Do you really believe in exposing at iso 320?

[Ororaro]

Based on the premises that:

If it is true that a film's ISO rating is an estimate, and that a camera's shutter speed is always off by a margin and irregular between clicks (if not electronically controlled), and if we agree that manual development is an unexact science (How do you inverse your tank? Are you 100% accurate and constant over time? Is your development time based from when the film is completely submerged to the tank completely emptied or when you start to empty the tank? Those two philosophies easily eat up or add up to 15 second of development time), and is your thermometer accurate down to 0.5 degrees Celsius or fahrenheit? Is your film very fresh? Has it been exposed to temperature variations? And when you meter a scene, are you sure your meter really understood the scene (because only a multi spot metered scene will give a definite accurate metering)? And is your meter really calibrated for 18% Gray? What if it's 12%?

In the end, what's more important: Being consistent and understanding our gear and personal development rituals or is it more important to rate a film at its "true" ISO rating? And is 1/3 stop visible in th end? What tells you it's the film and not your inversions?

 

[Samsam]

Hi NB23,
i do not really care about 0.5 degrees variations. What is the most important to me is understanding my gear and my way of shooting. By trying different process times, different ratings, different exposure metering, i've finally found the way i want the negatives to be
for example, i finally found that tri-x @ 250 developped in Rodinal is the best for me, i found the number of inversions i need per minute, development time etc...
another example : my metering technique is very special ( and may be considered very bad , but who cares, everybody does what he wants 🙂 ) , i usually do an exposure metering of the ground of the place i'm in ( weird, isn't it ?! )
So for me, i will answer your question by saying that it's definitely being consistent and understanding my gear and personal development rituals that count for me

 

[charjohncarter]

If you are talking about Tmax400 (new) or TriX, no. I believe in exposing them at E.I. 250.

TriX at 250:

Tmax400 (new):

 

[crawdiddy]

Ned, I assume you mean exposing 400-rated film at 320? And then developing at the recommended times for 400. Right?

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'm not sure what the point is for an entire roll, unless you're using autoexposure (which most folks here wouldn't be caught dead doing), and you think the particular film is rated incorrectly by the manufacturer.

Unless you're correcting a "faulty" rating, it seems like a game you're playing, the point of which I don't get.

 

[Ororaro]

John,

I find them slightly overexposed... But they look good, nonetheless.

Now, how do you develop? Do you compensate? If so, this defeats the whole purpose, don't you think?

 

[Ororaro]

Ned, I assume you mean exposing 400-rated film at 320? And then developing at the recommended times for 400. Right?

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'm not sure what the point is for an entire roll, unless you're using autoexposure (which most folks here wouldn't be caught dead doing), and you think the particular film is rated incorrectly by the manufacturer.

Unless you're correcting a "faulty" rating, it seems like a game you're playing, the point of which I don't get.

We're talking the same language...

 

[telenous]

I think it's possible to acknowledge all the issues your questions raise and still believe in 'true ISO speed'. However, for the kind of shooting that interests me (i.e. 'street'), true ISO is the least of concerns, with exposures in a roll all over the place but more often on the underexposed side. Knowing my propensity for underexposure, I rate my film as ISO 320 in the same way (and for the same reason) I make my watch run 5' fast: I prefer to err on the side of safety. Is it enough? Nothing disastrous has happened so far, and on a couple of occasions I got exposures (and made it to appointments) that otherwise I 'd have missed. And that's all.

 

[Keith]

I've never felt the need to pull a film at all but pushing ... I do regularly as I actually like the look of a film taken in this direction. Aside from trying to compensate for the wrong choice of film for bright conditions when you want to use a particular aperture and have run out of shutter speeds I see little point in pulling. Not quite OT sorry Ned but can someone give me a valid reason for overexposing a 400 film to say 200 or 100 and then having to compensate in the developing.

 

[P. Lynn Miller]

Ned,

I usually shoot my Tri-X at 400 but tend try to make my exposure errors in the side of over-exposure, so I could be rating my Tri-X at EI 320 in practice. When I am not shooting at rated speed, I would be pushing it, as high EI 3200.

The only thing I try to do consistently is take lots of photos. I set my exposure by eye, I shoot all mechanical cameras, so exposure can easily be off by a stop or two. I have simplified things to shooting Tri-X most of the time and I soup everything in D76 Stock or 1:1. I do use a digital thermometer which is accurate(supposedly) to .1°C, have a consistent agitation method, and use a timer on my laptop. I do not sweat the details.

