The Moon in Infrared Photos

[rguinter]

Greetings:

I've always liked landscape pictures with the moon showing clearly in the scene. Like the famous Ansel Adams photo.

Of course everyone knows how difficult it is to calculate the right (season, day, time, etc.) when the moon will be in a good position. And then have the weather cooperate as well.

So I was wondering, with infared photos and a filter that renders daylight skies black, has anyone had any success producing good landscapes with a new moon visible?

My instinct tells me that the moon's reflection may not have enough red and infrared to penetrate the filter. But I've never tried it. So has anyone had any success with this technique? I would like to hear.

Cheers. Bob G.

[Jerry Bodine]

Sorry, no experience with IR, but I believe you're thinking of "full moon" rather than "new moon" (dark side facing Earth). ;)

[rguinter]

Sorry, no experience with IR, but I believe you're thinking of "full moon" rather than "new moon" (dark side facing Earth). ;)

Well I'm scratching my head a bit. But I guess you're right about the proper phase.

I'm thinking about photos with the moon in the daylight sky. That's when infrared photography is possible and IR filters darken the sky and give good detail in the landscape. Bob G.

[al olson]

Bob,

I have made numbers of full moonrise photos. On only one occasion as I recall have I exposed monochrome, but never IR, although I use a lot of IR for mid-day shooting. In the past I have preferred color negative film for photographing full moonrises.

The techniques for monochrome are no different from color. Ideally you have something in mind for your foreground and you want to capture the moon in some detail. Blown out photos of the moon are usually pretty boring. Crescent moons being the exception. A photograph of just the moon would be better done with an astronomical telescope.

Considering that the moon will be rich in infrared while the darkening earth will be lacking infrared, I would expect that the Subject Brightness Range to be extreme.

You will want to take advantage of a couple of resources. The Naval Observatory site
(http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one-day-us) provides azimuth and elevation tables for both the sun and the moon at 10-minute intervals.

The next step is to get a USGS topo map, or some equivalent. Best is the 7 1/2 minute quadrangle at 1:24000 scale, that has your foreground subject located on it. Knowing the moon's azimuth at any given time, draw a line through your intended subject at the azimuth angle. The part of the line opposite the moon indicates the locations for setting up your tripod.

Normally you will want enough terrestrial illumination to balance the sunlight on the moon. Assume the Sunny 16 rule for the moon's illumination. Often it is better to do the exposure the day before the full moon because there will be more light on the earth when the moon comes over the horizon to balance your exposure.

For more detail on how to use the above resources I have written a guide (in need of an update) that steps through these procedures on the following link:
http://photo-artiste.com/existinglightguide.html

I hope you find this helpful.

[Lachlan 717]

If you have an iPhone, there is myriad solar/lunar apps that can give you lunar rise/set times and compass points for any given time and location.

There is a really good one that does lots of other LF stuff, such as bellows factoring.

[Jeff Conrad]

I was wondering about the phase myself ...

I can't help with IR, because I've never done it. I can understand the interest because it's usually almost impossible to handle the contrast of the Moon against a night sky (Adams's Moonrise was taken in late afternoon and the sky burned to simulate nighttime). The trick is usually to catch the Moon fairly near the horizon shortly after sunset.

The calculations aren't all that difficult, especially if you use the Sun/Moon Calculator (http://www.largeformatphotography.info/sunmooncalc) on this site. The hard part, of course, is getting the directions to the terrestrial features you want to include in the shot. There's a short discussion of how to do it in the Tutorial (http://www.largeformatphotography.info/sunmooncalc/SMCalcTutorial.htm) for the calculator above; Stephen Trainor's The Photographer's Ephemeris (http://stephentrainor.com/tools), in addition to other things, can help in getting the azimuths and altitudes of natural features from your favorite camera position.

Of course, it's still a fair amount of work, but without some effort in planning, you're unlikely to get the shot. You might just be heading south towards Espanola, NM some afternoon and have it happen before your very eyes, but you've got to ask yourself one question ...

