Moony 16?

EASmithV · May 22, 2009

Well, we are all familliar with the sunny 16 rule. I know that for one of his most famous pictures, Ansel Adams used the light from the moon as a constant to calculate exposure.

So, on a cloudless, clear night, what is the exposure time for a full moonlit landscape at f16?

Lee L · May 22, 2009

EASmithV said:
Well, we are all familliar with the sunny 16 rule. I know that for one of his most famous pictures, Ansel Adams used the light from the moon as a constant to calculate exposure.

So, on a cloudless, clear night, what is the exposure time for a full moonlit landscape at f16?

http://www.thenocturnes.com/

and another it took me some time to find

http://home.earthlink.net/~kitathome/LunarLight/moonlight_gallery/index.htm

Lee

Sirius Glass · May 22, 2009

A rough calculation is that the Moon is luminated by the same source the Earth is. The albedo [reflection] is on the very rough order of 0.5. So for back of the envelop calculation f/16 at 2 * 1/(the film ISO) seconds is a good starting point for a full moon.
So if the ISO is 400, the exposure would be f/16 at 1/200 seconds

Steve

Lee L · May 22, 2009

Sirius Glass said:
So for back of the envelop calculation f/16 at 2 * 1/(the film ISO) seconds is a good starting point for a full moon.
Steve

He's looking to photograph an earth landscape by moonlight, not a moonscape from earth.

So, on a cloudless, clear night, what is the exposure time for a full moonlit landscape at f16?

BTW, the moon's albedo averages 0.12, not 0.5.

Lee

jasonhall · May 22, 2009

Well to photograph the moon its self there is the Lunny 11 rule. But to shoot the land scape under a full moon? That will be a good experiment the next time it comes around and we can get rid of some of these clouds. f16 1/200 @400ASA just can't be right....

Jason

Q.G. · May 22, 2009

Remember though that instead of spending hours shooting a landscape lit by the moon, almost entirely the same effect could be achieved shooting it in a fraction of a second lit by the sun.
Different would be the star trails, which you don't get in the day , and the motion blur in anything showing teven the slightest movement.
And the funny colour cast caused by a very long exposure.

Lee L · May 22, 2009

Q.G. said:
Different would be the star trails, which you don't get in the day , and the motion blur in anything showing teven the slightest movement.

And perhaps the fact that the light source, although the same angular size as the sun, moves across the sky at about 15 degrees/hour, making for a much softer light over the length of the exposure.

Lee

Q.G. · May 22, 2009

Yes, indeed. Any other thing marking the passing of time will show too.

Christopher Walrath · May 22, 2009

Wirelessly posted (BlackBerry9000/4.6.0.167 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102 UP.Link/6.3.0.0.0)

I would start at an EV7 with a bright and high full moon and bracket long from there. And don't forget your tripod and remote shutter release.

Lee L · May 22, 2009

Christopher Walrath said:
I would start at an EV7 with a bright and high full moon and bracket long from there. And don't forget your tripod and remote shutter release.

Can you give the calculation for that?

The Sun is astronomical magnitude -26 and the moon is -13. That works out to 17.27 stops difference in the light source if I got my quick math correct.

The tables that I've seen recommend EV -2 to EV -3 for a full moon where the moon is more than 40 degrees above the local horizon. Gibbous moon about EV -4 and quarter moon (half lit) about EV -6.

Sunlight being EV 15 and subtracting the astronomical magnitude difference works out to about EV -2.3 for moonlight, in line with published tables.

Lee

ic-racer · May 22, 2009

Adams said the moon is 250 footcandles and used that info to 'place' the moon in the negative's tonal scale (he said Zone VIII for 'Moonrise'). Some of you are talking about the moon's illuminance (which is much less than 250 footcandles), but in Adam's famous case he was using the moons luminous exitance.

Lee wrote the moon is -13 in 'astronomical magnitude' but I wonder if he can confirm the 250 footcandles that Adams used.

Lee L · May 22, 2009

ic-racer said:
Lee wrote the moon is -13 in 'astronomical magnitude' but I wonder if he can confirm the 250 footcandles that Adams used.

Well, he was in the ball park. 250 footcandles works out to about 2690 cd/m^2. There's a table for lunar luminosity here: http://www.calphoto.com/moon.htm which takes into account atmospheric extinction, which is dependent on altitude. He was right for a moon about 15-20 degrees above the local horizon.

Also see the last note on that web page for comments on Adam's techniques and use of a single value for the luminance of the moon.

Lee

Q.G. · May 22, 2009

Lee L said:
Can you give the calculation for that?

How complicated do we 'need' it to be?

Christopher Walrath · May 22, 2009

Ah, no sweat. As to my EV7, that was a guess and a starting point, albeit far off. As to the 250c/ft2 and EV-2 thing, Ansel was photographing the sunlight reflecting from the surface of the moon. We're talking about photographing subjects lit by that light reflected form over 300,000 miles away. That's gonna be kind of diffused.

EASmithV · May 24, 2009

Q.G. said:
How complicated do we 'need' it to be?

:rolleyes:

Are you forgetting? This is APUG...

ic-racer said:
Adams said the moon is 250 footcandles and used that info to 'place' the moon in the negative's tonal scale

250 footcandles is like EV10... How can a moonlit landscape be EV-2 and also be EV10? I'm totally lost... Maybe I should get more sleep, but this is just not making sense...

