Does a RF-S lens focal length take the crop factor into account?

[aedcce]

Right now, for the EOS R cameras, there are RF and RF-S lenses.

If I were to get the RF 16mm for my R10, for example, the 1.6 crop factor would make it more equivalent to a 25mm focal length.

The RF-S lenses, however, are specifically designed for crop sensor cameras. Would I still add this multiplier or is the number the same as on the box for RF-S lenses?

[kvbarkley]

Focal length is focal length, a physical characteristic of the lens. The focal length listed is the actual focal length.

Have you ever owned a full frame camera? The *only* reason to care about crop factor is that you are used to 35mm fields of view.

[deebatman316]

All an APS-C lens does is provide an image circle large enough. To cover an APS-C image sensor size. The image sensor is what causes the crop. Not the lenses so there is always a 1.6x crop factor. Regardless of what lens you use on it. All lenses use 35mm focal lengths. They don't factor in the 1.6x crop factor. 

[kvbarkley]

"All lenses use 35mm focal lengths"

All lenses use focal lengths. 35mm has nothing to do with it.

[ebiggs1]

""All lenses use 35mm focal lengths"

All lenses use focal lengths. 35mm has nothing to do with it."

This is how the confusion gets started and how it is kept going. A lens is a lens is a lens and will always be. The camera it is attached to is irrelevant. Crop factor is a meaningless term that should have never been coined.

[normadel]

So how would YOU describe/label what happens when putting a lens on an APS-C body?

An APS-C sensor/body IS cropping what the lens takes in, showing what a full-frame sensor would see on a full-frame camera. The crop factor tells you the "equivalent". What's the problem?

[kvbarkley]

Why do you care? It has the field of view it has. There is no reason to make 35mm some standard of reference, especially if you have never used a FF camera.

[normadel]

I care because I like a clear, simple explanations for things, when there is one. Many folks have to dive deep into subjects here when questioners sound like they'd benefit from the KISS principle.

[Tronhard]

I too prefer an explanation: so in the best traditions of the KISS method:  🤔

In response to the OP's question:
"Would I still add this multiplier or is the number the same as on the box for RF-S lenses?" 
The focal lengths of lenses are a physical constant, so if one is considering a RF 50mm lens and a RF-S 50mm lens, they are both multiplied by the crop factor if one wants to know what the equivalent lens would be on a FF body to get the same Field of View.

[normadel]

Sorry, Tronhard. I don't see how your explanation says any more than mine did.

Oh well......