macrobild skrev:
Det är mer komlpiserat än så. Det du skriver stämmer, har själv påtalat detta långt före det diskuterades på dpreview. Såg det första gången 2001 med D1x.
Vad som nu tillkommit är att jag har identiskt lika tagna bilder i raw, dvs tagna manuellt med samma iso, tid , bländare. När vi sedan mäter upp bilden i lågdager,mellanparti och högdager får vi exakt samma labvärden där vi mäter. Vad vi kan se så skiljer sig inte sensorernas återgivning från vitaste till svartaste och grå yta i mellandagrarna.
Det handlar alltså mer om hur tillverkarna skriver sitt program, kurvor/kontrast/ för respektive kamera. Även hur man tar hand om det brus som uppstår.
Dessa bildfiler är också skickade till Stefan Olsson för kontroll.
mvh Mikael
Hej
Här är en som skrivit på Dpreview och menar att det är tvärtom?
"I ran a simple test on my D2X and determined that the metering is dead on but the resulting exposure is about 2/3 stop lighter than metered (i.e. the actual ISO is about 2/3 stop higher than the ISO set on the camera).
I metered an 18% grey card with the sun directly overhead on a bright, cloudless day. I had my ISO set to 100, and the lens stopped down to f/16. Per the "Sunny 16" rule, I should have gotten a meter reading of 1/100 sec, which is exactly what I got. I got the same result on both matrix and center weighted metering. I also got the same result on my D1X and F100. So as I said above, the metering is dead on.
I took a shot of the grey card at those settings and examined the histogram in Capture. The histogram of a grey card is simply a spike, and since it's a medium toned subject, the spike should be right at the mid-point of the histogram. For my test shot, however, the median value of the histogram was 164, or 2/3 stop higher than it should be (I know this is 2/3 over because it took a -2/3 ev setting in Capture to bring the histogram peak down to it's proper midtone position).
So what does this mean? Effectively, on my D2X at least, ISO 100 is more like ISO 160. I haven't tried this test at other ISOs. This is easily remedied, of course, by just dialing in a base exposure compensation of -2/3 ev.
By the way, some Canon trolls claim just the opposite, that the D2X ISO is a full stop LESS than indicated, and that to compare noise levels with Canon cameras, you have to set the D2X ISO a full stop higher than the setting on Canon cameras. This is hogwash, of course, and if anything, my test indicates just the opposite.
All part of getting to know a new piece of equipment, of course."
Jag brukat också minus kompensera med -2/3 på min Canon Mark2 för att få den exponering som jag vill ha.
MVH
Omar