It looks like one of the most requested new lenses for the RF mount is getting closer with the latest patent designs from Canon.
Canon News has uncovered a patent showing off two different, yet very similar optical formulas fora Canon RF 100mm f/2.8L IS USM Macro. A lens I expect will be announced in 2021.
Canon Japan Patent Application 2020-204744
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Don't tele lenses have longer backfocus? Why is the last elements so curved?
Also it is 5mm shorter. Yay for backpacking.;)
Totally agree and if they bring V2 then Canon is doomed! :P
Canon also has clearly shown that they consider it advantageous to put the last element close to the sensor even for tele designs, which is why the RF 70-200 mm 2.8 and 100-500 4.5-7.1 for example have no / limited compatibility with TCs.
Of course it can, question is why. IIRC, it was explained that the closer the last element is to the sensor, the more vignetting the lens would have, due to the angle at which the light rays would hit the sensor.
No compatibility with TCs is not an advantage.
But I don't believe Canon compromises on an aspects of their design like this without gaining an advantage by doing so. I won't pretend to understand what that advantage may be. Most likely, it isn't something as cut and dry like 'reduced vignetting by x amount'. I could see it beeing more likely that it is one of many aspects of these designs that allow Canon to produce these lenses which are optically excellent, while reducing the size and / or weight compared to previous version. Maybe it is just about saving costs or making manufacturing easier, but I doubt it.
From the original patents drawings I see that this lens is focusing internally (2nd and 4th of 5 groups are moved) so maybe they need the space to shift the moving groups and set the last element closer to the sensor. These macros aren't classical tele lenses - they bend the light to do 100mm 1:1 macro which needs 400mm length if you use a single thin lens in a compact package.
I think the last elements try to bend the light that it hits the sensor under an optimized angle to avoid vignetting.
I always used the 100L for still life and product photography so never really needed full 1:1 so the current 85mm suits me well!
The lens might feel a bit long iwth that adapter on it, but then, the camera is shorter.
Unless you double-count the adapter!
The "I know what I'm losing, I don't know what I gain, but it must be worth it" has the scent of fanboyism. At the very least, Canon's PR should have published what the gain is that they've compromised on no TC.
While the EF 100 macro (usm version w/o IS) will be used adapted for those 1:1 situations which are - as you said - rare for me too.
Well if you do I’m sure you’ll be impressed with it! Although I love the RF 35mm, I find the 85mm a bit more unique and just can’t stop using it!
As I said, I won't pretend to understand enough about Optics to challenge Canon's claims. Canon has actually already published a number of marketing and white paper documents that touch on these subjects. From page 9 on the R system white paper, they highlight a big advantage of the new system:
"Large diameter rear lens elements that are much closer to the full frame image sensor —enhancing overall optical performance (in particular, tighter control over optical aberrations at image extremities)"
TThey go on to show how this is handled in the EF Mount and contrast it with RF on the subsequent pages, if you want to have a look. Here is the link if you haven't downloaded it yet:
Canon Product Showcases | Canon U.S.A., Inc.
They don't actually compare it to an EF lens, just a simulation of a lens using a configuration similar to EF...
Canon have been very careful not to directly compare lenses across the two mounts. The 70-200 2.8 and 50 1.8 certainly don't perform better than heir EF predecessors.