Possibly piggybacking a SkyWatcher Esprit 120mm on a C11" EdgeHD on an AP1100 mount

Bruce Donzanti

I have been imaging with a Stellarvue 80mm APO triplet piggybacked on a C11" EdgeHD on my AP1100 for the past 4 years in my observatory with no issues.  Both scopes produce nice long exposure images with PHD2 guiding on the AP1100.  I was toying with the idea of removing the 8 lb 80mm and placing it with the 22 lb 120mm.  This is still within the weight capacity of the 1100 and the accessories are minimal (autofocuser, FW, dew heater).  However, would you expect imaging results to suffer due to the additional weight or is this a matter of simply trying it, and see?  

Dean Jacobsen

You could certainly try it and see.  My recommendation would be to swap the 120 mm refractor for the C11 and then you eliminate a potential source of error/flexure.
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/



I have a 130 Stellarvue refractor piggybacked on a 14.5 CDK mounted on a non-AE 1100.  Each scope has a camera.  I have had no problems imaging with either and sometimes both.
I can image unguided, using APPM-APPC model, with the refractor.  I guide when using the 14.5 with an OAG.


Bruce Donzanti

Thanks, Dean.  However, the C11 is the mainstay as my main imaging scope and I have not had issues with error/flexure, especially after refitting the standard secondary mirror with the Optec secondary mirror fast focus system.  Issues like flexure, mirror flop, and shifting are essentially nonexistent, even after doing 10 minute guided exposures all night long.   Perhaps the added weight of the Esprit might change that and I would just have to test it.

Bruce Donzanti

Thanks, Bryan.  This is good to know as I also image with both of my scopes but usually one at a time.  Your combined weight on the mount sounds about 70 lbs vs. the 50 lbs mine (minus accessories) would be.  So, this is very encouraging news.  I have been guiding, up to 10 minutes, with an OAG on the C11 and I use this also to guide the refractor with no issues as I am not using APPM-APPC.  So, this is something else I can explore.