Benklerk

Hi Michael The 174mm is about the same sentivity as the lode star but at 2/3 the cost. The Lodestar 2 is almost $1000 over here. The issue I had is, I could see the stars, but non of them we usable. They where comet looking shapes. Even a field flattener didn't help, and yes I made sure it was in focus. The other problem is the ZWO OAG mirror is half the size of the 174mm sensor.

Thanks for the replies, looks like OAG is the way. Few things, the G4 16000 has its own OAG and I think it’s the only OAG that will fit it. Without spending even more money I will be using my 174mm as it has a larger FOV. I’ll be aim to do 10 second guide subs, so that could be enough time to pick up faint stars. I can even bin it to improve pixel arc sec. https://www.gxccd.com/art?id=436&lang=409

I have read longer focal lengths better for OAG, but one down side is. Finding a star can become a problem. I stopped using my ZWO OAG on my 6" RC because it didn't find a guide star. I can guide 10min subs with no star trails using my guidescope.

I'm in the process on building my fixed setup. GSO 14 RC with a Moravian G4-16000 camera. I'm using a Skywatcher 72ED on my portable setup as a guide scope with a ZWO 174mm mini guide camera. I live in Bortle 3/4 skies and my seeing can get as low 1 arc sec avg is around 2", live around 1000m above sea level. The mount i'm getting will be the new JTW friction drive mount. I have attached the image scales using different setups. If I don't get the OAG adapter I can get the 290mm mini guide camera instead as they cost the same. So my question is, is going OAG worth it? The mount im getting will be very solid and I can do longish unguided. So when I do guide I can set guided pulses to 15 or 20 seconds or longer?