
For those members who may be interested I update my progress with the little observatory.
Notwithstanding careful measurements and "dry run" set ups I found both mounts in my little observatory suffer from the same problem. I have Polemaster which is a camera and software to determine the Celestial South Pole (CSP). The CSP is the point which all the sky rotates around and interestingly the angle between CSP and the Horizon is your latitude.
That's right determining your latitude at night is very simple as basically all you need is two pieces of wood hinged together to get your angle and a protractor...forget trying to learn how to use a sextant.
The Polemaster camera is fitted on the mount and needs to point at the general area containing the CSP..the problem was when fitted to either mount the camera could not "see" over the observatory wall.
In the case of one mount I had it on a pier fashioned from plywood layered up with fibre glass...I would have liked metal but I don't have a welder these days etc etc..anyways ply is good although unconventional and has a lower thermal equilibrium than metal so should be better actually.
So I added another section that gave that mount sufficient clearance.
The addition to that moumt needs to be layered up and you can still see the layers making up the ply in the photo herewith.
I add black tiling grout to the resin for colour, maybe strength?, and to spin out the resin...you can make it less viscos which is very handy..even like putty to fill holes.
The second mount is on a steel pier and by elongating the holes I was able to get it to rotate to where it needs to be ...almost...Have yet to make it perfect but it is sufficient to take wide fields with the DSLR (Nikon d5500) like the one above...I have taken more since that one but because there was moisture in the air they are not acceptable...to me.
The mount on the ply pier found perfect polar alignment after taking a fair amount of time such that I could run my 80mm triplet unguided for five minutes with acceptable star shapes ( if you have tracking problems the stars go oval) however to ensure sharp images I decided to limit exposures to one minute.
I took about 30 minutes for each filter.
So with the setting up adjusemts etc I didn't really start taking serious photos until a little before midnight and continued thru until after 3am.
I took some dark frames and tried to take some flats but could not get the flats perfect so I am now stacking just light and dark frames...I used only five filters Red, Blue,Green, Hydrogen Alpha and Luminance. I ran the camera cooler at minus fifteen degrees centigrade.
stacking each group of lights and darks will take approx two hours each, then each of the five will be individually processed which can be an hour or more each (particularly as I am drizzling the stack and each stacked photo will be over a gigabyte) ..very iffy before I get them reduced in size and a crash even on the last stack means I have to start individual processing all over

for all...anyways the five processed images are taken to Photoshop given their colour and merged into one image that can be processed downsized and posted.
Hopefully all the work I have done shows a reasonable result..but if it does I am not that worried as I have solved many problems and the observatory is pretty well complete save tidying, additional fibre glass, an additional floor, exterior paint, a second coat of interior paint, laying out electrical cables, and a wifi for one set up, a path and a nice flower bed around to help minimise heat build up.
Hope you enjoy getting an insite into astrophotography.
Alex