ISO setting question

haring · May 6, 2011

How do you set your ISO? Somebody told me that it is the best to set the ISO lower than the actual film you have? Foe example, if I have a 400ISO film, I should set the camera to ISO200 so the result will be rather overexposed than underexposed...What do you think?

R gould · May 6, 2011

It all depends on the film, developer,and the effect you are after, for instance, in FD10 developer I would set HP5+ to iso 250, rather than the rated 400, but in Rodinal/aph09 I would set the iso for hp5 at box speed, that is 400, now with Fomapan 400, which is my film of choice, I rate it at 320 rather than 400 in either of the 2 developers, and get good negatives, but the point is in most developers if you downrate the film the you must compensate with less time in developer,
Richard

Steve Smith · May 6, 2011

A common method is to halve the speed (i,e, give twice as much exposure) then reduce development by about 20%. This gives more shadow detail.

Steve.

haring · May 6, 2011

Steve Smith said:
A common method is to halve the speed (i,e, give twice as much exposure) then reduce development by about 20%. This gives more shadow detail.

Steve.

which means that I have to increase aperture. it will work! thanks!

haring · May 6, 2011

R gould said:
It all depends on the film, developer,and the effect you are after, for instance, in FD10 developer I would set HP5+ to iso 250, rather than the rated 400, but in Rodinal/aph09 I would set the iso for hp5 at box speed, that is 400, now with Fomapan 400, which is my film of choice, I rate it at 320 rather than 400 in either of the 2 developers, and get good negatives, but the point is in most developers if you downrate the film the you must compensate with less time in developer,
Richard

I have a lot to learn... I shouldn't have started shooting film...

R gould · May 6, 2011

haring said:
I have a lot to learn... I shouldn't have started shooting film...

We have all had to learn it, which is why forums like this are so good,in fact we are all still learning, the day you think you know all there is to know is the time to quit, just enjoy shooting film, and I would start with a known developer such as ID11 from ilford or D76 from Kodak, or perhaps Aculux 3 from Patterson, a great 1 shot developer, or maybe rodinal,with perhaps 1 film, such as HP5+ for 400 or FP4+ for a slower speed both from Ilford, use the film and developer as per the makers instructions, and when you know the film/developer backwards then start experimenting with other combinations and methods,
Richard

Bill Burk · May 6, 2011

haring,

You can get very good results immediately in film photography. Negatives I created when I was a teenager still make good prints (except they are a little scratchy). Almost every roll I ever shot is usable. I have very few rolls over my lifetime that had problems, and each time I learned a little more.

R gould said:
... the day you think you know all there is to know is the ...

Richard,

I agree with the start of your sentiment but I went to high-school once. It's OK to think you know it all. Soon enough it comes out that you still can spend 2 years learning more.

removed account4 · May 6, 2011

haring

it also has to do with the meter in your camera.
some metering systems ( in camera or hand held )
read the light different than others. so ... sometimes the best
thing to do is to shoot a roll of 400 iso film in a variety of subjects
and bracket your exposures -
so you expose one at 400, one at 200 and one at 800
( just vary your fstops --- one as the meter reads, one over exposed 1stop,
one underexposed 1stop rather than adjust your asa/iso )
then process your film as you always do in whatever developer you usually use "business as usual" ...
you will see what works best for your metering and developing ...
broad rules are great . but sometimes testing for your own working methods is best.

have fun !
john

MattKing · May 6, 2011

haring:

Just for clarity...

ISO is a standardised measure of the light sensitivity of film - it is an acronym of International Standards Organization (I think).

The setting you choose for your camera meter is more properly referred to as an Exposure Index or "EI".

The ISO (or "box speed") of film doesn't change*. The EI you choose varies with light conditions, your preferences, equipment, processing regimen and other factors.

In a very many cases, you will get quite satisfactory results if you choose an EI that is identical to the ISO.

Historically, ISO was preceded by ASA (American Standards Association) and DIN (???) ratings. Immediately prior to the change, the ASA standard was fairly close to the current ISO.

*There is one exception to the rule about unchanging ISO. For some films of yore, there was a different ISO for different light (usually daylight and tungsten).

Mike Wilde · May 6, 2011

Look up the late Barry Thornton's web site. His articles on Personal Film Speed, and Personal Development Times are clear jems I with I had found when I started out on this film journey about 30 years ago. Regretably I only found them about 5 years ago.

Sirius Glass · May 6, 2011

Especially since you are starting out, start with the box speed ISO until you learn the camera and the film. Color film, especially slide film, works best at box speed. If you use half the box speed with slides, the film will be overexposed and the highlights will be blown out.

Before one starts adjusting the box speed, one must know the camera, the camera must have the shutter speeds working accurately, the light meter needs to be accurate and the user needs to know how to use a light meter correctly. Otherwise the user will have trouble figuring out why the exposures are wrong.

