and worse products and published formulas out there. The best I have used so far is Tetenal Emofin, a widely used developer in Europe. This developer is based on colour chemistry and will achive extremely fine grain without rendering the overal tonal rendition too soft, which often is the case with very dilute developers. Unfortunately this product, which has been extremely popular with professionals in Europe for decades, is not available in shops in the US, but it can be ordered easily through mail order companies such as Fotoimpex. Emofin is more expensive than some other developers (around $8 per quart), but it will develop 17 films or more, which makes it very economical. In comparison with Acufine the grain is finer and the acutance -- usually a problem with 2part developers -- is not bad at all. The base fog, which necessarily is higher with 2part developers, is no problem. It is only minimally higher and you just print through it. Although even in this super fine grain formulation the grain will noticably get higher with push processing, but a compensation of up to 2 f-stops underexposure are possible without too much contrast buildup.

-- Volker Schier (Volker.Schier@fen-net.de), September 01, 2001.

I based my statment about "true speed boost" on EIs obtained for HP5+ in D-76H 1:1 and 1:3 vs Microphen 1:1. The EIs were determined by the usual .10 DU above fb&f for a "Zone I" exposure using a Wallace Expo-Disc (18% transmission), and the films were developed to pretty much the same CIs.

My normal speed for HP5+ in D-76H 1:1 or 1:3 is EI 400, in Rodinal 1:50 it's EI 250 and in Microphen 1:1 it's EI 640. Of course film developed to significantly lower or higher CIs will have different EIs.

TXP should respond fairly similarly to HP5+, although it's been so long since I've used any sort of Tri-X I certainly can't say that for sure.

The reason I recommended Microphen specifically for this is that recently I managed to underexpose a sheet of 8x10 HP5+ about a stop and the resulting neg was a bit thin; for the second neg I used Microphen 1:1 with development time extended by about 10% and got the expected shadow density plus a little more contrast to accomodate the somewhat low-contrast scene.

Considering developer claims, though, wild speed claims have certainly been made by many manufacturers but invariably any speed increase obtained with a PQ developer as opposed to a "standard" developer is only about 1/3 to 2/3 stop especially if development time has to be reduced to obtain "normal" contrast.

Before using any new developer for important film I'd strongly suggest shooting a test film to find out for sure if the developer will do what you want and if the recommended development time is valid.

-- John Hicks (jbh@magicnet.net), September 01, 2001.

I am surprised about the speed you get. A very recent test with HP5 plus showed that there is no way to get close to a true ISO 400. Even the ISO 320 are a little optimistic in many respects, since -- obviously due to the sensitation -- the film is problematic with green rendition. How do you evaluate your tests? which densitometer do you use? Which camera (how do you determine that your shutter is correct before testing)? If you read Ilford literature carefully you will notice some telling statements. They write that their speed ratings are most often not based on the ISO system, but on an evaluation of print quality! This says nothing else but that they sacrifice shadow rendition for film speed, which makes the film better to sell. When the first Deltas came to the market this was particularly obvious. Delta 400 had a true speed of only around ISO 100. This made it understandable that this film claimed to have "medium speed" characteristics. Off course I have not tested all films on the market, but I have run thorough tests on all films that I use on a regular basis, which includes -- among other things -- determining film speed and developing time for my specific paper grade. Occasionally I will include a test shot in my films to be sure that film characterstics do not change (they usually are very stable) and that my testing system is all right. A comparison with the test results of a friend also gives me some "safety" that I am not off. To sum up: I am fairly convinced that I can prove my statements about film speed with the test I made.

-- Volker Schier (Volker.Schier@fen-net.de), September 02, 2001.

I just saw another part in your statement: Developing to a different contrast level only marginally affects film speed -- again differing what is commonly published. This is particularaly true if you develop longer. The increase certainly is not 2/3rd and even with a marginal better relativ speed output you will hardly reach the "published" speed on the box. You will -- at least according to my experience -- also stay under this. In fact you will find out that after some time you will lose effective film speed. Every developer and film combination has a Dmax it can achieve. After this only the base fog will be affected and the overall contrast spectrum will decrease. Without a densitometer it is difficult to judge shadow densities. Many PQ claims originated in the publications of Goeff Crawley in the 1960s when PQ developers were claimed to change film developing. In recent publications Goeff Crawley strongly advocates using a lower determining point for fim speed. Crawley always had differing perceptions about the look of prints. Off course the industry was only too oblidged to use Crawleys statements for advertising their own PQ developers. It has become silent out there when the topic PQ is mentioned today, especially sind phenidone seems to have poor keeping qualities in solution and due to the low acutance in comparison to MQ formulations.

