ISO mem usage

[Xtreme02]

I tried a search for my question, but couldn't find any answers. sorry if this has been asked before but my question is when i shoot at ISO 100 on a blank 512 mb card i show around 151 or so shots, but when i go to a higher ISO my available shots start to get lower. I think at ISO 1600 i'm down to about 100 shots. (all on a blank card) I was wondering what makes the Higher ISO take up more space? thanks

[robertwgross]

At ISO 100, there is virtually no color noise, so the image looks "smoother", and the data of that image has more repetition, so it is easier to compress into a smaller data file.

At high ISO, there is a lot of color noise, so the image looks less smooth, and the data has less repetition, so it compresses into a larger data file.

---Bob Gross---

[Xtreme02]

thanks for the fast reply, i didn't think the ISO made that much of a diff. thanks again

[robertwgross]

For about my first year of digital work, I didn't realize the difference, either. When I went back and looked, the high ISO shots were all the higher file sizes, and the lower ISO shots were all the lower file sizes, all spread over 6-9MB.

---Bob Gross---