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William Jones

Guide Scope/Guide Camera FOV Question

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Hi guys

Can anyone help me work out the FOV  I am getting when I use my guide scope with guide camera?

The kit I have is:

BST 50mm mini guide scope (f3.2) 162mm F.L

With an Altair Astro GPCAMARO130C  guide camera

I am hoping the FOV is between 1deg and 2.5degs


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Sensor Size: 1/3" diagonal (4.8x3.6mm)
Pixel size microns: 3.75x3.75 um
Resolution in pixels: 1280x960

BST 50mm mini guide scope (f3.2) 162mm F.L



Image scale (arc-seconds/mm) = 206265 / Focal Length (mm)
        = 206265 / 162mm
        = 1273.24 arc-seconds/mm

Field of view = 4.8x3.6mm * 1273.24 arc-seconds/mm
     = 6112x4584 arc-seconds
     = ~1.7x1.27 degrees

Image scale (arc-seconds/px) = 206.265 * Pixel Size (um) / Focal Length (mm).
        = (206.265 * 3.75um) / 162mm
        = 4.775 arc-seconds/pixel
Field of view = 1280x960px * 4.775 arc-seconds/pixel
     = 6112x4584 arc-seconds
     = ~1.7x1.27 degrees

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Yes those are the theory calculations - you can load a picture into nova.astrometry.com which will plate solve it and tell you exactly as the focal length might not be quite as advertised.

Whatever it'll work for sharpcap polar alignment routine :)

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