Ad
Ad
Ad
Pages: « 1 2 [3]   Bottom of Page
Print
Author Topic: Shooting the Moon  (Read 22722 times)
b.e.wilson
Full Member
***
Offline Offline

Posts: 104


WWW
« Reply #40 on: February 09, 2004, 12:58:24 PM »
ReplyReply

Yeah, it's pretty clear we are arguing degree. I looked it up again:

f-stop = metered f-stop * (magnification + 1)

for a symmetric lens (where the iris appears the same diameter from the front or the back of the lens).

For the moon, where magnification is incredibly small (3000? miles down to less than an inch), the term (M + 1) equals 1.

For the extender, it seems silly to argue something so easy to test: meter a wall with your lens, add the extender, and meter it again. I'm pretty sure the lens opens up, but it's been a long time since I played with 35mm and I'm just not certain.
Logged

samirkharusi
Full Member
***
Offline Offline

Posts: 196


WWW
« Reply #41 on: February 14, 2004, 05:40:54 AM »
ReplyReply

OK, my 2 bits. IMHO the sunny 16 rule turns out to be more like a sunny 11 rule for the full moon. It's not beach-sand-white, more like charcoal grey. Some minor bracketing is often necessary. That said, double the exposure for half moon, quadruple for quarter moon, and go even further for a crescent. Here's an example of both a crescent moon and earthshine:
http://www.geocities.com/samirkharusi/earthshine.html
And then it all depends on what effect one is looking for. A "natural" looking moon or one showing intricate details? The latter, if done at full moon, requires a lot of contrast stretching:
http://www.geocities.com/samirkharusi/apollo.html
Logged

Bored? Peruse my website: Samir's Home
Ray
Guest
« Reply #42 on: February 18, 2004, 05:40:12 PM »
ReplyReply

Quote
Putting these together suggests that the moon needs about 1 to 1 1/2 stop more than "sunny 16 exposure", or about f/9 to f/11 at 1/ISO; this matches nicely with someone's suggestion of f/11 at 1/ISO!
BJL,
If your deductions are correct, my D60 light meter must be out by a mile.  Cheesy

A full moon on a clear night, about half way between the horizon and the mid point in the sky, required a 90th sec at F8 and ISO 100. With this exposure, the histogram was not quite fully to the right. I could probably have used 1/60th without blowing highlights. On another occasion I used 1/30th at f11 with extender, with good results.

As I recall, during discussions on the accuracy of the Sony F828 ISO settings, it came out that ISO 100 on the D60 is actually about 125. (I hope I haven't got this the wrong way round). Using the reciprocal of the real ISO, my exposure would then be 1/125th at f5.6. In other words, a sunny F5.6 rule.

I don't know what the dynamic range of the film used by Ansel Adams was, but modern B&W film has considerably greater latitude than any DSLR. If I were using B&W film instead of the D60, I think I could probably use 1/125th at f2.8 without blowing out highlights.

If we use the figures Howard has quoted, ie. the f stop is the square root of the ISO when the shutter speed is the reciprocal of the luminance in c/ft2, we get 1/250th at F10 and 100 ISO, which places the moon in zone 5. Moving it to zone 7, gives us 1/60th at f10 and in zone 8, 1/30th at f10 which is pretty close to my exposure of 1/30th at f11 at a 'real' ISO of 125.

What am I missing?
Logged
BJL
Sr. Member
****
Offline Offline

Posts: 5087


« Reply #43 on: February 20, 2004, 08:17:20 AM »
ReplyReply

One more comment on "Moonrise"; I looked at the photo again, and it really is striking how dark and contrasty the moon is compared to most moon photos, far darker than the clouds below it. That could in part be his printing choices of course, but clearly Adams aimed for a quite different tonality than is common in moon photographs, even though he knew he would then have to struggle to maintain detail in the shadowy foreground with special development procedures.
Logged
BJL
Sr. Member
****
Offline Offline

Posts: 5087


« Reply #44 on: March 12, 2004, 04:38:31 PM »
ReplyReply

Quote
With film, it is my experience that the ISO isn't as fast as the manufactorer claims in order to suit my tastes. ... Do you know if digital camera subject to the same "over rating?"
  In one sense it is far worse with digital cameras. Bearing in mind that there is absolutely no ISO speed/sensitivity standard for electronic sensors corresponding to the ISO/ASA/DIN ones for film speed, digital cameras seem to be all over the place in their exposure index scales.
   On the other hand, the good news is that as far as shadow handling, DSLR's generally compare favouably to film of speed significantly higher than the minimum speed setting of the DSLR. In other words, the minimum speed settings of most DSLR's seem to be significantly "under-rated", so are like "push processing" speeds.

