Choosing the Correct ISO?

[nicholasw]

How should I go about selecting the correct ISO level? I understand that the higher level the ISO then the more noise I get but with faster shutter speed.

Should i just aim to have it as low as possible then trial and error shots with a fixed aperture(depending on the shot I want) and just a variable shutter speed? Eg: if at ISO 200 I have to shoot at 1/4 second or faster to capture the action, but it comes out too dark i would up the ISO. How do i do this or calculate this without trial and error?

Thanks! :thumbup:

 

[Peanuts]

In most circumstances I judge what ISO to use by finding what works with a shutter speed of 1/100 (that is my 'safe' zone on essentially all of my lenses to avoid any shake) and within a stop of the widest aperture. Typically I try to go no farther up then ISO 800.

 

[revilo]

In most situations, I'd chose an aperture that suits the depth of field I require, then I'd chose a shutter speed that suits my needs (fast enough to freeze action of a moving object, fast enough to hand hold shots etc.) and then adjust ISO till the exposure is correct. If I had to push the ISO ridiculously high, I might do a little rethinking, and adjust my exposure so I didn't have to use a high ISO and introduce lots of noise. Generally I try to keep my ISO as low as possible, but noise is preferable to inadequate depth of field, or blurring due to motion (unless that's what you want, of course).

 

[elemental]

I choose my shutter speed and aperture and use ISO to get exposure correct up to about ISO 800. After that, I drop shutter speed or open aperture to keep ISO as low as possible. My camera is fine until 800, with a catastrophic dropoff thereafter (at least, by my standards). I would figure out the ISO you can live with and set accordingly.

 

[tsaraleksi]

Depending on what I'm shooting, I'll do the same as elemental but either up to 1600 for sports or casual stuff, and up to 500 or so for something like a wedding.

 

[gsgary]

In most circumstances I judge what ISO to use by finding what works with a shutter speed of 1/100 (that is my 'safe' zone on essentially all of my lenses to avoid any shake) and within a stop of the widest aperture. Typically I try to go no farther up then ISO 800.

1/100 will only give you a fast enough speed for 100mm on 35mm if you are steady, usually the speed you need is the focal length you are using

 

[gsgary]

I will start at iso100 and work my way up but will use every iso i need right up to 3200 when shooting bands