Photo Forum / Film Photography / Darkroom / October 2004
Eclipse of the Moon
|
|
Thread rating:  |
Travis Porco - 27 Oct 2004 22:03 GMT Dear Readers:
Any thoughts regarding photographing the eclipse of the moon tonight? An article in Sky & Telescope advised against using exposures longer than a few seconds with a stationarily mounted 500 mm telephoto lens; who has any thoughts on this? The same article gave a tremendous range of possible exposure times depending on the depth of the shadow, so the only thing to do it seems is massive bracketing. Since my telephoto lens is limited to f/8, I'm going to try to push Fujicolor 1600 one stop to EI 3200; is this a bad idea? Cheers, --travis
Michael A. Covington - 27 Oct 2004 22:52 GMT > Dear Readers: > [quoted text clipped - 3 lines] > seconds with a stationarily mounted 500 mm telephoto lens; who has any > thoughts on this? Anything longer than 1 second (with a 500-mm lens) will show some trailing as the moon moves across the sky. It probably won't be objectionable unless you go beyond about 3 seconds.
> The same article gave a tremendous range of possible exposure times > depending > on the depth of the shadow, so the only thing to do it seems is massive > bracketing. Right. You may be able to classify it as a light or dark eclipse after totality begins. Exposure calculator at www.covingtoninnovations.com/astromenu.html.
> Since my telephoto lens is limited to f/8, I'm going to try to > push Fujicolor 1600 one stop to EI 3200; is this a bad idea? Haven't tried that film. Of course, a grainy picture is better than no picture at all!
 Signature Clear skies,
Michael A. Covington Author, Astrophotography for the Amateur www.covingtoninnovations.com/astromenu.html
Travis Porco - 28 Oct 2004 19:12 GMT >> Dear Readers:
>> Any thoughts regarding photographing the eclipse of the moon tonight? An >> article >> in Sky & Telescope advised against using exposures longer than a few >> seconds with a stationarily mounted 500 mm telephoto lens; who has any >> thoughts on this?
>Anything longer than 1 second (with a 500-mm lens) will show some trailing >as the moon moves across the sky. It probably won't be objectionable unless >you go beyond about 3 seconds.
>> The same article gave a tremendous range of possible exposure times >> depending >> on the depth of the shadow, so the only thing to do it seems is massive >> bracketing.
>Right. You may be able to classify it as a light or dark eclipse after >totality begins. Exposure calculator at >www.covingtoninnovations.com/astromenu.html.
>> Since my telephoto lens is limited to f/8, I'm going to try to >> push Fujicolor 1600 one stop to EI 3200; is this a bad idea?
>Haven't tried that film. Of course, a grainy picture is better than no >picture at all! Thanks for your thoughts and to everyone else who responded.
cheers, --travis
Jean-David Beyer - 28 Oct 2004 03:00 GMT > Dear Readers: > [quoted text clipped - 5 lines] > push Fujicolor 1600 one stop to EI 3200; is this a bad idea? > Cheers, --travis It is probably too late, but:
1.) The moon occupies about 1/2 degree in the sky.
2.)The moon (and almost everything else) moves 15 degrees an hour. So you can figure an exposure of 1/30 hour will make a thing twice as long as it is wide (assuming a square moon). So two minutes exposure is surely too long.
3.) The moon reflects about 250 cd/ft^2, so your exposure might as well be 1/250 second using an aperture equal to the square root of your film speed, or equivalent.
Say your film speed is ASA64. Square root of that is 8, so an exposure of 1/250 at f/8 would work. You need not stop down anymore because how much depth of field could you need with something a quarter million miles away? And opening it up should not be necessary because you should not need more shutter speed.
 Signature .~. Jean-David Beyer Registered Linux User 85642. /V\ Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 21:55:00 up 4 days, 23:47, 3 users, load average: 2.16, 2.24, 2.12
Michael A. Covington - 28 Oct 2004 04:03 GMT > 3.) The moon reflects about 250 cd/ft^2, so your exposure might as well be > 1/250 second using an aperture equal to the square root of your film [quoted text clipped - 5 lines] > And opening it up should not be necessary because you should not need more > shutter speed. Impressively accurate! But those calculations, alas, are for the uneclipsed moon...
