David,
Yes, I read the item about the moon’s one stop illumination, and I now see that
the forcing function driving exposure of moon shots is not the light but the
motion of the celestial sphere, as it is called in celestial navigation. Hence
the N00 rules for many N’s.
You “pays yer money and you takes yer choice” about celestial motion: none if
you have a clock drive, or else, How much am I willing to stand?
After that long pole in the tent, to mix metaphors, comes the matter of
aperture and ISO, the other photographic concerns.
Now I get it.
Thanks,
Bill
On Jan 30, 2019, at 8:50 PM, David Young <dsy@xxxxxxxxxxxxx> wrote:
Good Evening, Bill!
The Looney 11 rule works for a fully illuminated moon ... or at least it's a
good starting point. It works because the moon reflects a bit less sunlight
(about 1 stop) due to it's grey surface.
For my own shots, I simply trust the TTL metering, though you do have to
watch the shutter speeds, during the total phase, and adjust the ISO
accordingly. That's what I failed to do for the recent "blood moon" ... and
I know better, having photographed many lunar eclipses and 5 total solar
eclipses.
The 400 or 500 rule is actually the 340 rule ... Fred Espenak (NASA) is the
world's leading expert on such events and runs the MrEclipse.com website. In
it, he states:
"Exposure (seconds) = 340 / focal length (millimeters). For longer
exposures, you need a clock drive to compensate for the Earth's rotation."
It can be found, here:
http://www.mreclipse.com/Totality2/TotalityCh12-2.html#Right_Camera
and scroll down to the section on "Telescope Clock Drives and Polar
Alignment" & start reading.
Also note, that when the rule speaks of focal length, it refers to the
EFFECTIVE focal length on crop-sensor (APS-C & mFT) cameras.
By using the 400 or 500 (some even say 600) you get more blur due to the
rotation of the earth... so which number you use depends on just how fussy
you are. I go with Fred, at 340. He's the guru.
A good article that uses the 500 rule, but which explains things quite well,
can be found here:
https://shuttermuse.com/how-to-avoid-star-trails/
For other sites, simply Google "eclipse 500 rule".
I hope this helps. If not, you know where to find me!
David.
PS: Next total Solar eclipse visible in the USA is April 8, 2024. Details
here: https://en.wikipedia.org/wiki/Solar_eclipse_of_April_8,_2024
though there will be an annular ellipse visible through much of Canada & the
US on Saturday, October 14, 2023,
Details here: https://en.wikipedia.org/wiki/Solar_eclipse_of_October_14,_2023
For solar eclipses over Europe and other places, consult MrEclipse.com
-------------
David,
I have had no luck with moon photos, trying to begin with the Sunny 16
rule because the moon is fully lighted by the sun.
I have never seen or heard of the 400 or 500 divided by ISO rule but I
did find a Looney 16 Rule, which has nothing to do with Canadian coinage:
https://en.wikipedia.org/wiki/Looney_11_rule
I quote:
"The basic rule is, "For astronomical photos of the Moon's surface, set
aperture to f/11 and shutter speed to the [reciprocal of the] ISO film
speed [or ISO setting]."
-
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