Initial impressions on RF 100-500 for birding

Chimpy boy wrote:

Brilliant review EBCowboy, I echo everything you and the other guys say about the RF 100-500.

I have the EF100-400 II and 1.4 III TC and I also use the RF100-500 and the RF 1.4 TC and I can say the RF set up beats the EF set up for quality and speed of AF.

Using the two lenses without TC's I would say the RF 100-500 just edges it in terms of sharpness but there isn't much in it.

I would like to add what most people don't factor into the mix is the superior "IS" the RF 100-500 gives you compared to the adapted EF lens, I can hand hold shoots at silly slow speeds using the RF100-500 compared to the EF100-400.

People seem to be hung up on the max f7.1 aperture at 500mm but lets face it isn't to far away from the max f5.6 of the EF100-400 its just about 1 stop? If I'm shooting a bird from a distance at 500mm its really no difference to shooting at f5.6 plus you are gaining another 100mm.

People pay a lot of extra money for one more stop and sometimes it’s the difference between getting a shot or not.  Does everyone need the faster aperture all the time?  Definitely not, but it’s not right to dismiss the difference.  If f/7.1 works for you, fantastic, if not that’s totally legit too.  If you’re trying to stop action then 2/3 stop can matter a lot.

To me the RF100-500 is the lens of choice if you don't have the EF 100-400mm but if you are new to the RF system and have the money the RF 100-500 is the better choice if you shoot wildlife or sports where the extra reach is nice.