Digital Photography 101: Film Speed

This is part two of a series of articles I’m writing about digital photography, as I learn more about it. You can find links to the other articles at the bottom of this one.

photos are back... Jessica Alba for startersI bet your new Digital camera has a setting for “Film Speed” on it… and if you’re like most amateurs (totally including myself here), you remember using different film speeds when you were a kid, and you actually bought film.

But I bet you always bought ISO 400 (or maybe it said ASA instead of ISO) because you never knew if you were going to take a photo inside or outside, and the clerk behind the counter (back when clerks actually knew something about what they sold) told you to go with ISO 400, because it was a good all around film speed.

Guess what? That clerk was right… but in today’s day of digital cameras, you don’t have to stick with ISO 400, because you can change film speed on the fly with your new digital camera. You don’t have to shoot a whole roll of 24 exposures, or waste the rest of those shots just to change speed.

So, like myself, you need to know what film speed to use when.

Here’s a little guide. I’ve read about 40 articles on the subject and am firmly of the mind that every photographer has their own opinion about exactly what film speed to use when and where, but, the generalities of this guide should fit most of the situations you find yourself in.

What does film speed mean?

Film speed is generally denoted as an ISO number: ISO 100, 200, 400, 800, and up…

Film speed is a measurement that indicates a film’s sensitivity to light. The higher the film speed, the faster or more sensitive it is to light

Which translates to:

Higher Film Speed -> less light needed, or faster shutter speed for action
Lower Film Speed -> bright daylight shots, static subjects, longer shutter time

Quick Guide to Film Speeds

  • ISO 100: “Slow” film, good for sunny, outdoor conditions
  • ISO 200: “Slow” film, good for overcast outdoor conditions
  • ISO 400: “Fast” film, good compromise for indoor/outdoor use
  • ISO 800 & up: “Fast” film, good for indoor use, low light conditions, or action shots

I’ve read recommendations to use ISO 1600 and ISO 3200 films (if you’re camera supports those) for extremely low-light situations when you just can’t use a flash… I’ll have to experiment more with those myself to see what I find useful.

The funny thing is that I’ve been taking photos for about 3 weeks with my “new to me” D60 completely backwards… now that I know the right way to pick a film speed, we’ll see what I get with my shots 😉

Other articles in this series:

And you can browse the rest of the Photography + Video category on this site for more links to relevant content.

7 Responses to “Digital Photography 101: Film Speed”

  • Also, note that ISO affects grain, so not only do you have to select the ISO for the lighting situation, you also choose ISO based on the aesthetic quality you want to get out of the photograph. Many times I will want a very fine grain so I shoot no more than 200 ISO despite the lighting situation.

  • Hello!

    I like the way you have explained this piece.

    Can you write a note on the combinations of shutter speed, aperture & film speed too?
    E.g. At night & with low flash , is it better to use high film speed, small aperture, slow shutter speed or high film speed, large aperture, fast shutter speed or normal film speed, large aperture, slow shutter speed ?

  • You’re right, Sidney. I also never use higher than ISO200 anymore, even for night shots. It’s just too grainy, too much noise. I can’t imagine using ISO 800 or higher. I made night shots with ISO 400 once, and they were all grainy and noisy. I learned from it. The article should mention this danger.

  • Nice blog, the understanding of ISO is key if you are going to master the use of your camera and nothing helps you get the right shot better than understanding what lighting conditions require what ISO values. That can make or break the exposure of your shot.

    As Sidney Lo said, one thing that wasn’t mentioned here is how higher ISO values introduce more ‘noise’ into the picture. The lower that you are able to go with ISO, the better. As camera sensors get better, however, there is becoming less and less grain with higher ISO values and their usefulness has increased greatly.

    As to Rahul’s question about the relationship of shutter speed to aperture and ISO, here is a post covering even more details about what ISO is including graphics and sample pictures:

  • Thanks for that. I’ve been looking all over the place for a straigh forward answer to that. at last I know what for less light I need a higher number and for lots of light a lower number. Why other sites had to go around the houses and be all technical I don’t know. Sorry for the rant I was getting frustrated


  • Great blog, The last time I had a real camera was 20 years ago (Chinnon 35) So my new E-420 is a revelation. Adam refers to high ISO and noise. Does this problem affect digital sensors to the same level as film?

  • I am trying to use a SunPak auto266D flash attachment made for a Nikon film camera on my Kodak P850 digital camera.
    Could you tell me what setting on the flash attahment to use for various distances from camera to subject.

    Thank you


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