Re: I'm planning building an EQ platform
Originally Posted by Aero787
In my case, the problem was my Dob and getting good polar alignment. The longer the focal length, the more accurate your PA has to be.
For my 17.5" Dob, FL = 2000mm. Without accurate PA, even a good GEM mount (assuming it could handle the enormous weight) would have trouble with FL = 2000mm for long exposures. The images would show star-trails (as you have in one or two of your M42 images).
I'm not saying you will fail. On the contrary, your Dob is probably more manageable than mine. And many have been able to build a good Eq Platform and make it work for AP. But the greater your FL, the more accurate you have to be -- more accurate with your cutouts, more accurate with your motor speed and more accurate with your PA.
I got very good accuracy with my motor speed (I was using a stepper motor powered by an Arduino). PA was difficult with such a big Dobsonian (~60 kg).
In lumine tuo videbimus lumen
SCOPES: DIY f/4.5 17.5” Dob -- Meade f/9 102mm APO
MOUNT: Celestron AVX
CAMERA: Canon 450D / Orion-SSAG / Fujifilm X-A1 (mirrorless)
EPs: TV Nagler 13mm / PARKS Gold Series--5 pieces / Zhumell 3mm