Dennis O’Clair from MarkerTek.com was nice enough to send me a cable to review to defeat or disable the AGC on the Canon DSLR like the 7D and T2i/550D.
It appears to be well made and works just fine as you can see in the video.
I think it is a little pricey at $26.95, but it is a very special cable that they mostly like will not make a ton of them. I made mine for a lot cheaper, but if you do not know how to solder this can be a big help.
To see what this cable does watch my popular video on my AGC hack.
You can purchase it here if you like. (I do not make any money off this cable).
Download the 19kHz tone (one hour long). To download from a PC, right click and “save target as” (unless you are really young you will not be able to hear this).