Newtonian Primary mirror alignment

frogman (Anthony Lord) · #1 14-04-2005, 10:07 PM

Can anyone tell me how to align my primary mirror... i took my secondry out so i didnt spray it with the adhesive spray and now saturn is such a lovely blob.....

seeing i dont have a collimation tool is there anything i can do ??????

I know I know if it aint broke dont bloody fix it.....

someone was going to help me collimate my scope proper like, but i cant remember who it was !!! DOH!!!

Anthony

westsky · #2 14-04-2005, 10:12 PM

Anthony, you can make a collmination tool from a film canister, just poke a very small hole in the bottom and it should fit nicely in the focuser.
Do a quick google search for collminating a scope there are lots of sites that explain how to do it and if your like me a picture is worth a thousand words :-))
cheers
David.

frogman (Anthony Lord) · #3 14-04-2005, 10:33 PM

but i have been told that my primary is out of "wack"......

I need sleep, 30 hours up is just too much....

Vermin (Tom) · #4 15-04-2005, 12:19 AM

Try this no tools collimation web site to get you back to a rough alignment:

http://www.vvm.com/~piscescs/collimat/NoTools2.html

This should buy you some time while you read the reviews of the myriad of available tools:

Site tube
Laser
Barlowed laser <- this is what I'll be using
Cheshire
Auto collimator
etc...

(Do a Google search for "collimation tools review").

RAJAH235 · #5 15-04-2005, 12:23 AM

Anthony, Try these>
http://skyandtelescope.com/printable...rticle_790.asp
http://www.andysshotglass.com/Collimating.html
HTH.

L.

Thiink · #6 15-04-2005, 12:25 AM

If you took your secondary out I'd guess that is the problem, its out of alignment. It's a little harder to collimate without a proper tool, but if you have an old film canister it should do the job. See here and here for details.

You can get a cheshire from Andrews for just $29, its basic but it works and its cheap! For a quick/light read on collimating (and general telescope information) I highly recommend the Orion XT6/8 manual. It can be downloaded from here.

iceman (Mike) · #7 15-04-2005, 06:09 AM

Forget about your primary mirror for the moment.. if you took your secondary out, you need to realign that squarely under the focuser. Once that is back in place and aligned, then you'll need to adjust the tilt of the secondary mirror so that you can see the primary mirror clips equally spaced around the secondary mirror.

Then you can adjust your primary.

As David said, I started out with a film canister with a hole in the bottom.

Do some reading and some research. Collimation is a necessary skill to learn when owning a newtonian so learn all you can. I still have much to learn about 'proper' accurate collimation, but I know how to get it very close.

But John's EZ laser thingo looked pretty cool last weekend and I want to get myself one of those now too.

frogman (Anthony Lord) · #8 15-04-2005, 05:18 PM

wow that film canister thing.... worked beautifully (i think) ill post tonight if its not too cloudy, and let you know

ausastronomer (John Bambury) · #9 15-04-2005, 06:07 PM

Duhhhhhhhhhhhhhh !!!!!!

It was me that was gonna help U with ur scope. because the secondary is not centered in the tube under the focuser, nor is its axial distance correct (distance to primary). In short the entire secondary assembly (including mirror holder) has to move sideways and up and down so to speak before you worry about adjusting the tilt of the secondary mirror.

I am also thinking its no closer than it was last Saturday

.

CS-John B

frogman (Anthony Lord) · #10 15-04-2005, 06:13 PM

HAHAHAHA ahhh ok sorry dude totally forgot !

Hey ......... John. ???????

frogman (Anthony Lord) · #11 15-04-2005, 06:15 PM

so tha means that it wasnt done propper like from the factory ??? yeah ????

Just wanted to be able to "see" till you can spare the time to help me.

ausastronomer (John Bambury) · #12 15-04-2005, 06:49 PM

Yes Anthony it wasn't done right at the factory. When I 1st checked my own scope after I got it the secondary was also a fair way out. The secondary was actually about 15mm too close to the primary. I have seen this on a couple of GS scopes.

CS-John B

robinsm · #13 16-04-2005, 08:43 PM

I purchased my GS 980 12 inch from Andrews and they aligned everything before I got it. Where did you get yours?

Cheers
Maynard

frogman (Anthony Lord) · #14 16-04-2005, 08:47 PM

Andrews GS 980 12"

frogman (Anthony Lord) · #15 16-04-2005, 08:49 PM

Hello Robinsm ahhh i got your first post (nothing like virginity

) whats your location ?

ausastronomer (John Bambury) · #16 16-04-2005, 09:25 PM

Robin,

I have seen 1/2 a dozen scopes from Andrews that were not properly collimated. Lee Andrews is a nice bloke and sells very cheap boxes but he is far from an expert on optics. If you got it from Bintel I would suggest an infinitely better probability that the scope was properly collimated when it arrived, thats why you pay a bit more from them. Mike Chator has been an ATMer for over a decade. In the case of Don Whiteman and Mike Smith they have both been ATmers for 3 decades.

I actually checked Anthony's scope myself and it isn't close to properly collimated, its miles out.

CS-John B

MiG · #17 18-04-2005, 05:51 PM

Is there any point in buying a collimated scope if it then travels 800 km to me in a truck?

slice of heaven · #18 18-04-2005, 06:12 PM

Mig
Yes, It can't get shaken that far out of whack.
gs do a poor job of aligning the optics.

Slice

gyro topple (Adam) · #19 23-04-2005, 12:17 PM

I don't know whether GS or Lee Andrews collimated my 12in but it was in great collimation after a 1500km roadtrip to be delivered to me.
While I am not even close to an expert in collimation, I found it quite easy to collimate well enough to get diffraction spikes with no tools at all - not even the film canister (now I have gone digital I don't have any loafing around any more)
Luckily the secondary was fine and it was just a minor adjustment of the primary - heaps easy using the defocus and centering the shadow method.

ausastronomer (John Bambury) · #20 23-04-2005, 02:00 PM

The problem with the factory collimation is that it is done with a normal laser collimator. This is fine if the secondary mirror and focuser are correctly positioned. When they are not, is when you run into problems using a laser alone. You can adjust the tilt of the mirrors and get the laser striking back on itself making things appear collimated when in fact they are not, a star test will quickly reveal that the scope is not collimated and the laser has told lies.

To Gyro:

You get diffraction spikes regardless of whether or not the scope is collimated. These are caused by "diffraction noise" off the spider vanes and have nothing to do with the mirrors.

Clear Skies
John B