I may have a problem brought on by myself. I have two scopes that I put together. Both of them have the same problem. I cannot collimate them correctly, it seems. I have tried until blew in the face. I have used a laser, a cheshire, a sight tube, and collimating cap. All these devices have a place to be used. I have made the image in the focuser look exactly like the instructions I have found all over the internet. But all this does not seem to work for me. Either the secondary or primary or some other thing seems to be wrong. Aiming these things perfectly at one another is next to imposible. How do you line up the perfect center of the secondary to the perfect center of the primary ? Using the laser is of no help to me at all because it will line them up even no matter where the primary or secondary is aiming. Sometimes, so far off, that the laser strikes the center of the primary but exits and strikes the tube side and then when you adjust the mirror for this, half the primary shows in the secondary but still aimed at the center of the primary !!!!! Good lord one could spend days doing this and never get it right. I feel like the monkey with a keyboard, if given enough time, he will type a word or two. I have read and read tons of articles on collimating but nowhere do I see how to line them up perfectly to get to a starting point. One thing that would help is to know that the primary is exactly level in the tube !! Then if the secondary is level and in the center, aiming should not be a problem.
A real pain. Collimating !!!!
Started by imgary, 11/26/2002 09:24PM
Posted 11/26/2002 09:24PM
Opening Post
Posted 11/26/2002 10:20PM
#1
I've found after getting things on pretty well by eye-balling, is easiest to use a star to de-focus on and see if the blur circle gets 'lopsided' and adjust based on which side is 'lopsided'.
In getting the secondary straight, it doesn't yet matter if the primary is level yet. Forget the centers for a minute and fiddle with the secondary until you can see the outer edge of the primary in the secondary's reflection, about equidistant in from the edge of the secondary surface all the way around.
Then worry about straightening out the primary, get the reflection of the secondary roughly in the middle and then fine-tune with a star if necessary (this seems the most accurate collimating method to me).
Have never used a laser-whatzis or cheshire or what have you. I'd probably be lost with these things, would probably laser myself or something. It seems like once you get the hang of this it gets to be very second-nature.
In getting the secondary straight, it doesn't yet matter if the primary is level yet. Forget the centers for a minute and fiddle with the secondary until you can see the outer edge of the primary in the secondary's reflection, about equidistant in from the edge of the secondary surface all the way around.
Then worry about straightening out the primary, get the reflection of the secondary roughly in the middle and then fine-tune with a star if necessary (this seems the most accurate collimating method to me).
Have never used a laser-whatzis or cheshire or what have you. I'd probably be lost with these things, would probably laser myself or something. It seems like once you get the hang of this it gets to be very second-nature.
Posted 11/30/2002 06:16PM
#2
Gary…
Have you contacted anyone in the Central Valley Astronomers? Several of our members are quite skilled at collimation. (I, on the other hand, am a rank amateur.)
Our next indoor meeting is Saturday, December 7, at 7:00 PM. You're welcome to come, and I'm sure we can find someone to help you. We meet at Fresno State in East Engineering, Room 191. If you don't know your way around the campus, East Engineering is one block south of Barstow at the NE corner of San Ramon and Barton. FYI, Barton is 1/4 mile east of Cedar. Room 191 is the lecture theater at the far east end of the building and it has an outside entrance. Our club banner should be near the door (assuming so-and-so doesn't forget to bring it!).
The theme for Saturday's meeting is "gadget night." Bring your favorite gadget to show everyone. It is also election night for 2003 club officers. But don't let that scare you, we're a pretty informal group.
Fred Lusk
CVA Board
P.S. You can e-mail me directly at [email protected].
Have you contacted anyone in the Central Valley Astronomers? Several of our members are quite skilled at collimation. (I, on the other hand, am a rank amateur.)
Our next indoor meeting is Saturday, December 7, at 7:00 PM. You're welcome to come, and I'm sure we can find someone to help you. We meet at Fresno State in East Engineering, Room 191. If you don't know your way around the campus, East Engineering is one block south of Barstow at the NE corner of San Ramon and Barton. FYI, Barton is 1/4 mile east of Cedar. Room 191 is the lecture theater at the far east end of the building and it has an outside entrance. Our club banner should be near the door (assuming so-and-so doesn't forget to bring it!).
The theme for Saturday's meeting is "gadget night." Bring your favorite gadget to show everyone. It is also election night for 2003 club officers. But don't let that scare you, we're a pretty informal group.
Fred Lusk
CVA Board
P.S. You can e-mail me directly at [email protected].
Posted 12/03/2002 08:54PM
#3
I have found out what the problem is. There is some kind of defect on the secondary mirror. I put in a new 1.5 inch secondary that I had here at the house and presto, it works even better than I had hoped for. Thanks to all of you for your input. I now have this scope working very well, I was suprised to find the secondary at fault. I can see that the premium coatings are brighter than my standard coatings. I can see finer detail than with the standard coatings. I am so happy you all talked me into being patient. Last night provided the best images of Jupiter I have ever seen. I really thought that the scope was a lost cause. Thank you to all.
Funding Member