-- Volker Schier (Volker.Schier@fen-net.de), September 02, 2001.

> How do you evaluate your tests? which densitometer do you use? Which camera (how do you determine that your shutter is correct before testing)?

I start by calibrating all meters to "Sunny f16" using a Wallace Expo-Disc. I believe "sunny f16" or, 1/EI @f16 for an exposure in direct sunshine with the sun high in the sky, to be valid for my area; tropical residents may need "sunny f22" or thereabouts while residents of the far north may need "sunny f11."

"Sunny f16" exposures result in the expected densities with a variety of film types including traditional b&w, C-41, E-6 and K-14.

So...why calibrate to "sunny f16" and not something else? The short answer is that there isn't anything else. There is no "industry standard." So I use what's consistent and consistently available.

The Expo-Disc is a dense diffusion disc that transmits 18%. Although the "standard" such as it is is 13%, trying to achieve a 13% reflectance by holding a Kodak grey card at the specified angle to the light, not shade it or not get glare off it, creates more potential errors. Someone with more knowledge of mathematics than me could calculate the difference between 13% and 18% reflectance/transmission, but I believe it to be no more than 1/3 stop.

For shooting test strips, I use a camera that has an electronically-timed shutter that I tested with a Calumet shutter tester a while back; it turned out to be consistently within 1/3 stop of the set speeds throughout the range I use for testing. I always use the same lens, beginning two stops down from wide open to avoid losses due to vignetting or falloff at wide apertures.

I shoot a series of test exposures through a range of 14 to 15 stops.

Developing the film is straightforward, either in a Jobo machine or using hand inversion tanks. BTW, I've gotten consistent changes in EI for the same CI with a couple of films on the order of +/- 1/3 stop when comparing continuous rotary agitation with intermittent inversion agitation.

I read the negs with an Eseco TR-90 densitometer, which is regularly calibrated to a step wedge, and plot the curves on paper. Not particularly automated. ;-)

For several years I've occasionally compared my results with three people who also do the same sort of testing as a "reality check" and we've usually agreed sufficiently well.

> sacrifice shadow rendition for film speed, which makes the film better to sell.

While I'll agree that it's easier to sell a film that's labeled EI 400 than EI 250, I don't think it's a valid assumption that shadow rendition is somehow being sacrificed. I believe it would be much more confusing to customers and users if the film needed to be labeled several speeds according to which developer is used; for HP5+ for example this could be anywhere from around EI 100 (PMK+) to EI 640 (Microphen). > To sum up: I am fairly convinced that I can prove my statements about film speed with the test I made.

I don't think it's a matter of proving anything; it's necessary to recognize that equipment, materials and methods vary and the results one person obtains may be somewhat different than the results another person obtains, all caused by variations and tolerances in manufacturing, calibration, procedures and above all, what constitutes a "good image."

-- John Hicks (jbh@magicnet.net), September 03, 2001.

> It has become silent out there when the topic PQ is mentioned today, especially sind phenidone seems to have poor keeping qualities in solution and due to the low acutance in comparison to MQ formulations.

Hmm...in the past five or so years we've seen four new Phenidone developers; Paterson FX-39 (Crawley) and Ilford DD-X are PQ types while Ilfosol-S is PQ/ascorbate and Kodak Xtol is P/ascorbate. FX-39 and Xtol are commonly noted for higher acutance than MQ developers; otoh in my experience the increased graininess of FX-39, Xtol and DD-X may not be a worthwhile tradeoff.

Gone, however, as you've noted, are the wild speed claims that used to accompany PQ developers; at most the manufacturers now claim only the film's rated speeds.

-- John Hicks (jbh@magicnet.net), September 03, 2001.

