filter factor for yellow #8

I keep seeing different information about what the filter factor is for a yellow #8 filter. The one I have is actually made by Hoya and they call it a yellow K2, but it's the same as a Wratten #8 apparently. ONe book said that there is no filter factor for this filter. But online I saw several charts that said the filter factor is 2. When I metered through the filter, the reading for a shadow area was 7.6, whereas it was 8 without the filter. But somebody said that meters are unreliable, particularly older ones, when it comes to reading through filters. So I wonder what filter factor to use.

Shannon, I don't own that exact filter, but my method is to normally meter through the filter and read a gray card for the amount of light to add, if I'm not sure. That having been said, I would just add a stop if it is a hand held meter and the filter factor is "2". With an in-camera meter, I would just use the camera meter's results.

Remember, the filter will act differently in shadow than it does in full sun. It will read differently with a blue subject color than a yellow or green one. This is why I tend to rely on a gray card reading when I'm not too sure. tim

Older meters may not read correctly through a colored filter. Filter factors actually vary some depending on which film one is using. However, a filter factor of "2" is 1 stop and this is the "usual" factor for a yellow K2 or #8.

I would meter without the filter and add a stop, or halve the ISO setting. Either way works. You'll know if your negs are right or not.

I am much unconvinced that older light meters that work properly are inferior to their desendants when reading thru a filter. I do not care much for the practice on a personal level beleiving that a filter factor appropriate to the film, filter and lighting conditions etc is better methodology.

If I were to read thru a B&W filter and the subject had important shadow areas..which is quite likely..then not only would I read from a gray card but also the card and meter would be in the shadow..if possible.

All pan films are not created equal. Filter factors can also vary by film. Even truer this is if one were to compare a pan film with ortho, blue sensitive or IR..these changes are capable of a very profound change.

To use a filter for precise predictable results in B&W in photography is actually quite complex. Photographer Fred Picker, deceased, has been quoted, in things I have read, as saying that he would alway take an extra exposure without the filter so the he would have something to print.

Claire Senft said:

I am much unconvinced that older light meters that work properly are inferior to their desendants when reading thru a filter. (snip)
To use a filter for precise predictable results in B&W in photography is actually quite complex. Photographer Fred Picker, deceased, has been quoted, in things I have read, as saying that he would alway take an extra exposure without the filter so the he would have something to print.

Click to expand...

I think I understand what you are saying, Claire, but in practical terms I've always applied filter factors, with total disregard for emulsion differences, etc. and got decent negs. I am equally unconvinced about differences in meters -- my WestonIII, LunaPro and Sekinic L558 all seem to give nearly identical metering (with or without filters). I'll bet there are minor differences in spectral sensitivity but the differences, in my experience, are so minor that I can't see a reason to worry about it. Re: Fred Picker... in the end, he was right!

I use an older spot meter. The reason I want to get this right is that I am going to be photographing a prison in bright TX sunlight. It is hard to get permission to photograph there, so we will probably only get one day to try to do it right in. Also I can't take a lot of film and film holders, so making two exposures of each scene isn't feasible either. But I anticipate that the skies will need some filtering to make the clouds look good. So I think I better practise ahead of time with my filter and see what the real filter factor is. I am thinking of making a test scene and photographing it using different filter factors. But my usual test scene is sort of in the shade. Maybe I should make one in full sunlight, to simulate the kind of light that we'll probably have?

Making a scene maybe overkill. A reasonable can probably be found locally.

I am less tham convinced that a filter is required in bright Texas sunlight to get pleasing sky values but that is your choice. My choice would be not to use one.

Be extremely careful when using a spot meter and reading thru a filter that You are reading a neutral tone..gray for example..or a color that has been matched to the confluence of the filter,film and meter thru experience.
Depending on the film chosen and the filter employed you may gain or lose contrast index.

Your decision to test is extremely sensible. In your test why not test 1 sheet of film without the filter?

It depends! If you basically want to leave your yellow parts of the scene at the same exposure as a non-filtered shot, and remove blue (darken a blue dress, sky, etc.) you could make no adjustment for filter factor. On the other hand, if you want to lighten yellow (contrast filtering) you might use 1 stop additional exposure to increase exposure of yellow and keep blue as it was without a filter. The kicker comes when you start to think about what you want to do with greens, orange, etc. Like much of photography, the "always do x" rules seem to get replaced by "what do you want to achieve on the negative?" approaches. Some of the older - 1950's - Leica manuals and Graflex manuals do a good job on contrast filter theory and applications.

Basic solution: experiment.

Ken