Flutterby™! : Trees in the fog 2004-02-24 22:54:10.220367+00

Trees in the fog

2004-02-24 22:54:10.220367+00 by Dan Lyke 17 comments

My sister was in town on Sunday, so I dragged her with me with the regular hiking group. Of that group only Bill, Lisa, and Bill's nephew Brett who's going to join the army soon showed. We started at Mountain Home Inn, went up the Gravity Car Grade 'til it hit Railroad Grade, then shortly took a right onto Temelpa. When we got to the gulley part, Brett and I went straight up. This was tougher than normal 'cause usually I'm being followed by Leo, not by a kid who's been training so that he can be sure to ace the assorted physicals and get those early promotions, and he wasn't about to let some aging hippy beat him, so by the time we hit the last switchback we were both surreptitiously trying to avoid coughing up blood. But it was a good burn. Back down Fern Canyon, and a tasty breakfast at Winships in Sausalito.

That afternoon I taught my sister how to use mail merge in Microsoft Office (I take back everything nasty I've ever said about OpenOffice.org).

This picture reminds me that I've been meaning to ask for recommendations/advice about film type when the subject matter includes subtle gradients - as in fog or sunsets.

I have some time elapsed photos I took of the moon this winter, with a variety of counts and f-stops, but all of them came out as nothing more than roundish blotches of white. Now I'm wondering if I should be using a faster speed film and/or if maybe the film I used (been trying to use up several canisters of 400 that have been bouncing around my camera bag) had gone bad on me.

For the moon shots, you're probably still overexposing. The thing to remember about taking pictures of the moon is that it's a sunlit object, and therefore hugely brighter than anything else in your scene. Think "Taking a picture of sidewalk concrete at noon. On a particularly clear day.". Back in the days before spotmeters and automatic cameras photographers were taught something called the "sunny F16 rule", which says that a reasonable exposure is one over the ASA/ISO speed of your film at F16. So if you're using 100 film, then at F16 you want to shoot at 1/125th, and with 400 at F16 you want whatever your camera's closest setting to 1/400th is (1/500th would be a full stop).

Of course the problem is meshing this with scenery, which is essentially the same issue that you have with sunsets, reflections on water, some fog scenes and the like. For the moon, the obvious way to deal is to insert the moon with a double exposure. Take a picture of the moonlit scene at seconds wide open, then insert the moon with a super short stopped down exposure.

For sunsets and reflections on water, get a graduated neutral density filter, I'd start with a .6 which is two stops if I remember right. I use the Cokin

"P" system, which is large enough to be used even for some medium and large format cameras and lenses, but still reasonable for 35mm. If you shoot mainly digital or don't have big honkin' lenses with 77mm fronts then a smaller form factor like the "A" series might serve you better. Get a cheap resin grad ND, put the graduation line at the horizon, and see how it looks.

Does your camera have a spotmeter? A quick refresher on the zone system might help understand what's going on here...

#Comment Re: made: 2004-02-25 21:34:08.576523+00 by: Shawn [edit history]

If I'm understanding what a spotmeter

is, I don't think so. As for the zone system, how about an initial instruction instead? My eyes started to glaze over halfway through the first paragraph the first time I read it through.

What you're saying is what I was seeing (I think). Shorter exposure times wouldn't get me other scene elements, like the wisp of cloud crossing the disc, and longer exposures just turned the moon into a blob of light.

After reading it through a few times I think I'm following most of the basics you've outlined, but I'm not familiar with some of the terminology you're using ("graduated neutral density filter", "resin grad ND", "graduation line", "zone system", etc.) [So far] the extent of my photography skills is an apparent inborn knack for scene composition. From time to time I have lots of questions about my equipment - like; why does my polorizing filter rotate and have a white mark on it?

What I've got is a standard 35mm (Pentax). It's got an auto mode (where the shutter speed and f-stop are chosen for me), which I frequently use as a rudimentary light guide, but I've been trying to experiment with using the manual settings. I only have a (very) vague idea how to use f-stops, so I'm mainly experimenting with various settings and seeing how things come out.

