Do you really believe in exposing at iso 320?

[oftheherd]

I was going to give a confused explanation of the relation between a reflected-light reading and what was really going on in the scene regarding shadow areas, but thankfully Roger came along.

I would say that precise and repeatable "home" processing conditions are, in my opinion, certainly achievable regarding the usual variables time, temperature, agitation and chemicals mixing. The only thing which could be tricky in some parts of the world is the water quality - and that may not be consistent from day to day. In that case you will probably know about it already (especially if you drink the stuff) and mix developer with distilled water of some sort. There is no need to have magical darkroom equipment to achieve consistency !

As I read down the thread, I was trying to remember all that I used to know about exposure and development. Silly me! I should have known that Mr. Hicks would chime in and give a lot more and more correct information that I could have. Thank you Mr. Hicks. It was enlightening to me too.

 

[Pherdinand]

Indeed, the difference is lost in the "noise" i.e. the inconsistency of the metering, development, etc.
BUT
the noise is centered around a alue. This value is the EI you are using.
It can be centered at iso 400 or iso 320 - and this might slightly matter, on a scale that statistically makes sense(i.e. thousands of films).

So i went for no because, what usually happens is, people advise others to expose the e.g. C41 black and white films at iso 320 instead of 400, because that seems to work for themselves (or because so they've read on internet). This is a worthless advice unless they KNOW how you meter, how you develop etc.

Finally, for c41 film, 1/3 stop hardly matters, even if you are 100% consistent. For slide, it might make a difference.

 

[visiondr]

What a great thread!
Thank you, Roger, for your easy to understand explanation.

 

[Pherdinand]

Warm up that dustcloud where you keep your developer, skibeerr😉
Or shake it a bit more.

 

[Anupam]

I have not yet experimented, if I want to try in wich direction should I go?

Your own. Most people just randomly tweak around with a variety of settings garnered from manufacturers, websites, internet forums etc. But that just leads to the circumstance NB23 is pointing out. Way too many variables and you don't know if they are canceling each other out.

Few people standardize and test their own because that is more difficult than getting it off RFF. So, I'd say understand the theory behind basic sensitometry and test and standardize on your own for your workflow. That is what I do. Test for my own EI and development time for the density range best suited to my enlarger and plan out the developing process precisely so it is as repeatable as possible.

 

[minoltist7]

I have been vaguely aware that some posters here seem to advocate such processing. I'm not sure what the point is. To me that's the same as shooting a frame at 1/3 overexposure, except you're doing it to the entire roll. To me, underexposure, or overexposure is a decision I make for an individual shot.

I deliberately overexpose to 1/3-1/2 films like 400CN or XP2.
but it's matter of taste. most C-41 films look too "gray-ish" for me

 

[Roger Hicks]

I try to do everything according to the kodak, Ilford, rollei book and get realy flat negatives.
I have not yet experimented, if I want to try in wich direction should I go?

Increase dev time 30% (Roll 1).

If that's too contrasty for you, halve the increase next time (Roll 2).

On the roll after that (Roll 3), go up or down as you think fit. Three rolls should see it.

Are you scanning or wet printing?

Cheers,

R.

 

[Pepe]

With only full stops in shutter speed and aperture setting possible on my meterless FED2.... I guess I have to say "I don't really care"

Exposing for ISO 320 turns out to be quite exactly the same as for ISO 200 ... or as 250 ... which happens to fit my sunny f16-meter

But I'm currently shooting C41 so that may all change when my darkroom has been rebuilt


(oh sure i can set the aperture between two clicks on those old Russian lenses, but seeing how a half or third stop are not located halfway or a third of the way between two stops, this is just guesstimation, too)

 

[charjohncarter]

Yes, thanks Roger, I remember those slavish days, too. David Vestal was the first guy I read that suggested finding your own numbers. That suggestion was even greeted with suspicion.

 

[Roger Hicks]

I am learning to print wet.

Kind regards,
Wim

Dear Wim,

Great!

It's much easier that way.

Harder in the (very) short term.

Easier (especially for negative evaluation) in the less short term.

Cheers,

R.

 

[bmattock]

All of photography is a series of compromises.

 

[Gabriel M.A.]

Do you really believe in exposing at iso 320?

I believe it. I've seen it happen.

 

[szekiat]

i do it for a different reason. Negs have a lot more latitude for overexposure but less for under exposure so over exposing it at 1/3 stop is sort of erring on the side of caution. If its properly exposed, than the extra 1/3 will not make any difference but if i have metered a scene wrong and underexpose it, the extra 1/3 might just save me some shadow detail. Granted its not much, but it'll be something.

 

[philipp.leser]

I think it's useful to test and measure your process at one point, because then all the not-quite-intented variations that do happen will at least vary around a point which was determined to be good.

I try to limit myself to only one or two developers and a very small selections of film, so I can really understand the process. It starts with making a few test shots a different exposures from zone 1 to 10 maybe, or even more if I feel like it.

I then develop and measure the log density of the negatives. The right speed of the film in the given developer is reached when zone 1 has a log density of 0.10 over fog and base. That is a very easy measurement!

