• 07-11-2011, 12:42 PM
Alex1994
Hi everyone

I went on evilBay to buy a Bay 1 yellow filter for my new Rolleicord. I always use K2 yellow as a regular B&W filter. The listing I bought had a pic of a medium yellow (K2 filter) but the description actually said it was a light yellow (K1) filter. Well, I didn't read that bit (note to self: read BEFORE you buy).

So my question is: will I see more or less the same effect with the light yellow as with the medium yellow I always use? I know the filter has little effect in cloudy conditions, but what about in sunlight, such as dawn/dusk conditions?

Alex
• 07-11-2011, 12:58 PM
Rick A
Yes, to some extent, but not quite as pronounced. What is the filter factor for it,one or two with a K1, 1/2 stop or one stop correction?
• 07-11-2011, 01:02 PM
Alex1994
The Rollei manual says the light yellow has a filter factor of 1.5, while the medium yellow has a filter factor of 2.
• 07-11-2011, 01:53 PM
Jeff Kubach
Close, but no ciger!

Jeff
• 07-11-2011, 01:54 PM
Alex1994
Quote:

Originally Posted by Jeff Kubach
Close, but no ciger!

Jeff

What do you mean? Similar effect but not quite?
• 07-11-2011, 01:55 PM
Bruce Osgood
Keep in mind, you do not want to confuse Factors with Stops.

My understanding is the Square Root of a Factor is the Stop. In the case of a Factor of two you would open the lens 1.4 Stops and a Factor of 1.5 would be 1.2 Stops.
• 07-11-2011, 02:01 PM
Jeff Kubach
Really I don't somke cigers! There is a small difference.

Jeff
• 07-11-2011, 02:15 PM
Ian C
Factor = 2^Δf

Δf = ln(factor)/ln2

Example:

#8 yellow = K2 is a 1-stop filter with factor 2

Factor = 2^1 = 2

Δf = ln(2)/ln2 = 1 stop

For the light yellow K1 (#6)

Δf = ln(1.5)/ln2 = .58 stop (usually rounded up to 2/3 stop)
• 07-11-2011, 02:20 PM
Rick A
Roughly between 1/2 and 2/3 stop. So, if your lens has two marks between stops, you use the second one. If there is only one mark between stops, use that.