[Jeff Conrad]

Be very careful about always assuming "Sunny 16" for the Moon's luminance. While that's correct for a full moon that's high in the sky (say, above 40° altitude), it doesn't work when the Moon is near the horizon--depending on the luminance of the sky, the luminance of the Moon can vary by as much as 10 steps between the horizon and 10°. During the day, this isn't an issue (except that the Moon may be hard to see on the horizon), but once the Sun sets, the sky quickly gets darker as the Moon gets brighter. I've made many shots in which the exposure window for the Moon in its desired position is only a minute or two.

[rguinter]

Thanks to everyone for all the numerous suggestions and links.

I have gotten lucky on occasion with the moon (or a sliver) in sunrise/sunset photos as most comments here suggest. One attached from one of my vintage Atlantic City, NJ sunrise photos. Just a thin crescent showing in the right corner of the panorama.

But really I'm thinking full daylight with the moon somewhat near full and prominant against a dark sky on infrared film. Just wondering if this is possible or if other infrared photographers have been able to produce photos with the moon in good contrast against a darkened daylight sky. Bob G.

[Wallace_Billingham]

A nice trick with IR film is to fake moon shots by using the sun as the moon. I have done this a few times now.

You need a day when there is broken cloud cover. When the sun is low in the sky during the morning or late aftnoon point your camera at the sun wait for it to go behind a cloud and make your exposure.

With the Efke IR820 film I have had good results with f/22 for .5 to 1 second with a Hoya R72filter.

It works best if you have something in the foreground to reflect the IR light such as water or green vegitation. The trick is to under expose everything else but the sun this will give you black skies like it is night and you will get just enough detail in the foreground to make it shine.

You need to keep the sun behind a cloud so it does not look strange like a blown out full moon.
'
This link http://www.flickr.com/photos/eye_of_wally/3737493718/ will take you to an example of mine (shot on medum format film)

[brianam]

I guess one watchout is length of exposure -- what's the old rule about the moon? it starts to blur after just 1/8 or 1/4 second? or similar, I thought.
I've tried to keep that in mind when imagining a sharp moon in a photo, versus the classic floating moon-sausage.

With the current crop of IR films rated down at ISO 1.5 or 3, it starts to push on this timing I imagine.
-Brian

PS -- would someone please reply to Jeff with "...Do you feel lucky, punk?" :-)

[rguinter]

Brian: Yes I'm sure length of exposure will come to play. Back when I was doing mostly small format I often tried to get a sharp moon in photos. Never really seemed to work because the length of exposure at sunset (when the full moon rises) turned out to be too long. So I eventually gave it up.

Hence the thought that had me starting this thread. I have quite a bit of HIE in the freezer just waiting for the right situation to make it worthwhile using some of it up. I've been rating it ISO 50 with a red filter and getting nice skies... probably ISO 25-50 with my B&W 092 filter. So I think I could get a sharp moon with f11-f16. And I've often seen a moon (close to full) in the morning sky with full sun. But of course it's rather washed out. Bob G.

PS. That's a classic old Clint Eastwood quote. Probably a bunch of us here remember it well with the guy on the ground looking up (or is that down) the barrel of his 10-inch S&W model 29. But my son probably wouldn't, even though he has a copy of Clint's photo with the 44 on his wall......

[Jeff Conrad]

General rule of thumb: the longest acceptable exposure time in seconds is

time = 5–10 x (lens focal length)/(format diagonal).

Based on my experience, I'd recommend staying close to the short end of the range.

[tgtaylor]

Last year I took shot a view overlooking San Francisco around noon with a 35mm lens on an F3 using Ilford SFX. I didn't care for that shot but the Quarter moon was clearly visible against the dark sky. I'm certain that the moon would be prominent on Rollie 4x5 IR.

[GPS]

General rule of thumb: the longest acceptable exposure time in seconds is

time = 5–10 x (lens focal length)/(format diagonal).

