What is this Summitar filter used for?

[gjlynx]

I recently acquired a IIIc with a 50mm Summitar and that prompted me to check out some filters that I received many years ago from my dad when he sold his IIIc and no longer needed them. The one in the picture is marked "PF" and is blue in color. Anyone know what this might be used for?

 

[gjlynx]

Would that be daylight or tungsten film color film?

 

[stuken]

Blue filters correct daylight film in tungsten lighting.

 

[Zathras]

I'm making a wild guess here, but I think that PF stands for Photo-Flood. This bluish filter would correct for the reddish yellow color balance of the incandescent photo flood bulbs, when used with daylight color film.

Mike Sullivan

 

[LeicaTom]

Yes, the PF means *Photo-Flood* ELNY filter ca. 1950

 

[John Shriver]

Yes, that would be for daylight film under 3200K light. Wratten 80A would be the Kodak designation.