I don't really consider the lack of mirror drop a problem. I only use the 600D for video, so I never need the mirror, the box can stay jammed up for all I care, it functions perfectly as the tool i need it to be.
I did use the TXi filter with a 550D too, and oddly enough it used to error all the time with filter in, getting annoyed and ERRor locking up with the TXi filter in place
The 600D doesn't care about it and has been rock solid.
I can't see how the mirror physically could drop down with it in place though, as the top of the filter rests against the bottom of the mirror, how can the mirror drop down in either model unless it isn't fitted correctly?
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Back on subject, all i meant is since the filter is designed to cut the 18MP full sensor to 1080p precisely, any other type of cropping or scaling of the sensor won't benefit from the TXi filter. Only cropping from that 1080p feed with those same lines skipped.
For example, 720p scaled from the full sensor is aliased. So if raw mode is cutting a crop from the 1080p image, scaled from the sensor then it'll work, otherwise it'll look different, but not anti aliased. At least that's what I gather. But I can just test it soon.
If properly fitted in 1080p mode though, it's quite brilliant.
