Question about ISO

[tatlyne]

New to DSLR's. Am I missing something or should I see a fairly significant difference in a photo using ISO 200 and 12800? -- because I don't? I've never been able to use ISO to give me more light with this camera. I just took 2 pictures both at F/8 and with the ISO set at the numbers already mentioned. They look almost identical? I would post the pictures but I'm not sure how to upload here. Thanks so much.

[Danny]

Hi, tattyne!

Inserting photos is easy! When composing your message, click the "Insert/Edit Image" icon at the top of the text box. It's near the center and it's a square with a pair of mountain peaks in it. You'll get instructions from there.

We hope this helps!

[tatlyne]

Thanks so much!

[kvbarkley]

What camera?

Post by clicking the little mountain icon. You might need to resize the image a little smaller.

An ISO of 12800 should be very grainy. There should also be a 4 stop difference in shutter speed. If the ISO200 -f/8 image was 1/20 of a second, the ISO 12800 -f8 image should at 1/1280 of a second.

[tatlyne]

Here are the two photos. The first is ISO 200 the second is ISO 12800. I understand the higher the ISO the more grain/noise is introduced into the photo but I also thought that I would increase ISO when I needed more light. These photos probably arent the best example because I really didn't need the light sensitivity (does a too high ISO not "over expose" a picture though?) If I go into a room that definitely needs more light, I increase my ISO -- even by lots like in this example but it doesn't seem to change anything. I don't get it?

[kvbarkley]

If you zoom in you can see the difference:

ISO 200:

ISO 12800:

Note the extra grain and lack of detail, probably due to the noise reduction. It is still pretty good for an ISO12800 image, though! Very usable. This is way you use a DSLR, the large sensor gives good noise performance.

[Ray-uk]

If you are using the camera in green square(auto), P,AV,TV or any of the scene modes then changing to a higher ISO will not cause over exposure because the camera will adjust either shutter speed or aperture to compensate and give you the correct exposure, if however you are in manual (M) mode then you will have to change these yourself to get the exposure correct.

[ebiggs1]

" I increase my ISO -- even by lots... but it doesn't seem to change anything."

Being new I think you might be falling for the huge increase in numbers and not the lesser increase in f-stops.

The rule is a doubling of numbers.  I.E., ISO 800 to ISO 1600, seems like you added a lot of numbers, however, you just increased the f-stop by one. So, 800 to 1600 is one to 3200 is two and 6400 is three. That makes ISO 12800 four stops faster than ISO 800 but the number spread is huge at 12,000!

Most current DSLRs can shoot cleanly at ISO 6400 and even 12,800.  Something that a few years ago would have not been possible.

[tatlyne]

" I increase my ISO -- even by lots... but it doesn't seem to change anything."

Being new I think you might be falling for the huge increase in numbers and not the lesser increase in f-stops.

The rule is a doubling of numbers.  I.E., ISO 800 to ISO 1600, seems like you added a lot of numbers, however, you just increased the f-stop by one. So, 800 to 1600 is one to 3200 is two and 6400 is three. That makes ISO 12800 four stops faster than ISO 800 but the number spread is huge at 12,000!

Most current DSLRs can shoot cleanly at ISO 6400 and even 12,800.  Something that a few years ago would have not been possible.

[ebiggs1]

Consider a tripod