So yes, RF100mm will be great, but it is very expensive. If you are buying just for film scanning, you will get great results with any EF macro lens on the adapter. Tamron 90mm, Tokina 100mm, Canon EF 100mm f2.8 (either non-L version). Or if you can find a manual only 1:1 lens, that can work too.
The 60mm EF-S lens is the only 1.6X lens that Canon makes that is worthy of your attention. Since it is a native EF-S lens, you get a DOF benefit, and when shooting 1" away from a subject, any DOF that you can get is great. Sharpness is near top-flight, even wide-open. Contrast is excellent. Autofocus is very fast. All of which has nothing to do with the question. I have never read a review or article about the original EF 100MM f2.8 macro lens or the EF 100mm f2.8L macro lens that mentioned focus shift. However, there are numerous articles about the RF 100mm f2.8L macros lens that describe the focus shift problem with sample images. (EF 100mm f/2.8L IS USM: currently $899) If you are willing to consider a good, used lens, there are more choices: - Canon EF 100mm f/2.8 Macro USM is an excellent macro lens that is a little older than the L/IS version mentioned above, but other than not having image stabilization has many of the same benefits of that lens. In order to serve this market, Canon finally released the Canon RF 100mm f/2.8 L USM IS macro. As professional-grade lenses go, the price for the entry ticket is on the high side at $1400/1500EUR - that's more than double the amount you have to pay for the faster RF 85mm f/2.The Canon EF 100mm f/2.8 Macro USM lens is a macro lens designed for SLR cameras. With a weight of 600 grams and a length of 119 millimeters, it is a compact and lightweight option for capturing close-up shots. The lens has a diameter of 79 millimeters and a filter size of 58 millimeters, allowing for the attachment of various filters to
8VvOIE.