Really yellow filters

[Ed Richards]

As I understand color filters, both yellow and red should knock out blue to the same extent, but that yellow, as a constituent of green, should do less damage to foliage than red.

So why is it that I can not find any deep yellow filters (+3 stops) equivalent to a red 25? Anyone tried stacking yellow filters to see if you can get a strong sky and not get black foliage? (This is less relevant if you have high mountain skies but is a big issue on the Gulf Coast where you often need a R25 to get any darkening of the sky.)

[Nick_3536]

#15 is the darkest yellow. A #12 which is lighter blocks all blue. The #15 will block all the blue and some green [I think green]

[Nick_3536]

BTW if you don't want to go to the #25 have you considered a #21? Dark orange?

[Bruce Watson]

As I understand color filters, both yellow and red should knock out blue to the same extent, but that yellow, as a constituent of green, should do less damage to foliage than red.

So why is it that I can not find any deep yellow filters (+3 stops) equivalent to a red 25? Anyone tried stacking yellow filters to see if you can get a strong sky and not get black foliage? (This is less relevant if you have high mountain skies but is a big issue on the Gulf Coast where you often need a R25 to get any darkening of the sky.)

Partly it's the nature of the beast - it's difficult to make a yellow of the hue and saturation that you seem to want.

But I know where you are coming from. I don't use filters much because they seem to throw the tonal balances off from what I want. But when I do want a filter, the yellow filters just don't seem to be enough sometimes, but red seems just too much. My answer has been a #22 orange filter.

The filters I carry with me keep dropping in number too. I'm down to just three - a #15 yellow, #22 orange, and #11 yellow-green (which does a nice job lightening green leaves - useful with magnolias and other dark leaved plants). I don't even carry a polarizer any more.

[Ron Marshall]

If you are not using a very wide lens then try a #12 and a polariser.

[Helen Bach]

...Anyone tried stacking yellow filters to see if you can get a strong sky and not get black foliage? (This is less relevant if you have high mountain skies but is a big issue on the Gulf Coast where you often need a R25 to get any darkening of the sky.)

Isn't the difficulty caused by the spectral distribution of the light from the sky having a gradual decrease as the wavelength increases rather than a sharp cutoff - so there is some green in a blue sky. This is quite obvious if you work in colour - there is some sky response in the green-sensitive layer. A filter that does not block green may not be able to produce a black sky.

Best,
Helen

[Brian Ellis]

Wouldn't an orange filter do pretty close (not identical but close) to what you want, i.e. darken the sky more than a yellow filter and with less effect on greens than a red filter? I almost never use a filter to darken skies any more, it's so easy to do that in Photoshop where it can be done without affecting anything else in the scene. And when I did use filters it was usually to alter tonal balances in the scene and prevent merger of colors (e.g. a green or red filter to make a red apple stand out from surrounding green leaves). But when I did use filters to darken a sky in b&w photography a medium orange was my favorite.

[Bill_1856]

"Just shoot it straight and you can fix it in Photoshop." Unquote.

[brian steinberger]

A #22 orange filter is excellent. I'm finding it more and more to be my favorite filter for darkening skies as well as the polarizer. But I would recommend the #25 or #29 red filter also. I know that results with a #29 can be "dramatic," but only when the light is actually dramatic. On a normal sunny day, with blue skies and and puffy clouds, the red filter can create very nice results. I'd recommend a #15 yellow, #22 orange, and #29 red. I like those three along with a polarizer.

[Henry Ambrose]

Along with the orange filter mentioned by several, an increase in exposure and less development will help bring the green foliage up. Try a 22 or 23 orange, maybe even a 25 red filter. But the increase in exposure and less development is important to help move the green densities toward the sky densities.

[Alan Rabe]

Generally when I am shoting foilage with flowers and such, and I want it tonally in balance I use a #58 green filter. It balances out all the colors so dark green stuff is darker than the light green. Also reds will appear darker that say a blue or orange of the same reflectance. Works quite well. Give it a try.

[David A. Goldfarb]

This is one of the situations where I'll sometimes use a color grad filter--you know, the ones that produce those hokey-cokey-velveeta sunsets. With B&W, though, a tobacco grad will increase contrast in the sky while leaving the foliage alone.

[Vaughn]

As we all know, filters lighten their own color and darken the opposite color.

With this idea in mind, I am developing a set of two filters to help the B&W photographer. I assume that no one here is crass enough to run out and try to patent this idea before I do.

It will be a set of black and white filters.

The White filter will lighten the highlights and darked the opposite...the shadows. This filter will give the photographer more contrast -- no more silly underexposing and overdeveloping the film!

The Black filter will lighten up those pesky shadows and darken the highlights -- thereby reducing the harsh contrast of scenes such as sunlight coming through the forest.

I am still working on determining the filter factors. I'll post again when I work out the details. However, I am offering a special pre-release price of only $29.99 per filter in 40.5mm size. Unfortunately someone hacked in to my Ya-Better-PayPal Account, so at this time I can only accept cash...I prefer small bills.