Off course there is an industry standard. They call it ISO and they even put in on the box. In fact the testing procedures are more or less a copy of the Deutsche Industrienorm (DIN). I do not think it a very good idea to say that this is only a "relative" number on the box. The test is standardize and testers all over the world use it and also publish their results. I must admit that the tests both of us run do not comply 100% to the ISO test, which is described in detail in the ISO regulations (film manufacuters use a transparent step wedge and a standardized exposure), but the results should be the same and also the ISO rating should be comparable. This can be seen when film speed is published by independent sources. Somehow I see then that my tests results are not bad after all, when someone performs tests under ISO conditions, such as with colour films and finds that almost all ISO 400 speed negative film are in fact much closer to ISO 200. When there is no standard, why do the manufacuters claim there is? And there are manufacuteres that put different speeds on the box. Efke for example says their film has ISO 50 (true ISO speed). In the box you will find a list of different developers and the speed they recommend you rate them, all of which are higher than the ISO rating. Why does Ilford and the rest not do this? Quick answer: Because it would not look good -- they feel -- on the marketplace. Honesty ist not always honoured by consumer. If you have the choice between two films, one advertised as 400, but has only ISO 200, the other one advertised as 200, and it has 200, which one would you buy if you look for an ISO 400 film? Also I have to repeat myself: Different developers do not affect film speed in a significant way. My perception is that the speed obviously is more or less determined by the film itself and that the developers only affect speed to a lesser extent.

-- Volker Schier (Volker.Schier@fen-net.de), September 03, 2001.

> Off course there is an industry standard. They call it ISO and they even put in on the box.

My statement regarded any "industry standard" for the calibration of light meters and the reflectance, transmission or luminance used to calibrate them. Not film speed.

> The test is standardize and testers all over the world use it and also publish their results.

Things have changed; the specific developer and development procecure is no longer standardized. Perhaps this is in recognition of the fact that the ISO speed rating for traditional b&w films had very little to do with the reality of what exposure was needed when the film was developed in a "normal" developer to CIs appropriate for pictorial usage.

Actually Ilford followed Kodak's lead in rating film by EI rather than ISO; Kodak never published an ISO rating for TMZ but simply rated it by EI depending on developer used and the CI the film would be developed to.

I think we're actually in agreement overall; when developed to CIs appropriate for most uses b&w films have usually needed more exposure than their ISO ratings indicate, sometimes quite a bit more.

-- John Hicks (jbh@magicnet.net), September 03, 2001.

Isn't the EI (and therefore the film speed) the point where you get .1 over film base + fog for a zone I negative? I know I am testing lots of different films now and all are coming is slow, slow, slow. Heck, in rodinal 1:50 neopan 1600 came it at EI 160! The only film I've found so far with any speed is TMZ which was EI 800 in emofin.
Anyway, I am interested in the argument here because if I cannot infulence the real film speed with the developer then that changes my search for a good film/developer combo...

-- Russell Brooks (russell@ebrooks.org), September 04, 2001.

Dear Russell, you can influence speed with different developers and developing to different contrast levels, but according to my experience in testing the influce is minimal, certainly far below what you would expect or what the manufactuer may say. Even Tetenal Emofin, which I like particularly, has its limitations and I never get close to the stated speed gains of 3-6 DIN. You are right about very high speed films: The true speed often is far, far below what the manufacuter states. The sacrifice of shadow detail is obviously built into the "system". I can only urge every serious photographer to find out HIS effective speed himself by running the standard tests with controlled underexposure. These test will take the whole system into account: Shutter, exposure meter, lens etc.

-- Volker Schier (Volker.Schier@fen-net.de), September 04, 2001.

Johh, I hope this answer doesn't come too late to help. I don't believe that any of the three developers you list will accomplish what you want. Suggest that you go and ahead and use the XTOL, but be sure and do a clip test with a small piece of film immediately before developing your 4x5s, to assure that it's gonna work. Bill

-- Bill Mitchell (bmitch@home.com), September 04, 2001.

