Moonlight film

[Kirk Keyes]

"Why would the film test have to be done on site?"

This is a good question. Even just going to a similar setup would work. Wouldn't have to be Fajada Butte.

"You just need to know what the exposure for moonlight is with the film you're using under similar conditions (phase of the moon, cloud cover)."

If you are planning on shooting on Dec. 15, then it's kind of late for that, as the moon is new right now, and there will not be a day before the 15th when suitable testing could be done as even the couple nights before full moon, the moon will have risen before sunset.

But you may want to try some test shots the night before after sunset, the moon will be higher, and about the same brightness, so all you should have to do is account for atmospheric effects. My calcs indicate the moon will be about 14 deg above the horizon 30 minutes after sunset on the 14th and about 4 degrees on the 15th.

Thanks for the paper link above - I was goingto ask if it was at Chaco.

Kirk

[Paul Butzi]

The date is very important for the test so there is no ability to do a film test on site before hand and there is no time to bracket exposures. You have to get it right the first time or wait a year.

Others have already pointed out that you can, of course, do tests during full moons in conditions that duplicate the site, in advance. You can go to the site having already worked out most of the details.

Beyond that, it's perfectly possible to bracket, even if you don't have time to make multiple exposures one after the other.

I checked the rule book, and it does not say that a photographer can only use one camera at a time.

Go there with four SLR's. You can even rig a tripod with a horizontal or vertical bar and multiple heads. Set the cameras for different exposures. When the moonlight hits the petroglyph, trip the shutters all at the same time. If necessary, you could actually have more than one person on hand so that you don't have one person frantically trying to drive multiple cameras.

[David Luttmann]

While most of the film I used to hyper was Kodak Tech Pan, I did process some Kodak PPF400 when it was available, along with some of the old Ektachromes. Hypering film that is only going to be exposed for 2, maybe 3 minutes is not going to give much of a speed advantage.....at most a half stop if you're lucky. As well, you'd have to do some tests with regards to how long to hyper each different film you may work with. Base fog and color shifts between layers can be a real problem when hypering color film. Storage is also an issue. Hypered film looses sensitivty when exposed to humidity. That is why I often went with the cold camera approach as it locked in color and lessened the chance of massive color shifts.

Unless you have a great deal of experience in hypering the films you choose, the results will in all liklehood be poor. Your best option is to go for a neutral chrome like Astia, which holds up well with regards to reciprocity characteristics, especially in short exposures less than about 4 minutes, and use a digital SLR to see how well your metering really is.

But don't bother hypering.....at best, the chrome films suggested will only benefit by about 3 stops....but that is only in exposures of 15 to 20 minutes or more. It is not relevant here.

You may want to to choose a digital capture device to benefit you in two ways:

1) Knowing you've got the shot

2) Accurate color without having to worry about shifts between layers during your exposure.

Best of luck.

[Kirk Gittings]

from william stone:

Thanks very much for posting the moon-lighting inquiry on the Large
Format forum. I appreciate your doing that. As expected, some of the
responses were off target, but there were a few helpful ones in
there as well.

I've since come across some helpful info on the web, including:

http://home.earthlink.net/~kitathome/LunarLight/moonlight_gallery/index.h
tm which has a lot of good technical info, and

http://www.mkaz.com/photo/tools/moonlight.html which gives some exposure
guidelines.

I've pretty much decided on (still working on the plan, however) using 4
cameras

(I think 4 tripods is about as many as I can haul up there -- I'm also
doing some surveying work on the butte on this trip and need to get about
75 lbs of survey equipment, plus cold-weather camping gear, plus
photography equipment hauled all the way up) -

I think I'll use:

one 35mm and three Pentax 6x7s (from my medium format days)

I think I'll shoot the same film and exposures on all 4 cameras (have the
cameras all lined up, different focal lengths, of course - so slightly
different views, and trip the shutter one after the other, then close the
shutters a minute or 2 later in the same sequence); then process the 35mm
film first and decide how much to push process...then process the 6x7
films one roll at a time, fine tuning processing as I go.

I think that, from my research, the best bet for film is going to be
Provia 100F, pushed 2 stops as a starting point.

I still need to compute the speed of the shadow's movement across the
petroglyph so I can determine just how long of an exposure I can live
with. I'm hoping that 1 minute, and prefereably even 2 minutes will be
OK.

I've got an inquiry in to find out the distance from the edge of the slab
that casts the pertinent shadow to the spiral. Since I know (from astro
software) what the angular speed of the moon is (how many minutes of time
per degree of movement), I can then figure out the horizontal speed of
the shadow as it moves across the spiral. Fun stuff to work on.

Still fleshing all this stuff out...now, if the weather will just
cooperate!

Thanks again for the help.

best, Bill