I am at a point in life where I want things to be simple and uncomplicated and I have applied this to my photography as well. My photography is not the greatest or even as good as it could be if I spent more time and care. But I am enjoying photography now more than ever. I figure that is all that really matters.

 

[projectbluebird]

...can someone give me a valid reason for overexposing a 400 film to say 200 or 100 and then having to compensate in the developing.

I shoot HP5+ at 200, but I develop it for the recommended time for 400. I do this because for the way I shoot, with the cameras I use, it gives me a fuller tonal range and a look that I like.

I test every film that I use to find the ISO that works best for me. Some are close to the manufacturer rating, some aren't. I don't worry so much about 1/3 or even 1/2 stops, because most of my lenses only have full stops. But there is a difference, and it might matter, or it might not.
It does to me, but it doesn't to a lot of people. YMMV.

 

[charjohncarter]

NB23, yes, I'll like them over developed, but that is me. I just don't like the blocked shadows that you see so much on the web. I don't develop so much that the highlights are blown. And no to whoever asked I don't do compensating development. You can do compensating development with HC-110 and Rodinal, the two developers that I am using now, but these are not images done that way.

Nice photos Lynn and Wray.

Keith, you do it if you test and you're testing to get a certain shadow detail (without blown highlights). It is the only way to arrive at the time/temp/agitation that works best for you.

 

[maddoc]

I used to expose 400 ISO rated film at 320 (1/3 stop over) and developed for 400 ISO. This way I was more on the safe side when using a hand held meter at night (having some bright light sources and otherwise lots of dark areas in the frame) With the M6 (and Hexar), I found that exposure is more accurate (and consistent) so I set to 400 ISO.
About developing ... to many variables to keep it consistent when "home-developing". Making repeatedly a solution of an exact concentration is already at laboratory (with exact balances and graduated cylinders) a difficult task and this is only one requirement (agitation, constant temperature are additional erratic factors).

 

[Ororaro]

Ray,

I firmly believe shooting 320 instead of 400 would show no real difference in real life. Same as shooting Plus-X 125 at 100. I often forget to adjust ISO settings and end up mixing up the ones I rated at ISO 125 and 100. Once developed, there is no way I can differentiate them. That's mainly because of the case by case metering for each shot as well as the different cameras I use as well as the shutter speeds probably reacting differently from shot to shot.

However, ISO 200 is very far from 1/3 stop difference, and I find this interesting. Your shot is on the lighter side with good contrast.
One thing all of us noticed is Kodak's stupid way of updating their films over the years. Like the old Tri-X 320 becoming the new 400 and a change in developing times which is seriously underrated. If people would follow Kodak's instructions they'd all end up with unusable underdeveloped negatives. The funniest part is they recommend the same developing times for TriX 400 and 800 (same for Plus-X 125 and 250). They claim the film's dynamic range is within the developing time tolerance. That's unbelievable and it drove me to test a whole 100ft roll rated at 100, 200 and 400 with HC110 with different dilutions. I came to a personal conclusion that ISO 400 was valid but the developing times needed to be prolonged.
Kodak's erroneous developing times is well documented all over photo.net.

Still, your shot looks good...

 

[wray]

Ned, I have to agree that a 1/3 of a stop is so narrow as to be within metering error of measurement! When you say lighter, are you referring to the midtones? Everything is there from pure black to white. The odd thing is that now I prefer a little more contrast to my images!

 

[Roger Hicks]

Based on the premises that:

If it is true that a film's ISO rating is an estimate...

Dear Ned,

You are of course absolutely right that an awful lot of people look for a precision which is not only absent, but impossible to achieve. You are also absolutely right that in many pictures, quite grievous overexposure and a certain degree of underexposure can be corrected at the printing stage.

On the other hand there are a few points I'd like to challenge.

First, it's not true that ISO speeds are an estimate. They are a compromise (for the reasons given below) but they are also fully replicable, which stops them being estimates. And they vary with developers. HP5, for example, is a good ISO 650 in Microphen and maybe ISO 250 in Perceptol.

Second, the losses in quality with over- and under-exposure are very different.

With a conventional film, increased exposure leads to reduced sharpness and bigger grain in direct proportion to the overexposure. With a colour neg or chromogenic B+W film, 'grain' (dye cloud) actually gets finer.

The loss in ultimate sharpness can be significant; an extra stop can drop resolution from 80 lp/mm or better to 65 lp/mm or worse. Those are actual figures from when I was reviewing a new film for a magazine a few years ago.

Decreased exposure has the opposite effect, but sooner or later, quality falls off the edge of a cliff: empty shadows, lousy tonality.

