topic Re: Canon RF 24-105 f4 L in Gear Guide

Canon RF 24-105 f4 L: USM vs STM model differences?

sikhanegi — Wed, 10 Dec 2025 14:47:35 GMT

I just bought the R6 Mark ll. I have my old lenses from my 5D Mark lV, the EF24-70 f/2,8L and EF70-200 f/2,8L. I bought the adapter rf-ef so I can use the old ones. I consider the rf 24-105 f/4L IS USM, but how big is the difference between the cheaper STM model? I will use it on dogshows with semi fast movement, a allrounder and maybe even portrait. Is the focus a big difference? A lot of movement, so I need a fast focus. Happy for feedbacks.

Re: Canon RF 24-105 f4 L

jrhoffman75 — Wed, 10 Dec 2025 11:43:55 GMT

@sikhanegi wrote:

I just bought the R6 Mark ll. I have my old lenses from my 5D Mark lV, the EF24-70 f/2,8L and EF70-200 f/2,8L. I bought the adapter rf-ef so I can use the old ones. I consider the rf 24-105 f/4L IS USM, but how big is the difference between the cheaper STM model? I will use it on dogshows with semi fast movement, a allrounder and maybe even portrait. Is the focus a big difference? A lot of movement, so I need a fast focus. Happy for feedbacks.

The biggest potential difference between the two RF zooms is the maximum aperture (f/4 vs f/7.1) at full zoom. Approximately 1½ stops of action stopping shutter speeds.

Re: Canon RF 24-105 f4 L

shadowsports — Wed, 10 Dec 2025 14:12:35 GMT

Greetings,

I would think that you're adapted EF lenses would perform very well on the R6 mkII. What challenges are you noticing using the EF 70-200 f2.8? Seems like a pretty good all-around lens for a dog show allowing you to stand back slightly without distracting your subject. I'm not trying to dissuade you from a lens purchase I just want to understand your challenge. John's point regarding aperture is definitely something I would consider if you need the flexibility of a wider angle with zoom without lens changes.

Re: Canon RF 24-105 f4 L

March411 — Wed, 10 Dec 2025 14:17:24 GMT

John makes an excellent point on the aperture. With you photographing dog shows with semi fast movement, assuming mostly indoors the f4 would be my minimum requirement and if it could be pushed into my budget the f2.8.

That being said, the EF lenses you own matched with a Canon EF/RF adapter will perform great on the R6 MkII. The only thing to be aware of is you may not reach max burst rate with these lenses.

Re: Canon RF 24-105 f4 L: USM vs STM model differences?

ebiggs1 — Wed, 10 Dec 2025 19:19:21 GMT

It sounds like you basically have "P" mode stuff to photograph. But I would always, I mean always, go for the faster constant aperture zoom lens.