Astrophotography is Fun!

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Astrophotography is Fun!
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Astrophotography

• Amy Eisin,
• with pictures by club members
• February 25, 2002

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Overview

• Camera Hardware
• Film
• Exposures
• Lens
• Telescope

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Camera Hardware

• Manual vs. Automatic
• T-ring (goes on camera)
• T-mount (telescope adapter)
• ISO exposure settings, cable release
• Size of film 35mm, Medium Format

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Film

• 35mm negative
• 35mm slide
• Color
• Black and White
• ISO rated speed
• Push processing

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Exposures

• Final image depends on film speed, focal ratio,
  and exposure time
• Film speed
• Higher ISO numbers give brighter images
• Focal ratio
• Lower f numbers give brighter images
• f/5 is brighter than f/10
• Exposure time
• Longer exposures give brighter images

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Film Differences

• Color reproduction
• Grain
• Sensitivity
• 4 M42 shots, different films, exposures

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Film Grain

• Film has inherent grain to it
• Faster films (higher ISO) are usually grainier
  
• Pushing film makes it grainier, sometimes much
  grainier

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Camera Lens

• Lens aperture
• Focal ratio
• Focal length image scale
• Lens hood, prevent reflections

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Photography methods

• Tripod
• Barn Door (poor mans clock drive)
• Piggyback
• Afocal (camera lens on camera focused at
  infinity, held near telescope eyepiece)
• Prime focus (with telescope)
• Eyepiece Projection (high magnification, for
  planets, very hard)

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Tripod Photos

• Max exposure of 20 seconds before stars trail on
  a typical lens (not zoom)
• Moon shot, right before sunrise, from Haleakala
  volcano, Maui
• 1 sec exposure

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Piggyback Orion Photos

• Exposure times
• Kodak E200 film, pushed 2 stops
• 30 sec (below)
• 120 sec (right)
• 150 sec (bottom right)
• Light pollution sucks!

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Mounting the Camera on a Telescope

• Duct Tape (Joke!)
• Piggyback adapter
• T-Ring / T-mount
• Eyepiece Projection adapter

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Telescope

• Clock drive
• Polar alignment (guiding)
• Focal ratio (ISO speed, etc)
• Magnification and atmospheric conditions (seeing)

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Vibration, Polar Misalignment

• Polar misalignment, wind, vibrations, even
  footsteps can ruin your images
• Take lots of pictures!

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Prime Focus Moon Shots

• Eclipse (top right)
• Varying exposures (bottom)
• Enlargement of brightest of the three (bottom
  right)

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Prime Focus M42

• 8 SCT at f/10
• Kodak E200 film pushed 2 stops (800 ISO equiv)
• Exposure time 40 seconds

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Summary

• You can do a lot with just a camera and a tripod
• There are many great web sites and books on the
  astrophotography
• Michael Covingtons book, Astrophotography for
  the Amateur is a great starting point