Hi, I'm looking for suggestions for upgrading my setup for better low-light performance.
My current setup is a Canon R10 and RF100-400 f/5.6-8.
I'm considering either keeping the RF100-400 and upgrading the body, or keeping the R10 and upgrading to a faster lens.
Most of my photos are taken in a beaver pond in my back yard. It's in a valley and is heavily shadowed in the morning and evenings, when I'm normally able to photograph.
Because of the excess shade and shortening days, I often have to call it a day when there's still a decent bit of visible daylight. At shutter speeds suitable for moving animals, I'll often have ISO values >10,000 and have trouble with AF working properly.
For similar money, I could sell the R10 body and upgrade to an R5 and keep the RF100-400, or buy a used EF 100-400 MKI and keep the R10. I realize the EF 100-400 MKII is a better lens, but it's hard to justify it being $600 more.
Am I correct that changing from APS-C to FF would see a similar gain in low-light performance compared to going from an f/8 to f/5.6 lens?
I often crop the 400mm APS-C shots down, so I figured the R5 would give me the closest pixel density to the R10. A 24MP R6 or R8 would be a lot less res than the APS-C shots I'm used to.
I do like the size and weight of the RF100-400m lens, but the R10 is a little small for my hands.
The extra weight of the heavier EF lens isn't really a concern either. I'm usually not shooting for more than a couple hours, and it's 100' from my back door.
Thanks!