Shawn, your long exposures are proper for picking up the scene elements other than the moon. What Dan is suggesting you do, I think, is to go for a double exposure using a mask. The graduated neutral density filter is used to mask out the bright moonlight. This filter has a dark half and a light half with a graduated demarkation line. Take a long exposure with the filter in place and then a short exposure without the filter. This lets you have a properly exposed moon *and* properly exposed foreground.

Your polarizing filter rotates and has a white mark on it to allow you to align the polarization with your light source. Take two polarizing filters and rotate them. When they are aligned you can see through them, when they are 90 degrees out of alignment you won't be able to see through them.

A quick "zone system" primer: Light falls on film, makes film dark (for negative film). For a given quantity of light, darkness is a result of film sensitivity (higher the film speed, darker the film) and developing issues.

Simplifying dramatically, film has limits. It can only be so clear or so opaque. So at some point more light doesn't make the film any darker, and less light doesn't make the film any clearer. In any given scene there will be places where you lose shadow detail (because not enough light fell on the film to change it) or highlight detail (because so much light fell on the film that a large region is as opaque as it can get).

How wide that range is is the contrast of the film. Where that range lies is the sensitivity of the film. So on any given scene, you have to pick and choose what parts of the scene appear where in the darkness or clearness of the film.

Spot metering is useful because if you know how your film responds to light, you can say "I know I want to see detail in that shadow, or that cloud, how do I have to expose the film to do that?" Or, "this picture won't work unless I have detail in that shadow or that cloud, will the film get it?" Darkening the cloud or lightening the shadow is why you use the neutral density filter, too.

Complicating this is that in the process of printing the photo there's a similar decision being made: The paper can only be so black or so white, and something's got to pick and choose what portion of the range recorded on the film ends up on the paper.

In black and white photography, you can actually change the contrast range and light sensitivity by how you develop the film and paper. "The Zone System" is Ansel Adams' formulation of this process, including testing your materials, looking at the fact that the correlation between light and dark in the range you can capture isn't necessarily linear, and can actually change with over what time period the material is exposed to light, too (called "reciprocity failure").

For color photography, you really can't screw with the contrast ranges of the materials on the fly because you'll muck up color balance. But you can choose films that are appropriate to your scenes. I'm mostly familiar with slide films, but you can make some intelligent guesses about print films from their advertising. Films advertised as "vibrant colors" like Agfa's ASA 50 color film are going to have really high contrast, not much light difference between dark and light. Kodak Gold Max isn't advertised with an ASA because it uses a very low contrast and can get extremely opaque, so it will capture huge ranges of light in a scene, but probably isn't the film you want to use when you want a landscape to really "pop" (might be something to try for your moon scenes, depending on how good your printer is).

Oh yeah, for another example of the polarizing filter effect: Go to a body of water, a stream or a lake, with afternoon sun. Look through the filter, rotate it, and see how it changes. If it's an expensive polarizing filter (also called a "circular polarizing filter"), also note that it has this effect when you look through it one way, but not the other.

Thanks (to you both), that was helpful. Much if it I already knew (conceptually) but, as with a great many things in my life, I just wasn't familiar with the jargon or technically-detailed application thereof. I'm a bit confused about the definition of contrast now, though. I've always been under the impression that higher meant more (as in "a clearer") difference between light and dark, not less.

ASA? Oh Loki, there's more numbers to pay attention to (than just film speed) when selecting film? Wonderful.

The upshot, it sounds like, is that 1) a faster speed film will help get a crisper image of the moon (bright object on dark background), 2) I'll need to apply a mask-like technique to the exposure times if I want to include a clear shot of anything else in the scene, and 3) doing this with a wisp of cloud that's actually crossing the moon sounds like a lot of work.

A few more details on my photography... baseline: I have some experience in the darkroom with B&W, but I haven't had access to that kind of equipment for many years. I've never done (shot) slides, only prints. We have a color printer, but the scanner isn't set up while we're still living with the in-laws. And in any case, I don't think I get as crisp a print out of it. Mostly I just drop my rolls off at the local Fred Meyer.

