A while back I asked for advice on collimating a reflector. It was a project I was doing for a friend.
I have gotten the scope as collimated as I can. Everything is lined up dead center, however nothing comes to sharp focus. Also, the focus seems sharpest (if you can call it that) when the object is dead center in the EP. The focus is worse when the object gets to any edge of the FOV. This happens even when I use my EP's that have good edge of field sharpness when used in my Mak.
When the object is out of focus, you can see the shadow of the secondary and the three spider vanes. Everything is centered when the out-of-focus image is in the center of the EP. When the object is in the center of the FOV, it is perfectly collimated. But when the object is at the edge of the FOV, I notice that the shadow of the secondary moves from one side to the other (depending on which edge of the FOV the object is moved to).
Even with a high quality EP that I know gives good views, no matter how much I try to focus, the object will still not come into perfect focus. What causes such a major shift in the location of the secondary's shadow (when out of of focus) just by moving the object so slightly in the EP FOV?
I did notice after I took the scope completely apart, cleaned it and replaced everything, that there is a bit of glue showing on the edge of the barlow/corrector lens in the focuser. Could the focuser (and/or the barlow/corrector lens) be of such lousy quality that no matter how collimated I get it, it will never come into focus?
I have seen scopes that are out of collimation, where the secondary's shadow is off center...but it usually stays off center in the same direction (placement relation to the edge of field of the out of focus star) no matter where the object is placed in the EP FOV. It doesn't shift it's location off center when moved about in the FOV...but this scope does.
How on earth could one ever get it collimated if on one side of the FOV the secondary is off in one direction, but when moved to the other side of the FOV, it's off in the other direction?
Any ideas? Can I replace the focuser? Any suggestions would be appreciated. This is a simple Newt reflector. Even if the mirrors were of low quality, I should be able to get somewhat decent focus if it's collimated shouldn't I?
I have gotten the scope as collimated as I can. Everything is lined up dead center, however nothing comes to sharp focus. Also, the focus seems sharpest (if you can call it that) when the object is dead center in the EP. The focus is worse when the object gets to any edge of the FOV. This happens even when I use my EP's that have good edge of field sharpness when used in my Mak.
When the object is out of focus, you can see the shadow of the secondary and the three spider vanes. Everything is centered when the out-of-focus image is in the center of the EP. When the object is in the center of the FOV, it is perfectly collimated. But when the object is at the edge of the FOV, I notice that the shadow of the secondary moves from one side to the other (depending on which edge of the FOV the object is moved to).
Even with a high quality EP that I know gives good views, no matter how much I try to focus, the object will still not come into perfect focus. What causes such a major shift in the location of the secondary's shadow (when out of of focus) just by moving the object so slightly in the EP FOV?
I did notice after I took the scope completely apart, cleaned it and replaced everything, that there is a bit of glue showing on the edge of the barlow/corrector lens in the focuser. Could the focuser (and/or the barlow/corrector lens) be of such lousy quality that no matter how collimated I get it, it will never come into focus?
I have seen scopes that are out of collimation, where the secondary's shadow is off center...but it usually stays off center in the same direction (placement relation to the edge of field of the out of focus star) no matter where the object is placed in the EP FOV. It doesn't shift it's location off center when moved about in the FOV...but this scope does.
How on earth could one ever get it collimated if on one side of the FOV the secondary is off in one direction, but when moved to the other side of the FOV, it's off in the other direction?
Any ideas? Can I replace the focuser? Any suggestions would be appreciated. This is a simple Newt reflector. Even if the mirrors were of low quality, I should be able to get somewhat decent focus if it's collimated shouldn't I?