The ISO standard is therefore a compromise to give good tonality along with the best sharpness and minimum grain achievable with that tonality. It also incorporates a small safety margin against underexposure; until 1959-60 the ASA standard had a full extra stop of safety margin.

Most in-camera meters are designed to give optimum exposure with slide films (exposure keyed to highlights) and will therefore underexpose negatives of subjects with a long subjecy brightness range (exposure keyed to shadows). This is an encouragement to rate neg films slower than they are. With a 1 degree true spot meter, I find I can rate films at or very close to their true ISO speeds. But hand the same meter to ten different people and ask them to meter the same scene, and you'll likely find up to a stop difference between their readings.

Conversely, few shutters run fast, and many run slow, which gives the film more exposure. One of my old Pentaxes is a full stop slow at most of the useful speeds, so I could rate ISO 400 at EI 800.

Many people prefer the tonality with a small amount of extra exposure: 1/3 stop, 1/2 stop, 2/3 stop. This gives a starting point.

As a result of all this, I would say that yes, 1/3 stop or 1/2 stop changes are worth worrying about, but only as a starting point.

In other words, if I set the meter on my MP at 125 when shooting Fomapan 200 (true ISO about 180 in the developer I use), then even after allowing for cumulative errors and my own metering technique, preferences, etc., I will get better pictures, on average, than if I set it at 160 and significantly more good pictures than if I set 200. I could equally well set 100 but then I'd be losing more sharpness than I need to and I'd be getting more grain.

A couple of references from my site that some may find interesting, on ISO speeds and subject brightness ranges, are:

http://www.rogerandfrances.com/photoschool/ps iso speeds.html

http://www.rogerandfrances.com/photoschool/ps subject brightness range.html

Cheers,

Roger

 

[maddoc]

Dear Roger,

I have one question now, when you slightly over exposure a film (1/3 stop for example), do you develop this film according to its "true" speed or the actual speed ?

Regards,

Gabor (maddoc)

 

[Roger Hicks]

I have one question now, when you slightly over exposure a film (1/3 stop for example), do you develop this film according to its "true" speed or the actual speed ?

Dear Gabor,

These are in effect completely different questions, and well illustrate the truth of what Ned says.

I develop films so that the majority of negatives on a roll print well on grade 2-3. This is a simple iterative process. If you find yourself needing 3-4-5 all the time, you are under-developing; increase your development time (in 30 second or 1 minute increments) until most go onto 2-3. Likewise, if you need 0-1-2 all the time, you are overdeveloping and need to cut dev times.

If I scanned, instead of making what I persist in regarding as 'real' prints, I'd cut dev time to give a thinner neg with smaller grain, and adjust contrast in Photoshop -- but as I regard the vast majority of inkjet prints (unless made with specialist ink sets, especially Piezography) as grossly inferior to real ones, I'm not the best person to ask.

The above is for conventional monochrome neg only. With colour neg or chromogenic, the standard processing time is fine.

To answer a couple of questions you didn't ask, but many do (for the benefit of lurkers), there is a significant difference between overexposure and 'pulling' or reducing development time. The latter has far less effect on film speed (the speed point, 0,10 above fb+f) than most people think, but it does give you a low contrast negative. This may suit subjects with a long subject brightness range but for normal subjects it's a pain in the bum because you have to use hard paper to compensate.

Hope this helps,

Cheers,

Roger

 

[maddoc]

Dear Roger,

thank you a lot for the information. It helped a lot for sure. 🙂

Cheers,

Gabor

 

[MartinP]

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 !

 

[Roger Hicks]

One more thing to add is that while ISO films speeds are replicable, they are not always the speed that will suit a particular photographer best, which is why they are recommended as starting points. All manufacturers tell you to make adjustments based on your own needs -- adjustments that are necessitated by the variables Ned lists, and more.

Exactly the same is true of dev times: the manufacturers advise you to change them as needed, in order to get negs of your subjects, shot with your kit, that print the way you like.

At this point it is easy to attack the manufacturers for giving wrong speeds or dev times but it is important to remember that ISO speeds are the best we have, and the best we have ever had -- far better than the days when film speeds were set by the marketing department. Generally, too, the manufacturers' dev times are the best starting point: far better than the maunderings of a self-appointed expert.

When I started out, I always felt I was doing something wrong if I didn't stick slavishly to the ISO (in those days, ASA) speeds and manufacturers' dev times. Realizing that they meant what they said, and that both ISO speeds and dev times are starting points and nothing more, was an enormous liberation.

Cheers,

Roger