The second important point is the contrast, which is determined by the development time (I use Diafine a lot, so using that developer it's not a variable). Just vary the development time so the negative has an copying range that fits a medium filter for your given paper and paper developer (which for me is around ISO R 70-80).

This might sound complicated, but it really is not, takes only one or two rolls of film and stays correct as long as you don't change your developers and film types every day.

Regards,
Philipp

 

[marke]

Didn't Kodak's originally rate Tri-X 400 at 200?

 

[Gabriel M.A.]

Didn't Kodak's originally rate Tri-X 400 at 200?

Yeah, then they spawned a "Leap of Faith" 320 version 😉

 

[Bob Michaels]

I believe the only correct answer to 99.9% of all photo related questions is "it depends".

 

[Al Kaplan]

In the early 1960's the ASA of all films, with a few exeptions, was doubled. Tri-X jumped from 200 to 400, but that still left about 1/3 stop safety factor. More puzzling was when ISO took over at first they listed both the ASA number followed by the German DIN number so Tri-X became ISO 400/27, then a few years later they dropped the DIN number. Yet DIN speeds are not directly comparable to ASA speeds. ASA sets speed by density part way up the straight line portion of the H&D curve while DIN measures density from a point above the base density of the developed film. In other words DIN is measuring minimum shadow density while ASA is measuring the speed of the mid tones. In the end you have to shoot your own tests with your brand of metering technique and your soup and and your agitation regimin. Have fun.

Professional Tri-X 320 is a whole 'nother ball of wax. It has a different spectral response, and the contrast, highlight and shadow rendering are optimized for studio portraiture. I don't think it's ever been marketed in 35mm, just 120/220 and sheet film. It also has (or had) a slight retouching "tooth" on the surface for pencil retouching. It doesn't push well either.

 

[Turtle]

small things add up. If I am getting a speed of 320 with a certain film (and it is not hard after VERY simple snap happy testing to be sure of this) then I will use it as this speed. I would be silly to use it at anything else -right? 1/3 of a stop can make a lot of difference if a neg is on the edge of having no shadow detail or on the edge of being blown beyond rescue with super hot highlights. The prob of not doing this is that if you shoot a film that is making 320 with your set up at 400 and then underexpose by 1/3 stop for what you were hoping to get in the shadows, you are now 2/3 of a stop under-done. Same thing could make life VERY tough in the darkroom for overexposure.

if a film is making 320 it is making 320. It is impossible to claim that this makes no difference because it can be proven quite simply that it does...it makes 1/3 stop difference. 1/3 stop can make the difference between something in complete silhouette and faint detail that lift it from the 2-dimensional. Film speed is not magic and it is not hearsay. It is a real measurable and testable thing and we all agree that proper exposure matters, right?

I went back to basics recently and did some fresh tests on 4 films before a trip to India, including with filters to nail down MY filter facors (which were appreciably out from the manufacturers as it turned out). I decided on 320 with several of them with my Mamiya 7. The result was some negs that were less than ideal but literally none that were a major problem. Had I gone 1/3 stop in either direction that would have increased my prolbem with hot highlights or thin shadows appreciably in a number of negs. Why use anything else if 320 is right? Its like using the wrong spanner when you have the right one sitting in front of you!

PS. There is no point worrying about 1/3 stops if you have not done filter tests, esp if not using TTL metering and having to apply the factor manually. I got + 1/3 with my yellow (listed as +1) and +1 1/3 or 1 1/2 with my orange (listed as 2). start by nailing down the film speed minus filters, then work out filter factors and before you know it you nail your exposures.... no more guesswork and you can concentrate on shooting confidently. It is worth noting that i found the 'real world' tests on filter factors agreed with those done against a lightbox with 3 different cameras agreeing on the factor even though they differed in their indicated base exposure. Its all about what actually works for you. I can see with my own eyes that X exposure is better than Y even when the difference is only 1/3 stop. If I can see that 1/3 stop difference what possible reason would I have for not applying it?

 

[Rob-F]

(I'm a bit late to this party, but here goes.) Every single answer in this thread seems quite valid to me. So I have only this one comment, which addresses the question of all those potential errors NB23 named. They are errors that could be cumulative, all adding up in one direction. Or, they could partially or completely cancel each other. So how to deal with all these unknowns when shooting?

Of course, the best way is to establish habits through testing and experience. That's already been said here, in a number of different posts. Here's another thought.

An old navigator's trick is to deliberately fly to the left of the destination. Harold Gatty knew that if he did that, he could count on the destination being somewhat to the right. Gatty was the navigator for Wiley Post, the first pilot to fly around the world in 8 days.

Now, what if I don't know how some variables will add up, and i want to make sure I get enough shadow detail? If I add one or two third-stop increments to my exposure, I know that I have erred on the side of more shadow detail. I'm flying to the left. Other posters have already talked about erring on the side of caution, so this is just a different way of saying it.

In practice, the extra exposure gets me a little more shadow detail, and it also lets me reduce my development to control contrast. That way, I can put behind me the days of blocked-up highlights I couldn't punch through with a laser beam. At times when contrast is too low, that's what contrast filters are for.

Tri-X at EI 250, developed in D-76 1:1 for 7 minutes is pretty foolproof on a harshly sunlit summer day. It's like an insurance policy against disappointment.