Re: 3-4" RA wiggling while PHD2 guiding with EXOS2-GT PMC-eight #EXOS2 #astrophotography


Doug Doonan
 

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

Doug Doonan via groups.io <dougdwd=aol.com@groups.io> schrieb am Do., 14. Jan. 2021, 19:09:
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 Engineering

Explore 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.

Join MAIN@ESPMC-Eight.groups.io to automatically receive all group messages.