RF 100-400mm for birding

[keenanbare]

I'm wanting to get into bird photography (specifically photographing ducks and waterfowl) and given my budget, have been recommended the Canon R10 with the RF 100-400mm.

My only concern is that the RF 100-400mm won't have enough reach to get some of the pictures that I'm hoping to get of ducks because many times wild ducks can be very far away. Although, having this lens on an APS-C sensor will up the max reach to 640mm which will help.

If anyone has shot pictures of birds or waterfowl with a lens of this focal length on an APS-C sensor and has insight into whether it had sufficient reach or not I'd love to hear down below.

[ctitanic]

640 mm is enough for birding. 

[Tintype_18]

Interesting request. I have some good photos of ducks on a local creek and Greenway. I took some at a waterfowl pond in a WMA but had an older camera with only a 150mm lens.

BTW, ducks are classed as waterfowl.

[ctitanic]

I probably went to the path that many followed with the R7. I got the RF100-400 first, it was cheap and a year ago seemed to me like the logical path. Later on I found that the used EF100-400 L m2 was affordable enough if I trade in for my RF100-400 so I did. 

Why? I found that the RF at 400 mm was not good enough for me specially in cloudy days. The EF100-400 with a maximum of f5.6 is giving me a lot less noisy pictures and if I can point to a weakness of the R7 it's noise. The EF100-400 is a L lens so it's superior in all aspects than the RF100-400. Yes you need an adapter but Canon did a good job with the the RF ecosystem and how they handle the old EF lenses with the adapters. EF photographers will not miss anything switching to RF cameras.