I hadn't thought about it before, but this means we can quickly get a rough estimate of battery on time just by dividing the CIPA photos number by two to get an on time in minutes.
Huh, that is true, hadn't thought of it myself... The whole community would probably benefit from spreading that little fact around! Although the figures are still a poor relative comparison in some cases. From what I remember they test cameras with a built in flash by forcing it on, so those without one will inevitably pull ahead, not sure what they do in the case of bundled clip on flashes.
Yeah, in CIPA, the built in flash is flashed every other photo (5 out of 10 photos). That's rarely how a flash is used: more often never, or sometimes always. Add then some built in flashes are much more powerful than others (example: GH4's GN 17m@200ISO vs GX7's 7m@200). Then add that different lens result in different numbers (like the 20mm/1.7 being over 8% less photos/time than the 14-42mm II in the GX7's pages I posted). And then the GH4 tests different lens than the GX7 (12-35/2.8 and 14-140mm II)! It makes sense to test with lenses that are most often used with (and kit is probably the most used), but that makes it harder to really compare. And I'll bet my 100-300 uses more power than any of these four lenses (at least I get noticeably less on time when I use it, but then again I normally use it with different settings than most of my other lenses).
And then what each user users? AF vs MF, AF-S vs AF-C, jpg vs RAW vs RAW+jpg, wifi on/off, OIS / IBIS / no IS, lens A vs lens B, well lit vs low light, normal temperatures vs freezing cold vs ultra hot, etc. Oh yeah, impossible for a perfect comparison photo count or time.
But CIPA photo count is probably as good as we can get for dSLRs. OTOH, that photo count is terrible for mirrorless cameras (or dSLR in liveview, or P&S). The on-time-while-CIPA-testing (photos/2 = minutes) should be as good for mirrorless as CIPA photos is for dSLRs. IOW poor, but good enough for a rough estimate.
