Canon 50 f/1.4.. Little red R?

[bhop73]

On the right side of the dof scale, in between the 5.6 and 8 marks, there's a red letter R, only on the right side though. Anybody know what this is for?

I just got this lens Friday and have been wondering about this, but haven't been able to find info online..

 

[xayraa33]

It is a focus mark when using infrared film.Focusing with infrared film is a little different than most of us are used to. We normally focus visually because we are dealing with light in the visual spectrum. Infrared film is beyond the visual spectrum and focuses on a different plane. In order to focus for infrared you will need to focus visually and then readjust your point of focus by taking the distance that is in front of your focus mark, and aligning it in front of the infrared focus mark.

 

[Carlos Cruz]

It's a a copyright mark 😀 not
Actually it's a marker for infrared photography

 

[bhop73]

Ah, I see, thanks. I was about to post that I just noticed a little dot in the dof scales on my Nikon lenses, it must be the same thing.