Longshadow wrote:
I can't imagine how it would (might) increase the FPS on any camera...
The camera can only shoot & store so fast.
Au contraire, monsieur...
Some Nikon are able to shoot at higher frame rate when fitted with a battery grip:
- Nikon D850 can do 7 frames/sec on its own, but is able to rattle off 9 frames/sec with its battery grip installed.
- Nikon D300s can do 7 frames/sec on its own, increases to 8 frames/sec with grip installed.
- Nikon D300 can do 6 frames/sec on its own, or up to 8 frames/sec with grip installed.
- Nikon D700 shoots at up to 5 frames/sec on its own, but can do 8 frames/sec with grip installed.
With other Nikon there is no change in frame rate by adding a grip, including: D500, D600, D610, D750, D800, D810.
I don't know about Nikon mirrorless.
It was the case with some Canon film cameras, too. For example:
- Canon EOS-3 can shoot at 4.3 frames/sec without a battery grip. But when the grip (which Canon called a "Power Booster" or "PB-E2") is fitted, it can shoot at up to 6 or 7 frames per second.
- Canon EOS-1V used the same PB-E2 to become an EOS-1V "HS" or "High Speed" with a very similar speed increase. But it could do even better... up to 10 frames/sec... by instead using a rechargeable Nimh battery pack (BP-E2) instead of eight AA alkalines.
The Elan 7 and 7N (also "E" or eye control versions) also called EOS-33 and EOS-30 film camera
did not see any increase in 3.5 frames/sec speed with its grip attached, even though it is from around the same time period as the EOS-3 and EOS-1V. The Elan 7 (and it's variants) are among the quietest film SLRs you'll ever find (I sometimes used on for wedding photography, for that reason).
AFAIK, no Canon DSLR or mirrorless increases frame rate when a grip is installed.
I don't know about Sony, Pentax, Fuji, Oly etc.
For many years I've used battery grips on my cameras for other reasons:
- Extended shooting time... extra batteries allow more shots.
- A more comfortable grip and secondary controls when holding camera in portrait orientation.
- Better balance with large lenses.
In addition to those reasons, I also used them on EOS-3 and EOS-1V for the increased frame rates... But have to say I used that very judiciously because blasting through entire 36 exposure rolls of film in 4 to 6 seconds gets really expensive, really fast! Plus you spend a lot of time just reloading the camera! Thank heaven for digital and memory cards that can hold hundreds or even thousands of images!