P.S. The base ISO standard for digital sensors measures the highest exposure level (lowest exposure index) for which one has adequate highlight headroom; it has nothing to do with the film speed concept of determining the lowest exposure level (highest exposure index) for which one gets adequate handling of shadow regions.
Logged
Lin Evans
Sr. Member
****
Offline Offline

Posts: 269


WWW
« Reply #45 on: April 11, 2004, 12:49:20 AM »
ReplyReply

Quote
Ansel Adams produced one of the most famous moon photographs; I forget the title, but I mean the one in New Mexico with gravestones in the foreground lit by the last of the setting sun and some details in clouds too. Adams has written a detailed discussion of his exposure decisions (with no light meter available!) that kept detail in all the main elements, and it has been reproduced in various books, both his own, and volume 1 of the "Ansel Adams" books by Schaeffer. I will try to dig up a detailed reference.

Actually, the correct title was "Moonrise" Hernandez, New Mexico"

Hernandez is a very poor rural district just north of Espanola, NM and the shot was made in the late afternoon while it was still daylight from just off the shoulder of the road. The sun was low on the horizon and beautifully illuminating the white crosses in the cemetary. He exposed for the moon with an "estimate" because he couldn't find his Weston meter and the light was rapidly changing. He was shooting with a Wratten (G) filter, ASA 64 film and shot it at 1 second at F/32. Later, Ansel said that he should have given 50 percent more exposure (a half zone) because of the "low value" of the foreground which would have made the foreground slightly more dense. He had lots of difficulty with the print and several years later used Kodak IN-5 intensifier on the lower part of the image. He did lots of selective burning to get the effect he wanted and said on numerous occasions that no two prints were exactly alike.

Officially, the date and time of the shot were established by Dr. David Elmore of the High Altitude Observatory at Boulder, Colorado as 4:05 pm, October 31, 1941. Ansel never kept good notes about the time and day of his photos :-)

Today, the old church still stands north of Espanola. The bell has fallen from the bell tower and the roof has a different pitch. It's no longer possible to get a similar shot from the highway and the entire area has given way to junked autos, trashy travel trailers and such. The back of the church has debris and chain link fencing piled against it, but it still makes a nice shot from the front. It's in bad need of repair - hopefully the state of New Mexico will eventually contribute toward its preservation. Here's what the front looks like today:

Lin

Logged

Lin
gwarrellow
Jr. Member
**
Offline Offline

Posts: 65


« Reply #46 on: February 08, 2004, 05:02:12 AM »
ReplyReply

Quote
Thank you very much. so f16 @ 50 seconds for iso 100?
Exegeter, definitely not the exposure time you have suggested! If you go to the website Richard suggested you will see a link to Michael Oates' "exposure calculator". Make this device and it will guide you well. I don't have the calculator myself but I would guess that for a full moon at f16 you would need around 1/125 sec at ASA100. The secret is to bracket and keep notes (if you don't shoot digital).

There is actually no point in shooting at f16 as the moon is essentially at infinity in photographic terms. A wider aperture will allow a shorter exposure with less chance of blurring due to the earth's rotation. This effect will be dependent on the f.l. of your system; in my telescope I need to engage the motor drive even for relatively short exposures.

Other things to watch out for are precise focusing, use a tripod and cable-release, and mirror lock up if you have it. Precise focusing is more difficult than it sounds and is a particular problem with longer focal length lenses or when shooting through a telescope.

What type of equipment are you using? You will find that it is very difficult to obtain an exposure that is able to reveal lunar details and cloud features/colours and is dependent on the lunar phase and whether you are shooting in the "twilight zone" or at night. Some people resort to shooting more than one exposure: one for the moon and the other for the other feature and then combine in something like Photoshop.

