Another question about filters

[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?

Thanks in advance

Alex

 

[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?

 

[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.

 

[Jeff Kubach]

Close, but no ciger!

Jeff

 

[Alex1994]

Close, but no ciger!

Jeff

What do you mean? Similar effect but not quite?

 

[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.

 

[Jeff Kubach]

Really I don't somke cigers! There is a small difference.

Jeff

 

[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)

 

[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.