With a digital camera set to ISO 200, my exposures at f/10 were about 1/125 during penumbral phases, up to 2 seconds during the outer part of totality. I'm not trying to photograph deep totality. See: www.covingtoninnovations.com/michael/blog (October 27 entry).
I'm doing very similar film photos, but of course they aren't developed yet
:) A digital camera makes an excellent exposure meter for difficult subjects.
Clear skies, Michael
Nicholas O. Lindan - 28 Oct 2004 17:55 GMT > "Jean-David Beyer" <jdbeyer@exit109.com> wrote in message
> 3.) The moon reflects about 250 cd/ft^2, so your exposure might as well be > 1/250 second using an aperture equal to the square root of your film > speed, or equivalent. Does this 1/(cd/sqft)seconds @ f-sqrt(ASA) produce an 18% grey?
It does produce a 'sunny 16' exposure for the moon.
 Signature Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com
Jean-David Beyer - 28 Oct 2004 21:18 GMT >>3.) The moon reflects about 250 cd/ft^2, so your exposure might as well be >>1/250 second using an aperture equal to the square root of your film [quoted text clipped - 8 lines] > Impressively accurate! But those calculations, alas, are for the uneclipsed > moon... So what? Since the moon has, according to most sources, no atmosphere, there will not be a lot of diffraction of the sunlight, so the exposure of the part still illuminated by the sun will be the same. Naturally, if there is a total eclipse, you will photograph nothing in any case.
I.e., changing the illumination of one part of the subject does not affect the illumination of the rest, and does not change the required exposure.
> With a digital camera set to ISO 200, my exposures at f/10 were about 1/125 > during penumbral phases, up to 2 seconds during the outer part of totality. > I'm not trying to photograph deep totality. Of course, but unless your digital camera had a spot meter in it, small compared with the 1/2 degree size of the moon, and pointed at the illuminated part, its exposure will be wrong (overexposed) to begin with and worse as the eclipse deepens.
> See: www.covingtoninnovations.com/michael/blog (October 27 entry). > > I'm doing very similar film photos, but of course they aren't developed yet > :) A digital camera makes an excellent exposure meter for difficult > subjects. If you say so. I would not.
 Signature .~. Jean-David Beyer Registered Linux User 85642. /V\ Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 16:10:00 up 5 days, 18:02, 3 users, load average: 4.09, 4.09, 4.02
Michael A. Covington - 28 Oct 2004 21:53 GMT >> Impressively accurate! But those calculations, alas, are for the >> uneclipsed moon... [quoted text clipped - 6 lines] > I.e., changing the illumination of one part of the subject does not affect > the illumination of the rest, and does not change the required exposure. But during the partial phases of a lunar eclipse, the moon is already in the earth's penumbra. If you were standing on the moon, in the light "uneclipsed" part, you would not be seeing full sunlight. You would be seeing a partial eclipse of the sun by the earth.
>> With a digital camera set to ISO 200, my exposures at f/10 were about >> 1/125 during penumbral phases, up to 2 seconds during the outer part of [quoted text clipped - 4 lines] > illuminated part, its exposure will be wrong (overexposed) to begin with > and worse as the eclipse deepens. With a 5-inch telescope in front of the camera, I had the moon completely filling the metering area of the picture -- nearly filling the whole frame.
>> A digital camera makes an excellent exposure meter for difficult >> subjects. >> > If you say so. I would not. Why not? Assuming comparable field of view, of course.
 Signature Clear skies,
Michael A. Covington Author, Astrophotography for the Amateur www.covingtoninnovations.com/astromenu.html
Travis Porco - 28 Oct 2004 23:20 GMT
>>>3.) The moon reflects about 250 cd/ft^2, so your exposure might as well be >>>1/250 second using an aperture equal to the square root of your film >>>speed, or equivalent.
>>>Say your film speed is ASA64. Square root of that is 8, so an exposure of >>>1/250 at f/8 would work. You need not stop down anymore because how much >>>depth of field could you need with something a quarter million miles away? >>>And opening it up should not be necessary because you should not need more >>>shutter speed.
>> Impressively accurate! But those calculations, alas, are for the uneclipsed >> moon...
>So what? Since the moon has, according to most sources, no atmosphere, >there will not be a lot of diffraction of the sunlight, so the exposure of >the part still illuminated by the sun will be the same. Naturally, if >there is a total eclipse, you will photograph nothing in any case.
