How many pixels to dither

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starfield United States of America
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How many pixels to dither

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Post by starfield »


A while back I started dithering my images. I started by setting the max dither step in SharpCap to 15x pixels. I noticed that I had large stacking artifacts around the edges of my images, but they seemed bigger than 15px. I've now realized that those pixels referenced in SharpCap's dither settings are "guide camera" pixels and that I've probably been pushing my imaging camera closer to 45 pixels with each dither which seems excessive. Question - What's a reasonable dithering target in pixels for the imaging camera? I've heard some folks say 10 and other recommend something more aggressive. Curious what you all think.

FYI, I'm running a 294mc pro on a 550mm refractor and using PHD2 to drive the guiding.

Thanks. Steve
Scopes: Esprit 100, 12.5" Telekit Dob
Camera: 294 MC Pro, 224 mc, 2600mm
Guiding: ZWO 290 mini on 120mm guide scope
Mounts: EQ6R-Pro, EQ Platform.
Filters: Optolong L-Pro & L-Enhance, Chroma 36mm LRGB, 5nm HA, 3nm OIII, 3nm SII.
Software: SharpCap, SGP, StarTools 1.7, Photoshop, Pixinsight
The Death Star Observatory
Astro Photos:https://www.astrobin.com/users/starfield/
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JayTee United States of America
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Re: How many pixels to dither

#2

Post by JayTee »


The book answer is 10 to 20 pixels.

Find the ratio between your guide camera imaging scale and your imaging camera imaging scale. Use this factor to "guide" you as to how big the dither should be in sharpcap.

Cheers,
JT
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

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starfield United States of America
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Re: How many pixels to dither

#3

Post by starfield »


Perfect. Next step up now is to tackle my guiding and see about optimizing that! So much to learn....
Scopes: Esprit 100, 12.5" Telekit Dob
Camera: 294 MC Pro, 224 mc, 2600mm
Guiding: ZWO 290 mini on 120mm guide scope
Mounts: EQ6R-Pro, EQ Platform.
Filters: Optolong L-Pro & L-Enhance, Chroma 36mm LRGB, 5nm HA, 3nm OIII, 3nm SII.
Software: SharpCap, SGP, StarTools 1.7, Photoshop, Pixinsight
The Death Star Observatory
Astro Photos:https://www.astrobin.com/users/starfield/
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