Archived posting to the Leica Users Group, 2009/01/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Jan 24, 2009, at 11:58 PM, Geoff Hopkinson wrote: > Using jpg will certainlty affect contrast and dynamic range as the > in-camera > processing is discarding some data. So the test would be valid if > that's > what you shoot, but not the best case for the camera. True. I chose this Jpeg Basic method because I wanted the smallest possible file out of the camera; and did not want to have to post process a dozen images; then possibly defend the methodology of post processing procedures. I presented this basic test at the request of a couple readers of the thread. > Dynamic range appears to decrease as ISO increases (according to > Henning's > posted DxO thingie link). So using the native sensitivity (160) of the > sensor would give the biggest dynamic range. Of course if you use > ISO 640 > you want to see the results for that ISO Probably true. However, untested by me on any of my three digital cameras. > Leaving the minus third exposure in place will skew the results, > although > each step difference comparison should still be valid. It might > affect the > result at the two ends though. I question the term "will skew;" while the -1/3 setting may "skew" test results for those, like yourself, who do not implement the compensation; it will give accurate, un-skewed, valuable test result data for those who regularly use -1/3 compensation. > For a mechanical camera, aperture adjustments might give different > results > rather than speed adjustments IF the speeds are not accurate. I > guess I > should take the speeds as accurate. True. The test assumes, perhaps falsely, an accurate shutter. Bottom line I presented the test and its results, on request, as a "how-to" not as anything useable for anyone, even myself - because I never photograph in jpeg basic mode. I have, however, done the test at ASA 160, RAW, and 0, -1/3, and -2/3 compensations. The results reinforce my confidence in the continued use of -1/3 compensation for auto exposure, under most of my "normal" conditions. The results also demonstrate exactly how to expose for highlight control and what to expect from shadows in any metering situation - using the camera's meter. Handheld meters may require adjustments to synchronize with the cameras meter. Regards, George Lottermoser george@imagist.com http://www.imagist.com http://www.imagist.com/blog http://www.linkedin.com/in/imagist Picture A Week - www.imagist.com/paw_07