As a hobbyist, what sold me on this lens is that all the reviews of it are comparing it to lenses that are 5x more expensive and way out of my price range :D

That 100-400 is freaking amazing. The photos you're going to get with it simply because you actually have it with you seriously level it up beyond the 100-500 in many ways.

Comparisons are the killers of joy. Someone who buys a $2700 lens has to tell him/herself that it is better than the cheaper choice, to psychologically justify the huge amount of money spent, for a small difference in picture quality. $2700 dollars gets you weather sealing, better build quality, and a nice white paint job, or red stripe. That is really what you are paying for, not necessarily a $2000 image quality difference. I returned the RF100-500, got me an R6 Mark II, and the RF100-400 and I literally can not tell the difference in picture quality, unless I start pixel peeping.

But even then the differences are so small, I just could not justify spending that much money on a lens. I don't print large prints so the RF100-400 is perfect for my case. I was also able to buy the RF800MM lens, which is a nice lens for wild life photography. I was able to buy all this just by returning one lens 🙂.

If you travel or fly a lot, I think the 100-400 is the better lens, IMO. The difference in IQ is slight, but the difference in weight, cost , and form factor is massive. It punches way above its weight. Not weather sealed, but also cheaper to replace if it’s damaged, or stolen, and it also doesn’t attract as much negative attention in certain parts of the world. I’ve had and still have a lot of the EF L series tele lenses. I have adapters, and they work well, but they mostly stay at home as I can’t afford the weight in my carry on. To have almost as good quality as my old L lenses in such a light lens has been a revelation. The joy of walking all day without a sore back and shoulders, or using the saved weight to take along a thermos of coffee has given me more joy than looking at photos that are 2% sharper when I zoom in to 100% on my 5k screen, but print exactly the same, or close enough with a bit of post. I don’t like the idea of ai improving my shots, but for others, software like topaz will eventually completely close those gaps. It won’t make your lens lighter though, pay for physiotherapy on your back, or increase your carry-on allowance. I 100% get the other argument, but now have a different perspective on it all. I still own a lot of EF L series tele lenses, and have them all available on my shelf, but they still stay home, and I take my light lens and my coffee instead. And I love my days out shooting more than ever, without a worry in the world.

Great review per usual. Loved the bar graphs, the comparison images and the the detailed rundown of image quality and situational focus acquisition. You packed a lot of great info into 20 min and kept the discussion objective/judgement free, enabling viewers to make up their own minds. Well done.

I am a hobby photographer. I am sold on the RF 100-400mm lens. Thank you for educating me on these two lenses.

If you plan on doing any editing at all with the 100-400 you can get such great results. Almost comparable at less than half the cost. I think that’s worth it

Man what an excellent video!
Throughout the video, I kept thinking "Ohh but what about this?" And then you'd cover it perfectly moments later.
Usually photography youtubers just make useless long videos with 90% yapping and 10% substance, but this one was so refreshing.
Well done!

Thank you Fabian, you just saved me 2000 euros 🙌🏼

This review is gold, thank you for the effort!

Thanks, Fabian, for so great clear and detailed honest review! ) I use 100-400 on R7. Indeed a great combo. I am very happy with it. Shooting a lot of wildlife, birds mostly. Very quick focusing, quite sharp. I use it a lot also for macro, flowers, insects. Actually, I was amazed how good image quality this lens provides. Much better than I expected! What surprised me most was how beautiful bokeh this lens provides! So soft and creamy! I shoot a lot of art macro, so now I use this lens even for art macro thanks to its so beautiful and pleasing creamy bokeh. I don't want a full frame camera for shooting wildlife and macro of insects, because R7 gives me the possibility to shoot at much longer distance and with much bigger magnification. The huge advantage of the 100-400 fir me is its amazing weight. Now I carry R7 + RF 100-400 everywhere with me for any walk and take many very nice pictures occasionally. With a heavier lens even like 100-500, I would not be able to carry it with me everywhere, so I just would miss all these shots ). The only real advantage of the 100-500 is more of background blur. But actually if you take a really great picture and want a little more of background blur on it, you can just do it with modern software quite easily and beautifully ). Earlier I shoot a lot with EF 100-400 II. A superb lens, but quite heavy. So I am really happy to have now the RF 100-400. Truly just amazing lens for its weight and image quality! Thanks Canon for it )

Great review! I'm impressed that you bought the lens specially for this video.
I have both lenses, and still reach for the 100-400 when size and weight are key, such as when out hiking.

Excellent video. The information was so clear and easily understood. The photo comparison really helped

I had RF100-400 and then bought RF100-500L for $2500. In my opinion both lenses are great. Obviously 100-500 with 3x price isn't overall 3x times better lense than 100-400. But still 100-500 is noticeably better and really improved quality of my photos.
The only real disadvantage of 100-500 (except price) is its weight. In size it's not much larger than 100-400 and fits in my same backpacks. But weight is a real difference, arms getting tired much faster, especially when I'm taking photos of birds high on the trees. Also good strap is must have for this lense. And good grip on a camera (fortunately R7 has one).

Btw Canon R50 + RF 100-400 is ultimate compact set for travelling/hiking (~1 kg).

Great review!  That 100-400 punches way above its weight class.

if you use a crop sensor like r7 you can shoot at 300mm on the rf 100-400 and get 400mm at 7,1 similar as 100-500.  In a hide situation for example you would probably not even need 400mm in most cases so you could dial it back even further on the crop sensor. Nice video, thankyou for all the work on it.

The best review on youtube. It's great that you compared 100-400 to L 100-500 it is always hard to understand about lens performance just looking on sample pictures without any "reference". Thank you.

I bought the 100-400 when it came out, then got the 200-800 recently. I still use the 100-400 when I’m traveling light. Combined, they still cost less than the 100-500.

Your videos are so helpful! You're an exceptional teacher and reviewer, and I appreciate it very much. This particular video has been helpful in deciding what to do about my next telephoto for birding.

This is the best review on this topic.