View Full Version : Separating Light Grey Siltstone from Blue Sky

Eric Leppanen
18-Feb-2006, 12:17
I will soon be visiting Fantasy Canyon in eastern Utah, and am trying to figure out the best way to photograph it with my 8x10 using B&W film. Fantasy Canyon consists of light-grey siltstone badlands and hoodoos, which are typically photographed against the blue sky. Its features benefit from being photographed in direct sunlight (shade degrades the sensation of texture and depth) yet I understand some of the structures cannot be photographed during the "golden hour" (right after sunrise or before sunset) since the sun becomes blocked by nearby hills. Here is a typical example of the type of compositions involved:


I have the familiar problem of photographing a light colored, contrasty subject with highly pronounced shadow areas in bright sunlight: I need to open up the shadow areas without blowing out the sky, yet at the same time the sky needs to be dark enough to be properly separated from the light grey siltstone. How can I best accomplish these seemingly contradictory objectives?

A #8 yellow or #15 yellow-orange filter would darken the sky but also the shadow areas, which would seem to gain me nothing. A polarizer would potentially have the same effect.

I had planned to use HP5+ (easier to handle high contrast than my alternative TMX), but now I'm wondering whether to use a color print film such as Fuji 160S to if nothing else assure a proper rock/sky separation by color, if not by tone.

Any suggestions to handle this situation would be appreciated! Waiting for an overcast sky or clouds to cover the sun would be nice, but my schedule will be tight so I'd like to have a strategy to handle a clear sky if possible. Thanks!

Jay DeFehr
18-Feb-2006, 12:31
How about a graduated filter; either ND or tobacco? This might allow you to expose for the shadows without losing the sky. I would also use a film with a long, straight curve, like TMY, and a staining developer that gives full film speed, without much fog or general stain, like 510-Pyro. Good luck.


Ron Marshall
18-Feb-2006, 12:41
A #12 filter and a polarizer together should darken the sky enough without signifigantly affecting the shadows.

Warren Weckesser
18-Feb-2006, 12:58
It seems to me that a polarizer would help, unless you
are shooting directly towards or away from the sun.
The polarizer should darken the sky more than the diffuse
light coming from the rocks. (Disclaimer: my comment
is not based on actual experience!)

Ole Tjugen
18-Feb-2006, 15:22
I have no idea of the "real colour" of those siltstones, so take my suggestions with a spoonful of salt.

You can try making the sky dark with a red filter. Or IR film and an opaque filter. OR: You can try increasing the internal contrast in the slitstones by picking a filter which enhances that contrast. An example is using a blue filter to show warm-white cliffs against a blue sky - the sky will be flat white, but the rocks will be wonderfully textured. Sometimes it works, most of the time it doesn't...

18-Feb-2006, 15:28
Weston and Adams solved a similar problem in Death Valley by using a medium yellow filter but not applying a filter factor. (See the AA/Newhall book, "Photography in Death Valley.")

Michael Gudzinowicz
18-Feb-2006, 17:55
Fortunately you don't have clouds so your high values are restricted to the gray stone. My approach would be to use Tri-X developed in HC110B (not diluted) in order to create an upsweeping film curve.
The curve will provide higher contrast in the lighter stone areas of the print, giving those areas a "brilliant" look. With filtration (yellow, orange or red), you should be able to drop the sky and shadow details down close to the toe separating them from the rocks, however, you will have to expose more than the usual factor in order to retain detail in the shadows lit by blue light. After that, it's a matter of dodging and burning, and perhaps accepting some black negative areas, which would not be out of place in a harsh landscape.

Note that when you use a red filter (and orange) with T-Max, the inherent contrast of the film decreases. In other words, if you shoot a grey scale with the filter, contrast is less than an unfiltered neg with the same development. Tri-X increases contrast with red; decreases with green (opposite of T-Max). The effect is likely due to sensitizers' spectral response.

To get a preview of the effect, open the jpeg and alter the contrast curve to an upsweeping curve, reducing low value contrast, and boosting high value contrast. Then adjust brightness and contrast.

Another approach for exposed negatives was outlined by David Kachel ("Variable-Contrast Control From Graded B&W Papers") in D&CCT (1992, issue 3, page 54). What you can do is print on a grade 5 paper, and bleach the latent image with dilute ferricyanide to reduce contrast before development. The paper's curve is altered giving perhaps an overall contrast of G2, with G3 in high values and G1 in low values. The working solution is 1 g per liter, that is further diluted 1:10 and 1:100. The paper is well exposed for the high values, bleached for 2-3 min, and then placed in developer. The bleach concentration adjusts contrast. I've used the method extensively including printing of old plates with a density range of 3.0 and more. It's reliable, though the highly diluted bleach baths should be replaced after each print.

Paul Metcalf
19-Feb-2006, 08:40
Depending on how much of the rock structures protrude into the sky area of your composition, HITECH (out of UK) makes split neutral density filters in red, yellow, orange, green (and blue I think). These are handy for bringing sky into balance and keeping foreground/shadows open.

Brian Ellis
19-Feb-2006, 12:08
If you scan and print digitally it should be a simple matter to expose for the shadows in the rock, then select and darken the sky.

Donald Qualls
19-Feb-2006, 20:00
If you expose for the shadows (without a filter) you should still be able to retain plenty of detail in the sunlit rock, which will often be *lighter* than the sky (especially if you can avoid angles that put the near-horizon sky behind the rocks). Alternately, as suggested above, a *blue* filter will lighten the shadows *and* the sky, possibly enough to make the sky distinctly lighter than the sunlit rocks. A blue plus polarizer might be the best bet of all -- lighten the shadows relative to the sunlit rocks, and darken the sky with the polarizer.

BTW, of the ISO 100 films I've tried (not a huge selection, I'll admit), Fomapan 100 (aka Arista .EDU Ultra 100) seems to have the longest red response, based on the way it separates clouds from sky without a filter. That would suggest it will do a better job of lightening the rocks relative to the sky than, say, Plus-X, though a blue filter is likely to erase that advantage.

Eric Leppanen
21-Feb-2006, 21:50
Thanks everyone for all the suggestions! I'll conduct some experiments over the next few days using similarly colored subject matter, to see what technique works best. Thanks again!