Jim Davis wrote: > I thought evaluative broke up the scene into many segments of a grid.
I'm sure it does, but as several others have pointed, it sees only luminances, with no idea of what they represent. And it depends on how the different segments align with the light and dark areas. > ... or else evaluative is more like simple centre-weighted than we've been > lead to believe. Unlike center-weighted metering, evaluative can detect luminance differences in different parts of the subject. > Isn't there some kind of database of scenes in camera memory that are being > compared? I suspect the "database" is simply a matrix of luminance range and overall luminance, much like the fairly well documented Nikon matrix metering of a few years back (I haven't used Nikon for 10 years, so I can't comment on the latest version). It's quite possible that the exposure matrix was developed by examining thousands of images, but the actual matrix in the metering system probably isn't all that complex. > The problem comes from this: sunlight is not varying much, it is > consistant. But areas of the scene shooting with a long lens (100-400 > at the long end being 640mm for me) vary signifigantly. I do need > consistant metering while using compensation based on experience. > (white bird go down one stop, light grey, half stop down) If you can find the right metering for your main subject, set manual mode and the changing backgrounds won't bother you. > ... I must change exposure now manually, > plus add my compensation. I'd be wary of setting compensation with anything but narrow-angle metering (preferably spot, when it's available) and fully understanding what's happening. If you're not familiar with the Zone System (I'd start with Adams) it's worth a read, even though you won't be controlling contrast by varying development. > Or I could use partial metering and try and find a medium grey value > in the scene and set Manual with comp to that. Use a neutral test card (or your palm and increase exposure by one step) if it's in the same light as your main subject. When appropriate, the Sunny 16 rule also works quite well. > What do you guys do? Manual exposure, usually with spot metering (built in or handheld). Jeff Conrad * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
