At 16:58 3/3/02, Andy Gilbert wrote:
Thanks John, your photos also answered another question I had in mind, "Can
I put a 2x converter on it & photograph the moon?" :) Also, you have some
great pictures on your site, which I have bookmarked so I can take a good
look later.
Andy,
Yes you can use a 2X TC, but I recommend the OM 2X-A. Even though the
300/4.5 is not one of the lenses it's specifically made for, it has worked
very well for me [the 1.4X-A does list the 300/4.5]. Quality in a 2X TC
makes a huge difference. Had a dirt cheap two-element "generic no-name" 2X
TC long ago and it's probably worth more if I punch out the glass and use
it as an extension tube.
Use of a *sturdy* tripod that does not wobble and using the lens tripod
mount is all but a requirement even without a TC, but most especially with
the TC. Use it very carefully. I found with the 2X-A I could cause shake
visible in the viewfinder simply actuating the cable release.
Notes about the "moon" photographs:
(a) They are about 2X or so of what they appeared as in the slides. IOW,
you're not going to get the moon that size on film. It will be
smaller. About 1200mm focal length is required to begin filling the film
frame.
(b) At an effective 600mm focal length, be prepared to chase the moon
across the sky. That magnification level reminds one quickly both the
Earth and the Moon are in motion! Each frame made (about a half dozen for
each) required readjusting the tripod head. Watch exposure time
too. Earth rotation and Moon orbital motion will blur the result if it's
more than a fraction of a second.
(c) Air quality also makes a big difference. Best is a very clear nights
with many stars, usually cool to downright bitter cold and very low
humidity. High humidity, heat and especially smog will blur and haze
details making you think it's the lens.
For a full moon, spot meter on the moon. If all else fails, estimate it
using the "looney-11" rule for a full moon; f/11 at shutter speed = 1/film
speed, then bracket exposure. Less than a full moon shows more crater
detail from side lighting, especially a crescent moon, but requires more
exposure just as any other side-lit subject material would. Bracket until
you have experience with it to know what works! Kodak has the following
about the Moon in (with a slight difference in exposure recommendation):
http://www.kodak.com/cluster/global/en/consumer/products/techInfo/p150/p150a.shtml
The moon. Since the moon is our closest celestial neighbor, it presents
exceptional opportunities for astrophotography. The full moon requires the
same exposure as a sunlit subject here on Earth. The gibbous moon (between
half and full) requires two times as much exposure as a full moon (1 stop
more); the half moon requires 2 stops more exposure; and a crescent moon
(less than half) requires 3 1/2 stops more exposure than a full moon.
Although the moon appears large to your eye, it is a very small subject to
photograph. For example, with a 50 mm camera lens, the image of the full
moon will be less than 1/50 inch (0.5 mm) on your film, hardly more than a
speck. But you can take excellent pictures that will show some surface
detail if you use a lens of at least 12 inches (305 mm) focal length and
make a photographic enlargement to gain additional magnification.
You can determine in advance the approximate diameter of the moon's image
that you'll get on your film by dividing the focal length of your camera
lens by 110. Use the same units--inches or millimetres--for both image
diameter and the focal length.
-- John
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