noise or focus

[carrbowl]

I was at the park yesterday and found my neighbors there as well...we have been wanting to take some photos of their adoreable daughter. She was 3 this month. My ISO was only at 250, but it looks like there is alot of noise in the photo. I've attached two photos, one with Noise ninja and one without. Why would there be noise only at 250?? Not sure you will even be able to tell the difference...

[kenw]

take a crop from the 100% size version and whatever it is will show better.

(iow, take a 800x600 section from the 100% sized image, not resized)

[snidow]

What were the other settings when you made the exposure?

[carrbowl]

ok, so I took the photo to 100% and then cropped at 700 by 500 PIXELS!!!

Laurie, they were taken at 250 2.8...which were way too dark. I wonder if irt is because I adjusted the exposure so much in RAW????

[andyz]

http://www.texasphotoforum.com/forum...ad.php?t=74503

You have replies to the scratch disk question on your other post.

[carrbowl]

So what happened? What did I do wrong??

[kenmyers70]

This looks to me like a picture a little out of focus and underexposed. You will have noise in every picture--not just high ISO. Adjusting the exposure up in PP to compensate for an underexposed image will also enhance the noise. How many stops under exposed was this? The flat lighting doesn't really help either.

[carrbowl]

It was the exposure...it was way underexposed...way...under...that must be the issue. I was chancing her around...literally. Facing the light, light behind her...more snap shots than posed official photos. This was the "most posed" she was interested in. Thanks Ken.

[JohnT]

Even with a 5D at low ISO, if you severely underexpose an image then crank it up in post, noise is going to be an issue. The best way to avoid noise is to nail the exposure even at low ISO. A judicious use of noise reduction would help this image, but you want to be careful not to plasticize her skin. I took your 100% crop, ran it through Noise Ninja, then applied some light sharpening for portraits just as an example.

[kenmyers70]

Renee,
Think of it this way: The Intensity of the pixel is (Noise+Signal) X ISO
A high ISO will multiply both the signal and the noise. If this signal is much larger than the noise, you won't notice the noise. If the signal is small, the noise will be noticeable-no matter what ISO is used. How do you get a small signal? Underexpose.
The noise determined by the sensor size (5D=good), electronics, sensor type (CMOS=Good), temperature.