About Visual AstronomyCustom Telescope ModsTips & TricksNewsObservationsRSS FeedContact

Monday, February 4, 2008

Why Not to Rely on the Laser Collimator


This is why you shouldn't rely solely on the laser collimator to check your Newtonian or Dobsonian's collimation. The other night, I spent an hour or two getting my scope precisely aligned using a Cheshire collimation tool. Just out of curiosity, I inserted the laser collimator in the focuser drawtube and this is what I see...


The laser dot should be pointed precisely in the center dot of the primary mirror. At first, I thought I had not collimated my scope very well, but when I put the Cheshire back in, everything was dead on. And the Cheshire does not lie. The reason the laser is so far off is because the laser itself is not collimated very well (or at all) from the factory. The laser is also prone to huge errors due to mechanical slop in the focuser and elsewhere. The Cheshire method is much more reliable, as this image proves.

NOTE
: I have since added a tutorial on how to fix this issue!

Clear skies!

15 comments:

MiketheChap said...

Thanks for this tip.

A couple of questions: First, did you use the whole Cheshire collimation tool set (including the auto collimator) or just the Cheshire tool? Did you also use the sight tube (I don't understand everything in this yet so if the question seems stupid it probably is)?

Also, Zhumell has a deluxe collimator. Would it be any better than the one included with the scope, do you think?

Sean Welton said...

I don't currently have an autocollimator, but the Cheshire I have is a sight-tube/Cheshire combo tool. It functions both as a sight tube and as a Cheshire, so I can use the same tool to do everthing from centering the secondary to aligning the primary with one tool.

As far as the Zhumell deluxe laser, I'm sure it might be a little nicer, but the inherent problem with a laser collimator is that it needs to be collimated, just as the scope needs to be collimated. Putting the laser in a Barlow will diffuse the beam, which can be quite useful. By placing a paper target on the Barlow, you can center the shadow of the center dot on that target. Then you know that you are perfectly collimated, as this is not dependent on the laser's collimation.

Hope this helps. Once I get a hold of a Barlow, I'm going to do a write-up on Barlowed laser collimation.

February 12, 2008 at 2:29 PM

MiketheChap said...

DO you have a recommendation as to where to buy the collimation tool set from? I'm looking at getting an order turned in so I can really see!

Sean Welton said...

I got mine at the Cloudy Nights Classifieds section. This item at telescopes.com is similar to my Cheshire eyepiece.

February 28, 2008 at 10:34 PM

CheekyGeek said...

Your headline would have been more accurate if it had said: Why Not to Simply Rely on a Laser Collimator.

Perhaps a good follow-up post would be how to collimate your laser collimator. Assuming it has a round body, this is fairly straightforward.

Clamp a piece of angle iron or aluminum in place and lay the collimator in it (pointing at a wall). Now roll the collimator (rotating it in place 360 degrees). If perfectly collimated, the laser should stay at the same point on the wall. If it travels in a circle, it is out of collimation.

Good laser collimators can themselves be collimated. I have an Orion Lasermate Deluxe. I'm told the collimation screws are under a self-adhesive label.

Sean Welton said...

You bring up a good point, cheekygeek, as most laser collimators do have a means to collimate them. I've been meaning to make such a jig, but school lately has been hectic!

On my Zhumell laser, the collimation screws are set into the body, inside some little holes. If I remember correctly, they are allen screws.

Anyways, another way to collimate a laser is to actually put it in the telescope, and adjust your secondary WAY out of whack, so that the laser beam misses the secondary entirely on the return trip and exits the objective. Then your telescope has become the jig, and you can get a decent collimation of the laser in this manner. If I get time this weekend, I'll do a write-up of the process for future use.

Thanks,
Sean

April 10, 2008 at 9:18 PM

Super Nova said...

I had the same mechanical slop problem with my 10" LightBridge using the LaserMate collimator until I found a company solves the slop problem with their new SCA technology. I went ahead and bought the SCA laser collimator last week, and the laser works like a charm.

It uses its own self centering adapter to lock the laser without the thumbscrew and automatically centers the laser in the focuser. It is about time to have someone to come up with this brillient idea. You should check out their website, hotechusa.com. The laser is so accurate with repeatable installation, I don't even need to barlow the laser to compensate the mechanical slop.

Clear skies!!

