Astronomical Photographs I have taken
Information for future reference ... perhaps I can save
myself (or others) a few rolls of underexposed shots.
- Oct 17, 1997: RIT Observatory grounds.
Moon via afocal projection with Astroscan and telephoto lens.
- Unguided and piggyback exposures with 28mm and telephoto lenses,
Aug/Sept 1998. I learned the following (for ASA 1600 film):
- at f/5.6, a 300-second exposure starts to pick up background sky.
Even longer exposures might be better.
- using 200mm f/5.6 lens, 300-sec exposure goes to maybe mag 10;
much deeper than Skalnate Pleso
- using 200mm f/5.6 lens, 90-sec exposure goes to maybe mag 8.5;
slightly deeper than Skalnate Pleso
- using 28mm f/2.8, 60-sec exposure goes to maybe mag 7.5; about the
same as Skalnate Pleso
- 200mm lens shows M13 as slightly non-stellar, shows M22 as distinctly
triangular in shape
- sky at RIT observatory is bright; 90 sec at f/2.8 near S horizon
produces background which is a bit too bright;
60-90 sec exposures probably best for wide-angle views of sky
- using 28mm f/2.8 lens, exposures of 10-20 sec show constellations
at roughly naked-eye limit from RIT
- some piggyback exposures show evidence for "bouncing" or "jiggling"
of the camera during exposure. Must be very careful not to
bump telescope, or yank on cable release. Probably a good idea
to use hat or cardboard to cover lens as mirror flips up at
start and end of exposure.
- Images of Jupiter and Saturn taken by Anne Young, using the
Meade 10-inch f/10 and ASA 1600 film.
- Jupiter's clouds best around 1/250
- Galilean satellites may be compared in brightness at 1/2
- Saturn's clouds maybe reasonable around 1/15 - 1/60?
- Saturn's moons may be compared in brightness at 4-10 sec