Re: Laser versus Non-Laser Collimation

dkelvey_at_hotmail.com
Date: 03/09/05 

Date: 8 Mar 2005 16:39:41 -0800

Hi
 You can not do a fine star collimation without seeing the secondary's
reflection as looking offset relative to the primaries edges. This is
a myth of non-offset collimation. What happens if the secondary is
not offset relative to the tube is that the final collimation will put
the optical axis tilted relative to the tube. This is not usually
a problem except fast mirrors on EQ mounts.
 If there is an offset along the tube that should be fixed correctly.
Even so, this offset does not effect the reflection. This is the
centering
of the secondary as seen in the focuser tube.
 Please go back and read Olif's site more carefully. This is a hard one
to understand.
 I've used the Barlowed laser and it works great. It is so good that I
wouldn't even bother playing with a spot laser type. There are so many
trivial non-critical things that will make a spot laser alignment bad
that the Barlow ignores.
Dwight

Relevant Pages

  • Re: Laser versus Non-Laser Collimation
    ... Conversly, when I use the eyepiece cap, and get a nice ... The diagnosis was an out-of-round focuser tube. ... My personal practice in collimation is not to use one, ... Sirius is presently well-positioned at 9pm to star test your ...
    (sci.astro.amateur)
  • Re: Laser versus Non-Laser Collimation
    ... > collimation techniques. ... That may be helpful but note that as you said, offset is a one-time ... reflection of the secondary will be centered in the reflection of the ... not only will the optical axis not be parallel ...
    (sci.astro.amateur)
  • Re: Newtonian Sonotubes
    ... > weaken at all and hold their collimation just fine. ... out moisture) from much use over the years, that it's tube is as healthy ... such as around the focuser or mirror cell, ... This is NOT a fault of the material. ...
    (sci.astro.amateur)
  • Re: RCX400 review ?
    ... the tube and my Obsession 20 Dob doens't even have a tube! ... Meade has had some problems with the focus and collimation motors. ... main concern with the Meade RCX design as described on paper. ...
    (sci.astro.amateur)
  • Re: Collimation Question
    ... if you are interested in checking your collimation without ... There is only one way I know of to make a laser accurate enough ... Are you confusing secondary offset with being out of collimation? ... focuser as seen as the reflection through the primary. ...
    (sci.astro.amateur)