Nikon Coolpix 990 Digital Camera uses a 3.34 Megapixel CCD with true (non-interpolated) image resolution of 2048 x 1536. Its 3x Zoom-Nikkor lens 8-24mm focal range is equivalent to 38-115mm coverage in 35mm format.

Advantages of using Nikon Coolpix 990 for astrophotography include:

• Quickly learning from my most common mistakes of exposure settings, focusing, framing the object, etc.
• Full manual control for controlling shutter speed, aperture and focus.
• Coolpix 990 aperture is controlled by a 7 blade iris diaphragm which useful for reducing chromatic aberrations when used with fast focal ratio achromatic refractors.
• Coolpix 990's histogram displays pixal brightness and quantity to show tone disptribution in an image which is very helpful in setting the manual exposure for imaging the moon.
• Swivel design is very helpfull to position the LCD monitor in a confortable position when the camera is mounted on the telescope.
• Flash cancel mode is necessary for turning off the flash for astrophotography.
• Automatic timer is used to take an image without shaking the camera.
• Focusing is made easier with the Nikon's 990 image sharpening in manual focusing.
• Video out channel to a TV monitor is very helpful when focusing and using the Nikon 990 at the telescope.
• 28mm lens threads are used to attached the Nikon 990 to the telescope.
• Lower cost than 35mm film after about 2,000 photos
  (4 x 6 inch print & film development equals about $.50/photo) divided into (Nikon 990 list price = $1,000) equals 2,000 photos. From June 2000 to October, 2000 I have taken over 4,400 digital images and stored them on six CD-ROMs which costed $.29 each.
• Digital images take up alot less physical storage space than the albums that hold my 4 x 6 inch photos.

Disadvantages of using Nikon Coolpix 990 for astrophotography include:

• Limited exposure of 8 seconds. (upto 60 seconds when Nikon makes the remote shutter-release cord MC-EUI available). Typical astronomy CCD cameras operate in the tens of minutes for exposures which is great for deek sky objects.
• Dark noise starts to appear in exposures greater than 1/4 seconds. Typical astronomy CCD cameras are cooled to reduce dark noise.
• The RGB channels are limited to 256 levels. Typical astronomy CCD cameras are black/white with 4,096 to 65,536 levels.
• Number of images is limited by the CompactFlash card size.
• Nikon 990 lacks computer controlled operation for taking a sequence of images

Disadvantages of using typical astronomy CCD cameras as compared to using the Nikon Coolpix 990 for astrophotography include:

• Typical astronomy CCD cameras need to take three images taken through RGB filters versus the Nikon 990 single exposure for color images.
• Nikon 990 is small and compact size as compared to typical astronomy CCD cameras.
• Typical astronomy CCD cameras have alot less pixels then Nikon 990.
• Typical astronomy CCD cameras require a computer to operate.
• Typical astronomy CCD cameras require alot of power to operate.
• Typical astronomy CCD cameras take longer to setup.
• Typical astronomy CCD cameras are difficult to use for nonastronomy imaging.

© 1998-2003 David Haworth