View Full Version : #8, #25 filter question

21-May-2001, 12:44
I recently decided to seriously pursue B&W, shooting Tri-X and developing in HC- 110. I picked up two filters for my B&W work, a #8 yellow and #25 red. The filte rs are Calumet's brand, which the salesman said are actually coated Hoya filters . I intended to order B+W but they were out of stock and being a few days away f rom an out of state trip I decided to go with the Hoya/Calumet filters.

This weekend we had a beautiful blue sky day so I decided to do some tests to se e the effect of each filter. I made three exposures of the same composition, one unfiltered, one with the #8 and one with the #25. I increased exposure for each filter according to The Negative: +1 stop for the #8 and +3 for the #25. After developing the negs and letting them dry I put them on my light box to evaluate. To my eye I can see almost no difference whatsoever between the unfiltered neg and the one shot with the #8. With the #25, I estimate the sky area of the neg d ropped in value, at best, about 1/3 stop. Definitely not the dramatic effect I e xpected from the #25.

The next day I decided to repeat the test thinking I may have forgot something s imple. Same result - a very slight reduction in the sky area with the #25 and no real detectable difference in the others. I'm totally perplexed as to why I'm g etting such negligable results with these filters. My color slides come out fine so I doubt the problem is camera or lens related. Because the negs otherwise lo ok pretty good I am at a loss as to the cause. I find it hard to believe that th e filters are the cause but lacking any other explanations I don't know what els e to think. There must be some variable I'm missing. Any body got any ideas? Tha nks as always!

Kevin Crisp
21-May-2001, 13:03
Andy: A few observations. I usually use the same film and developer you do. The effect of a lght yellow filter is variable, highly variable, depending on how "blue" the sky is. It doesn't have a dramatic effect on every "blue" sky. A viewing filter (Kodak wratten 90, I think) is a helpful way to get at least some idea of the relative darkness of the blue sky with no filter. The effect is most noticeable when the blue is being darkened against something white like a cloud. If you're not shooting clouds, a light colored building against the sky, or something like that the difference isn't going to jump out at you. As I read your post, you are looking at negatives and saying no big difference. If you "proper proofed" the negatives side by side with identical exposure for the contacts you will be much better able to judge it than looking at the negatives. I often think the negatives look the same filtered vs. unfiltered with yellow filters, but the proofing shows me which exposure was which. I think it likely that a proof will show you the red made more difference than you think. The red should produce a negative (in sunlight) with remarkable empty shadows, because it blocks so much blue. Without looking it up I think the #8 is a light yellow, or the equivalent of what people my age call a K1. If so, the effect is subtle most of the time and nearly impossible to pick off a negative. The next darker yellow has a more noticeable effect on sky (is this #12, the equivalent of K2?). Often you'll look through the viewing filter and find adequate contrast of sky and land, buildings, etc. with no filter at all. The light yellow provides just a tad of darkening. It can make all the difference. If you go too far you look "filtered." As a further complication, filter factors are useful but not always accurate. If your "proper proofs" show that the filtered versus unfiltered shots have the same highlight exposure, then that would tend to rule out an exposure difference which is masking the effect of the filters. I apologize in advance if I got my filter numbers mixed up, I'm talking about light yellow vs. medium yellow and I hope this makes sense anyway.

Joseph Dickerson
21-May-2001, 14:15

Where was the sun in relation to your lens axis? All black and white contrast filters give the maximum effect when shooting at right angles to the direction of the sun. Shooting directly into or with the sun at your back you will see little or no effect from the filter.

This is true of a polarizer as well.

Pick up a copy of Steve Simmons View Camera book. Gordon Hutchins has come up with a better method of applying filter factors that takes into consideration, and corrects for, the empty shadow syndrome.