PM me for prices of larger filters!

Vaughn

[Ed Richards]

I will assume from all of the interesting answers to questions that I did not ask, that no one has tried stacking yellow filters to see if that does a better job at darkening the sky and not the folage than a Red 25. I think I have a couple of yellows, I will give it a try and report back.

[erie patsellis]

You may want to try stacking 2 CC50Y filters, it'd get pretty yellow.


erie

[Nick_3536]

A filter is like a sieve. Stacking two on top of each other will still lead to the smallest one deciding what gets by. Stacking two yellow filters will still leave you with the darkest yellow filter controlling the light that gets passed to the film.

[Henry Ambrose]

What Nick wrote.

Once the filter cuts the wavelength it cuts that given wavelength is gone and the next filter of the same color won't do any more work. What it works on is not there.

[Ed Richards]

> Once the filter cuts the wavelength it cuts that given wavelength is gone and the next filter of the same color won't do any more work. What it works on is not there.

Think of it as three filters - two yellows and a weak green. I will get the benefit of the double yellow, and not much at all from the green, but that is OK. I would use two yellows if I had them.:-) Plus filters only cut the wavelengh proportional to their densition - look at the red series of 23, 25, 29. What I want is a yellow 25.

> You may want to try stacking 2 CC50Y filters, it'd get pretty yellow.

That is a good thought, and you can stack gels without much effect on the image. Three of them would get you to two stops.

[Nick_3536]

Two #8 are basically one #8.

A #8 and a #15 is basically a #15.

[erie patsellis]

Nick,
never worked with CC filters I take it?


erie

[Henry Ambrose]

Here ya' go:

http://www.kodak.com/global/en/professional/support/techPubs/b3akic/b3akic.jhtml

A 16 is what you want. (from actual experience, I like a 16 very much)

Doubling light yellows won't get you there. You'll just get longer and longer exposures the more filters you add.

[Ole Tjugen]

Doubling light yellows won't get you there. You'll just get longer and longer exposures the more filters you add.


Depending on the filters, you may not even get longer exposures.

There are basically two types of filters: Full absorption, and partial absorption. CC filters are of the second variety, so adding more filters gives a stronger effect.

Many other filters cut everything in a certain wavelength range, and putting two of these together makes virtually no difference at all.

To see (without trying) which are what you need the transmission spectra of the filters.

[Ron Marshall]

Depending on the filters, you may not even get longer exposures.

There are basically two types of filters: Full absorption, and partial absorption. CC filters are of the second variety, so adding more filters gives a stronger effect.

Many other filters cut everything in a certain wavelength range, and putting two of these together makes virtually no difference at all.

To see (without trying) which are what you need the transmission spectra of the filters.

Here are the absorption spectra for common filters:

http://photo.net/learn/optics/edscott/cf000010

[John Berry]

These concerns are why I have driffted to ND grads instead of color filtering when the sky is involved. I still use color filters when I wish to seperate colors in B&W.

[Miguel Coquis]

Once the sky have been darken by filter effect, some control is possible over different gray values by diluted developer. The action of developer can centered over a chosen Zone.

[Miguel Coquis]

Once the sky have been darken by filter effect, some control is possible over different gray values by diluted developer. The action of developer can be centered over a chosen Zone.

[Ole Tjugen]

Here are the absorption spectra for common filters:

http://photo.net/learn/optics/edscott/cf000010

Those spectra are really quite useless. What's the vertical scale? Is it log or linear?

But they do at least suffice to show that putting similar - say 2 #8 filters - on the lens at the same time do very little more than one of them would do.

[Daniel Geiger]

Re stacking two filters, you can refer to the Kodak Wratten Filter Handbook or some of the quoted web sources. Note that when you add two filters, that the extinction coefficients are multiplied with one another for each wavelength. That means, that two yellow filters stacked do NOT give just give half the transmission with the same extinction curve, but that the slopes of the curves are steeper. In areas of 100% extinction of any given filter, it does not matter, but anywhere else it does.

If you want to get exact filtration, then you have to go to dichroic (narrow band interference) filters, but I doubt that is what you are after. Also quite pricy.

Additionally, you could also experiment with different films, as the spectral responses are not identical; certainly unsenitized/ortho/pan-chromatic, but also within each category they will show differences; I would expect most differences between spherical and T-grain films but that is just idle speculation. Then the combination of a particular's film response curve with filter extinction curve could yield the desired effect.

Last but not least, the illumination source can be taken into account, either in the studio using different type of lamps, or by taking pictures at different times during the day. If you want to get more predictable results, consider the purchase of a color meter. I have a Minolta Colormeter III and love it.

You could also take the same scene with B&W with/without filtration and as a color image, and then compare the effects on the light table. Not perfect given all the color reproduction issues with color film, but may help visualizing/analyzing what's going on and what is working why. Trying to do it from memory is certainly worse.