ste© said:Oh come on Paul, if you're going to post all that boring stuff, at
least give us a paragraph on the best camera settings or something!
;-)
Well after a few bottles of San Miguel Cerveza I suppose I could.
Rule number one: Use a daylight exposure. It's sunny on the moon, so
use a daylight exposure, like 250-f8. That's for a normally lit moon.
That's a useful thing to know actually, it's the brightness of the
subject that's important, not the brightness where you are. For
example, with flash photography the important thing is the distance from
the flash to the subject, not the distance from the camera to the
subject. The moon is lit by sunlight, so you use a sunlight exposure.
This will render the moon grey (which is its correct colour) rather than
a blown out white.
Note to myself: I really must go back to Porth yr Ogof (Caves) sometime
and play with my B option. Leave the camera shutter open while I wander
around the cave lighting up bits of it with my flashgun. Never tried
that with digital before, it would be great to be able to check the
results instantly. Previous attempts with film have either been lucky
or [censored].
Rule number two: An eclipsed moon is much darker. Pretty obvious
really. So you need brighter exposures. There are three ways of doing
this. One is a slower shutter speed - careful with this, too long and
the moon will blur - that's the biggest problem to watch out for.
Second is a wider aperture - great if you're using a lens with a wide
aperture, but not so good otherwise - unless you are using a telephoto
lens costing 5 grand or more, you probably won't be able to manage
better than f5.6. Thirdly, use a faster film (or increase the film
speed on your digital camera) - this is by far the easiest option. Sure
it's grainy, but it doesn't cost a fortune and it doesn't blur the moon.
Rule number three: Telephoto lenses blur more easily. The moon moves
(well actually it's the rotation of the earth that's the problem). The
longer your telephoto lens, the faster the relative movement (in a high
powered telescope the moon moves amazingly quickly). So the longer the
lens, the faster the shutter speed needs to be. I'm sure there's a
definite rule for this but I don't know it offhand, but I'm pretty sure
that 1 second exposures at 600mm won't hack it. It's better to
underexpose and get a dark but sharp moon, than a properly exposed
blurred moon.
What exposure? Don't know offhand (really, there are plenty of websites
that will tell you this, just Google).
My best advice is to use a digital camera. I never had this luxury in
the past. I've wasted entire rolls of film taking mostly blurred and
badly exposed shots. Digital is absolutely ideal for an eclipse because
you get instant feedback. Take the shot, if it screws up, alter your
settings and take it again. You can't do that a week later when your
film is developed! You've got six hours altogether and over an hour for
the actual eclipse, so there's plenty of time to experiment.
A word of advice for the latest Canon camera owners. Set your RAW &
jpeg settings so that the camera saves a large jpeg with the raw file.
This allows you to zoom into the picture to check the sharpness at high
magnification. Normally I set my camera to small jpeg to save storage
space, but in this instance it's worth using the large setting to be
able to check sharpness on the spot.
So...
1. Use the longest telephoto focal length you've got.
2. Make a number of test shots to determine the slowest shutter speed
you can use without blurring. You don't want the moving moon to blur,
that's the prime factor! There's probably a relationship between
shutter speed and focal length, but I don't know what it is offhand.
3. Once you know the minimum shutter speed, never go below it. As the
moon gets darker, widen the aperture. When the aperture is at max,
increase the film speed. When the film speed is at max, just accept a
darker exposure, *don't* reduce the shutter speed below the minimim
determined earlier. You can always brighten the pic later.
Of course, if you own Focus Magic you might accept a blurred moon and
try to fix it using motion focusing, but I'd recommend you try to get a
sharp moon in the first place.
Paul
--
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