The upcoming EOS R5 is expected to be a 45MP camera. Higher resolution cameras demand top quality lenses. Anything less will show up as problems in images. Keep this in mind when selecting lenses for the R5.
Canon issued a list of "recommended EF lenses" along with the 50MP 5DS/5DS-R camera release. There needs to be similar consideration for the R5, should it have a 50% increase in resolution compared to the original R and a nearly 75% increase compared to the RP.
I don't have either of the RF lenses you mention, so can't tell you anything from personal experience. But you should be able to find online tests and info such as MTF charts for those lenses that can be helpful.
Just a guess on my part.... I assume that a more modest zoom like a 24-105 would be optically better than a more extreme 10X like the 24-240. That's usually the case. Also, the 24-105 is an L-series, while the 24-240 is not. (There also is a cheaper RF 24-105mm f/4-7.1 IS STM "non-L", but that's not the lens you asked about.) Obviously, the 24-240mm would be a more versatile lens. And it's actually only slightly heavier and larger than the RF 24-105L. OTOH, it's got a variable aperture that drops to f/7.1 at 240mm. In fact, while the 24-105L offers f/4 across its entire range of focal lengths, the 24-240mm only has that large aperture at 24 to 26mm focal lengths. It drops 1/3 stop to f/4.5 from 27-43mm, loses 2/3 stop to f/5 from 44-69mm, a full stop to f/5.6 in the 70-104mm range, then 1-1/3 stops (f/6.3) and finally even 1-2/3 stops (f/7.1) less at longer focal lengths.
You can find a lot more info about these lenses, including tests shots done with them that can be compared side by side, at The-Digital-Picture website:
RF 24-105L:
https://www.the-digital-picture.com/Reviews/Canon-RF-24-105mm-f-4L-IS-USM-Lens.aspxRF 24-240:
https://www.the-digital-picture.com/Reviews/Canon-RF-24-240mm-F4-6.3-IS-USM-Lens.aspx24-105L versus 24-240 image quality:
https://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=1222&Camera=1221&Sample=0&FLI=0&API=0&LensComp=1416&CameraComp=0&FLIComp=0&APIComp=0Keep in mind that those lens tests, other image quality comparisons and image samples were made with 30MP EOS R... Not with the more demanding R5, which is rumored to have 50% higher resolution.
sergiohm wrote:
The 24-105 is much better, the 24-240 has severe vignetting (it is corrected in the camera for JPEG and in Lightroom for RAW), but what you see when you take the picture is not the same after processing it in a computer due to correction and it’s not whether sealed nor it has the additional control ring.
The 24-105L appears to have more vignetting than the 24-240...
At 24mm:
https://www.the-digital-picture.com/Reviews/Lens-Vignetting-Test-Results.aspx?Lens=1222&Camera=1221&FLI=0&API=0&LensComp=1416&CameraComp=1221&FLIComp=0&APIComp=1And at 105/100mm:
https://www.the-digital-picture.com/Reviews/Lens-Vignetting-Test-Results.aspx?Lens=1222&Camera=1221&FLI=5&API=0&LensComp=1416&CameraComp=1221&FLIComp=2&APIComp=1Presumably the same would be true at focal lengths in between, which weren't test shot with the 24-240, so can't be compared.
But, you're correct. That's easily corrected in-camera or in post-processing.
You also can compare to the RF lenses to the EF 24-105L "II" or "I", if you want to consider using it with an adapter. (Decide for yourself, but personally I've never been all that impressed with the EF 24-105L... even the "II" only saw modest improvements. IMO, any of the EF 24-70Ls or even the far less expensive EF 28-135mm were competitive with the EF 24-105Ls. )