AF expectation has gone up dramatically with the mirrorless / software based Af systems. I don't own any RF glass, my entire lens catalogue (which is quite vast) are all EF lenses. I tried a EOS R and didn't like it, it felt too much like a beta camera. I tried the R5 and love it, but it was too expensive and the R6 was a bit too low res for me to make the jump from my trusty and proven Eos 5Diii's. I bought a R8 just after launch to dip my toe into the newer Canon ecology and was blown away by how far Canon had come with their tech. I soon wanted a better version of the R8 and bought a R6ii as my primary camera and my R8 was my second camera. Only recently have I upgraded my R8 to a R6iii (I dallied with a R5 for 6 months, but that's another story).
When I started reading the first couple of lines, I immediately thought: the r6iii must be for you
turns out, it is
Most of the RF glass is a wee bit better in some regards to the EF glass. Some of these benefits are marginal and others are quite dramatic. However, if you already have great EF glass and it's giving you great results (and it's paid for) then it's free and doesn't cost you anything. Where as the RF lenses are expensive for sometime very little benefits for the cost.
Of course, a one to one comparison between the lenses is necessary, but also your lens collection as a whole. When I upgraded from APS to full frame (EOS R) I owned four EF lenses and two RF lenses. But, after going on a six-week trip I was fed up with the mixed EF/ RF collection. The biggest pain for me of having EF and RF was handling the adapter. Sometimes, I just left the adapter on the camera, other times I had to look for it in my bag because it was still on different lens and so on and so forth... it really got my nerves. I then had three choices:
1. all native RF lenses
2. all EF lenses and keep the adapter on the camera
3. buy an adapter for every EF lens used.
4. keep one EF lens with one adapter
In the end (long story) I opted for no. 1 although I started with no. 4.
For example, the EF 100-400 f5.6 LIS II vs the RF 100-500mm f7.1 LIS. Sure the newer lens is slightly lighter, longer and it's AF is a bit better too. However optically, the old one is brighter and equally sharp. In the UK, the nwer lens retails at around £2.5K, the trade in for a the EF lens is often quite low, maybe £800 in trade in.
I traded the EF 100-400mm for the 100-500mm. I did pay a premium, but it was absolutely ok because I got the RF for a great price (with discounts, great currency exchange and before all the price hikes) and due to the pandemic I even got more money for my 100-400mm then I originally paid for. Nowadays, the value of the EF version has declined and the RF had some price hikes... I couldn't/ wouldn't want to do it again concerning financials.
Concerning the lenses itself: Saving more than 10% of the weight (1750gr vs 1530gr), four times vs five times zoom, with TC additional 200mm range, slight faster AF (imo) were worth the money.
At that point, I thought that would have been my only upgrade because the RF 14-35mm had an RRP of 1.819 € at launch in Germany. That was 2,5 times the money I paid for the EF 16-35mm. Sure, better magnification, 2mm wider, less weight (especially with the adapter) were intriguing, but the price wasn't. It was only by chance that I got the RF version on a refurbished sell-out sale and the upgrade cost me slight less than 300 €. To cover that I ditched the Sigma, the EF 50mm and the adapter as well and bought the 85mm F2 from the extra money. I think I actually had some money left.
All in all, my EF to RF tranistion went - financially speaking - pretty smoothly with only losing one lens in total and a manageable amount of money. But this is a very individual case because I didn't have a big EF portfolio.
So I would still need to find £1.7K, which is a LOT for something that's only a bit better than my existing lens.
Other lenses like the RF 50mm f1.4 VCM L and the RF 24mm f1.4 VCM L have no direct EF lens comparision that is worth mentioning.
Some lenses like the EF 11-24mm f4 L are amazing performers and gain the option of using drop in filters behind the lens when using a EF to R adapter. This means that a large and bulbous lens like this can use filters very efficiently when crossing the EF to R mount divide. It's RF equivelent is the sublime RF 10-20mm L. Which is a stunning little lens. It's a little wider, not as long and it looses the drop in adapter option (obviously). But it is so much smaller and easier to use than the giant EF version. Sure, the EF version doesn't rely on corner stretching / math geometric correction, but compare the size difference and it's a night and day experiance.
This one is though. I don´t own either lens, but I imagine the decision could be hard: keep the EF with the ability to add filters or carry a soooo much lighter and wider lens. You win some features, you lose some features
(as you said)
As you can see, you gain some features and loose some others. it's not quite a like for like comparison.
I am currently looking at macro lenses: the decision is between the EF 100mm F2.8 L and the RF 100mm F2.8. Do I really need the magnification of 1,4:1? Is it worth a premium of about 400-600 €? I don't think so because I am not that much into macro... only thing with the EF... I need an adapter once again... grrrr
