Right now, I am not planning to replace my K10D with a K7, because the latter does not seem to have significantly better low-light performance. By reputation, the K20 is about 1 1/2 stops better than the K10 in low light, and the K7 is about a half-stop worse than the K20 (thus a stop better than the K10).
That seemed simple, until I began looking into low-light performance test results. The noise testing on dpreview used only jpgs until their review of the K7, which compared RAW noise in the K7 and K20. For chroma noise, a score of 10 (y-axis) corresponds to an ISO of about 2800 for the K20, and about 2000 for the K7; this agrees with others' observations that the K20's low-light performance is about a half-stop better. When one goes to dxomark.com, things get confusing. Even though the low-light performance of the K20 is reputed to be about 1 1/2 stops better than the K10, the low light ISOs are 639 and 522, which is only about a 1/3 stop difference; and the overall scores (blending low-light ISO, dynamic range, and color depth) are almost identical. The K7 sensor has a lower overall score than the K10 by 5 points, having 1 stop less dynamic range and almost the same low light ISO. Which leads me to think that the K10 and K7 sensors' low light performance is almost the same, and only slightly worse thana the K20's. So where does the K20's reputedly better performance come from? Firmware? Comments or explanations? Cheers, Rick P.S. I am very intrigued by the dpreview results on the Kx sensor, which (in RAW) has a chroma noise score of 10 at an ISO of 6400. No dxomark testing yet. If a similar sensor found its way into a K7-like body, they'd have a sale. http://photo.net/photos/RickW -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
