Porta 160 Data Sheet

**kansasjhawk** · 25-Dec-2012, 00:53

This seems strange to me.....on the Porta data sheet they rate it at 40 ISO for Tungsten lighting....does anyone actually do that? That seems strange to me......I can see using the 80A filter, but I don't see why they would change the ISO rating based on that. http://www.kodak.com/global/en/profe...4051/e4051.pdf

**JBelthoff** · 25-Dec-2012, 01:08

I have never used that combination however a Wratten No. 80A has a filter factor of 4. Which means you need to open up 2 stops. 160 opened up 2 stops is 40 ISO.

**kansasjhawk** · 25-Dec-2012, 09:32

Originally Posted by JBelthoff

I have never used that combination however a Wratten No. 80A has a filter factor of 4. Which means you need to open up 2 stops. 160 opened up 2 stops is 40 ISO.

Thanks, John. That makes sense and is what I was thinking they meant. I've just usually seen it referenced in Stops and not ISO numbers.