Debating the Canon rf 100-500mm

Overread · May 24, 2024

Greetings all, sounding out some thoughts on upgrading my longer lenses this year and I've got a quandary

Right now I've got the following - mounted to either a 7D or R6MII

Sigmar 120-300mm f2.8 OS (the edition that came just before the "sport" version)
Canon EF 70-200mm f2.8 MII L

The 70-200mm I don't want to give up at all, its a great general purpose lens, but it lacks the long reach. The 120-300mm works great in its range and it offers me f2.8 performance through the whole range; but its heavy and its focus is decent but not as fast as newer lenses (esp canon ones). In concept I like it, in practice I find it gets stuck; 120 isn't wide enough for general purpose and 300m is too short.

My general subjects are wildlife and equine/events

So I've been doing some looking and I've found a few options;
1) Canon rf 100-500mm (new). The most practical generalist range on offer of the 3 with not a bad weight for what it offers. From what I can see it out-performs the ef 100-400mm MII and the 100-500 doesn't seem to have the copy-variation problems that plagued the early 100-400mm (or if it does I've not found mention of it yet). My main concern is that its aperture at the long end isn't all that special. Whilst the R6MII has awesome high ISO performance, I do worry that being effectively at f8 at the long end might just be too limiting at times on the creative front.

2) Canon ef 300mm f2.8 IS L MII (secondhand). Yes its a prime, its mostly on the list because the original 300mm L was one of the early "I want that lens" dream lenses I had way back ages ago. The secondhand price isn't that far from the 100-500mm. Of course the downside to this is that its a 300mm prime, so suddenly I've got to put TCs on it (I do have 1.4 and 2 ef TCs) to get the range increase for wildlife; and I don't have the benefits of a zoom for events.

3) Canon ef 200-400mm (built in 1.4TC) (secondhand). Even secondhand this is way more expensive an option. Like the 300m its main boon is having more aperture to play with, esp at the longer end. A bit more light gathering for better AF performance in lower light; a bit more creative freedom on the aperture chosen. The built in 1.4TV is a boon as well on reach. The big downside is weight, even the 120-300mm f2.8 I have now is lighter than the 200-400mm.
Another boon is I could trade-in/sell my 120-300mm though it won't have a huge impact on the price.

Right now I'm warming to the 100-500mm. I feel like its offering me the best all-round performance whilst excelling at nothing save for being an all rounder. It doesn't give me the creative freedom of the other two in aperture, but it gives more all round practicality. I'd also still have my 2.8 lenses for lower light situations (though again I could possibly trade in the 120-300mm).

I'd be interested to hear if any others have had a similar choice and if there are other lenses I've overlooked; or considerations I've not taken into account. Or if I've drawn some wrong conclusions along the way.

Overread · May 26, 2024

Also another spanner in the works that I'd discounted but more research is making it sound more attractive

200-800mm. Which to me sounds like a nuts amount of zoom to have in a single lens and yet the results I've seen are showing its not doing badly as a generalist lens, esp for smaller wildlife like small birds.

Downside is that I think its much more of a small birds/wildlife lens than the 100-500mm which seems to have a touch more of the general eventing/generalist around it. Of course the pair combined then end up being as much as the 200-400mm secondhand, which whilst heavier is a better performer with a wider aperture (even if it needs a 2X to get to that equivalent range).

RacePhoto · Mar 10, 2026

I don't have an answer for you, I'd like any one of them.

I've owned the 100-400, I was not impressed. (oh re-reading, yes early release version. Soft at anything below f/8 from 300mm on.) I sold it. But that was the first issue. I still own a 300mm f/2.8 non-is, I have a living relationship, we are very happy together, but not my bride. I'd love to try a 200-400mm if I win the lottery. I have owned the 70-200mm f/2.8 great lens, all around and you can put a 1.4 TC on it and still have a nearly as great lens. It has more to do with the zoom range IMHO than the design itself. The 100-500 sounds intriguing, but once again, out of reach.

BUT... on my list of things I'd like to try some day, Sigma 150-600mm which is manual and they list it as a "Sports" lens. I don't do wildlife, I don't know about the sharpness. But it's been one of those lenses that sticks in the back of my mind as something fun and entertaining and potentially, extreme. For the price, that's a bundle of fun. If it has the flaws and resolution of a kit lens with an aftermarket TC, well, my mistake.

An honest personal opinion answer. How much control do you have over the situations and environment? I mean, a prime lens is always going to be better than anything with a TC. But if it means get the shot then there's some give and take in a zoom. How far is the maximum? You can make images with less, if you can crop? You can make images with a crop camera, if you can zoom. The same lens, which is already a crop in effect.

How much do you want to spend.

If the 100-500RF is within your budget and needs, it sounds pretty dreamy for range and quality. Speed? It's always something. Like the triangle of exposure, where you gain in one place, you often lose in another. Do you have enough light? Do you shoot on a mount of some sort? ps I'm a monopod guy.