Re: Astrophotography Done with the iEXOS-100, EXOS 2, and G11 Post your Pictures and Details! Lets Show What These Mounts Can Do. #iEXOS-100 #G11 #EXOS2 #astrophotography

Bill Black

Hi Gernot,
Thanks! I'm glad it is useful.

For focusing at long focal lengths, I'm going to say the most important factor by far is the "seeing".
I've tried automated focus routines, like the ones in the SharpCap tools, and I've used my Bahtinov mask as well. They work pretty good, but they work much better when the seeing is good. If the seeing is bad, none of them work for me and you end up fiddling back and forth and get no real improvement.

When I shot the footage of Jupiter the other night, the seeing was very good. I focused without using any tools other than my eyes and electronic focuser buttons. I added a Crayford focuser to my SCT and modified it with an Orion AccuFocus kit (little electric motor that attaches to the shaft on your focuser). However, if the seeing is good, I think you can achieve decent focus with the stock equipment.

Atmospheric is a great tool for predicting what your seeing will be like. It's a weather forecast, so its not 100% accurate, but it seems more accurate than others I've tried.

Another thing that will affect your seeing is the altitude of your target. The higher the altitude of your target, the better the seeing, because there is less atmosphere to contend with. The other night, Jupiter was less than 40 degrees above the horizon, which is really to low to even be trying in my opinion, but the seeing seemed very stable, so I gave it a shot. Really, I would rather my target be at 50 degrees plus. Mars is a great planetary target this year because it is climbing above 60 degrees. 

Decent focus will be easier to achieve on M57 and M13 for a couple of reasons, I think. One is that they were probably above 50 degrees and two is that you were able to use a shorter focal length (less magnification).

I'm curious what others do for focusing as well, especially at long focal lengths. It is still one of my biggest struggles after many years in this hobby.

Location: Dallas, GA
 Celestron C8, AstroTech 80mm APO

Mounts: EXOS II PMC-Eight, LXD75

Cameras: ZWO ASI294MCPro, ASI385

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