1. ## Question about filter factors

I would have thought that Google would find my answer, but the pages always seem to miss key issues which elude me.

In short I want to find out what the filter factors or compensating aperture adjustments are for the filters, which I managed to purchase at a photo swap meet (as a group, therefore the overlap).

They are the following Tiffen filters:

Green 11
Orange 16
Deep Yellow 15
Red 25
Yellow 8
Yellow KZ

They are all identified on the following Tiffen web site, except for the last one:

http://www.tiffen.com/results.html?s...w-In&page_no=3

but no where is the filter factor given on the Tiffen site

nor did this following general explanation of filter factors help me:

http://en.wikipedia.org/wiki/Filter_factor

It is not evident that the Wratten number is the same as the Tiffen number. The wratten number 11 is for Yellow/Green, but my Green 11 is quite a deep green as shown on the Tiffen web page ( 11 Green 1) which causes me to doubt the Tiffen numbers are the same as the wratten numbers.

Can anyone point me to the correct reference?

Thanks

2. ## Re: Question about filter factors

Perhaps just do a before/after exposure reading.

It's as easy as taking a reading (spot is best) of a given subject without the filter in front of the meter and one with it in front.

3. ## Re: Question about filter factors

Originally Posted by Lachlan 617
Perhaps just do a before/after exposure reading.

It's as easy as taking a reading (spot is best) of a given subject without the filter in front of the meter and one with it in front.

Not strictly true. The difference will depend on what colour you are metering in combination with what colour of filter.

e.g. metering something yellow through a yellow filter will show hardly any difference at all, whereas metering something blue through the same yellow filter will show a greater difference.

4. ## Re: Question about filter factors

Originally Posted by Joanna Carter
Not strictly true. The difference will depend on what colour you are metering in combination with what colour of filter.

e.g. metering something yellow through a yellow filter will show hardly any difference at all, whereas metering something blue through the same yellow filter will show a greater difference.
Good point. I should have added a grey card etc. Assumption is a dangerous thing...

5. ## Re: Question about filter factors

I recently bought a Tiffen filter and went looking for their factors as well. No luck. I can't imagine why they don't post them on the website. And nothing came with the filter that mentioned it either.

6. ## Re: Question about filter factors

Originally Posted by Frank_E
In short I want to find out what the filter factors or compensating aperture adjustments are for the filters,

Green 11
Orange 16
Deep Yellow 15
Red 25
Yellow 8
Yellow KZ
I dug out a small pamphlet that came with one of my Tiffen filters and here is what they recommend:

Yellow 8 - 1 stop
Deep Yellow 15 - 1-2/3 stops
Orange 16 - 1-2/3 stops
Green 11 - 2 stops
Red 25 - 3 stops

No mention of the Yellow KZ filter. What color does it look like?

-Darren

7. ## Re: Question about filter factors

Originally Posted by Frank_E

but no where is the filter factor given on the Tiffen site
Suggest you go back and look properly.

8. ## Re: Question about filter factors

Originally Posted by Frank_E
I would have thought that Google would find my answer, but the pages always seem to miss key issues which elude me.

In short I want to find out what the filter factors or compensating aperture adjustments are for the filters, which I managed to purchase at a photo swap meet (as a group, therefore the overlap).

They are the following Tiffen filters:

Green 11
Orange 16
Deep Yellow 15
Red 25
Yellow 8
Yellow KZ

They are all identified on the following Tiffen web site, except for the last one:

http://www.tiffen.com/results.html?s...w-In&page_no=3

but no where is the filter factor given on the Tiffen site

nor did this following general explanation of filter factors help me:

http://en.wikipedia.org/wiki/Filter_factor

It is not evident that the Wratten number is the same as the Tiffen number. The wratten number 11 is for Yellow/Green, but my Green 11 is quite a deep green as shown on the Tiffen web page ( 11 Green 1) which causes me to doubt the Tiffen numbers are the same as the wratten numbers.

Can anyone point me to the correct reference?

Thanks
There's no connection between Wratten numbers and Tiffen numbers. In fact there's not a lot of connection or sense even within Wratten numbers alone but that's another topic.

You have to remember that filter factors are only approximations. As Joanna mentioned, the amount of light transmitted and blocked by a filter of the kind you have depends on the colors in the subject matter. A red filter will transmit a lot more light if you're photographing the side of a red barn than it will if you're photographing a blue car. However, since black and white film has a fairly wide latitude, and since most subjects aren't comprised of a single color, approximations for filters are generally close enough.

FWIW here are the factors I used to use for the most common filters for b&w photography (I no longer use any filters except polarizers and grads, the filters available in Photoshop do at least as good a job and give you much more flexibility than on-camera filters).

Yellow: 1 stop (factor of 2)
Orange: 2 stops (factor of 4)
Red: 3 stops (factor of 8)
Green: 2 stops (factor 4)
Polarizer: 2 stops (factor of 4)

Obviously filters have different strengths within each color (e.g. light red, dark red, etc.) but these are close enough in my experience using HP5+ and TMax 100 film.

I never meter through a filter with a 1 degree spot meter. As Joanna also said, you'll get very different readings metering with a spot meter through a filter depending on the color of the spot you're metering. I did used to meter through filters with averaging-type meters found on 35mm and medium format cameras but found that even there some adjustments were required (View Camera magazine published a table of adjustments many years ago that worked very well for me but I can't find the table now).

9. ## Re: Question about filter factors

Your KZ is probably in reality a K2, which was once by far the most common filter used, and was often just left on the lens at all times. Factor is 1-2 stops, (depending on the light, the film, and the subject). Most of us just used 1 1/2 stops and didn't worry about the details. Great for separating blue sky, green foliage, and caucasian skin tones, without calling attention to itself.

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