Read about the Camera ISO noise tests in the help section to learn more about the tests and how they are conducted. A key take-away from that page is that noise reduction is completely off unless otherwise specified.
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As you likely already know, the amount of light recorded in a specific amount of time (shutter speed) and at a specific lens opening (aperture) doubles with each doubling of the ISO sensitivity value. Because image quality degrades as the ISO setting is increased, using the lowest ISO setting the particular shot scenario will allow is desired. Not enough light is the big reason for using a higher ISO setting.
Obviously, there are many comparisons to be made from the above samples - I'll comment on a couple of them.
Looking at the XSi /T1i comparison, the T1i's resolution advantage can be seen in the tiny threads. High ISO noise (better seen in the next comparison) does not appear to change. Very obvious is that the T1i has 3 additional stops of high ISO settings available. While the highest settings (ISO 6400 and 12800) will likely be reserved for emergency-use-only by most, ISO 3200 will see more action.
They share the same sensor resolution, so it is expected that the 50D and the T1i would deliver similar image detail as the comparisons above show. What I was not expecting was the reduced high ISO noise from the T1i. The improvement at and above 3200 is especially noticeable in the comparison below. Canon got the red out.
Auto white balance was used for these daylight color temp shots. The 50D is rendering this scenario a little more red than the other cameras in this test, but custom white balancing the 50D images to an Xrite Mini Color Checker included in each shot and used for the CWB (Custom White Balance) in the primary comparison below makes little difference in the results.
I should note that the Rebel bodies allow full-stop-only ISO changes while the rest of Canon's EOS bodies allow 1/3 ISO setting increments over their non-expanded range.
The T1i's NR (Noise Reduction) samples utilize DPP's noise reduction with settings ranging from 1/1 to 7/13 (Luminance/Chrominance) from ISO 100 to ISO 12800. While DPP can always be used for high ISO noise reduction, the T1i's new DIGIC 4 processor allows for excellent in-camera noise reduction for those opting for JPEG image capture.
Evaluating noise is easier in the color block comparison below. Note: backgrounds of images not consuming the full image size are identified and were shot at the same ISO setting as the selected image (this feature is intended to make comparisons easier).
I know, it was mean to include the Canon EOS 5D Mark II in this comparison. Just keeping everything in perspective.
Again, the Rebel T1i's improved-over-the-50D high ISO performance was surprising to me. This improvement once again creates a dilemma repeated with each new Rebel / xxxD DSLR release - The consumer-level Rebel delivers better image quality than the prosumer xxD. But, let's keep our heads on straight - these improvements are primarily at ISO settings that are best avoided in the first place and the 50D is a better camera in most aspects. Still, even identical image quality at this price is a bargain.
Back to the Canon EOS Rebel T1i / 500D Review.
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