300mm. f/5.6 拍 4 個小時......
那我的 F2.8 拍2小時應該也差不多這樣囉
你要挑戰的是這一張
Lens: Canon 300mm f/2.8 L USM IS telephoto lens
F/stop: f/2.8
Exposure: Composite of 57 frames, each 2 minutes long for a total of 114 minutes exposure
Mount: Polar-aligned tracking equatorial mount, auto-guided
Camera: Canon EOS 20Da DSLR
Mode: Raw
ISO: 1600
White Balance: Daylight
In-Camera Noise Reduction: Off
Filter: IDAS LPS
Temp: 52F
Time 9:22 PM EDT
Date September 27, 2005
Location: Scott's Pitt, NJ
Calibration: Darks: 16 x 2 min dark frames averaged together as a master dark. Auto-dark calibrated each light frame in Images Plus v2.75beta. No Flats, no bias.
Processing: Automatic Image Set Processing in Images Plus v2.75 where all light CR2 raw files were converted to 16-bit linear TIFF files with No White Balance, Color Filter Array as the white balance type, then calibrated with the master dark. The light frames were then Bayer interpolated to convert them to color images. The light frames were then registered and aligned in Images Plus. The light frames were then composited together and "stacked" in Images Plus using min-max excluded as the method. Digital Development was then applied to this 16-bit linear master light file. The image was corrected for vignetting with GradientXTerminator. Color balance was then adjusted with levels and curves modifications. Color saturation was increased. A high-pass filtered copy of the background layer was blended via lighten mode in Photoshop CS2. Noise Ninja was used to reduce noise in the image.
http://www.astropix.com/HTML/SHOW_DIG/M31_Andromeda_Galaxy.HTM
觀星論壇 