Taking good lunar pictures is not as easy as it seems. If you venture further into astrophotography you will find another world again.

Good luck!
Graham
Logged
Howard Smith
Guest
« Reply #47 on: February 14, 2004, 01:27:03 PM »
ReplyReply

Your examples look good, so I think you have it.  What looks "normal" is probably over-exposed on film since your eye opens up for the night sky and is blown out by a very bright moon.  The guide lines you give are simple to remember too.

As for the "sunny-16" rule, I have always found with my particular camera/film combinations, it is more like 16 1/2.
Logged
Howard Smith
Guest
« Reply #48 on: February 09, 2004, 12:45:00 PM »
ReplyReply

The moon has about the same eflectivity as the earth.  The sunny 16 rule works fine.  Remember to increa exposure to account for overcast, haze and other atmospheric things.

Be careful with your TTL meter.  It will be reading ots os black and trying to make it gray.  Hence, overexpose the moon.

"Magnification"maens nothing.  f/16 @ 1/125 is the same for any focal length.  Remember, when using an extender, you are hanging the foal length, so f/16 isn't f/16 anymore.   The diameter of the diaphragm hasn't changed, but the focal length got longer.  The effect is a reduced f/stop.  You will need to open up or increase exposure time.
Logged
BJL
Sr. Member
****
Offline Offline

Posts: 5087


« Reply #49 on: February 18, 2004, 02:19:09 PM »
ReplyReply

Quote
The photo is "Moonrise" over Hernandez. It is detailed in "Examples, The Making of 40 Photographs."

Adams said he knew the moon had a liminance of 250 c/ft2. He used this and the Exposure Formula to determine his exposure.

The Exposure Formula is discussed in "The Negative" by Adams. It says that the key f/stop is the square root of the film speed. The shutter speed is the reciprical of the luminance in c/ft2. This will place the subject in Zone V. He exposed the moon for Zone VII, which he claims is ideal. (The modern problem is not many meters read in c/ft2.)

In the discussion of "Moon and Half Dome," Adams provides some information on selecting the exposure for the moon in the evening and in the dark.
Howard,
  thanks for the details.

  Probably the most useful piece of information is the idea of placing the moon on Zone VII, or two stops above "middle gray", combined with someone else's mention that it reflectance is about 25%, or about 1/2 to 1 stop above the 13% to 18% variously quoted for light meter calibration. Putting these together suggests that the moon needs about 1 to 1 1/2 stop more than "sunny 16 exposure", or about f/9 to f/11 at 1/ISO; this matches nicely with someone's suggestion of f/11 at 1/ISO!
Logged
Howard Smith
Guest
« Reply #50 on: February 20, 2004, 09:04:46 AM »
ReplyReply

Perhaps it is in the printing.  But the clouds are white and the moon isn't.  Quite different reflectivity with about the same illumination.  The moon may even have less illumination because the light path psses through all of the earth's atmosphere twice (the moon is near the horizon and full).  The clouds are quite near, so the light passes through about half of the earth's atmospere once and a very short distance back to the camera.

It is my opinion that many landscape images that include the moon over expose the moon - approach or achieve the washed out white disc Adams wanted to avoid.  That may be why his moon appears darker than is common.  Getting shadow detail at eveni requires more exposure to capture shadow detail and risks over exposing the moon.  The range of luminance is huge, and common TTLs will have trouble.  The moon is a small bright spot with little effect on overall exposure, so it gets lost.
Logged
Howard Smith
Guest
« Reply #51 on: March 12, 2004, 05:12:57 PM »
ReplyReply

Thanks for the info.  I was thinking to compare exposures of film and my digicam to find an equivalent digital ISO.  Maybe that won't work?

As for the moon image, the "right" exposure is the one that works for you.  A sharper mage may be more important than merely a darker image and a bit of highlight detail.
Logged
BJL
Sr. Member
****
Offline Offline

Posts: 5087


« Reply #52 on: March 14, 2004, 11:16:46 AM »
ReplyReply

Quote
Or perhaps you are right and things look different from Oz.
Indeed the moon looks the other way up Australia; I had never seen the "man in the moon" until I got to the Northern Hemisphere!
Logged
Pages: « 1 2 [3]   Top of Page
Print
Jump to:  

Ad
Ad
Ad