Steve

semeuse · May 6, 2011

If I'm shooting a film I haven't used before, I'll start with the manufacturers recommended ISO. But after playing around a while, discovering what the film can and can't do, with this or that developer, etc., I set my own exposure index. It's all a matter of getting to know the tools.

Sirius Glass · May 6, 2011

semeuse said:
If I'm shooting a film I haven't used before, I'll start with the manufacturers recommended ISO. But after playing around a while, discovering what the film can and can't do, with this or that developer, etc., I set my own exposure index. It's all a matter of getting to know the tools.

Exactly my point. There is no logical reason to start off cutting the film speed in half automatically when one has never used the film before. One does it when one has a good reason based on their own experience.

haring · May 6, 2011

I will take my kids to the park in less than 20 minutes. I have two extra 120 rolls in my packet...I am getting excited!!!!

Jose LS Gil · May 10, 2011

film type?

haring,

What kind of film are you using?

Black and white gives you some room for errors in exposure as does color print film.

Chromes or slide film is much less forgiving.
With color films it is also wise to use the film for what it was designed for. Some film is daylight balanced, or balanced for tungsten, indoors artificial lighting. You can usually correct the film with color correction filters, but that just means you need to fuss with more gear.

If you are starting off learning to use film. I would suggest B&W first, then color print film, with chrome or slide films as you gain practice and learn the way your equipment works.

You didn't mention what type of camera you are using or subjects.
Does your camera have thru the lens metering (TTL)?
Are you using a hand held meter to determine your film speed setting?
If hand held meter. Are you measuring reflective light, light reflecting off the subject? Or are you measuring incident light? Light falling onto the subject.

I know, it can get a little confusing but it becomes second nature after a while.

Good luck.

Poisson Du Jour · May 10, 2011

Sirius Glass said:
[...]
Before one starts adjusting the box speed, one must know the camera, the camera must have the shutter speeds working accurately, the light meter needs to be accurate and the user needs to know how to use a light meter correctly. Otherwise the user will have trouble figuring out why the exposures are wrong.

Steve

My thoughts exactly. Do not assume that what a meter tells you is gospel: at best, it's a guide. At worst, it's a recipe for disaster. Invest in experimentation, progressive knowledge and thus experience, and not rely blithely on what is printed on a box, what your camera tells you, or what a meter says is right.

Starting with transparency film will make you sensitive to the effects of small changes in ISO as opposed to the much greater and thus harder to define steps of B&W. Having said that, you do need a good knowledge of how your camera meters and what situations will produce unfavourable or unacceptable results (subjectively, what is "unfavourable" or "unacceptable" is a matter of personal interpretation).

haplo602 · May 11, 2011

semeuse said:
If I'm shooting a film I haven't used before, I'll start with the manufacturers recommended ISO. But after playing around a while, discovering what the film can and can't do, with this or that developer, etc., I set my own exposure index. It's all a matter of getting to know the tools.

This is the best aproach. I shoot slide film always at the rated ISO, C41 color print film a bit below (usualy 1/3-2/3) to overexpose a bit. B&W film depends on film and developer combination used.

Get to know the film at the rated speed first, then experiment.

markbarendt · May 11, 2011

There were a fair number of things that pushed me toward shooting at 1/2 or more off box speed.

The work of Jose Villa and others for one. IMO it's simply a set of style choices here: 1-a placement choice, bright beautiful faces; 2-a lighting choice, backlighting is the norm so subjects have nice even low contrast lighting (open sky) that makes shooting a white dress with detail next to a black tux with detail easy and provides a nice hair light and nobody is squinting; 3-the understanding that the background is strictly "second-fiddle" to the people, this is a bit oversimplified, but the background is there just to make the people look good in his shots. To put it bluntly, he's not shooting landscapes.

Practicality is important too.

My Holga, 1/100th @ f/11 is all there really is, from what I can gather the aperture switch is there for looks. Portra 400NC mid-day white salt flats in Death Valley, so 3-stops over, and the detail in the highlights still prints pretty.

My RB shutter only goes to 1/400th and I like shooting at f/4 & f/5.6 for effect, so 3-4-stops over on a front lit full sun exposure, still get great results with most negatives.

The other biggie with negatives is choosing the lesser of two evils, a bit of overexposure is almost always better than a bit of underexposure. 1/2 box speed helps me avoid underexposure with in camera meters. If I'm incident metering underexposure is almost never an issue so I see no practical advantage.

Just because you can overexpose doesn't mean arbitrarily shooting at 1/2 or 1/4 box speed is the best choice. Accurate exposure has it's advantages. Jose Villa is very accurate in his work, he's not guessing, he knows darn well what works for him by experience and is setting the camera to get exactly that.

ISO setting question

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