ISO - Help Me?

Bear in mind that I took my first and only Photography class this year - Digital Photography One - as a freshman in highschool.


What exactly is ISO? I know we went over it, but I can't remember any of it at all, to be honest, and I'm pretty sure ISO's a big deal in the photography world.

Basically, if I kick up the shutter speed really, really slow, it let's in more light, making the picture unbearably light, right? So, to counter this, you have to mess with the ISO, I'm pretty sure? How and to what would I do it to?

Just an example. If you have any knowledge of ISO, I'd like it. :3

If you have a really slow shutter speed, you'd need an ISO below 100. I would suggest using a smaller aperture if your photos are still too bright after that. ISO is only useful to me when using high shutter speeds, but upping the ISO means more image noise. Hope that helps. =]

You have a fast shutter speed, such as 1/400 of a second or higher, make the ISO higher. The higher the ISO, the more sensitive your camera is to light. If you have a slow shutter speed and you're not shooting at night, you'll have to significantly lower your ISO to prevent overexposure.

Yeah, what Bright Blue Yoshi said. Digital cameras adjust the sensitivity of the sensor circuits to settings that can be compared to film of the same ISO. The change in sensitivity involves amplifying the electronic sensor's data that creates the image. Which is why the higher they are, they come out fast but the sensors make issues in some areas that will come out looking grainy. With most of my photos, I usually have never had to go above 800 unless there was something faster-paced I wanted to take a shot of. I liked the fact that use could also adjust the aperture on the camera I had. Reason I bought the camera was because it could go full-manual.

quote karrynx3

Think of ISO as your eye's iris. The bigger it is in diameter, the more light comes in and the brighter a picture is.

Actually, I'm pretty sure you're talking about the "Aperture" or "F-stop," the aperture is the size of the "iris" of the lens.

quote Alpha

Basically ISO is artificial gain in light capture. The lower your ISO, the less grainy & higher quality your photos will be - Generally.

Pretty much this. I will elaborate though the functionality and what the different ISO settings are best utilized for.

The sensor sensitivity which is the "ISO" is the measure of the sensor's sensitivity to light. Though be careful when using manual settings because the higher your ISO is set to, the lesser quality the photograph may turn out. Appearing grainy with noise.

• 100 ISO is used for bright light and bright sunlight
  
• 400 ISO is for a duller color
  
• 800-1600 ISO is better for indoors and with quality lighting.
  
• Anything beyond 1600 is more-so used for faster shutter-speeds for action shots, etc.

quote Quierta

quote karrynx3

Think of ISO as your eye's iris. The bigger it is in diameter, the more light comes in and the brighter a picture is.

Actually, I'm pretty sure you're talking about the "Aperture" or "F-stop," the aperture is the size of the "iris" of the lens.

Quierta is correct. The aperture controls how much light the lens lets in. So if we are sticking with the "iris" analogy, the aperture(f-stop) is the eye-lids controlling how much light is let in, then the ISO is the sensitivity the eye has to the amount of the light. So utilizing the f-stop in low-light conditions is optimal for you so that you don't have to switch to a higher ISO, thus compromising any quality of the shot.