What is a YA3 filter?

[Vics]

...and what is its factor? It's orange in color. I think I've asked this before, but I can't find the thread.

 

[nikon_sam]

The YA3 filter has a filter factor of 4 so increase the exposure 2 stops...
Here's more on that filter...http://www.forcamerafilters.com/filter_basics.swf

 

[sevo]

That is the regular b&w orange (a.k.a. "G") filter in one (maybe Japanese?) nomenclature. Beware, there seems to be no practical standard for the transmission curve of black and white letter code filters - I have one that is a deep orange (Wratten #22) equivalent, and another much lighter one (probably Wratten #16 or #21).

Given that variability in filter density and the no less variable red response of films, that can mean filter factors anywhere between 2 (1 stop) and 8 (3 stops). Test it, or bracket like mad - even more so on subjects illuminated with coloured light or by non-continuous light sources like fluorescent or LED, where all exposures can be off by another two or three stops.

 

[Vics]

Thanks to both of you for those responses. Sevo, you're right about it being Japanese. It's a Soligor filter. I have a very nice little kit of filters, all Wolz except for this one, to fit my Carl Zeiss Sonnar 50/1.5 lens. I had been shooting this lens on my Contax IIIa, but now that I have one of Amadeo's amazing adaptors, I'll be shooting it more on my Leica M3.
The effect would be somewhere between the yellow Y2 and the red R1? Today will be a good test day for filters, with partly cloudy skies. Thanks again.