Re: Astrophotography Done with the iEXOS-100, EXOS 2, and G11 Post your Pictures and Details! Lets Show What These Mounts Can Do. #iEXOS-100 #G11 #EXOS2 #astrophotography

Jerry Hubbell - Explore Scientific VP Engineering

On Wed, Jun 5, 2019 at 09:01 AM, Chris Tardif wrote:
Great....Here is my North America nebula....I am still trying to figure out Field of View..

You can calculate your field of view based on some of your systems specs.  If you know your camera's ccd pixel size, and resolution, and your focal length, then you can calculate the FOV directly:

 Plate Scale (arc-sec/pixel) = Pixel size (microns) x 206.265 / Focal Length
FOV (degrees) = Number of pixels x Plate Scale / 3600 

So for your camera - Canon Rebel T5i the pixel size based on the information I could find on your sensor is 4.3 microns, the resolution is 5184 x 3456 pixels (I assume you are using full resolution) and your FL is 400 mm

Plate Scale = 4.3 x 206.265 / 400
                   = 2.217 arc-sec/pixel

FOV (long side)   = 5184 x 2.217 / 3600
                            = 3.192 degrees
FOV (short side) = 3456 x 2.217 / 3600
                           = 2.128 degrees

FOV = 3.20 x 2.13 degrees

If you don't know your focal length or anything else about your image, you can submit your full-size image to and it will do a plate solve to tell you the center coordinates (RA,DEC) of your image, the FL and FOV.
I submitted your image and here are the results

The pixel scale for the image you attached is larger because you reduced the full-size image down by a factor of about 4.7x The FOV is very close to what the calculation shows above.

Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at
1010 S. 48th Street
Springdale, AR 72762

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home

Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!

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