Based on my experience, I'd recommend staying close to the short end of the range.

Com'on Jeff, you know better than that. Recheck it and make it useful advice...;)

[Jeff Conrad]

Com'on Jeff, you know better than that. Recheck it and make it useful advice...;)

Woops ... it should be


time = 5–10 x (format diagonal)/(lens focal length)

Kodak publication P-150, Astrophotography Basics (http://www.kodak.com/global/en/consumer/products/techInfo/p150/P_150.pdf) (PDF), uses "focal length of normal lens" in the numerator. A quick analysis revealed that the middle of the range resulted in blurring similar to that used in the normal criteria for determining the circle of confusion for depth of field. Because the blurring is unidirectional, I suppose it might be slightly easier to spot, but I've found the above guideline quite workable. I can say this: the one time I unthinkingly failed to heed it (for an exposure time about twice the upper limit, during a lunar eclipse in 2003), the motion blur was noticeable.

[ROL]

It is my custom not to respond to forum threads unless I am able to clarify from personal knowledge and experience, as well as adding to a broader knowledge of the subject. As I read the OP's question, it seems to be less about the use of infrared films, and more about achieving a reasonably bright, full-ish moon in a reasonably dark sky, with monochrome films. So, I will attempt to add something(s) of value to what seems to me to be a poorly focused question, in order to educate, so far as I can, anyone landing upon this thread.



I've always liked landscape pictures with the moon showing clearly in the scene. Like the famous Ansel Adams photo.
"Moonrise, Hernandez, NM"? (http://www.anseladams.com/content/ansel_info/ansel_ancedotes.html)


Of course everyone knows how difficult it is to calculate the right (season, day, time, etc.) when the moon will be in a good position. And then have the weather cooperate as well.

Not "everyone", of course. Consult any book of astronomical tables located in virtually any public library, or use this handy little shareware software program: HourWorld (http://www.hourworld.com/index.htm). Use these in combination with a map and your personal knowledge of the location and local weather conditions (admittedly, as a meteorologist, I may have a slight advantage here) to set up any composition of any scene with any moon you wish.


So I was wondering, with infared photos and a filter that renders daylight skies black, has anyone had any success producing good landscapes with a new moon visible?

This is the part of the OP's question that prevented me from entering this discussion, until now, as I have limited experience with IR films or its easier incarnation, SFX. What I can say is that no infrared (IR), longwave heat radiation travels far enough from the moon's surface to penetrate the earth's ionosphere, much less its troposhere in order to render the moon succinct from the sky on true IR films.


My instinct tells me that the moon's reflection may not have enough red and infrared to penetrate the filter. But I've never tried it. So has anyone had any success with this technique? I would like to hear.

I guess your "instinct" might be correct here but the statement seems pretty nonsensical to me, as the use of IR films (not SFX) is to record a part of the spectrum beyond the visible red wavelengths (i.e., heat).

I have often come across photographers of less than rigorous bent who try to ape a certain style of landscape interpretation with overwrought filtering (i.e., red) and special films to add contrast to the sky and its cloud and/or moon inhabitants. There is nothing about the kind of scene you describe and wish to emulate that cannot be achieved with normal panchromatic films (SFX included) and a properly educated technique.

Now, in these digital days this can difficult to discern, even when viewing the work of a master, what you are actually looking at. Is it a digital image, a digitally processed negative, or a digital scan of traditional print? You see, here is where photographic shooters and photographic artists diverge.

What I can assure you of is that "Moonrise, Hernandez, NM" (http://www.anseladams.com/content/ansel_info/ansel_ancedotes.html) is a print, labored over in a darkroom where manipulations of light reflected the hand of an artist intent on bringing his full vision to the gelatin silver print (gsp), wringing out every piece of information gathered from light registered within the negative at the time of exposure. There are, and I'm sorry I cannot remember where, other versions of this print in which the sky was not burned black, and light cirrus is visible (contained in the negative) competing with the moon's brightness - and not preferred by Adams.

