Members: 77,714   Posts: 1,716,463   Online: 843

1. ## Another question about filters

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

2. 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?

3. The Rollei manual says the light yellow has a filter factor of 1.5, while the medium yellow has a filter factor of 2.

4. Close, but no ciger!

Jeff

5. Originally Posted by Jeff Kubach
Close, but no ciger!

Jeff
What do you mean? Similar effect but not quite?

6. 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.

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

Jeff

8. 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)

9. 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.

 APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY: