Yellow (12) & Orange (21) Filters

[Matt5791]

Hi there - just arrived in California from the UK and before I came I have invested in two Lee resin filters as in the title......

Can anyone confirm the exposure adjustment for these filters? I am guessing about a stop for the yellow and almost 2 stops for the orange?

Many thanks for any help,

Matt

 

[Poohblah]

the filter factor for my #8 is 1 stop and for my #25 (red) it is 2.5 stops, but i used this webpage to figure that out: http://www.jackspcs.com/filters.htm

unfortunately he didn't list the filter factors for either 12 or 21, but i would extrapolate from the given information that they are approximately 1.2 stops and 2 stops, relatively.

 

[Chuck_P]

I enjoy good success using a factor of 2.5x (+1 1/3 stop) for the orange #21 using a T-grain film. Using a non-T-grain film like Tri-X would require a bit stronger factor. I do not have the #12.

 

[Paul Verizzo]

Hi there - just arrived in California from the UK and before I came I have invested in two Lee resin filters as in the title......

Can anyone confirm the exposure adjustment for these filters? I am guessing about a stop for the yellow and almost 2 stops for the orange?

Many thanks for any help,

Matt

It depends on your film. Use the film manufacturer's information, not the filter company's.

BTW, a question like this is probably best answered in one of the other forums. This one is about chemistry.

If you are in southern CA, be sure to visit Freestyle in Hollywood! Wow.

 

[nworth]

The exposure correction needed for a filter depends on the light, the subject, and the film. A certain amount of bracketing and experimenting is expected. Most filter manufacturers provide a list of filter factors for their products which is at least a starting point for the exposure correction. (Divide the unfiltered exposure index for your film by the filter factor to get the effective exposure index to use with the filter.) For instance, Kodak recommends a filter factor of 2 in daylight and 1.5 in tungsten light with panchromatic film for their No. 8 medium yellow filter. But if you were using a film with high red sensitivity, you would need to reduce these factors, and with orthochromatic film you would have to increase them. Filters vary from one manufacturer to another, but Kodak recommends a filter factor of 2 (one stop) in daylight for their No. 12 (Minus Yellow) filter. They do not list filter factors for their No. 21, but looking at the absorption curves and comparing it to No. 23A, I would estimate a filter factor of 4 (two stops) or a shade more for that filter.

Note that a No. 12 filter produces much darker skies than the usual No. 8 filter. It also gives greater haze penetration. Filters are generally used to produce additional contrast, lightening colors similar to the filter color and darkening the complementary color. Obviously, the subject color will affect the exposure. Here is where exposure can become tricky and bracketing can be wise. If you want to darken blues, you want to reduce their exposure in relation to the other colors. That is just what a yellow filter does. Other colors may not behave as expected, and different films can behave differently. The filter factors generally work fine to give contrast effects, but it can get tricky.

 

[panastasia]

.... a filter factor of 2 (one stop) in daylight for their No. 12 (Minus Yellow) filter.....

Note that a No. 12 filter produces much darker skies than the usual No. 8 filter. It also gives greater haze penetration. Filters are generally used to produce additional contrast, lightening colors similar to the filter color and darkening the complementary color. Obviously, the subject color will affect the exposure. Here is where exposure can become tricky and bracketing can be wise. If you want to darken blues, you want to reduce their exposure in relation to the other colors. That is just what a yellow filter does. Other colors may not behave as expected, and different films can behave differently. The filter factors generally work fine to give contrast effects, but it can get tricky.

#12 (minus blue) is a stronger yellow filter than #8 but has the same filter factor of 2. It filters all blue light and some ultra violet (I think) - the reason blue skies are darkened further than with #8. They appear to be identical to the eye when looking through them side-by-side. #12 will probably work better at high altitudes and in winter with lots of snow and shade illuminated by blue sky.

 

[Silverhead]

On the other hand, you could just throw a test roll in your camera and see how your meter adjusts to the filters...

...and yes, visit Freestyle. You can pick their staff's brains to your heart's content. You'll have a lot of fun there.

 

[Matt5791]

THanks for the help everyone. - I may have a chance to visit Freestyle at the end of the trip - we are staying in Beverley Hills and have a rental car so no excuses really for not getting there!

Matt

 

[Davesw]

Question : if you have a spot meter and a filter you do not have a filter factor for, can you hold it tightly to the lens of the spot meter to get the corect exposure?

 

[Frank Szabo]

Question : if you have a spot meter and a filter you do not have a filter factor for, can you hold it tightly to the lens of the spot meter to get the corect exposure?

That may work, but try this - aim your meter at anything relatively bright and take a reading. Now, with the filter in front of the meter's sensor (taking care not to introduce sidelight interference), take another reading thru the filter noting the difference in the meter's reading. That's your basic allowance for the filter. Doing this, you needn't worry about manufacturer's recommendations or carry a pile of papers around with you in the filter bag. You have a fresh reading according to actual conditions and not generalities as you would get from recs or even your own notes.

Go ahead and meter as you normally would paying attention to the part of the subject you are using the filter to enhance and to that particular reading add the value you just determined, or subtract or whatever you care to do.