Summary of my RF 200-800mm testing

[AlanF]

To me, it looks more like a slight mis-focus. I regularly use my EF 100-400IIL + 1.4x TC, fully racked out and it's super sharp. The main issue for me is the reduced AF speed and accuracy.
To put my comments in to some sort of perspective, I also use a EF 400mm f2.8 LIS mk II, which is known to be a one of Canon's sharpest lenses ever made. I also use a R8 and R6ii, whihc both share a very sharp 24mp sensor. Both my EF 400mm f2.8 LIS II, native, with a 1.4x or a 2x TC seem to still out resolving the Sensor on my two camera bodies. My EF 100-400mm f5.6 LIS II with or without a 1.4x TC are also out resolving my camera sensors. So between my 400 prime and my 100-400 zoom, wide open with say a 1.4x TC...there is no sharpness difference between these two optics. However on a R5, or a R7 which has a far higher pixel density, you might see more of a difference. On my R6ii, I get exceptional sharpness with either lens.

DocSmith, The comparision between the EF 100-400 f5.6 LIS II and the RF 100-500LIS are well documented.
There are slight benefits and deficiencies with both lenses. The EF lens is brighter natively, but less focal length. A good copy of the EF lens is slightly sharper (even with a 1.4x TC on the EF lens), but this is marginal and propbaly would not be seen in real world photos. The EF lens is reputedly slightly more robust and old skool build. However, the RF lens is lighter (due to it's newer build construction). It's hood is way better than the EF version, which seems to not work as well when reversed. The Rf lens gets a longer focal length at the long end for a reduced aperture rating. The Rf lens has a removable tripod collar (The EF's removable foot is an appaling design and prone of issues). The RF has a superior AF and IS system. At MFD, there is little between them and they both focus breath substantially. The Rf lens can capture samll erratic moving bugs way better than the EF version...it's AF just isn't in the same league. For many, the RF lens is the slightly better option, however if you already ahve a great copy of the EF version, one questions the rationale of side grading to the RF version. the SH value of the Ef version is plummeting into bargain status and the RF version is generally only available new and it's eye wateringly expensive.

AlanF, Your sharpness observations of your RF 200-800 LIS at 800mm are in line with what I've observed, reading the MFT charts. I think that the RF 200-800 LIS is an ideal partner on a R6ii. It's lover pixel density will allow this lens to shine and will be more than sharp enough for 100% crops with that combo.

I've had 3 copies of the EF 100-400mm II, and have compared the best with the RF 100-500mm on the R5. A lot of truth in what you write. A few points in addition. At mfd, the 100-500mm is significantly sharper and better for insects. The RF lens takes the 2x TC better than the EF. The RF is superior at 100mm end.

 

[AlanF]

Both lenses have the same physical aperture, 70mm, what makes you believe the EF one is brighter? If it's the aperture value reported in the EXIF, that is unrealiable. You can get it to show a 'brighter' value just by telling your camera to use 1/8 stops instead of 1/3 stops. Like the focal length on zooms, the reported aperture value needs to be taken with a grain of salt.

And please tell me you don't mean 'f/5.6 is brighter than f/7.1'.....

The actual measured value on an optical bench for the RF 100-500mm at 393mm is f/6.95. https://www.photonstophotos.net/Gen...ample02P.txt,figureOpacity=0.25,AxisO,OffAxis

As you imply for comparing the 400mm f/5.6 vs 500mm f/7.1 full open at wide end, both put the same number of photons on a duck.

 

[Dragon]

One way to interpret that is that you really can't go wrong either way.

I briefly tried out a friend's 200-800 with my R3 this past weekend, I was left with the impressions that there was not a meaningful difference in the image output compared to my RF 100-500L + 1.4x, and not much difference in the handling (the 200-800 weighs more, but it really didn't feel significantly heavier in use, to me.

One thing I didn't care for with the 200-800 was the long zoom throw. The 100-500 with the 1.4x has a much shorter range, being limited to 420-700mm, but the throw is very short over the limited range.

Personally, if I did not have the 100-500 and TCs already, I would be tempted by the 200-800, but having the 100-500 already (and the 600/4 if I really need top IQ and longer reach), I have no plans to get the 200-800. Of course, you're in a different spot. My guess is you'd be less pleased with the IQ at 800mm compared to your EF 100-400L II, but if you consider everything over 400mm as a bonus, you could live with it. Assuming you don't have the RF 1.4x, that plus the 100-500 would deliver similar IQ beyond 600mm but cost at least $1000 more.

Put another way, if you plan to keep your 100-400 II and swap to the 200-800 only when you need longer than 400mm, that makes sense. If you plan to replace your 100-400 II with an RF lens, selling the 100-400 II would likely offset the price difference between the 100-500 + 1.4x and the 200-800 and the former would give you as good/better IQ compared to the 100-400 out to 500mm and similar IQ to the 200-800 beyond that, for a similar price.

I find that the 200-800 works well as a push-pull zoom (particularly the push part). If you start wide, the lens is quite easy to simply push out to the long end without loosing your subject. For me it works much better that twisting the ring.