I believe some of the information regarding this question was actually previously dealt with in this very forum last year:
"Scenes with Full Moon at night" (http://www.largeformatphotography.info/forum/showthread.php?t=51842)
I will elaborate on my response to this previous thread based on the tenor of the OP's question, as I can best interpret it. The (only) example in the entire thread, posted by me, is a scan of real gsp, not a negative. Since there was no direct light anywhere in the scene, the sky was burned in the darkroom to satisfy my personal visualization of the scene, while dodging the moon to keep it as bright as possible. The darkroom manipulation (in this case burning the sky) amounted to more than 30 times the initial exposure when printing as large as 24"X40".

Hope this helps.

[rguinter]

Comments to ROL:

Goodness you read my mind about everything in my original question. Only problem is you read it mostly wrong.

Yes my question is very specifically about use of infrared films. I really did think that part of my question was clear. I have been doing about 75% infrared work lately and there are several members of the group here who I know are bitten with the infrared bug. So I was hoping someone would come through and tell me how well these films can render a daylight landscape with a crisp (nearly full moon) against a near black sky. Essentially the idea I am hoping to try when the time is right.

Well yes it is a bit difficult for me anyway to predict exactly when the moon will be in relation to some specific landscape I might have in mind. Like directly above the empire state building while observing from center span of the brooklyn bridge in daylight. One of the thoughts I had for a nice photo but haven't had the chance to actually check its feasibility, or plan it out and try to accomplish it.

And the infrared wavelengths of current films are well below the wavelengths for heat. The old Kodak HIE is sensitive up to about 1000nm. All the rest of the current films drop off much lower than that. Some with sensitivity maybe up around 850nm but not much higher. These are not heat wavelengths. If they were I suspect there would be no such thing as infrared film which would be fogged as soon as it came out of the freezer.

Anyway. I may be able to answer my own question soon. There was a waning moon this evening just above the 9/11 memorial near where I work. It was very bright in a cloudless blue sky. So I took some shots with infrared Ektachrome which I had previously loaded in my carry-around camera. The EIR does not produce black skies like HIE but usually quite dark and saturated blue. So when I get the film processed I may have a better understanding of the essence of my question.

Bob G.

[rguinter]

P.S. I never studied how Ansel Adams produced the Moonrise in Hernandez photo so I thank everyone for enlightening me on how it was done. Silly me for thinking perhaps it was a print from a negative without much "photoshop-ing." Apparently Adams used extensive techniques to enhance the negative.

[Jeff Conrad]

A contact print of Moonrise can be seen here (http://notesonphotographs.eastmanhouse.org/index.php?title=File:Moonrise_contact_print.jpg) at George Eastman House.

You won't ever find the Moon over the Empire State Building from the Brooklyn Bridge, because the Moon never gets that far north in New York City; minimum azimuth of rise is about 50°, and maximum azimuth of set is about 310° (and those are extreme values that seldom occur at the time of full moon).

[al olson]

This coming Monday, weather permitting, should be a good example of what you can expect for good photographic conditions. The moon is waxing and there will be 99% illumination so the disk will appear round. Full moon is on Tuesday.

A check of the Naval Observatory site for Monday for New York (http://aa.usno.navy.mil/cgi-bin/aa_pap.pl) shows that sunset is at 7:48 EDT. Moonrise is at 7:17 EDT and begins at about 112 degrees azimuth (from http://aa.usno.navy.mil/cgi-bin/aa_altazw.pl) and during the next hour moves southward to 122 degrees.

At sunset the moon will be at 117 degrees and elevation will be 4.7 degrees. (Note that for the above links the first gives times in Daylight Time and the second link gives them in Standard Time.)

To get the moon at a higher elevation on Sunday the moon's elevation at sunset will be 16.7 degrees with 97% of the disk illuminated. (Tonight's moon will only be 91% illuminated so it appears out of round.)

