Quote:
Originally Posted by 5ash
With my ED80 unguided on an neq6 mount i can get ~70% pictures with round stars at exposures of 3-4 minutes. My other scope is a c9.25 which even with a .67 focal reducer will still give me a focal length of around 1600mm , which is unlikely to give me long exposures without elongated stars.
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The EQ6 has a huge periodic error (45 arc secs peak-to-peak, I've heard) so it's no surprise that you'd lose a lot of exposures without auto guiding.
There are several people here (including me) who use a GSO RC8 at prime focus on an EQ6: the focal length is just over 1600 mm.
Here's an example of round stars with 6 min exposures at 1600 mm - guided with an Orion 50 mm mini guide scope (162 mm focal length) and QHY5 using PHD.
I've tested longer exposures on that set up and it still worked fine, but the DSLR subs were becoming waaay too noisy.