Russel, I forgot this. There are very effective ways to increase true filmspeed. Mercury vapor – no forget it, you do not want to poison yourself. All vapor methods work best with low speed films. There you can get huge increases. Well, mercury is obviously the exception. It seems to work with all sorts of films and speeds, but again I can only urge everyone not to use it. It also has some side effects such as very noticeable grain. Raising the latent fog level is the other method. I once took several rolls of TMAX 100 on an airtrip (at the time when I did not know there also were decent B&W films on the market). It was bulk loaded and I had run tests before on the same batch. At that time I used D76 1:1 made from scratch and the speed rating was around ISO 50. After returning my redone tests showed a speed increase of 100% due to what must have been the Xray security checks at the airport. Try to get this speed increase with pushing or "effective" developers! I would judge that putting a film through the machine 6 times (that was about the amount it must have had due to changing planes) will raise the toe of the film that much. In the literatue there are many other descriptions of how to "preflash" film, all of which are tedious at least: Unrolling film, pinning to the wall (off course in total darkness), taking a flashgun, using the auto setting and setting it off at a very close distance to the opposite wall. Nothing for me. Also rewinding film in a 35mm camera quickly in the darkroom with open shutter and in front of a red safelight does not sound very repeatable. A trip to the airport with a bag full of film and getting acquainted with the security personnel might solve some of your problems – and it would be extremely cheap despite the beers you hight have to buy. Flashing or Xraying by the way also works after taking pictures! You could also take exposed films to the airport. Only make sure that you select a "film safe" machine. Some experimenting may bring even higher speed ratings, depending how often you put the film through the machine before visible fogging occurs. With high speed films you probably should put it through the machine less often, since the threshold for visible fog obviously is lower than with a medium speed film. Also the effective speed increase also will be lower than in the case of low speed films. According to what heard and read it should be fairly easy to increase the effective speed of an ISO 25 film to ISO 100 with flashing. Additionally you would have the benefit of softer tonal rendition. I have not tried it though.

-- Volker Schier (Volker.Schier@fen-net.de), September 04, 2001.

I live downstream on the Columbia River, from the now inoperative Trojan Nuclear Plant. since it shutdown, I have noticed a 100% decrease in film speed. should I seek out the rod repository and decent radiation levels, or simply start concentrating more on my photography.

and my hair feels so much thicker now ...

John, try Ilford's Ilfosol S as an Xtol substitute. it seems closer to, and almost as refined as Xtol, without the mystery of random failure. one-shot, cheap, easy to store.

-- daniel taylor (lightsmythe@agalis.net), September 04, 2001.

> Isn't the EI (and therefore the film speed) the point where you get .1 over film base + fog for a zone I negative? I know I am testing lots of different films now and all are coming is slow, slow, slow.

That's the "traditional" speedpoint and perhaps the easiest to determine. There are other methods but the resulting EI should be pretty close to what you're using.

Now...why are you getting really slow speeds? While you should expect to find EIs perhaps a stop different than the film manufacturers' ratings, if you're getting several stops difference, you're using a "standard" developer and you're not developing to a very high or low CI then it's time to start looking for an error and checking calibration.

If we examine high-speed films in particular, we find that the manufacturers' ratings are actually push-development ratings; this is almost kept a secret, buried in spec sheets etc. For the films you mentioned, EI 800-1000 is the "real" speed of TMZ (and Delta 3200) and I believe EI 400 is the "real" speed of Fuji 1600. That may be the "error" that's causing what appears to be very low EIs with those films. If you go for push development, which is essentially underexposure and overdevelopment, you can expose those films at the speeds rated on the boxes and get usable negs; not necessarily good because shadow density will be low and contrast will be high, but usable.

When pushing, though, you can't go by the usual .10DU to obtain the EI because you're intentionally underexposing. You have to use another standard; I think it's personal and I've never seen any recommended standard to be used other than "does it print reasonably well?"

I start by plotting a curve for normal exposure and normal development, then for the pushed film look for the EI that causes its curve plot to cross the normal curve at Zone IV. If you want more shadow density use a lower crossing point or if you can tolerate less shadow density use a higher crossing point. That's just getting into the ballpark; what really counts of course is how the negs print.

Now..back to "normal" film and normal development. The first step imho is calibration of light meters. Calibrate to what? In a big debate in another forum between Ctein and George Wallace (Expo-Disc inventor) Ctein pretty thoroughly showed that there is no industry standard for the calibration of light meters, that manufacturers use their own standards, and that what passes for a standard, the Kodak 18% grey card, if used as intended actually provides 13% reflectance.

