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Ray J Wallin
23-Jan-1998, 00:30
I just bought my first 4x5 camera. I have been using the zone system with my 35 mm for 5 years now and am very familiar with it. I wanted to establish my perso nal ASA for Tmax 100 for the 4x5. I bought the film, loaded it, took a high con trast set of a few pictures of the downtown skyline. I placed the shade of a da rk building that still contained texture on zone III. I took a picture and brac keted as well 1/2 and one stop. I developed the film in TmaxRS and an unexposed sheet as well. I went into the darkroom and exposed a test strip with the unexposed sheet to fi nd my 'standard printing time'. When I expose the negative of downtown, the pri nt is completely white. I am now confused. I will repeat the process, but I am sure I did everything right. What would you do?

Andrew Herrick
26-Jan-1998, 08:20
Dear Ray,

Firstly, T-max can be a real headache. It's not a film for beginners (and I shou ld add that I'm still coming to grips with it). The reason is becasue its maximu m density is over 3.0; most films taper off at a maximum density of around 2.0, but T-max keeps on going. I don't know if you're familiar with characteristic cu rves and logarithmic density units, but that means that a T-max negative can be 10 times denser than an ordinary negative!

So my guess is you've overdeveloped your negative, that's why its coming out fla t white. With a film like Tri-X that has a sloping shoulder the highlights would have blocked and the negative wouldn't have been too dense. But because of the long scale on T-max, if you overexpose or overdevelop it you wind up with a nega tive that's unprintable. (Let me know if you're not familiar with terms like sho ulder). So if I were you I'd halve your development time and start again.

Also, are you using a prewash? I was using a prewash with Delta 100 and I just d iscovered you're not supposed to. It was causing me to overdevelop my negatives.

Finally, you don't use the 'standard printing time' test for determining your AS A; that's for the development time. You determine your ASA by shooting bracketed frames of a dark surface you place on Zone I; the one that produces a density o f 0.10 above film base is the correct ASA.

Let me know how you go.

Andrew

andrewherrick@hotmail.com

Brian Ellis
6-Feb-1998, 01:31
I don't mean this answer to be flippant or sarcastic but I would buy or check ou t of a library any book that contains detailed instructions on how to perform th e film speed tests The method you used seems very rudimentary. Any number of pho tography books contain such instructions. A few that come to mind are Ansel Ada ms' book "The Negative," Fred Picker's book (the name of which I forget but he o nly wrote one), or "The Zone System Craft Book" by John Charles Woods. There are many others but these are three I am familiar with.

Ornello
10-Feb-2022, 09:11
Don't forget the iris/shutter correction. Small apertures and high shutter speeds will present a problem.

Also, shutters are not absolutely perfect in repetition, and batches of film vary too.

Just down-rate the ISO about 2/3 stop and you'll be fine!

Ornello
10-Feb-2022, 09:41
Dear Ray,
............
Also, are you using a prewash? I was using a prewash with Delta 100 and I just discovered you're not supposed to. It was causing me to overdevelop my negatives.

Andrew: How does pre-wash cause you to overdevelop? If you do your tests always the same way, the washing 'effect' (if any) will automatically be taken into account. I started doing this decades ago.

neil poulsen
10-Feb-2022, 10:25
This thread goes back to 1998, so a response isn't likely.

Addressing the content, I've not heard of that strategy for establishing ASA for a film. Typically, when one brackets to determine ASA, it's half stops, not 1.5 at a time. And, it doesn't make sense to determine ASA with Zone III exposures. There's too many things wrong the OP's approach to waste time critiquing.

The best way to determine film ASA (in my view) is to use Ansel Adams technique with a densitometer, which is to find the ASA that renders a Zone I exposure as 0.1 density units above film base plus fog. (In his early description of this method, Adams recommended between 0.07 and 0.15 density units.) Develop the film at the manufacturer's recommended develop time and temperature.

When I do this with ASA 400 black and white film, I invariably establish the ASA as close to 1/2 the manufacturer's recommended ASA, which would be about ASA 200. Use this ASA to expose and process films using Zone System methodology, which sums up to exposing for the shadows (Zone III) and developing for the highlights (Zone VII).

I usually think of manufacturer's recommended ASA's as being "suitable" for generic overall exposure readings when photographing, and when processing the film at the manufacturer's recommended time and temperature. (Blaaah; pinch nose and breathe through mouth.)

Ornello
10-Feb-2022, 10:38
This thread goes back to 1998, so a response isn't likely.

