Quote:
Originally Posted by theodog
Yes, I had to refocus and then readjust the frame size to get the stars to match. Also you can see I didn't place the camera back in exactly the same position after removing the SA. 
It was a fiddly job. 
How does the knife edge/SA distance affect the image?
Ah next investigation.  |
Not sure yet as it has been cloudy. In theory it should be as close to the CCD as possible. The image is not focussed when it passes through the SA so the knife edge should have a blurry side. I read somewhere that the resolution of the spectrum is determined by (among other things) the number of grating lines the star image crosses on the grating. This means the more blurry at the SA the better. This will blurr the edge also.
I will have to experiment.