Naturally the midday sun will be most IR-rich. My experience with using IR in the winter is that the oblique sun angle apparently filters out much of the infrared. This would be a problem with light at sunset as well.

I am interested in hearing how your efforts turn out. Keep us informed.

I still have about 20 sheets of HIE that I have been hoarding in my freezer waiting for the right opportunity. I hope it is still good.

[ROL]

Goodness you read my mind about everything in my original question. Only problem is you read it mostly wrong.


Good Luck finding prints photoshopped by Adams, anything approaching the red from the moon alone, and shooting that "waning" moon tonight!

[rdenney]

Good Luck finding ... anything approaching the red from the moon alone...

This is, finally, an answer directed to the question, except that it doesn't answer the question with any authority or usefulness. The question was, pretty obviously to me: Is there enough red and IR in the illumination of the Moon to make a good exposure on IR film? I suspect the reason there have been no authoritative answers is that nobody who has responded knows.

As it turns out, the Moon reflects IR just fine--maybe a bit better than in the visible spectrum. So, if the Moon, absent absorption by the Earth's atmosphere, exposes similarly to sunlit objects, so it should with IR. If so, then in theory, the Moon's relative exposure on IR film should be about the same as a cold gray rock on the Earth in sunlight. Thus, I would think it worth the experiment for someone wanting to know. Obviously, nobody here has conducted that experiment, but we can guess what might work from other science. The open question is whether the Earth's atmosphere absorbs IR sufficiently to affect the answer, and I rather doubt it.

Here's a paper showing the reflectance of the lunar surface with respect to wavelength. Note the graph at the end of the paper (which is all I looked at, admittedly). IR is the region just longer than 750 nm. The graph suggests that UV photography of the Moon is likely to be a bust, though.

Scientific paper showing graph of Moon's reflectance with respect to wavelength (http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1269.pdf)

Rick "wondering what in the heck Ansel Adams's manipulations of Moonrise has to do with it" Denney

[rguinter]

A contact print of Moonrise can be seen here (http://notesonphotographs.eastmanhouse.org/index.php?title=File:Moonrise_contact_print.jpg) at George Eastman House.

You won't ever find the Moon over the Empire State Building from the Brooklyn Bridge, because the Moon never gets that far north in New York City; minimum azimuth of rise is about 50°, and maximum azimuth of set is about 310° (and those are extreme values that seldom occur at the time of full moon).

Thanks for that Jeff. I've shot the empire state building from the brooklyn bridge several times trying to get a good photo. The concept has many technical difficulties. And while doing so I was thinking how nice a really good photo from that vantage point would look with the moon setting above.

But you saved me some effort trying to deduce if it is feasible. From your analysis I see it is not. So I won't ponder the concept any longer.

The best I've been able to do so far is attached... having me surely wishing that Kodak Ektar 100 had been available this time last year.

Thanks for your analysis though and I'll keep trying to improve the shot. Done with a Takumura 400mm tele lens on 4x5-inch Provia if I recall.

Now back to thinking about infrared which was the initial thought of this thread.

Cheers. Bob G.

[rguinter]

Bob, ...You will want to take advantage of a couple of resources. The Naval Observatory site
(http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one-day-us) provides azimuth and elevation tables for both the sun and the moon at 10-minute intervals...



Al: many thanks for the link. I've bookmarked it and will refer to it as needed.

Years back when doing only small format I used to buy the nautical tables every year with the data printed for each day of the year. That helped me predict sun and moon positions for telephoto shots that I was doing. Not LF but a few examples attached.

The Naval Observatory link will help if I decide to try doing some of these again.

Cheers. Bob G.

[rguinter]

Good Luck finding prints photoshopped by Adams, anything approaching the red from the moon alone, and shooting that "waning" moon tonight!

Was using the term "photoshop-ing" in the figurative sense... meaning "enhanced" beyond what the negative captured.... Bob G.