Addressing the content, I've not heard of that strategy for establishing ASA for a film. Typically, when one brackets to determine ASA, it's half stops, not 1.5 at a time. And, it doesn't make sense to determine ASA with Zone III exposures. There's too many things wrong the OP's approach to waste time critiquing.

The best way to determine film ASA is to use Ansel Adams technique with a densitometer, which is to find the ASA that renders a Zone I exposure as 0.1 density units above film base plus fog. (In his early description of this method, Adams recommended between 0.07 and 0.15 density units.) Develop the film at the manufacturer's recommended develop time and temperature.

When I do this with ASA 400 black and white film, I invariably establish the ASA as close to 1/2 the manufacturer's recommended ASA, which would be about ASA 200.

I use 35mm, and I find the same to be true across the board. The revision to the ASA speeds that occurred in 1960 was unneeded. The speeds in use at that time were based on the cameras, films, and processing techniques that had been in use for decades. For the most part, these were roll-film cameras with leaf shutters. The films were generally contact-printed. I remember seeing B&W photos of my relatives from the 1940s and 1950s, in smallish formats that had to be contact prints (from photofinishers). They were probably made on Velox paper. Leaf shutters tend to give more exposure than focal-plane shutters when the lenses are stopped down more than half-way. Shortly after 1960, 35mm SLRs with focal-plane shutters became popular, and these gave less exposure to the film at small apertures, and 3x prints, rather than contact prints, became the norm for photo-finishing.

There was no problem with the exposure, rather it was the development that was excessive for 35mm films.

In other words, using half ISO speeds is generally going to give optimum results.

Jim Noel
10-Feb-2022, 10:44
ASA or ISO is established by the manufacturer and can not be changed. What you are trying to do s establish a personal exposure index.

bmikiten
10-Feb-2022, 20:55
Please consider reading "Beyond the Zone System" by Phil Davis. It will make your life so much easier and provide a technical vocabulary that will assist you in large format work.

Brian

neil poulsen
17-Feb-2022, 10:36
ASA or ISO is established by the manufacturer and can not be changed. What you are trying to do s establish a personal exposure index.

I'm finding the ASA that's optimum for the method that I use to expose and process film.

Bear in mind that, stated ASA values can have a substantial impact on potential customers' decision whether or not to purchase a film.

Doremus Scudder
18-Feb-2022, 13:59
Let's agree on the distinctions between ISO, ASA, DIN and E.I. just to avoid confusion. Yeah, we all know what we mean, but precision is a good thing, right?

ASA was the American Standards Association's method of determining film speed. The German equivalent, although expressed differently, was codified in the Deutsche Industrie Normen (DIN). These were subsequently harmonized and unified by the International Standards Organization (ISO) and uses both the earlier ASA speed and the DIN speed degrees (e.g., ISO 320/26° for 320Tri-X. Note the two speed designations, the first being the old ASA number and the second the DIN degrees). ASA and DIN are no longer used; they have been subsumed in the ISO speed rating.

ISO speed, like its predecessors', is determined with standard developers, development to a specific contrast gradient and a specific method of determining the speed point. This is all prescribed in the standard. The speeds so determined are good for comparing films (assuming they've been tested using the appropriate standards, some off-brands don't seem to be...) and as a starting point for deviation. Many find these speeds just fine. Note, however, that different developers than the standard ones used in the ISO testing can result in different effective speeds (Kodak notes this for their films and developer combinations) and that metering technique, equipment variables, etc. can necessitate using films at a different effective film speed than the ISO rating.

When one uses a film at a different effective speed than the ISO rating (or "box speed"), it is called E.I., or Exposure Index, which is a practical divergence from the norm for whatever reason. Many Zone System users work with a metering technique that works best when the film is rated around 2/3 stop slower than the ISO rating. Others "push" film by rating it faster, intentionally underexposing and compensating with extended development at the expense of shadow detail. Others simply find that they get better results at a different E.I. than box speed for whatever reason; developer, meter variances, shooting style, etc. etc.

So, when one is finding the effective film speed that works best for how they expose and process film, it should really be referred to as E.I. or effective speed. ISO, ASA and DIN really don't apply here.

Best,

Doremus

Greg
18-Feb-2022, 16:09
If one had to limit oneself to only one book on the ZONE System:

photography: CONTROL & CREATIVITY by T.L. Bollman and G. E. DeWolfe.

A small book published by Special Services, Rochester, New York 1972. The first part of the book (all of 28 pages) is EXPOSURE AND DEVELOPMENT FOR CONTRAST CONTROL IN BLACK-AND-WHITE PHOTOGRAPHY and covers a very simple method for ZONE System testing.