Mark II + 550EX Flash Underexposure

[scottbergerphoto]

Myself and many others have been experiencing significant and consistent underexposure of 1/2 to 2 stops using the combination of the 1D Mark II and the 550EX. This occurs in all Camera Modes and the flash on ETTL regardless if the flash is set to Cfn. 14 (0)Evaluative or (1)Averaging.
Here is the thread on Rob Galbraith's forum:
http://www.robgalbraith.com/ubbthreads/showflat.php?Cat=&Number=247684&page=0&view=collap sed&sb=5&o=&fpart=1
This is not a "fill flash" reduction problem as it occurs in Manual Mode as well as Tv, Av and P.
Have any of the Mark II owners on this forum had this experience?
Regards,
Scott

[Mike H]

You may want to review the article at the link below; it has a brief test of the Mark II's flash metering system.

Mike H

http://www.wlcastleman.com/equip/reviews/Eos1Dm2/E-TTL_II/index.htm

[scottbergerphoto]

I read that some time ago Mike. That test in my opinion shows under exposure for the series of shots taken against a light background. It doesn't address the issue that many Mark II owners have been complaining about to Canon. In all kinds of situations the Mark II consistently underexposes with the 550EX by 1/2-2 stops. In addition contrary to what is posted on that test, flash exposure on the Mark II (ETTLII) is not influenced by the active focusing points or the choice of spot vs. evaluative metering on the camera. In ETTLII there are 17 flash metering segments in the central elipse. In CFn. 14-0,(evaluative) the camera decides based on the preflash which sensors to use based on the difference between the data recorded by that sensor and ambient light. In CFn. 14-1, the camera averages all 17 segments. No relationship to the metering modes for ambient light.

I did some additional testing this morning and I found that there may be some relationship to this issue and the lens being used. I did identical shots with white and grey cards first using the 85mm f/1.8 and then with the 24-70 f/2.8. The camera settings were identical in Manual Mode. The shots taken with the 85mm f/1.8 were properly exposed. The ones taken with the 24-70 f/2.8 were underexposed by 1/2-1 stop as they were yesterday. This is puzzling. Any ideas?
Scott

[slin100]

My 10D constantly underexposes with my 550EX. I've found that dialing in about +2/3 FEC seems to compensate--most of the time. So, why I am replying to this thread? It's to suggest that, perhaps, Canon has chosen to deliberately underexpose flash exposures in all their D-SLRs. After all, I've seen D60, 10D, 300D, 1D, and 1DMKII owners complain about flash underexposure. Who knows, maybe they're trying to avoid blown highlights.

OTOH, 1/2-2 stops is a pretty large range of underexposure. It may be that ETTL-II hasn't solved the consistency problems common to ETTL-I.

[Mike H]

I don't really know what to suggest at this point. I'm pretty disappointed to hear about the problems. E-TTL2 was one reason that I bought the Mark II (after frustration with the 10D/550EX combination).

I'm sure glad that I don't use flash very often (I'm an available light guy whenever I can get away with it).

It sounds like the biggest problem, as the previous writer suggested, is the variance of exposure error. If it were off by a consistent amount, the problem would be easily solved. It sounds like we will have to check the review screens often.

Mike H

[scottbergerphoto]

It seems that different users are experiencing different amounts of underexposure. I am experiencing 1/2-1 stop underexposure consistently with my 24-70 f/2.8 and none with my 85 f/1.8. I have to test my others.
Scott