Jump to content

NLC-Banner.thumb.jpg.acb5ba835b9e8bf0718b90539633017d.jpg

Barlowed laser


bosun21
 Share

Recommended Posts

I have just started using the Barlowed laser method for collimation on my 8” Dobsonian. This is the first times that my Cheshire and laser agree every time. Before when using just the laser there was always a discrepancy when checking with the Cheshire. Are most folks using the Barlowed laser method?

 

  • Like 2
Link to comment
Share on other sites

  • bosun21 changed the title to Barlowed laser

Most cheap lasers need collimating themselves that's probably why your laser and Cheshire did not correspond. 

The barlowed method is a good collimation for longer reflectors so you don't need to stretch your arms down to tweak the primary. 

Nothing beats a good Cheshire/sight tube IMHO. 

 

Link to comment
Share on other sites

2 hours ago, wookie1965 said:

Most cheap lasers need collimating themselves that's probably why your laser and Cheshire did not correspond. 

The barlowed method is a good collimation for longer reflectors so you don't need to stretch your arms down to tweak the primary. 

Nothing beats a good Cheshire/sight tube IMHO. 

 

My laser is a hotech and I checked the collimation with an engineers v block and it’s good at 5m. I think it’s that with the compression clamp in my focuser i never re site the laser the exact  same way twice. I’m in the process of fitting a click lock, so that should be better. I agree with you that the Cheshire is my main tool, although I like a final check on site and in the dark the Barlowed laser is great. I must be doing it right as my star tests are good and at the end of the day that’s the important part 

 

Link to comment
Share on other sites

22 minutes ago, Spile said:

My goto tools are the Cheshire eyepiece and sight tube combination tool for the secondary (secondary and primary) and cap (primary).

That’s what I use as well, although I use the laser on site after arriving and setting up. It’s much easier and quicker in the dark 

Link to comment
Share on other sites

I use all three methods but mostly a simple cheshire eyepiece. I'm most confident about the cheshire because post adjustment star tests seem to demonstrate that this device gets it right.

My secondary mirrors rarely seem to need adjusting. Usually it is just a tweak to the primary tilt that is required.

Edited by John
  • Like 2
Link to comment
Share on other sites

Same with me. I had to initially adjust my secondary mirror before first light and haven’t had to since. That’s where the Barlowed laser comes into play as all that’s ever required is a tweak to the primary.

  • Like 1
Link to comment
Share on other sites

I’ve never used a barlowed laser, though it does seem a popular method. I use a Concenter for the secondary and a Hotech laser for the primary. I confess I’ve never checked the collimation on the laser but the results are good so I reckon it must be fine. With the Hotech you don’t use the focuser locking screws, it has its own self centring mechanism.

  • Like 1
Link to comment
Share on other sites

The only times I have tried to barlow a laser was using the cheap single lens barlows that come with starter scopes (I have amassed a few). With these ones - and I'm sure you know the ones I mean - the laser light reflects straight back from the first uncoated surface and lights up the target so brightly that you can't make out anything else.

  • Like 1
Link to comment
Share on other sites

I use a barlowed laser to collimate my skywatcher 190MN. The secondary has a center mark which I can see projected on the primary. I align this with the mark on the primary, and both back on the laser's disk. I also check that the secondary mark is centered in the focuser.

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.