R7 or R6 Mark II for wild life/bird photography?

ttbirds wrote:

MAC wrote:

my plan is R8 _ RF 100-400 + RF 1.4 EXT

then add the RF 800 F11 later

400FOV

560 FOV

800 FOV

aren't these reaches enough?

R8 with e-shutter and better control of rolling shutter and much better low light focus acquisition than R7 for the same money

I use M43 for bird photos because of compactness, 2x crop and large DOF and have been considering this exact R8 combination as an alternative setup.

My only concern would be how much image stabilization is lost with the R8 (lens IS only) vs the R7 (IBIS and lens IS working together) at the effective focal lengths of 400, 560 and 800mm. Any feedback on this from experienced users would be greatly appreciated.

I am not convinced that there is any benefit to added IBIS for distant subjects with long focal length OIS lenses, for a relatively steady, experienced shooter.  Added IBIS does not correct or further correct pitch/yaw at all; the lens does all of the pitch/yaw correction, and most of the recent ones are very good at that.   All that added IBIS can do with OIS lenses is add correction axes of "Roll", which twists the sensor in a rotational motion to correct any rotation of the camera with very slow shutter speeds, and "X/Y" which corrects motions where the camera moves in the plane of the sensor.  Most telephoto photography does not use a shutter speed slow enough for "Roll" blur to happen, and also anchors the back of the camera against the face, heavily restraining and X/Y motion of the camera body.  When trying to correct the very tiny blur potential of these axes, the IBIS can quantize the motions or overcorrect, causing errors that limit maximum stability.

For someone shooting from a vehicle moving on a rocky road, or with an un-dampened tripod in the wind, perhaps there is a net benefit to X/Y translation correction, but for most skilled telephoto use, I think that the pitch/yaw correction of OIS is all that you really need.

IME, IBIS errors are largest with EF lenses.