Re: 3d comet

[Joel.Alpers@xxxxxxxxxxx]

#
#Anyone have any suggestions on how to shoot comet Hyakutake this week?.  
#Sunday night is the closest approach (9.3 million mile).  I'd like to try 
#to get a few stereo pairs and wonder if anyone else will be trying.  Any 
#help on f-stop/exposure length and lense seperation would be greatly 
#appreciated.  I'll probably use either my Realist 3.5 or my Minolta SLR.

Lens separation won't do much good, though approaching close to earth
(.1 AU) it's still _really_ far away. But you can get a stereo "effect"
by taking two photographs separated by time. The movement of the comet
against the star field gives a "psuedo" stereo effect (not referring
to pseudo-stero, where you mix up left and right film chips).

Right now in my town (Fort Collins, CO) the comet is _barely_ visible
to the naked eye, and appears as a "smudge" in binoculars. Two nights
ago I photographed it, and got a small smudge in the photo (with
some sharp star pinpoints) with a barely discernable tail. The tail
is really not terribly impressive right now as the comet is heading
pretty much towards us.

Film: I used TMAX 400, pushed one stop in my darkroom, at f/2.8 on
a 165mm lens on my Pentax 6x7. The equivalent focal length for a 35mm
camera would be about 80mm. At that focal length, on a tripod, I 
got "not too bad" exposures in the 5-10 second range. At 10 seconds+,
the stars were definitely starting to trail. At 20 seconds, trailing
was very obvious. If you use a 50mm lens you'll be able to get up
to perhaps 20 seconds exposure, but of course the comet will be
smaller! Now, my photos were taken in my back yard, in a city of
100,000. A dark site would be _much_ preferable, as I lost detail
I could see in the binoculars to background fog in the photos.

Tonight I plan to try a dark site, and TMAX 400 pushed 2-3 stops,
as well as some 35mm TMAX 3200P @ EI 1600 or 3200.  I'll be happy
to post the results if there is interest.


Joel Alpers
Rocky Mountain Memories - Equipment and Supplies for the 3D Photographer
rkymtmem@xxxxxxxx
http://www.frii.com/~rkymtmem



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