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astrophotography targets

wide angle astrophotography:

star trails:

guided stellar scenes:

100mm effective focal length at f/2.0-2.8:

  • eg. 85mm lens on a Canon 1D 1.3x crop dSLR (111mm in 35mm terms) or 60mm on a APS-C dSLR with 1.6x crop (96mm in 35mm terms)
  • eg. 50mm lens on an Olympus dSLR (see my comet McNaught P1 photos).
  • this will give an angle of view of about 20.6deg x 13.8deg (thus the moon would occupy only 3.5% of image height)
  • unguided exposures need to be less than 8secs to avoid significant star trails which would limit one to the brighter stars and planets only with magnitudes greater than about 5 using ISO 400-800
  • on a cheap HEQ5 equatorial mount you should be able to get good 60-90sec sub-exposures which should be good for a range of star clusters and nebulae (the latter if H-alpha emitters image best if you have the IR blocking filter removed).
  • targets 10-20deg in size:

200mm effective focal length at f/2.8-3.2:

  • eg. 135mm lens on a Canon 1D 1.3x crop dSLR (176mm in 35mm terms) or on a APS-C dSLR with 1.6x crop (216mm in 35mm terms)
  • eg. Olympus 50mm f/2.0 macro with 2x TC = 200mm f/4 - perhaps better to settle for the 1.4x TC and 140mm f/2.8
  • this will give an angle of view of about 10.3deg x 6.9deg (thus the moon would occupy only 7% of image height)
  • unguided exposures need to be less than 4secs to avoid significant star trails which would limit one to the brightest stars and planets only 
  • on a cheap HEQ5 equatorial mount you should be able to get good 30-60sec sub-exposures which should be good for a range of star clusters and nebulae (the latter if you have the IR blocking filter removed).
  • targets 5-10deg in size:
    • comets when they have short tails
    • star clusters
    • Lambda Orionis nebulosity (~7deg but faint)

 

300mm effective focal length at f/2.8-3.2:

  • eg. 200mm lens on a Canon 1D 1.3x crop dSLR (260mm in 35mm terms) or on a APS-C dSLR with 1.6x crop (320mm in 35mm terms)
  • eg. 150mm f/2.0 Olympus ZD lens on a Olympus dSLR = 300mm f/2.0
  • eg. Olympus OM 135mm f/2.8 or better, a Leica R, Carl Zeiss or maybe Nikkor on Olympus = 270mm f/2.8
  • this will give an angle of view of about 6.9deg x 4.6deg (thus the moon would occupy only 11% of image height)
  • unguided exposures need to be less than 2.5secs to avoid significant star trails which would limit one to the brightest stars and planets only 
  • on a cheap HEQ5 equatorial mount you should be able to get good 30-60sec sub-exposures which should be good for a range of star clusters and nebulae (the latter if you have the IR blocking filter removed).
  • targets 2-5deg in size:
    • comets when they have short tails
    • northern hemisphere:
      • Andromeda Galaxy
      • Alpha Persei star cluster
      • Gamma Cygni nebulosity (H-alpha)
      • California nebula (H-alpha)
      • Veil nebula
      • Northwest Monoceros nebulosity
    • equatorial:
    • southern hemisphere:

450-600mm effective focal length at f/2.8-4:

  • eg. Canon 300mm f/2.8 EF on an APS-C = 480mm f/2.8
  • eg. Canon 400mm f/2.8 IS, f/4 DO or f/5.6 EF on an APS-H = 520mm
  • eg. Olympus 300mm f/2.8 ZD on an Olympus = 600mm f/2.8
  • eg. Olympus 150mm f/2.0 ZD with 1.4xTC = 420mm f/2.8
  • eg. Olympus 150mm f/2.0 ZD with 2xTC = 600mm f/4.0
  • eg. Olympus OM 300mm f/4.5 on Olympus dSLR = 600mm f/4.5 - but may need to stop down to f/5.6
  • targets 1-5 deg in size:
    • comets when they have short tails
    • northern hemisphere:
      • Andromeda Galaxy
      • Alpha Persei star cluster
      • Gamma Cygni nebulosity (H-alpha)
      • California nebula (H-alpha)
      • Veil nebula
      • Northwest Monoceros nebulosity
    • equatorial:
      • M8 & M20 Triffid nebula: 4x4min @ f/2.8 ISO800
      • Pleiades (~1.5deg) 
      • Zeta Orionis complex - Flame nebula & Horsehead nebula
      • Orion nebula
    • southern hemisphere:

