This post only represents my point of view, which I will not ask anyone to agree with. I hope it will not be treated as some kind of heresy.
This thread could easily be renamed to „Problems with AF on birds in cameras from the R family”.
I just sold my little used EOS 5DS R. I used the money from the sale to subsidize the purchase of the RF 70-200mm F4L IS USM lens and attach it to my EOS R.
From the minimum focusing distance (MFD) up to 5 meters it works as it should, but when it comes to distance equal to or greater than 5 meters especially when the smaller AF point frame size (Spot AF in EOS R5/R6 models) protrudes with its edges beyond the target that's another story.
Camera: EOS R with firmware in version 1.8.0
Lens: RF 70-200mm F4L IS USM with firmware in version 1.0.8
Accessories: Hoya Fusion Antistatic Protector circular filter installed.
Conditions: When taking pictures outside, strong gusts of wind with a speed of 23 km/h blowing to the side of the lens. I did not have a lens hood fitted.
Camera settings: RAW, Fv, Av, Tv, ONE SHOT, Silent shutter, 1-point AF EOS R (normal AF point frame size), 1-point AF EOS R (smaller AF point frame size)
Lens settings: FULL, AF, STABILIZER ON, STABILIZER MODE 1
In all comparison photos on the left there is a photo taken when selecting normal AF point frame size, and on the right there is a photo taken when selecting smaller AF point frame size.
The dimensions of this rectangle with a checkerboard with the inscription „SpyderLENSCAL” (excluding the ruler and these two feet from the base) are 11.7cm high and 10cm wide. According to https://www.whatbird.com/browse/attribute/birds_na_147/51/Size/
very small birds have a size in the range 3-5in (8-13cm).
All photos are handheld with the lens stabilization turned on.
Click on a single screenshot and it will open in a new browser tab, click on it again in a new browser tab and it will enlarge.
70mm at MFD
200mm at MFD
70mm at 2.5m on the distance scale
200mm at 2.5m on the distance scale
70mm at 5m on the distance scale
200mm at 5m on the distance scale
70mm at infinity (closer to the left end of the infinity symbol) on the distance scale; the test board was in close proximity to the tree
200mm at infinity (closer to the left end of the infinity symbol) on the distance scale; the test board was in close proximity to the tree
70mm at infinity (closer to the left end of the infinity symbol) on the distance scale; here I moved the test board away from the tree
200mm at infinity (closer to the left end of the infinity symbol) on the distance scale; here I moved the test board away from the tree
Two days ago I managed to get a few sparrows in front of the lens at a focal length of 200 mm. I had the smaller AF point frame size selected. The photo on the left was taken from a distance 2.5 m (this value showed up on the distance scale), the photo on the right was taken from a distance 5 m (this value showed up on the distance scale). In the first case, the AF system broke through the fence mesh, branches and landed on the sparrow. In the second case, the AF system landed on the sparrow's tail (at least i think so).
Do I have any ideas to solve this problem (Is this a problem at all or am I creating one myself)?
1. See advice from AlanF https://www.canonrumors.com/forum/threads/problems-with-af-on-birds-r5.39490/page-5#post-878983
2. After focusing with AF, turn on the instant image magnification (one finger swipe on the EOS R touch bar) and apply the correction manually using the MF ring. This is probably a bad idea when it comes to photographing very lively birds or anything else that moves very lively.
3. Wait for the camera firmware update as it was in the case of EOS R cooperation with lenses RF 70-200mm F2.8L IS USM
and RF 100-500mm F4.5-7.1L IS USM
4. Buy yourself an EOS R5 or EOS R6 because of Animal Eye AF?