Shawn, I think you got contrast range right: Higher contrast means smaller changes in light cause bigger changes in image darkness.

ASA is the old term for film speed, unfortunately short of getting the manufacturer's spec sheets (which I've gotten for the films I use) there's no standard for contast.

I don't think so, because the issue here is relative brightness. A faster film speed will expose both the moon and the clouds more, and since you're already massively over-exposing the moon there's no advantage to being more sensitive.

It's becoming more and more apparent to me why I waited for good digital camera's before getting into photography for personal use. Even with years of experience working with film, dip tanks, 'automated' processors.. Heck, "back in the day" I even fixed Hasselblad large format (105mm) camera's.. and other weirder imaging equipment.. I've even taken "photographs" with electrostaticly charged glass plates.. thermography..

The difference that some humans can enter into the process is not only the artistic composition.. but also that 'feel' that only time and lots of film with a camera and set of lenses added to the variables discussed above. It's cold out.. give another tenth of a second.. the light is bouncy, close the apeture a smidgen.. adding the countless variables the natural environment throws at a photographer, on top of the 'man made' ones.. I'm suprised anything comes out at all, especially with a feedback loop delay of days or weeks to see your final images. And yet: art happens.

Aha! So Meuon's comments reminded me of a reason that faster film might help: You might get less flare from the brightness moon if your lens is stopped down more. Try the shot at F11 too...

That was kind of the direction my thoughts were groping - with faster film, I could expose less (less time, ... uh... more?/less? aperature) for the same level of... clarity.

Time probably isn't an issue, because you're probably not pushing your film in terms of "reciprocity failure" (where a silver halide crystal doesn't get enough simultaneous photons to push it up to the next energy level, even though the total number of photons should be equivalent, usually in exposures longer than 30 seconds, but for some films out to minutes), but lenses tend to have a "sweet spot" where they're sharpest and have the least internal reflection and flare, and a good starting place when looking for that sweet spot is F8 to F11.

More closed down than F11 and you start getting into issues of diffraction patterns and fractions of light wavelengths, and the more open the lens is the more the overall quality and consistency of the lens matters.

Re: timing - recommendations for intervals between times? I'm not sure how much difference there is between one-second or five-second intervals, for example. Is there enough difference to make it worthwhile to try 1, 2, 3 & 4 seconds? Or should I just try 1 and then jump to 5? Obviously, this will depend on the available lighting, but I'm wondering what kinds of guidelines there might be.

Exposure is log scale, so each doubling of the exposure time is a single "stop". Thus 2 seconds is twice the exposure of 1 second, and 4 seconds is three times the exposure or 3 stops. If this were slide film you'd be concerned with 1/2 or 1/3 stop increments, but with print film even two stops is going to get lost in the drug store processing.

But with the moon, anything measured in seconds is quickly going to become completely flooded with light. If you can't be doing it in less than half a second, I'd say don't bother.

On second thought... How about either a filter holder with a piece of glass or plastic in it with a moon sized dot drawn on, you can try to put that over the moon. It should be fairly dark, maybe draw it on with a Sharpie (not to be confused with a Sharpei). Depth of field will blur it out a bit, softening the edges, and this might give you a moon that actually has detail.

In fact, if you go to a photo store and look at their gels, for each .3 in density you're getting roughly a "stop". Figure out the exposure of the moon with the "sunny F16" rule, take a good guess at how much the moon is illuminating the clouds (maybe meter off a streetlight lit scene that looks about as bright), and try to match the number of stops difference in darkness relative to those gels. So if you're using ASA 100 film and your camera thinks the clouds are 4 seconds, try 1,2 and 4 second shots with the equivalent of 2 or 3 layers of .9 density gel. Should be worth a try.

#Comment Re: made: 2004-02-27 01:59:25.053731+00 by: Shawn [edit history]

Truthfully though, mucho thanks. I think I have enough understanding now to do some useful experimenting. I'm certainly gonna save this thread for reference.