Posted by Rick Cloran on November 21, 2006 at 2:44 PM
I ran into an interesting situation that I wasn't aware of. Apparently the EOS cameras(at least my 1V and 1D Mark IIN) shift over to evaluative metering when you connect a dedicated flash (even through the coil cord). Since I like to meter using spot, this caused problems and had me baffled for a while until I ran across another photographer who seemed to be aware of this undocumented (at least I couldn't find anything on it) quirk. The Canon reps I have spoken to since souldn't confirm or deny.
Can anyone else add something to this?
Thanks
Rick
Posted by Robert Fisher on November 21, 2006 at 4:03 PM
What you're referring to, I think, is the latest edition of Canon's flash metering system, E-TTL II. Only your 1D MkIIn is E-TTL II capable, your 1V is not, I don't believe.
With the previous E-TTL system, metering was evaluative but connected to the active focus point, ir I recall. In this case, it basically metered in spot mode even though the metering defaults to evaluative. If the active focus point was on an overly light or dark object in the scene, it would impact the flash exposure accordingly because of the greater or lesser reflection of the pre-flash. With E-TTL II, the metering is tied to the active focus point but the camera does a calculation after the metering pre-flash to balance out the light from other areas of the scene, supposedly for a better overall flash exposure and balance of flash and ambient.
The reason, I believe, Canon has its cameras default to evaluative metering is to get a better overall flash/ambient balance. If you used spot metering and were metering off an overly bright or dark subject, you'd have to compensate for the overall exposure but you'd also have to compensate for the flash exposure. Canon's tried to take that work out of your hands and make it easier for you.
Check out this link for much more information on the EOS flash system. Photonotes is probably the most comprehensive resource on all things EOS.
Discussion
1 repliesCan anyone else add something to this?
Thanks
Rick
With the previous E-TTL system, metering was evaluative but connected to the active focus point, ir I recall. In this case, it basically metered in spot mode even though the metering defaults to evaluative. If the active focus point was on an overly light or dark object in the scene, it would impact the flash exposure accordingly because of the greater or lesser reflection of the pre-flash. With E-TTL II, the metering is tied to the active focus point but the camera does a calculation after the metering pre-flash to balance out the light from other areas of the scene, supposedly for a better overall flash exposure and balance of flash and ambient.
The reason, I believe, Canon has its cameras default to evaluative metering is to get a better overall flash/ambient balance. If you used spot metering and were metering off an overly bright or dark subject, you'd have to compensate for the overall exposure but you'd also have to compensate for the flash exposure. Canon's tried to take that work out of your hands and make it easier for you.
Check out this link for much more information on the EOS flash system. Photonotes is probably the most comprehensive resource on all things EOS.