p.4

Above picture shows the same fragments of the chart made with the same lens at the same resolution with the same camera, only the ISO speed was different, given on the photo. As you can see, the picture quality is deteriorating with rising sensitivity. Even the difference is noticeable between 50 and 100 ASA. More accurate answer gives statistical analysis of the pixel brightness in different color channels but this goes beyond the scope of this article. Excellent information on this subject (the numbers derived from pixel color analysis) you may find in Digital Photography Reviews. The photos above were made with Canon 1Ds at 2032x1352 resolution (2.7MB image). The resolution does not depend on ISO speed, as shown on the next image, below.

This is a comparison made on the same camera as the first photo, but made on high resolution, 4064x2704 (11 MB photo), except that the last photo is a 4000 dpi scan (Nikon Supercoolscan 4000 scanner) of a Kodak Gold ISO 200 negative made on Canon AE1 with the same 100mm lens (image size was reduced about 20% after the scan to match the size of the 11 MB images). Although the resolution of all images is approximately the same, the negative scan looks the worst. As I compared more negatives to the digital images, it appeared to be obvious that using Kodak Gold ISO 200 negative film matches the quality and appearance of a 4-5 MB digital image at ISO 100, although the line resolution of negatives matched 11 MB digital photos.

To me using this resolution chart was essential in selecting a good camera and assembling my collection of lenses. If you perform this test on your new camera it will give you more critical information than just about any review you can read in popular magazines.

 

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