张栋 said...

nba jerseys
pandora jewelry
cheap uggs, http://www.uggboot.com.co
mcm handbags
kobe bryants shoes
rolex watches uk
michael kors outlet
ralph lauren uk, http://www.ralphlauren-outletonline.co.uk/
babyliss pro
roshe run men
foamposite gold
christian louboutin sale
stuart weitzman boots
coach outlet, http://www.coachoutletstoreonline.in.net/
michael kors outlet, http://michaelkors.outletonlinestores.us.com/
louis vuitton outlet
polo ralph lauren outlet
chanel handbags
instyler ionic styler
replica watches
oakley outlet
iphone 6 plus cases
oakley,occhiali oakley,oakley italia,oakley occhiali,oakley sunglasses
air force 1 shoes
gucci,borse gucci,gucci sito ufficiale,gucci outlet
michael kors outlet, http://www.michaelkorsoutletonlinestores.us.com/
nike free uk
washington redskins jerseys
oakley sunglasses
new orleans saints jerseys

dong dong23 said...

louis vuitton outlet
coach outlet
oakley store
oakley sunglasses
christian louboutin sale
cheap oakleys
kevin durant shoes
replica watches
longchamp handbags
north face outlet
kevin durant shoes 8
louis vuitton outlet
coach factory outlet
oakley vault
cheap jordans
hollister clothing
ray ban outlet
oakley sunglasses wholesale
michael kors outlet clearance
tiffany outlet
michael kors outlet
ralph lauren polo
michael kors outlet
kate spade outlet
cheap oakley sunglasses
polo ralph lauren
fitflops sale clearance
coach outlet
ray ban sunglasses
michael kors outlet
nike free run 2
cartier watches
coach outlet
jordan 8
hollister clothing store
nike trainers
toms shoes
ray ban outlet
toms
michael kors outlet
20164.9wengdongdong

Yuanyuan Lin said...

7.14lllllyuan"tiffany and co"
"michael kors outlet"
"hollister uk"
"michael kors outlet"
"salomon shoes sale"
"ralph lauren outlet"
"bottega veneta outlet online"
"fred perry polo"
"true religion jeans"
"michael kors outlet"
"camisetas futbol baratas"
"cartier outlet store"
"hollister"
"christian louboutin shoes"
"nike soccer shoes"
"polo ralph lauren"
"polo ralph lauren"
"michael kors outlet"
"longchamp handbags"
"fitflops sale"
"michael kors outlet"
"coach outlet online"
"louis vuitton handbags outlet"
"adidas shoes"
"tory burch shoes"
"chrome hearts eyewear"
"tory burch outlet"
"michael kors outlet"
"replica watches"
"burberry sunglasses on sale"
"louis vuitton bags"
"coach outlet"
"jordan shoes 2015"
"michael kors outlet"
"abercrombie outlet"
7.14

Zheng junxai5 said...

zhengjx20160715
coach outlet store
christian louboutin outlet
lebron 12
michael kors outlet clearance
hermes birkin handbags
air jordan shoes
ghd hair straighteners
toms wedges
michael kors outlet
air jordan femme
coach outlet online
nfl jerseys
michael kors canada outlet
kobe 10
cheap oakleys
polo shirts
tory burch outlet
christian louboutin shoes
air jordan homme
nike store uk
ghd flat iron
louis vuitton handbags
toms wedges
coach outlet online
coach factory outlet
abercrombie outlet
oakley canada
coach outlet
tods outlet store
pandora jewelry
oakley outlet
tods sale
jordan 6s
oakley sunglasses
kobe 8
cheap oakley sunglasses
longchamp outlet
louis vuitton handbags
cheap oakleys
christian louboutin wedges

Rudy Lay said...

Super website with a great sha and amazing stories is ur web.. please keep doing what u do now.. thanks to you.
Agen Bandarq

Agen Domino99

Domino Online

Agen Poker

Bandar Domino99

Rudy Lay said...

Super website with a great sha and amazing stories is ur web.. please keep doing what u do now.. thanks to you.
Agen Bandarq
Agen Domino99
Domino Online
Agen Poker
Bandar Domino99

Arachel Octavia said...

Thanks for your post! it contains quite a lot of things to learn! it's great that I known this site!

cinemaindo
layarkaca21
DAFTARPOKER
BandarQ
BandarPoker
Bandar Kiu
Agen QQ

chenlina said...

ralph lauren outlet
oakley sunglasses
coach outlet canada
omega watches
sac louis vuitton
gucci outlet
louis vuitton handbags
giuseppe zanotti shoes
adidas yeezy
patriots jerseys
chenlina20170307

Post a Comment