Seriously guys, without busting a flux capicitor, what would the exposure be using 400 speed film at f16 on a full moon night under ideal atmospheric conditions? If the Sunny 16 rule can be so simple, why can't the Moony 16 rule be as simple as well?

EASmithV · May 24, 2009

EASmithV said:
:rolleyes:

Are you forgetting? This is APUG...

250 footcandles is like EV10... How can a moonlit landscape be EV-2 and also be EV10? I'm totally lost... Maybe I should get more sleep, but this is just not making sense...

Seriously guys, without busting a flux capicitor, what would the exposure be using 400 speed film at f16 on a full moon night under ideal atmospheric conditions? If the Sunny 16 rule can be so simple, why can't the Moony 16 rule be as simple as well?

Wait, so the moon itself is EV10, and not the landscape lit by the moon? I could always just get a spot meter reading of the moon if I wanted to shoot it, that's not a problem. What I want to do is figure out the exposure for a moonlit landscape.

WGibsonPhotography · May 24, 2009

can you not just take spot readings when you're shooting the picture and come up with your own Mooney {insert aperture here} after you shoot enough moonlit landscapes?

maybe I'm missing something because I'm tired. I'll probably edit or delete this tomorrow (actually later today ) when I read this thread again.

Tom A · May 24, 2009

With slide film I use Moony 2.8 for landscape photos. Moony 2.8 is based on experience and only works with the full moon.

Moony 2.8:
100 ISO slide film, f:2.8,
photos with nigthfeeling, exposure time 2 minuts
photos which almost look like day photos, exposure time 4 minuts

For B&W-film I would use these settings and times as a starting point.

Regards,
Tom

Lee L · May 24, 2009

Tom A said:
With slide film I use Moony 2.8 for landscape photos. Moony 2.8 is based on experience and only works with the full moon.

Moony 2.8:
100 ISO slide film, f:2.8,
photos with nigthfeeling, exposure time 2 minuts
photos which almost look like day photos, exposure time 4 minuts

For B&W-film I would use these settings and times as a starting point.

Regards,
Tom

f:2.8 for 2 minutes with ISO 100 is EV -4. Depending on the slide film, that's pretty much EV -2 to EV -3 with reasonably common reciprocity failure thrown in.

Like an incident meter, astronomical magnitudes are a measure of the light arriving from a light source (and can be used to determine the distance to an object if you know its intrinsic brightness), and I know the solar and lunar magnitudes and how to calculate differences off the top of my head. That also makes them a very good indicator of exposure by moonlight relative to exposure by sunlight. So it's a good quick check on whether a suggestion of EV 7 (which "felt" way off to me for any normal film) is in the ballpark. The aim was reasonable accuracy using simple 9th grade algebra and two known facts.

Very few light meters are spec'ed for EV -2 and below, although a few may work reasonably well there. So a simple meter reading of the moonlit scene may not get you correct exposure.

Lee

BTW, the first good measurement of distant objects (like galaxies) was done using astronomical magnitudes. Henrietta Swan Leavitt realized that she could determine the intrinsic brightness of certain variable stars from their pattern of variability (measuring from photographs). Knowing their intrinsic brightness (aka absolute magnitude) and their apparent brightness (visual or photographic magnitude) allows the use of the inverse square law to determine distance. It was her work that Edwin Hubble used to settle the issue of the size of the universe.

Q.G. · May 24, 2009

Lee L said:
Knowing their intrinsic brightness (aka absolute magnitude) [...]

Which we do only in theory, of course.
Which means the measurement is only as good as the theory.
And that becomes a big problem if you then base new theories on these measurements.

EASmithV · May 24, 2009

Tom A said:
With slide film I use Moony 2.8 for landscape photos. Moony 2.8 is based on experience and only works with the full moon.

Moony 2.8:
100 ISO slide film, f:2.8,
photos with nigthfeeling, exposure time 2 minuts
photos which almost look like day photos, exposure time 4 minuts

For B&W-film I would use these settings and times as a starting point.

Regards,
Tom

Which would be 15 minutes at f16 using 400 speed film?

Tom A · May 24, 2009

Yes - plus some extra time for reciprocity failure, which just keep getting worse as time addes up.
Reciprocity failure is also dependent on the film, some film has little (Fuji Acros) other has more than plenty (Fomapan 100), so my guess would be that 15 minutes are not enough, maybe 30 or 60 minutes is enough, I don't know. You will have to make some test exposure to find out!

Regards,
Tom

Ian David · May 24, 2009

Q.G. said:
Yes, indeed. Any other thing marking the passing of time will show too.

Which all leads to the result that a long exposure by moonlight at night can be a significantly different look from a short sun exposure by day, depending upon the subject of the shot...

(It may also e.g. allow a shot of a scene that is empty of people/cars/etc at night that would be crowded during the day. And lights that are on at night will obviously look different to lights that are not on during the day. Etc etc)

Q.G. · May 24, 2009

iandavid said:
Which all leads to the result that a long exposure by moonlight at night can be a significantly different look from a short sun exposure by day, depending upon the subject of the shot...

Indeed.
A moon-lit tennis match, for instance, would look completely different.

Ian David · May 24, 2009

Formula 1 is also a pleasing subject, I believe!

Moony 16?

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