# Telescope Vanes

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Xmo1, Jul 21, 2018.

1. ### Xelasnave.1947Valued Senior Member

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This is not entirely correct and to achieve focus is an exhausting proceedure.

In the program Startools there is a function "Sync" which enables one to enter details about the vanes, thickness etc, so the program can minimise the effect of the vanes on an image.
I dont use that feature at the moment as I actually like diffraction spikes in my images...some dont.

Alex

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3. ### Xelasnave.1947Valued Senior Member

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As to focus...

When you get to the pointy end of the game one usually replaces the standard focuser that comes with any scope with an after market unit that have a greater carrying capacity and have a temperature sensor that is read by an appropriate program which automatically adjust focus as temperature varies during the course of an imaging session.
The cost of a good focuser can cost up to $4000. I use a free program called Sharpcap for mount control, camera control, filter wheel control and to turn on and control the camera cooler unit. And in that program there is a feature to assist getting focus near perfect. In the old days I may take 50 photos in the course of getting focus perfect where as now it takes only about 5 to 10 minutes. I use a focuser mask that shows three lines intersecting which the program looks at and tells you that they are balanced which is better than eyeballing the "cross". I adjust focus manually between each run of say 20 images of 2 minutes each as I dont feel inclinded to spend$4000 to automate that aspect of the proceedure.

I can get away with manual focus because I use relatively short focal lengths although my 8 inch Newtonian reflector has a focal length of 1000 mm which would benefit from a temperature controlled focuser.

As I tune the set up I will probably have to go for such a focuser as the motor can move the focuser thru much smaller steps than one can do manually.

I do have electric focusers but rather cheap at \$100 for each scope but these are not yet controlled via software...but maybe they will save me getting the one with a temp control.

Alex

Last edited: Sep 8, 2018
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