[tgtaylor]

This is, finally, an answer directed to the question, except that it doesn't answer the question with any authority or usefulness. The question was, pretty obviously to me: Is there enough red and IR in the illumination of the Moon to make a good exposure on IR film? I suspect the reason there have been no authoritative answers is that nobody who has responded knows.


It's no big deal but in my post somewhere above I stated that I once shot an overlook of San Francisco at midday with a half moon on 35mm Ilford SFX and the moon appeared against the black sky on the print pretty much as it looked when I shot it. IMO Rollie IR film - esp 4x5 - will give a much better rendition. You can capture the moon when it's closer to the horizion if you do the math and choose the appropriate shutter speed. I shoot Rollie (rated 400ISO) with a Cokin 007 IR filter at an ISO of 6. (Note: Focus and determine the normal exposure at ISO 400, place the filter in the holder and then open up 6 stops - simple stuff.) When the moon is close to the surface pay close attention to the shutter speed. Again, do the math for the focal length of your lens. You can find the formulas in star atlas and guide books such as Nortons as well as on the web. If you're going to shoot the moon at night, then take a spot reading off the lunar surface - that's Zone 5 - and go from there. Piece of cake. Infants do it.

[Jeff Conrad]

The U.S. Naval Observatory Data Services site page is migrating to http://www.usno.navy.mil/USNO/astronomical-applications/data-services

Several pages are useful for photographers:


Complete Sun and Moon Data for One Day (http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one-day-us), which gives Sun and Moon data for one day, but doesn't give the azimuths of rise and set.

Rise/Set/Transit Times for Major Solar System Objects and Bright Stars (http://www.usno.navy.mil/USNO/astronomical-applications/data-services/mrst-us), which gives Sun or Moon data, including azimuths of rise and set, for one or more days.

Altitude and Azimuth of the Sun or Moon During One Day (http://www.usno.navy.mil/USNO/astronomical-applications/data-services/alt-az-us), which gives positions of the Sun or Moon throughout the day.

You might also want to look at the Sun/Moon Calculator (http://www.largeformatphotography.info/sunmooncalc) on this site, which gives complete data (rise/set times or positions) for the Sun and the Moon in one step, and gives all times in daylight time when that's in effect. And it gives all the information for times or positions in one step. It also allows searching for dates on which the Sun or Moon will be in a particular position, which sounds related to what you're trying to do.

Yet another useful tool is Stephen Trainor's The Photographer's Ephemeris (http://stephentrainor.com/tools), which is more of a graphical interface. It includes a tool for measuring the directions of features from a given point, which is helpful for determining where you want the Sun or Moon. The tool won't help much with the altitude angle of man-made features like the Empire State Building, but it will give the azimuth.

[rguinter]

...If you're going to shoot the moon at night, then take a spot reading off the lunar surface - that's Zone 5 - and go from there. Piece of cake...

Yes done the moon many times at dusk and in the evening. Spot metered it and went from there. Sometimes multiple exposing over time to get a series. Piece of cake.

It's the daylight IR shot that crossed my mind as potentially a nice photo. Have a freezer full of HIE in 4x5 that is just waiting for the right conditions to warrant using it. Can shoot it at ISO 50 or so with a deep red filter. Thanks for the note. Cheers. Bob G.

[Jeff Conrad]

Metering the lunar surface isn't as easy as it first appears. The Moon's angular diameter is approximately 1/2°; with a long lens and a TTL spotmeter on a small-format camera, it may be possible to get an accurate reading, but most handheld spotmeters are 1°. For a full moon against a dark sky, you could theoretically correct for this difference by assuming that the actual lunar luminance is two steps brighter than the meter indication (if the meter reading is taken as Zone V, the Moon is effectively placed on Zone VII), but that's assuming quite a bit about the meter's acceptance angle. During the day, this doesn't work because the sky is often as bright as the Moon. Of course, during the day, exposing for the landscape usually works just fine for the Moon, at least with normal film. I haven't worked with IR, so I can't say whether the same holds true.