>I.e., changing the illumination of one part of the subject does not affect >the illumination of the rest, and does not change the required exposure. If the moon's surface receives less illumination because the earth is blocking the sunlight, then the moon will be darker, and more exposure will be needed. Also, in total eclipse the moon is still illuminated by sunlight diffracted into the earth's shadow by our atmosphere. It's really a strange sight to see the quiet red moon among so many stars in such a dark sky, and allows us for a moment to look at familiar things as though they were new.
----------------------------------------------------------------- kind regards, --travis Rage, rage my opinions only against the dying of the light
Robert Vervoordt - 28 Oct 2004 03:15 GMT >Dear Readers: > [quoted text clipped - 5 lines] >push Fujicolor 1600 one stop to EI 3200; is this a bad idea? >Cheers, --travis When I was on a film shoot, we had to get a closeup of a Moon that was nearly full; say 85%. The film we were using was 7254, rated at 100 and shot at 24 fps, which gave us 1/48 ofr a second. Since we only needed about 6 seconds, maximum, we just shot 10 second takes at every aperture, from f-2.2 through f-22. The best was between f-8 and f-11 I forgot this when I shot a partial eclipse with a still camera some years later. I followed advice from a camera magazine and wound up about 3 stops over on slide film.
Don't forget that the Moon is a Sunlit object. The MP shots were done with a daylight filter, so the effective film speed was 64. Since we were using an Angenieux 12-120 at mavimum telephoto on 16mm, we got great big framing of a Moon who's surface was fully detailed and showed texture..
Watch out for overexposure, even with negative film.
Robert Vervoordt, MFA
The Wogster - 28 Oct 2004 04:09 GMT > Dear Readers: > [quoted text clipped - 4 lines] > bracketing. Since my telephoto lens is limited to f/8, I'm going to try to > push Fujicolor 1600 one stop to EI 3200; is this a bad idea? S & T is a group of astronomers, not astro-photographers......
One thing to remember, the moon is a fairly light coloured object, lit directly by the sun, so often the best exposures are the same as for any other sun-lit object. It's not uncommon to, with 200ASA film, to use a shutter speed of 1/250th @ f/16 and get a pretty good shot. With the eclipse, your looking at an object in shadow, it should be darker then the same object when fully lit, so maybe add 1 or 2 stops, be careful though, it's easy to way over-expose it.
With a lunar eclipse, the last thing you want to do is severally overexpose it, or you will simply wash it out and lose the effect of the eclipse, you want it darker then normal, but not so dark that you lose the detail.
If you take (took)a whole roll, warn your lab, they will go nuts trying to compensate for printing, and often you get a washed out moon on a medium gray background......
W
Michael A. Covington - 28 Oct 2004 04:56 GMT > One thing to remember, the moon is a fairly light coloured object, lit > directly by the sun, so often the best exposures are the same as for any [quoted text clipped - 8 lines] > eclipse, you want it darker then normal, but not so dark that you lose the > detail. But remember the penumbra! No part of the partially eclipsed moon is as bright as the normal full moon.
> If you take (took)a whole roll, warn your lab, they will go nuts trying to > compensate for printing, and often you get a washed out moon on a medium > gray background...... Yes, they need to know that the background is black.
rolleifix@rolleiman.com - 28 Oct 2004 07:03 GMT Well, now that it's past, I hope you got some decent shots. I tried it with my Hasselblad using provia 100f and a 150mm f4 lens. Last time I took pictures was with a Rolleiflex 2.8F (80mm) using the same film and exposures of about 10-15 seconds. The results were great. Not perfect as some celestial movement did occur during the exposure. What really made them neat was the path of the airplanes flying though the frame so I have a few slides of the eclipse, as well as the red and white lights from the planes. Oh, and the stars too.. One thing to remember when shooting the moon is what it's reflecting.. The sun. The eclipse, of course, is the earth blocking the light path from the sun to the moon. If it's something you'd want to play with more, there are all kinds of tracking devices that can be built to follow the paths of your subjects..
8) Jeff
> Dear Readers: > [quoted text clipped - 5 lines] > push Fujicolor 1600 one stop to EI 3200; is this a bad idea? > Cheers, --travis
|
|
|