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Field of View Comparison 12" vs 8" Schmidt-Cassegrain Telescope:  M33

 

 

Object The Pinwheel Galaxy (M33), in Triangulum   
Telescope (Photo) Top:  Meade LX200GPS 12 SCT @ f/6.3
Bottom:  Celestron 8" SCT OTA @ f/6.3 on Losmandy G11 Mount
Telescope (Guiding) Top:  Meade LX200GPS 12" SCT @ f/6.3 (off-axis)
Bottom:Televue 85mm refractor @ f/7 on Losmandy G11 Mount
Camera (Photo) Top:  Canon 20Da DSLR
Bottom:  Canon 50D DSLR, with Hutech filter modification
Camera (Guiding) Top:  Meade DSI II Pro w/PHD Guiding
Bottom:  Meade DSI III w/
PHD Guiding
Exposure Detail Top and Bottom:  excluded-average combination of 17 images at 300 seconds each, ISO3200;  RAW file conversion, full calibration (flat, dark, bias, and flat-dark), and initial image processing using ImagesPlus 3.80; final image processing using Photoshop CS3
Location Cincinnati Astronomical Society's Dark-Sky Site (Adams County, Ohio) (N38.876, W83.464)
Date  09/12/09
Comments The images in this sequence were taken at the same time on the same night at the same site using different optical tube assemblies (OTAs).   The Canon 20Da image was resized to the same pixel dimensions as the Canon 50D image, although this affected only pixel density and not image dimensions.  The top image was rotated 90 degrees only to show the same orientation as the bottom image.  Neither image is cropped.  This comparison shows how the different focal lengths of the two OTAs affects image size.