Michael Thomas Mitchell wrote:
I've been using Sterling Tek batteries going all the way back to the D30 (the original 3MP model, not to be confused with the later 8MP 30D) and D60 models. For those who remember, these early models were somewhat power hungry, and you counted on going through at several in a full day of shooting (such as a wedding). The BP-511 batteries were very expensive in those days. I discovered Sterling Tek somewhat early on, and because Canon wisely adopted an existing battery from their video camera line, Sterling Tek had it from the start and they were a great price, about 1/5 the cost of OEM.
The STK BP-511 worked fabulous. Maybe not quite as many shots, but only a small difference, and I could afford to own a ton of them. Successive camera models, like the 10D all the up to the 40D used the same battery, and STKs went right alongside the Canon models all through the years. Today, I still have a stable of them powering my 40D bodies for business.
(I will point out here that I have also used third-party batteries for my 1D-series bodies, though it's a completely different beast. Results have varied. Never a STK version, though.)
The day I ordered my 6D, I ordered a couple of STKs to to with it. Charging was fine. Usage was fine. However, I have noticed some problems with battery info reportage. Shooting a wedding, for instance, with the camera powered on the entire day, I noticed that even after hundreds of shots, the camera still reported 100%. Knowing that was impossible at about shutter count 250, I turned the camera off took the battery out, inserted back in and powered up to find the capacity reported at 78%. Later, I found that simply turning the camera off/on updated the report.
Obviously, the Canon battery does not behave like that, providing a constant update without having to power off.
Is this minor inconvenience a deal-breaker? Not necessarily. I'll keep using the STKs. But I'll probably stick to OEM from now on. Of course, only one battery is needed for an entire day of shooting, so I doubt I'll ever need additional units. But clearly, even the STKs are not 100% compatible.