[Leica] Need Knowledge; Use of Dark Yellow Filter w/B&W Film

[rsphotoimages at comcast.net (Bob Shaw)]

My local Leica dealer (Glazer's in Seattle) is dumping their B+W Filter 
inventory (digital marches on...) so I pawed through three large boxes 
and came up with a B+W ProLine 67mm Dark Yellow for my R-Vario Elmarit 
28-90 Asph.  I couldn't find a 77 for my 70-180 but in retrospect, I 
decided I'd be less likely to use it on that lens; the 28-90 is my "on 
camera" lens most of the time.  I have a Heliopan Circular Polarizer 
for both lenses which I use a lot.

Back to Dark Yellow:

According to ilford's website, "A typical yellow filter will have a 
filter factor of 2; the manufacturer will supply the exact factor with 
the filter. Most cameras with TTL metering will correct automatically 
for the filter factor but check the camera instruction book".

OK.  i get it.

But on the box, the label states "Dark Yellow 3X Coated".

My question is:  even though the R8 and R9 read through the lens, do I 
want to open up a stop or two, or go with the internal meter reading 
and just shoot away?

Thanks for any unfiltered light you can shed on this.

Regards,


Bob