750mm effective focal length at f/5.6:

1000mm effective focal length at f/5.6:

  • eg. 800mm lens on a Canon 1D 1.3x crop dSLR (1040mm in 35mm terms) or 600mm on a APS-C dSLR with 1.6x crop (960mm in 35mm terms)
  • 500mm f/4 IS EF lens with TC1.4x  gives 1120mm on APS-C dSLR and 910mm on APS-H
  • eg. Nikkor 500mm f/4.0 lens on a Olympus dSLR = 1000mm f/4.0
  • eg. Olympus 300mm f/2.8 ZD with 2x TC = 1200mm f/5.6
  • this will give an angle of view of about 2deg x 1.4deg (thus the moon would occupy only 37% of image height)
  • unguided exposures need to be less than 0.8secs to avoid significant star trails which would limit one to the moon and perhaps Jupiter 
  • on a cheap HEQ5 equatorial mount you should be able to get good 10sec sub-exposures which may be pushing it for a star clusters and nebulae (the latter if you have the IR blocking filter removed).
  • you really need a high quality mount for this such as a Losmandy
  • a Tak 180ED astrograph which is a 500mm f/2.8 could be used without autoguiding on a Losmandy mount for 1min exposures, slower apertures will require longer exposures and the hastles of autoguiding.
  • for example, the Andromeda galaxy imaged with a total 50min at f/8 at 1600ISO, could be imaged at 12min total at f/4, and 12x1min is MUCH easier than 10x5min, and if you use the Canon 1D mark III, its improved noise would allow 3200ISO and thus maybe 9X45sec at f/4 using a 1.4x tele-extender with the Tak 180ED to give 1120mm effective focal length at f/4.
  • targets 0.5-2deg in size:

2000-3000mm effective focal length at f/5.6:

  • prime focus telescopes
  • eg. 1850mm f/5.6 (eg. 10“ f/5.6 Newtonian on APS-H dSLR)
  • eg. 2276mm f/5.6 (eg. 10” f/5.6 Newtonian on APS-C dSLR)
  • eg. 2560mm f/6.3 (eg. 10“ Meade LX200 on APS-C dSLR)
  • eg. 2800mm f/5.6 (eg. 10” f/5.6 Newtonian) on a Olympus dSLR
  • at 2000mm, this will give an angle of view of about 1deg x 0.7deg (thus the moon would occupy only 74% of image height, while Jupiter & Saturn would occupy ~1.8% or about 50 pixels on a 10mp dSLR - must verify this when I get my 1D)
  • unguided exposures need to be less than 0.4secs to avoid significant star trails which would limit one to the moon and perhaps Jupiter, Mars and Saturn
    • Saturn (mag. 0.4)
      • webcam users often use 4000mm eff. f/l at f/40, 1/25th sec and resolution is only 640x480px
      • Canon 1DMIII with OM 2xTC + 10“ f/5.6 Newtonian gives 3700mm f/11 so perhaps 1/50th sec at ISO 3200 - I need to try this (cannot use EOS TC's on telescopes as get error message)
      • Olympus E510 with two 2x TC's gives effective 11,400mm f/22 and need at least 1/15th sec 1600ISO but at this magnification you will be severely limited by poor seeing &/or poor focus
  • on a cheap HEQ5 equatorial mount you should be able to get good 10sec sub-exposures which is pushing it for star clusters and nebulae (the latter if you have the IR blocking filter removed).
    • Omega Centaurus (mag. 3.7 ie. ~4EV less bright than Saturn but a lot bigger) needs about 30sec f/2.8, 800ISO ⇒ 30sec, F/5.6, 3200ISO ⇒ 
      • a Canon 1D Mark III could do 15sec, f/5.6, 6400ISO which may be good enough
  • you really need a high quality mount for this such as a Losmandy
  • targets 0.1-1deg in size:

 

 

photo/ast_photography_targets1.txt · Last modified: 2013/02/07 13:27 by gary1