wrishel
8th of April 2002 (Mon), 18:09
I just brought a Powershot G2 after dithering for awhile between it and a CoolPix 5000. I was somewhat suprised to see the amount of sensor noise that this camera provides at high ISO numbers. It seems a lot more than I experienced on my Coolpix 950.
I am wondering if this is normal for most 4-5 megapixel cameras or, conversely, is it not normal for a G2 in which case I have a defective camera.
Unfortunately, I broke the 950 so I can't do a side-by-side compare. But I did compare the output of the G2 at different ISO settings. My conclusion is that I must use ISO 50 whenever possible and go above 100 only when desparate for an extra stop of exposure. On the 950 I felt comfortable leaving it on 400 all the time.
The image at http://www.rishel.com/downloads/CanonG2%20Noise%20vs.%20ISO.bmp shows the noise on a deliberately out of focus stretch of wall, at four ISO settings. It is best viewed by copying the image into an editor and expanding it to 300% of its normal size.
(Lest someone complain that it hardly looks noticeable let me say that I started this investigation because pictures taken at ISO 400 and viewed in normal picture sizes looked grainy.)
Here is the procedure used to create this image.
1) camera on tripod, largest image size, superfine JPEG, flash off, point it at a wall, set it on manual focus and make it way out of focus.
2) set ISO 50. Press the shutter button half way and notice the camera's exposure settings (1/25, f/2.0)
3) set camera on full manual and set 1/25, f/2.0. Take picture
4) set camera to ISO 100, change shutter speed to 1/50. Take picture.
5) repeat step (4) for ISOs 200 and 400 with shutter speeds 1/100, 1/200.
6) bring each image into PhotoShop and select a 100x100 pixel square from the same place in each image. Assemble the images into a single impage and label with ISO speeds. Save as .BMP.
Note that the noise is far more notable on blue than the other colors and red has more noise than green.
I am wondering if this is normal for most 4-5 megapixel cameras or, conversely, is it not normal for a G2 in which case I have a defective camera.
Unfortunately, I broke the 950 so I can't do a side-by-side compare. But I did compare the output of the G2 at different ISO settings. My conclusion is that I must use ISO 50 whenever possible and go above 100 only when desparate for an extra stop of exposure. On the 950 I felt comfortable leaving it on 400 all the time.
The image at http://www.rishel.com/downloads/CanonG2%20Noise%20vs.%20ISO.bmp shows the noise on a deliberately out of focus stretch of wall, at four ISO settings. It is best viewed by copying the image into an editor and expanding it to 300% of its normal size.
(Lest someone complain that it hardly looks noticeable let me say that I started this investigation because pictures taken at ISO 400 and viewed in normal picture sizes looked grainy.)
Here is the procedure used to create this image.
1) camera on tripod, largest image size, superfine JPEG, flash off, point it at a wall, set it on manual focus and make it way out of focus.
2) set ISO 50. Press the shutter button half way and notice the camera's exposure settings (1/25, f/2.0)
3) set camera on full manual and set 1/25, f/2.0. Take picture
4) set camera to ISO 100, change shutter speed to 1/50. Take picture.
5) repeat step (4) for ISOs 200 and 400 with shutter speeds 1/100, 1/200.
6) bring each image into PhotoShop and select a 100x100 pixel square from the same place in each image. Assemble the images into a single impage and label with ISO speeds. Save as .BMP.
Note that the noise is far more notable on blue than the other colors and red has more noise than green.