To compare noise levels under real-life conditions we shot the same scene using the Canon EOS-400D / Rebel XTi and Canon EOS-350D / Rebel XT within a few moments of each other using their best quality JPEG options, and at each ISO setting. Both cameras were fitted with the EF-S 18-55mm f3.5-5.6 kit lens, set to an aperture of f11 in Aperture Priority mode; f11 was necessary due to the high brightness of the scene.

The image left was taken with the Canon EOS 400D / Rebel XTi at 100 ISO using the EF-S 18-55mm f3.5-5.6 lens at 25mm f11 (40mm equivalent); the original JPEG measured 3.8MB. The crops are taken from an area just below and to the left of the centre.

As with our first outdoor results page, there's little to differentiate the above results from the EOS 400D / Rebel XTi and the earlier EOS 350D / Rebel XT. Both show similar levels of detail and noise up to 400 ISO, and a loss of ultimate detail at 800 and 1600 ISO. Interestingly though, the EOS 350D / Rebel XT appears to deliver a slightly better result at 800 ISO, especially around the foliage which appears less detailed on the 400D / XTi.

It's a very close result though and only those closely examining 100% crops on a high quality screen are likely to notice much difference. The important thing is the EOS 400D / Rebel XTi delivers smooth, low noise results throughout its range, and while noise is visible at 1600 ISO, it's by no means obtrusive.

Note: we have compared 100% crops from each camera measuring 282x136 pixels. Since the Canon 350D / Rebel XT has a lower resolution sensor, its crops therefore represent a slightly larger area relative to the EOS 400D / Rebel XTi. Consequently any artefacts visible on the 350D / XT crops would be slightly larger and more obvious than the 400D / XTi if the image was reproduced at the same physical size.

You may also wish to compare results taken with the Sony Alpha A100 of the same section, albeit on a different day in our Sony Alpha A100 review. Note the Canon 350D / XT samples on this page are different from those on the Sony page and were retaken especially for this review.

To compare the effect of in-camera processing and compression, we took the 100 ISO sample in Large / RAW mode, and have compared both files for each camera below. At the time of writing, Adobe Camera RAW did not support the RAW files from the 400D / XTi, so we used Canon's own Digital Photo Professional version 2.2 to convert files from both it and the 350D / XT.

We used the default settings for DPP, then transferred the data to Photoshop with 16-bit tonal depth before converting to 8-bit, then cropping and saving using the same settings as the JPEGs above. We will update this page when Adobe Camera RAW supports the 400D / XTi for consistency with our existing results.

The processed RAW file from the EOS 400D / Rebel XTi at first glance appears sharper than the in-camera JPEG, but look a little closer and there's undesirable artefacts especially around the fencing. Interestingly, there's little difference between the RAW and in-camera JPEG of the 350D / XT using the file above.

Since we have used Adobe Camera RAW to process RAW images on earlier reviews, we will return to these files once Adobe supports the 400D / XTi and provide full analysis.