Originally posted by Suhndog OK, I'm new here, and cannot locate where to make a new post.. Eeks!
I'm new to astro-photography. I own a K5 with only the basic, kit lens. I also own an Apertura AD10 10" DOB with nice EP's [Explore Scientific 82deg. 30mm and 11mm, and others]. I would like to explore the possibilities of both using my DOB with an EQ dual-axis platform, and trying the O-GPS1 unit.
My initial questions are:
1) What Pentax [or 'better'?] telephoto lens is best for deep-sky imaging using the O-GPS1?
2) Is the O-GPS1 really worth buying - I've read various complaints...
3) Can the O-GPS1 be used with my DOB, or is it not suitable, considering the algorithms in the camera?
-- I'll await answers before asking more..
Thank you! -- Marc
1) It really depends on what deep-sky objects you what to photograph. Many objects are very small and dim indeed. But used together with the O-GPS1 you should restrict yourself to about 200mm and downwards. And, obviously, you should go for as fast optics as you can afford. Personally, I go up to some 350mm to 400mm and f/5.6. but then I am also willing to accept that tracking errors will occur (much) more frequently.
2) We are many happy users of the O-GPS1 - see all the images posted in this forum and elsewhere - but "worth buying" will eventually be a personal assessment. The O-GPS1 is not a full subsitute for a good equatorial mount, but it is an extremely handy and quick grab-and-go assitant in a great many instances.
3) No, the sensors in the camera will believe that your optics is pointing at a right angle to what it acrtually is. And most dobsonians will have a far too long focal length to be sensibly used with the O-GPS1 Astrotracer function.