Anyone use barlowed laser technique?

[wavelandscott]

Just curious if anyone was using the barlowed laser technique for collimation...

I am interested in your experiences likes and dislikes...

Relatedly, what are you using for your target?

Specifically, has anyone used the Howie Glatter Blug?...again, any likes/dislikes...Santa is looking for a stocking stuffer and I was wondering if this might be a good thing for him to bring for me...

Cheers and Thanks!

[iceman]

Are you not achieving collimation using your current methods? How do you do it now?

I remember at Kulnura last month your collimation was way out.

[wavelandscott]

It did get pretty bad through the night...my secondary has developed a bit of "wobble" I've got to tend to...a seperate item at this time...

Mostly asking about the "blug" as it falls into a nice price range for a Christmas gift from some family members (in-laws) who feel the need to get me something astronomical...

While there is still some light I use a chesire collimating eyepiece (Orion) and it works a treat...I also have a laser but I rarely use it....the "blug" sounded interesting so I thought I'd ask...mostly for the above reason (gift recommendation)

[janoskiss]

I used to use it. But since my laser died all I use is a Cheshire. I hand held a white cardboard screen with a hole in it to the back of the focuser. Having to hand hold it is not a problem as the outgoing beam after the barlow is still fairly localised so you can easily tell when it is centred on the hole in the screen.

[Starkler]

The success of the barlowed laser depends upon accurate pre alignment of the focuser axis and optical axis. As the target will be some distance away from the focal plane this is most important and that there be no focuser slop for the same reason.

I have read on a CN review that the blug has some practical shortcommings w.r.t. focuser fit.

[wavelandscott]

Yep, I've been reading that too...that is why I am asking about practical experiences...

Thanks!

[janoskiss]

Anyone who saw Bird's demonstration of the barlowed laser at Snake Valley would have seen that focuser slop and misalignment makes no difference. That's the beauty of the technique. I guess if the screen is far enough away from the focal plane then you might see it make a difference, but in practice it's not likely to be a problem.

If in doubt, try and see: Loosen the retaining screw/ring holding the laser + barlow in the focuser and wiggle the barlowed laser around. You should see the light on the backreflection screen shift about but the shadow of the primary centre spot should stay put.

[xstream]

This might also be worth considering Scott.
I've only ever heard of good reports about it.

Cats Eye (http://www.catseyecollimation.com/ceyeflr1.html)

[Starkler]

I have used a barlowed laser myself. As you wiggle the laser around you can see the illuminated part shifting around whilst the reflected shadow of the centre spot stays still, but a wiggling focuser can still result in a lateral shift of the target you are trying to align to, especially if the barlow is long.

I guess its not a big factor, but I think everything would have to optimised to get any better results than you would with a basic cheshire.

[janoskiss]

I see your point, Geoff. This LED in translucent screen would solve that problem if it was placed in the focal plane. I'm with you on the Cheshire. Seems to do the job very well even if a bit tricky to do by yourself on a big scope (as is the barlowed laser too).

[bird]

I rely on the barlowed laser, and it seems to work fine for me. Especially at night when I don't have a light source for the cheshire it's very nice to just look in the tube at the target over the end of the laser. I can't think of a faster or easier way to do it.

cheers, Bird

[dcnicholls]

Try the modified Krupa collimator (see the post "New type of newtonian collimator (http://www.iceinspace.com.au/forum/showthread.php?t=15474)") if you don't mind a bit of construction. It works a lot like the Barlowed laser, but is easier to use.

DN

[Roger Davis]

Just started making my own Focused Krupa collimator. Looks like my lathe will be working late into the night! (As long as it isn't clear skies, that is)

[dcnicholls]

Roger, I've just added some new dimensions to the diagram (red figures) based on a second model I made. I've added a bit of new text, too. Either version works fine, the second is perhaps marginally better.

DN