Hi Bassliner,
Thanks for the info.
And where does the 3.6 come from?
Doug Doonan
-----Original Message-----
From: Andreas Volz via groups.io <bassliner303@...>
To: MAIN@espmc-eight.groups.io
Sent: Thu, Jan 14, 2021 1:23 pm
Subject: Re: [ESPMC-Eight] 3-4" RA wiggling while PHD2 guiding with EXOS2-GT PMC-eight #EXOS2 #astrophotography
Hey Doug,
The formula is:
pixel size (microns) x 206.3 /focal length in mm = image scale in arcsec/pixel
206.3 results out of:
3.6 * (180 degrees / pi) = 3600/1000 * (180 degrees / pi) = 206.26
Jerry,
Where does the 206.3 in your formula come from, and what are its units?
Doug
-----Original Message-----
From: Jerry Hubbell - Explore Scientific VP Engineering < jrh@...>
To: MAIN@ESPMC-Eight.groups.io
Sent: Wed, Jan 13, 2021 8:34 am
Subject: Re: [ESPMC-Eight] 3-4" RA wiggling while PHD2 guiding with EXOS2-GT PMC-eight #EXOS2 #astrophotography
Hi Walter, Yes, I would suggest a 2x Barlow or tele-extender instead of a 3x. The formula for pixel or plate scale is: Pixel Scale = (Pixel Size x 206.3) / FL, So for your combination: Pixel Scale = (5.2 um x 206.3) / 162 mm = 6.6 arc-seconds/pixel BTW, your calibrations look spot on, no problem there, -- Jerry Hubbell
Vice President of EngineeringExplore Scientific, LLC.
jrh at explorescientific.com
www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811
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
Mounts: 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!
--
Doug Doonan
HomeBru 6 inch Reflector f 6.6
HomeBru 85 mm Refractor f 5.6
PMC-8, EXOS 2
Long retired EE.
-- Clear skies,
Andy
Mount: ES PMC-8 EXOS2, ioptron SkyGuider Pro
Scope: SkyWatcher Explorer 150/750 PDS
Cameras: Canon 6D, Canon 7D Mk2
Guiding: ZWO ASI120Mini mono, ZWO 30F4 Guidescope, PHD2
Msc: TS Optics Coma Reducer Corrector 0.95x
Software: N.I.N.A, APT, Pixinsight, DeepSkyStacker, Photoshop
-- Doug Doonan HomeBru 6 inch Reflector f 6.6 HomeBru 85 mm Refractor f 5.6 PMC-8, EXOS 2 Long retired EE.
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