Hasselblad CB80mm IR focus

[emanded]

I'm about to start experimenting with IR - when my film & filter arrive!
I have a 501cm and all my lenses apart from the aforementioned CB80mm have the normal IR red mark for focussing. Can any of you well versed Hassy chaps give me an idea where the focus point on the barrel markings should be?
Cheers

 

[Q.G.]

It will be in a different spot depending on what the dominant wavelength is (i.e. what filter you put in front of what film) you want to record.

This is a tricky one.
You need to know how the particular lens performs in that range to be able to give an answer. Or put in other words: you do have to know the answer to know the answer.
Not something you can calculate based on 'trivial' data like focal length.

 

[emanded]

Thanks for the reply QG.
On closer inspection, one of the focus lines (on f4) on the lens is a dotted white line in a similar position as the red line on my other lenses. I presume this must be the IR focus.
If anyone can confirm this then great, but if not then I'll be shooting a fairly large dof anyway so will try it and see.