[rdenney]

It's no big deal but in my post somewhere above I stated that I once shot an overlook of San Francisco at midday with a half moon on 35mm Ilford SFX and the moon appeared against the black sky on the print pretty much as it looked when I shot it.

You did and I missed it.

Rick "who had another target in mind" Denney

[rguinter]

Metering the lunar surface isn't as easy as it first appears. The Moon's angular diameter is approximately 1/2°; with a long lens and a TTL spotmeter on a small-format camera, it may be possible to get an accurate reading, but most handheld spotmeters are 1°. For a full moon against a dark sky, you could theoretically correct for this difference by assuming that the actual lunar luminance is two steps brighter than the meter indication (if the meter reading is taken as Zone V, the Moon is effectively placed on Zone VII), but that's assuming quite a bit about the meter's acceptance angle. During the day, this doesn't work because the sky is often as bright as the Moon. Of course, during the day, exposing for the landscape usually works just fine for the Moon, at least with normal film. I haven't worked with IR, so I can't say whether the same holds true.

Jeff: I dug out my old field notebook from 1994. I kept lots of notes on the end sheets. My note from sometime back then indicates the full moon metered at eV 11.5 with my spotmeter. I recall making shots at that time based on that info with good results. Looks like I also spot metered the noon sun... believe it or not. Through a series of heavy ND filters. And estimated it to be eV 31.5 based on the reading plus the filter factors. For whatever good it did me at the time. I don't recall ever using the estimate for anything.

About IR film... well for those of us that use it I suspect most would agree... exposure is almost always an educated guess with bracketing if one wants to be assured of a good shot. One attached that I took last December with a sheet of HIE. Was f22 @ 1/4s with a Tiffen 87 filter. And not much blue sky that day.

Cheers. Bob G.

[Jeff Conrad]

... the full moon metered at eV 11.5 with my spotmeter. I recall making shots at that time based on that info with good results.

Could well be, but many variables are involved, especially the sky brightness and the Moon's altitude. Against a dark sky, I typically read about 2 EV less than what I would expect, but about is the operative word. Suffice it to say that the reading is a combination of the Moon and the surrounding sky. In fact, even the reading of the Moon's surface is a combination of light from the sky and the Moon itself, as Adams pointed out in the chapter "Moon and Moonlight" in Natural Light Photography. He was wrong on assuming a constant 250 cd/ft^2 for the Moon itself, but just about everything else in that chapter remains the definitive treatment as far as I'm concerned. Of course, because it doesn't cover IR, you might consider it lacking ;)

[tgtaylor]

Looks like I also spot metered the noon sun... believe it or not. Through a series of heavy ND filters. And estimated it to be eV 31.5 based on the reading plus the filter factors. For whatever good it did me at the time. I don't recall ever using the estimate for anything.


Somewhere, several years ago, I read that when photographing the sun to meter off the sun's corona. The corona is is the super heated plasma atmosphere surrounding the surface and extends for many millions of miles into space. I've used that technique with great sucess. Use extreme caution when pointing any optical device at or near the sun. Also, I'd be very leary about metering directly off the surface. The light is so intense that it may blow the meters sensor - in addition to leavng you blind.

[rguinter]

Well my eyes are failing a bit these days but mostly because of age I would guess. Making the reading through heavy ND filters kept the reading within the range of the spot meter so was only a little brighter in the viewfinder than with normal usage.

I've often shot photos with the setting sun directly in the view as the major element. My technique was to spot-meter the sky eV several sun diameters adjacent and use that reading as the basis for my exposure... with bracketing of course. Was very effective. Bob G.

[al olson]

The U.S. Naval Observatory Data Services site page is migrating to http://www.usno.navy.mil/USNO/astronomical-applications/data-services

. . .


Jeff, thanks for the heads up on the change. I was on that site less than a week ago and did not catch any notification that they were changing their links.