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My laptop has 1 x USB 3.0 and 3 x USB 2.0 ports so I'm good there.
So I ordered the 618M for $149 reduced from $499 with free shipping (too good an opportunity to miss at the sale price) and will add a 60mm / 240mm FL guide scope once funds allow.
The calculation for pixel ratio I believe is =
pixel size / FL x 206.3
and you want the ratio to be greater than 0.25 or less than 4x greater depending on how you do the equation
Looking at my own configuration (Canon 550D DSLR pixels of 4.3mu, 65EDQ 420mm, 618M 5.6mu, potential 60mm guide scope 240 mm) I get
Long ways -
Imaging: ([4.3mu x 2 (bayer)] / 420mm) x 206.3 = 4.22
Guiding: (5.6 / say 240mm) x 206.3 = 4.81
Ratio - 4.81/4.22 = 1.14
Other ways - (pc/ft)/(pg/fg)
pg = pixel size guide camera
fg = focal length guide scope
ft = focal length of main OTA
pc = pixel size imaging camera x 2 for bayer sensor
pg = 5.6
fg = 240
ft = 420
pc = 2*4.3
So, current rig = 0.87 which is > 0.25 so all good ?
This means I think that for every 1 pixel movement of the guide scope, the main OTA moves by 0.87 pixels.
Andy
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