So you really ought to calibrate your meters to your own personal standard. It really doesn't matter what that standard is as long as it's consistent, but to make things easier it probably should be reasonably close to the default standard of 1/EI @f16 with a Kodak grey card in sunshine.

So, if you meter the grey card, meter an Expo-Disc or use an incident-light meter, in full sunshine that meter should indicate 1/EI @f16. If it doesn't, adjust the EI you set until it does; the amount of that adjustment becomes a correction factor to be applied to all EI settings applied to that meter, and only that meter. Another meter may be, and probably will be, different.

The next step is checking shutter speeds. Timing tolerances have to be accepted, but I think that in most cases an electronically-controlled shutter can be assumed to be fairly accurate while a mechanically-time shutter should be assumed to be rather inaccurate and non-linear. If you're using mechanical shutters you could have a local shop prepare a speed chart that'll show what the shutter's really doing or you could buy or borrow a shutter-speed tester (Calumet's is relatively inexpensive).

> cannot infulence the real film speed with the developer then that changes my search for a good film/developer combo...

You _can_ influence the real speed, but not by much. Compared to a standard MQ developer such as D-76 and film developed to the same CI, a developer that contains Phenidone such as Microphen, DD-X or Xtol will usually give a little more real speed but it's only on the order of 1/3 to 2/3 stop. Some developers give less speed; these include Rodinal and straight Microdol-X. Some developers also give more speed with dilution or to put it differently, give less speed loss; a couple of them are Microdol-X 1:3 vs straight and Xtol at a variety of dilutions vs straight.

Also, in my experience, high-speed films (EI 400 and faster) respond more to speed-increasing or speed-decreasing developers than slow films (EI 100 or slower).

-- John Hicks (jbh@magicnet.net), September 04, 2001.

This may sound petty, but: The slower the film speed the more effective are all methods to alter film speed -- chemical and physical. The opposite is true for high speed films. The effect can be seen in astro photography. The film speed of the extreme low speed emulsions is greatly affected by gas hypering. Several articles in the past have shown that these methods show by far not as great success on higher speed films, also due to the fact that some films already incoroporate preexposed silver halides.

-- Volker Schier (Volker.Schier@fen-net.de), September 04, 2001.

Daniel, even if you make fun of me: Physical methods to alter the toe of the rendition curve of films have been effective strategies often used by professional photographers, because -- different from pushing -- they do not have any negative side effects, such as increased grain and contrast. This was particularly true decades ago when films were used for press work that are today considered as medium speed. There is no difference in which way you create the additional latent fogging: Radiation is radiation, if visible (light) or invisible (Xray, gamma, neutrons etc.) The power plant will work off course, if you can get close enough to the rods, but I fear that calibration will be the problem and it might affect your hair in a rather adverse way. The nice thing about the airport security system seems a high degree of repeatability if you checked it out once and calibrated your "system" of run throughs. I was totally serious about this. Since I had some films left over from the trip I off course used them with the higher film speed. But this experience also showed me, that there is always some effect of airport Xray on the film, even if you do not see it on the developed film. From then on I insisted on manual checks when I transported exposed material.

-- Volker Schier (Volker.Schier@fen-net.de), September 04, 2001.

Volker,

I didn't mean to poke fun at you. your findings are sound. I was attempting to express the idea that we can take things to a level that our endeavours no longer resemble photography. I do appreciate that there are those interested at the molecular level, and those that empirically discover what works well and manage to make outstanding photographs. room for both extremes, but I do wonder sometimes if we don't needlessly entangle ourselves.

-- daniel taylor (lightsmythe@agalis.net), September 04, 2001.

No problem, although I thought that these findings were rather empirical, although more or less accidental. Honestly: I do not know why no manufacuter has come up with an easy to use device to "pre-" or "postflash" film to a preset level. The Xray machine would be one, but due to its price nothing to everyone. In the past many "cazy" things worked extremely well in photography, what did not work well at all was pushing film.

-- Volker Schier (Volker.Schier@fen-net.de), September 05, 2001.

