[Startrek (Martin)]

I’ve been using APT for 4 months now and in regard to Dithering have left the default setting of 1 in Dither Distance
Looking further into the dithering process on a few sites , a general rule of thumb or recommended Dither for the main imaging camera should be a move of around 8 to 10 pixels
Below are some calculations I put together for my two imaging scopes using APT and PHD2 which came up with vastly different Dither settings than the default setting of 1. Also when I joggle through my fits frames zoomed in I noticed the frames only shift very slightly and sometimes not at all which lead me to post this query

Dithering in APT

APT Dither settings
Assuming PHD2 Dither scale is 1
APT Guide Camera Pixels
1 0.5
2 1
3 2
4 3
5 5

6” f6 Bintel GSO Newt
ZWOASI2600MC imaging camera
Orion 60mm Guide Scope
ZWOASI120MM-S guide camera

Pixel scale for 6” f6 Bintel GSO Newt
3.76 x 206.3 / 900 = 0.86 arc sec / pixel
Pixel scale for Guide scope
3.75 x 206.3 / 240 = 3.22 arc sec / pixel

So ratio or multiplier is 3.8 x

General rule of thumb for dithering is to move the main imaging camera about 10 pixels on each frame

6” f6 Bintel GSO newt
So therefore an APT Dither Distance of 3 should move the imaging camera about 8 pixels which is satisfactory


8”f5 Bintel GSO Newt
ZWOASI2600MC imaging camera
Orion 60mm Guide Scope
ZWOASI120MM-S guide camera

Pixel scale for 8” f5 Bintel GSO Newt
3.76 x 206.3 / 1000 = 0.77 arc sec / pixel
Pixel scale for Guide scope
3.75 x 206.3 / 240 = 3.22 arc sec / pixel

So ratio or multiplier is 4.2 x

General rule of thumb for dithering is to move the main imaging camera about 10 pixels on each frame

8” f5 Bintel GSO newt
So therefore an APT Dither Distance of 2 should move the imaging camera about 8 pixels which is satisfactory

I would appreciate some feedback to see if the above is correct and if so I will change the APT Dither Distances accordingly

Thanks in advance