I have an R5, and am going to get a RF100-500. The question is which extender.
I use a EF 1.4x on my EF 100-400. I tried the EF 2x series III but found it too soft as compared to the 1.4 extender.
This on my 5D4, not my R5. The 100-400 + 1.4ex works well on my R5 with the control ring adapter.
I know the RF 2x extender will lose me 2 stops which should make the lens at 1000mm about F11.0 whereas the 1.4ex will make it a F9.0 at 700mm I think.
Have there been any tests or comparisons? Anyone have any experience with either of these extenders?
I would not even consider the 2x on the 100-500 based on the low IQ.
There is no miracle from the 100-500 with TCs compared to the 100-400 II with TCs.
Get the RF 1.4x if you must, but the 1.25 increase in magnification from the 100-500 vs. 100-400 lens is the major gain. You are getting more pixels per duck with the R5 at 500 mm compared to the 5D IV at 560 mm. I've used both, so it is not just theoretical. The R5 and 100-500 sure AF better than the 100-400 II +1.4X on the 5D IV, which was dicey at best off center.
Take a look at the 100-500 results at 500, 700, and 1000 at TDP for example if you have FOMO for a 2x on the zoom.
Since getting the RF 2x, I haven't used my RF 1.4x on my RF 100-500mm and R5. It's quite different from the EF 1.4xTCIII and EF 2xTCIII where the 2x isn't as good as the 1.4 - the RF 2x on the 100-500 is excellent, unlike the EF 2x on the 100-400mm II. I and others have posted loads of bird and dragonflies on CR and I also posted this thread https://www.canonrumors.com/forum/threads/extenders-on-rf-100-500mm-rf-800mm-and-ef-400mm-do-ii.40550/
I found the loss of micro-contrast even with just the 1.4TC on that lens made me keep it off the lens more often than not. Now I never owned/tried the 2xTC but after seeing how the 1.4 did I wouldn't have wanted to.
I really think it is best to just shoot the bare lens with these zoom lenses. I used to use TCs all the time but now I'm moving away from it.
When I did my controlled tests I found that images taken with bare lens and cropped to FOV of the 1.4TC shot came out about even. So why lose a stop of SS/ISO by using one? I figured it wasn't worth it.
But if you want to get a TC I'd recommend the 1.4 over the 2.0 for that lens. f/7.1 is slow enough already. Your calculations are incorrect. You will be at f/10 with the 1.4TC and f/14 with the 2xTC at the long end.
Look guys, don't condemn the RF 2x without having tried it. I have taken 1000s of shots with both the 1.4x and 2x on the RF 100-500mm and R5. Like Geoff, I find the 1.4x loses microcontrast but the 2x is much better. It's tremendous for close up shots and I get much better ones of dragonflies and insects with the 2x on the 100-500mm than with the bare lens. At long distances, it squeezes out extra resolution. I've kept the 1.4x to use on future primes - it actually works well on the 800/11 but the 2x is not good on that. Most of the time I use the bare 100-500mm.
