Rollei filter factors.

Hello, Rollei User's -

For my E-2 Rolleiflex, (Xenotar 3.5,) I use Bay ll red and orange Rollei filters, and am clueless as to why the factors

engraved on their filter faces use two ascending values. As engraved they are as follows.

Red -2...-3.5 Orange -1.5...-3

Other brands like Leica and B+W seem to list just one value, i.e. -2 or -3, wondering if any of you might know the

reason for Rollei using multiple factors. I haven't come across a reference to it in my reading of Rollei materials.

Thanks in advance.

Patrick

I am not sure but it may be a reference to the different spectral sensitivity of ortho-chromatic and ortho-panchromatic films that

were common in the early years of the Rolleiflex TLR. The filter factor ranges are confirmed by literature (Prochnow, 24-514). Please note that

a range is provided for the orange and red filters only.

"Modern" b/w film is panchromatic and much more sensitive to red colours than the ancient ortho-chromatic films.

After posting my earlier message I remembered that I own Dr. Walther Heering's "Das Rolleiflex-Buch", 1969 (The Rolleiflex

Book). He writes that filter factors are given for panchromatic film but should be seen as general guidance only and that the

actual filter factor to be used is depending on the specific nature of the film.

I was going to suggest that it had something to do with earlier emulsions that were more blue sensitive or maybe it was for

Tungsten or Daylight source.

Glad someone had a definitive answer.

To the three post's above, thank you so much Ferdi and Bruce.

I'm still unsure of which factor number to select as the primary, for my typical use. I almost exclusively use Ilford Delta or Fuji Neopan, both very modern emulsions I would think.

I thought perhaps I'd pair the color density of my Rollei Bay ll Red and Orange filters against others I own, (Hasselblad, Leica and B+W,) to see which is closest, then use that factor as the primary for my Bay ll use. I have placed my digital Gossen meter behind the filters, while aiming at the photo object, but not at all sure that it's a realistic measurement for determining factor. Seems to work OK, but I still may not be optimizing exposure value.

Ah, the troubles we amateurs cause the more knowledgeable, and we're always looking for your help. Thank goodness for PNET and those of you that offer to assist.

Any further thoughts you or others may have would certainly be most appreciated, thanks once again.

Patrick

Patrick,

I would try 2 stops for the orange and 3 stops for the red.

This will give you a base to work off of. Personal ISO and developing times all come into play so I would think that would get

you in the ball park and then you can fine tune it.