There are many people who run websites giving information about Canon lenses. I'd be interested to see images taken with new kit and compared with older kit. For example, the new RF100-500 seems to be an upgrade to the EF100-400 II.Some say that the 7.1 aperture is too limiting, but it depends. A school-level analysis says that the minimum angle for the diffraction limit is arcsin(1.22 L/D) where L is the wavelength and D the aperture (actual) of the lens. Taking L=555nm (peak sensitivity of the eye is green light) a 500mm lens with an "aperture" of 7.1 has a diameter D of 70mm. That makes the angular resolution due to diffraction 10 micro-radians. At a distance of 500mm (the effective focal length of the lens focussed at infinity) that carves out 5 microns at the image plane.
Assuming Canon get somewhere near perfection, this corresponds to a 45 megapixel sensor on full frame (4.3 microns) or roughly 20 Mpix on APS-C. Therefore, this lens would only just be becoming diffraction limited on an R5. On an R6 (approx 6 micron pixels) you may not notice. It does suggest that you might see better images on an R6 with a 1.4x, but either a 1.4x or a 2x TC would struggle to improve on an R5.
The RF600 and RF800 lenses, this also suggests, are better suited to the R6 than the R5. If you have an R5 then I'd expect you would be looking to f/4 to f/5.6 for the sharpest possible images.
Of course actual results are affected by the anti-aliasing filter (except on the 5Dsr currently) and how close to ideal the lenses are.
So it would be useful for readers to be able to see real world images comparing say a 100-400 II with an extender (800mm) with the RF800 and how the RF800 performs on an R6 and R5, and similiar comparisons for other lenses to help choosing new kit.
Assuming Canon get somewhere near perfection, this corresponds to a 45 megapixel sensor on full frame (4.3 microns) or roughly 20 Mpix on APS-C. Therefore, this lens would only just be becoming diffraction limited on an R5. On an R6 (approx 6 micron pixels) you may not notice. It does suggest that you might see better images on an R6 with a 1.4x, but either a 1.4x or a 2x TC would struggle to improve on an R5.
The RF600 and RF800 lenses, this also suggests, are better suited to the R6 than the R5. If you have an R5 then I'd expect you would be looking to f/4 to f/5.6 for the sharpest possible images.
Of course actual results are affected by the anti-aliasing filter (except on the 5Dsr currently) and how close to ideal the lenses are.
So it would be useful for readers to be able to see real world images comparing say a 100-400 II with an extender (800mm) with the RF800 and how the RF800 performs on an R6 and R5, and similiar comparisons for other lenses to help choosing new kit.
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