Joe Dick

Dave Willison
21-May-2001, 14:44
I would agree with the above post(s) regarding the angle of the sun and the color of the sky. I use on-camera filtration as a first step when I previsualize dark skys and higher than average cloud-sky contrast. My next step is to print using split filtration on VC paper. In doing so, I normally add 55-95 magenta on the sky portion of the print while printing the lower portion without filtration. If I need more contrast, I will then use a small brush with bleach to increase the highlights in selected parts of the clouds. I hope this helps.


21-May-2001, 20:02
Andy - The effects of these filters will be much more apparent when you have some white clouds to contrast against the density of the blue sky. With a featureless sky you could simply burn the sky down during printing, but with clouds in the scene you'll probably want them to remain white hence the use of minus-blue filters (yellow/orange/red) during the taking process.

Go outside when there's some puffy clouds in the sky and shoot with and without the filters, then PRINT the negs. I think you'll see the sky deepen progressively as you go from none to yellow to red, while the clouds remain white.

Also, I've found the #15 yellow to be more useful than the #8. It seems to give an effect halfway between no filter and a #25 (and the filter factor is 1 1/2 stops). The #8 is supposed to render hues "naturally" on panchromatic film (i.e. normal b&w film like Tri- X) so you won't see a big effect. For real drama, use the #25 (or #29 deep red) along with a polarizer. You'll get the over-the- top "moonscape" effect.


John Hicks
21-May-2001, 21:55
I agree on the #15 yellow filter; it'll render an ordinary blue sky pretty much normal-looking without dramatically darkening foliage as a #25 often does.

Test the filter factor! I found the #15 to actually need one stop compensation with a sunlit subject and 1.5 stops in the shade; note that this is a bit less than the published factor. Also, what factor you need to use depends on the film you're using.

Gene Crumpler
23-May-2001, 09:34
Here is an example of the dramatic results with a 25A on t-max 100;


Gene Crumpler
23-May-2001, 09:36
Here's an example of an 25A on t-max 100;


Brian Ellis
28-May-2001, 09:21
There are a couple things you don't metnion that may be relevant. First, where were the photographs made? At low sea levels, like my home state of Florida, the sky often is seldom a really deep "blue" like you find at high sea levels (such as the places Ansel Adams photographed for most of his career). At low sea levels the sky usually is more of a very pale blue or cyan color. With that kind of sky I've rarely seen any effect of using a yellow filter (light, medium, or deep makes no difference). For that reason I've stopped using the yellow entirely (for skies) and switched to an orange filter, which produces some but not much effect. A red filter will usually produce a noticeable effect on the sky but it often has such an adverse effect on other parts of the scene (such as green foliage) that I don't really like to use it very often. Second, is it possible that you just overexposed the negatives? Third, how did you meter - i.e. did you meter the sky, meter the rest of the scene, and take an average, or did you meter and expose for the shadows, did you read through the filter and then apply the factors or just read normally (whatever that means for you) and then apply the factors? All of these methods usually will give different - not necessarily "better" - results. You probably are aware of the fact that filter factors are "guesstimates" at best since the amount of light that they pass depends on the colors in the scene - i.e. a red filter used when photographing a red barn will pass much more light that a red filter when photographing a green barn. FWIW, with a 35 mm or medium format in camera averaging meter of any kind, a method I learned from an article in "View Camera" magazine has worked well - meter the scene with the filter on the lens, then open up one additional stop if using an orange or green filter, two additional stops if using a red filter, no adjustment if using a yellow or polarizing filter. This method goes against the conventional wisdom that with an in camera meter and a filter on the lens the effect of the filter will be taken into account so that adjustments aren't necessary but it has worked will for me. It's more difficult to use this method with a spot meter. Finally, with a decent blue sky combining a red filter with a polarizing filter will produce a seriously big effect (with the sun more or less at right angles to you) though the light loss from this combination is about 4 1/2 stops so you normally would have to use a very slow shutter speed. On the few occasions I've tried it, the sky has come out almost black, close to the effect of infrared film.