500mm vs 600mm?

ffabrici wrote:

My take is that the 500L with a 1.4XIII converter is the most commonly used set-up for birding due to the sweet spot of portability vs. reach. I remember to once having seen an EXIF analysis concluding that close to 70% of all small bird photo's posted are taken with a 500mm plus 1.4x converter, across Nikon and Canon brands and lens generations.

If you want more reach and don't worry about the portability then consider both the 600L II and the 800L and buy a super sturdy carbon tripod with at least a 20kg load limit plus a gimbal head. Don't save here because it is obviously no advantage to get unsharp pictures from a super expensive lens due to an insufficient tripod.

I would suggest you rent the lenses considered during a sunny weekend and compare them side by side with and without converters. The available super-tele reviews and test are not very consistent as they exceeds most reviewers test benches and they are not done at the same time with the exact same set-up; distances, support, camera etc. Vibration/shake and thermal distortion are your top-two enemies and real life side-by-side testing will answer all your questions. All current Canon white tele's are incredibly good, but I would recommenced avoiding combinations requiring a 2X converter other than as an emergency set-up.

I have the 100-400L II, 300L II and 800L and I have tested/used the 200L f/2, 400DO II, 500L II and the 600L II as well as the 300L , 400DO and 500L from the old series, plus all types and generations of converters. The 1.4XIII converter is very good indeed, but I'm not a big fan of any 2X converters as the penalty in terms of AF speed and quality is so significant that cropping with a 1.4III gives the same results using a 20+ MPix camera.

NB: I bought my 800L while originally saving up for a 500L and I have not regretted that decision, because it gives me maximum reach for the same weight and size as the 600L II, and it takes the 1.4XIII converter incredibly well on 7DII and 5DIV. The 800L doesn't receive much love on DPR, mainly from people who have never used one, or compared it to the 600L II with a 1.4X converter for that matter, but it is admittedly a very special lens, which only Achilles heel is the MFD of 6m :-).

God luck with your decision.

Thanks for all the great insights, I was wondering if the difference between the 600mm f4 IS II and the 500mm f4 IS II is just 730 grams is it such a big impact? Thanks!