Hope I'm not comparing apples and oranges here but does anyone have an opinion on using a suresharp vs. a flip mirror to focus a C-8? Can truly accurate focus be obtained with a properly parfocal flip mirror system? If so it seems much easier to use than a suresharp (or other ronchi screen). Any feedback would be much appreciated. Thanks!
Suresharp vs. Flip Mirror
Started by skywise_22, 10/23/2006 06:34PM
Posted 10/23/2006 06:34PM
Opening Post
Posted 10/23/2006 08:35PM
#1
At one time or another I have had three flip mirrors and two Stiletto's. I have never had a Suresharp.
My impression is that you are in fact mixing apples and oranges.
The flip mirrors I have had have been quite useful for finding and centering guidestars. However, I would not trust them for focusing. There are just too many things to shift ever so slightly. I do not know of any system that is absolutely parfocal.
And besides, the flip mirror does not do what the suresharp does. The flip mirror just changes the lightpath. You still need an eyepiece to focus with. And at that point, you are not going to get as sharp a focus as with a knife edge. It is simple physiology/psychology that lets the brain adapt the eye's impression to what is sharp. Meanwhile the knife edge gives a pretty much focus/not focused answer.
At least that is the way I think it would be.
Alex
My impression is that you are in fact mixing apples and oranges.
The flip mirrors I have had have been quite useful for finding and centering guidestars. However, I would not trust them for focusing. There are just too many things to shift ever so slightly. I do not know of any system that is absolutely parfocal.
And besides, the flip mirror does not do what the suresharp does. The flip mirror just changes the lightpath. You still need an eyepiece to focus with. And at that point, you are not going to get as sharp a focus as with a knife edge. It is simple physiology/psychology that lets the brain adapt the eye's impression to what is sharp. Meanwhile the knife edge gives a pretty much focus/not focused answer.
At least that is the way I think it would be.
Alex
