PHD2 dithering settings help needed

[Ady Alex]

Hi all

I have a beginner question about dithering.

 Gear:

 TS-Optics PHOTOLINE 80mm f/6 : Aperture 80 mm  Focal length 480 mm / focal Ratio f/6

 Sky-Watcher 9x50 Finderscope :focal length 181 mm ,I think...

 QHY5 Monochrome for guiding: Sensor Mitron MT9M001, 1/2 inch, BW Effective Pixel: 1280x1024, 1.3 Mpixels Pixel Size 5.2µm x 5.2µm , I don't know the pixel size.

 Canon EOS 450D for imaging : pixel size 5.20 micrometers. , I think....

 What dithering settings shroud I use in PHD2 and APT. Maybe some one can explained the formulas using my gear?

I read that the dithering scale for canon must be between 5 and 10. What do you think?

[Ronclarke]

I have a similar set up but only use 2 in PHD2 and APT. Works for me...

[Craig a]

I don’t use Apt I use nebulously for capture control I believe if imaging with a dslr you need to move the main dslr image by about 15 pixels to smooth out colour mottling, in neb I use very high dither and dither scale of 3 in phd but that’s with a st80 guidescope guiding a 1000mm Newtonian, I would experiment with it until you see the image shift by a couple of star diameters just use short exposures to speed it up until you get the desired result, I hope this helps 

Edited March 31, 2020 by Craig a

[michael8554]

A DSLR should be Dithered about 12 pixels, but the Dither Setting isn't as simple as  "between 5 and 10" 

If your guide image scale is say 4 arcsecs/pixel, and your imaging image scale is say 1 arcsec/pixel, then to move the image camera 12 arcsecs (12 pixels) , the guide camera must be Dithered 12/4 = 3 pixels

QHY5 pixel size  is 5.2um, 450D is also 5.2um, so it's simply the ratio of the focal lengths. 

480/181 is about 2.8, so a Dither of 3 pixels would do. 

Michael