spordniar

On 29/04/2020 at 05:41, ursamajorro said:

I found another formula who seems to be more real and it's better for dithering calculations:

arcsec/pixel = 206,3 x pixel size in um/focal in mm

So, for my Canon dSLR I have for a focal of 135 mm (my old Jupiter lens) I'll have

206,3 x 4,3 / 135 = 6,57 arcsec/pixel

and if I want to dither 10-15 pixels I should set my dithering field in SAM console to 6,57 x 10 or 15 = from 65,7 until 98,55 arcseconds, ie 1,1 or 1,64 arcmin.

I think Fred's formula is exactly the same as yours, just simplified.

(206.3 * 10) * pixel size / focal len = arcsec
(206.3 * 10 / 60) * pixel size / focal len = arcmin
34.383  * pixel size / focal len = arcmin

So I guess 35 give you approximately  10 pixel dither, and if you want 15 pixel just multiply by 1.5.

Nice post guys!