ISO help

[LeroyLion]

So, I finally got my slr about a week ago and Ive been playing around with it quite a bit. I understand aperture size and shutter speed fairly well, but Im still having trouble with ISO. Im just wondering if there are any real guidelines for ISO settings, or if its just one of those hit or miss, you get better as you go kind of things.

 

[kellylindseyphotography]

ISO ties in with exposure. You might have better luck googling it to learn its technicalities.. but a broad generalization is that low ISO (100 or so) is great for bright sunny days. It also provides the best clarity, least grain.

Higher ISO is used in low light situations, which is ideal when you don't want to use a flash. Problem is that high ISO's tend to cause grain so you try to avoid them . Generally, a higher ISO is preferable to pop up flash though...

Thats as simple as I think I can get it

 

[tirediron]

Kelly's right on. In simplest terms, ISO (Which actually stands for "International Standard's Organization) is simply a numerical expression of the sensitivity of your camera's sensor to light. The higher the number, the more sensitive it is to light, or the less light you need to take a picture. As mentioned, the higher the ISO, the higher the sensor-induced noise (digital "grain") will be.

Always shoot at as low an ISO as you can, and never leave ISO in 'Auto'.

 

[LeroyLion]

Yeah, Ive pretty much already learned not to trust the camera in auto mode.

Good answers though, I guess I just didnt understand what ISO really was. Very much appreciated guys.

 

[Big Mike]

When you turn the ISO up, the camera amplifies the signal from the sensor. This amplification causes distortion and the distortion can show up in the image as digital noise.

So to avoid noise, it's best to use the lowest ISO possible and only turn it up when you need to (to get a faster shutter speed, for example).

Also, take note that noise is easier to deal with, if you 'expose to the right' because noise becomes more apparent when you brighten an image in post. So if the image is already bright and you only need to darken it a bit, the noise will be suppressed.

 

[maulrat]

Although noise can really stress you out at times of low light, don't be so quick to toss noisy photos in the recycle bin. Here is a couple of photos that had some noise yet came out pretty okay to me after some B&W and artistic post processing.

#1

http://farm4.static.flickr.com/3222/2826651397_1c57e4cb86.jpg
#2

http://farm4.static.flickr.com/3168/2777549920_10085a7c1b.jpg

 

[William Petruzzo]

ISO is kind of the current manifestation of film speed. Once you get how it works, you can select it stylistically and use it to aide you in producing the look and feel you're going for. There are times when I intentionally choose a higher ISO simply because it has the look I'm going for.

Don't just settle for getting the gist of it, go and do some more research. The better you know your camera, the more great pictures you can take on purpose.