There is one other way to increase film speed. An overall light exposure DURING the image exposure. Concurrent photon amplification. There was an article in the June 1976 issue of Popular Photograpy about a company that modified 35mm SLR's. They put tiny light bulbs in the mirror box. The upshot was that it took much less exposure than pre or post flashing to get a stop or more of shadow speed increase. They claimed no fogging or contrast reduction like with pre/post flashing. It seems to me white LED's would be perfect for this today.

-- Tim Brown (brownt@flash.net), September 05, 2001.

Tim, LED is a good idea, since you can finetune them in accordance with the sensitation gaps of the emulsion and it would even work on colour nicely that way. On the other hand: Pre- postflash does not fog a film if done correctly, since the exposure stays under the threshold. It also does not affect overal contrast rendition, only shadow rendition. Highlights and midtones are virtually unaffected. The opposite is true for positive flashing: Only highlights are affected, midtones and shadows stay more or less the same. The method you describe is just a very clever way to apply this flashing, a way that should be pursued further. I do not see why manufacturers of SLR cameras should not incorporate this. Flashing is for example used in slide duplicating. Bowens uses a glass sheet to creat flare (= fog), Multiblitz uses a fiber optics to channel light into the bellows. You see, there are various ways to do it, but someone has to find workable ways to use it. The xray machine may be a little extreme, but if someone has easy access to one, this certainly is a more than practicable way. A friend of mine for example is working in a building were he has to go through a security check every day. If I should need high speed film (which I rarely do for my work) then I would surely send him a parcel of film to take through several times. Other people may have to find different solutions.

-- Volker Schier (Volker.Schier@fen-net.de), September 05, 2001.

'White' LEDs aren't really white. They're a mixture of red, green, and blue emitters in one package. The individual colours are practically monochromatic, and there's no guarantee that these narrow bands would line up with the tripack filters of a colour film. I'd be very surprised if pre-flashing with white LEDs didn't alter the balance of a colour film.

-- Pete Andrews (p.l.andrews@bham.ac.uk), September 06, 2001.

Well Pete,
There are now white LED's that are blue emitting chips with a phosphor coating. This gives a blueish white light. Check out www.ledlite.com Regarding the older 3 element pseudo white LED's, the individual red, green and blue emitters wouldn't have to perfectly "line up" with the color film layers. As long as each element affected its corresponding film layer the brightness of each element could be adjusted to maintain color balance. Also, since the level of illumination is so low balance shouldn't be critical. The big problem with 3 element LED's is a lack of spatial color uniformity.

-- Tim Brown (brownt@flash.net), September 06, 2001.

Thank you all for your suggestions. I think I will use Microphen because it will give me a little speed gain and I think I will be able to get an adequate, moderate increase in conrast.

Volker, I was interested in your suggestion for Calbe A49. Here in Australia we have quite a good range of photo supplies, but Calbe is unknown. You refer to Agfa Atomal: we can get Atomal FF. I was under the impression that its natural speed is on the low side. Is this correct? OR might it be suitable for my purpose?

I promise to develop these films soon and report my results!

-- John Stockdale (jo.sto@bigpond.com), September 08, 2001.

I may have made a mistake. I ment Atomal F not FF. You are right about FF, which is entirely different to A49. Up to the 1970s AGFA East Germany sold A49 as Atomal F and when AFGA East and West split up Orwo, the new East German company, changed all the former AGFA proprietary names by using the Agfa receipe book number and the first letter of the former product name: Atomal F = A49, Rodinal = R09, Neutol = N113 etc. At least at that time the products remained the same, although A49 was further improved in subsequent years. I have used AGFA Atomal FF but I am aware that it is different to A49. I know nothing about the formulation of Atomal Atomal FF. In fact Agfa produced a whole family of Atomal super fine grain products. Sadly AGFA Leverkusen took "normal" Atomal off the market a couple of years ago and only the Atomal FF remained. Agfa Atomal had similar charcteristics in comparison to A49, although I guess the formulation was rather different. A49 is based on one of the few East German colour developing compounds. Atomal developers developers had extremely fine grain, while maintaining good acutance and a particular nice tonality.

-- Volker Schier (Volker.Schier@fen-net.de), September 08, 2001.