Weird collimating issue..

cjpops (Craig) · #1 30-01-2011, 02:56 AM

Hi all,

Weather is clearing up now, so im preparing my Lightbridge 12"..

I've got an Orion Lasermate Deluxe and collimated my scope for the first time, the scope was completely off the circle on both mirrors.

Here's what i don't get, After they are on/close to the circle (the laser) i've re-inserted the Lasermate to double check and it's off the centre? third time, same issue..

Is it just me or this is normal?

barx1963 (Malcolm) · #2 30-01-2011, 09:42 AM

Hi Craig
Congratulations on the 12"LB. Am I right in thinking this is a new scope and this is the first time you have collimated?
From your description it is ahrd to tell what is up. May I suggest you go through your procedure in a bit more detail so we can see if you are missing a step?
Remember the laser is really only the last step

Malcolm

cjpops (Craig) · #3 30-01-2011, 10:24 AM

Hi there,

Sorry i wasnt clear, ill explain a bit further.. And yes, this is my first time ive attempted to calibrate the scope..

Firstly, i adjusted the secondary mirror screws to move the laser pointer to the circle mark on the primary mirror.

Secondly, i untightened the white 'lock' screws in the bottom of the scope so i can make necessary primary mirror adjustments with the black screws.. I was able to get the laser pointer on the lasermate itself to the centre of the circular mark then tightened the white 'lock' screws carefully and evenly..

Both primary and secondary are now in the centre before i take out the lasermate device from the focuser/finder.. I then re-inserted the lasermate to double check and the laser is slightly outside the circle again.. I redid this proceedure and its different every time i re-insert the lasermate..

The laser point itself is not completely sharp and there's a bit of light leak on the sides i'm not sure if i have a dodgy one? I cant find an example on the net to compare with mine

barx1963 (Malcolm) · #4 30-01-2011, 02:02 PM

Ok, much as I suspected you are jumping the gun a little.
This website here
http://www.astro-baby.com/collimatio...on%20guide.htm
is the guide that I used. Don't know if it is the gbest but it worked for me!
Notice it doesn't actually talk about using the laser. I follow the procedure in this guide every few months and use the laser each session to check the collimation and make fine adjustments to the mirrors. I also will check with the laser during the night if the temp has changed by a fair bit. All the parts are metal and are going to move as the temp changes so I have a quick check now and then.
Would also recommend buying a complete Bobs Knobs set, makes the whole process MUCH easier!

barx1963 (Malcolm) · #5 30-01-2011, 02:12 PM

Oh and a couple of other points.
I find after I unlock the locking knobs, get everything adjusted so it looks "nice" tichten up the lock knobs and the spot in the laser collimator moves. Once I have tightened them all up, it usually ends up back in the right spot. Also, don't over tighten the locking knobs. I only turn them until I just feel resistance (once again Bob Knobs are much easier than the supplied gadgets)
With the light leak, I use the weakest setting that is visible in my laser as that reduces the size of the spot. Mine has settings from 1 to 8. In the dark (I usually do it in the dark!) It use either 1 or 2 but in daylight have to go much brighter. The laser with usually not produce a perfect round spot, so don't worry if its isn't.
And one more thing, give us a report on how your observing goes!

Space Dog (Ric) · #6 30-01-2011, 02:41 PM

Hi Craig, one other possible cause of your collimation error is that your lasermate may itself need collimating.
Try loosening off your thumb screw and rotate the laser colimator 360 degrees.
You may find that the red beam wanders all over the place, if so you will need to collimate the lasermate.
I have a standard Orion laser collimator and I fixed the problem by adjusting the laser beam with the three grubs screw hidden under the brand label, so that when you rotate the colimator the beam stays in the centre.
Probably the best way to is rest the collimator on a block of wood with a suitable V cut in it to take the collimator and aim it at a wall a couple of metres away.
Cheers, Ric.

cjpops (Craig) · #7 30-01-2011, 04:54 PM

Thanks for the feedback guys, I was told this lasermate deluxe collimator doesn't require calibration as long as i don't 'drop it'..

In regards to the laser when i'm pointing it to my wall - it's not a sharp dot, but more like a rectangle shape.. when i turn around the collimator the rectangle turns so not sure if this shape is ok.

I've re-calibrated the scope earlier again and i'm getting used to it - very minor adjustments was required.. then i careful re-inserted the lasermate - paying attention to the tightness in the viewer and it was just the way i left it beforehand.. i think i may under/over tightened the lasermate on the viewer causing all sort of issues..

will definitely buy those Bob knobs for the secondary mirror - would be much safer than dropping my phillips screwdriver down the tube.

Kevnool (Kev) · #8 30-01-2011, 05:03 PM

My two bob worth.

I have an older colimator that i dont use now and it collects dust now thanks to Howie Glatter. But anyway check the slop between the colimator and the focuser then you may find you have to put one layer of sticky tape around the colimator to get a snug fit.

Try and put the colimator in the spot every time you put it in and pull it out.

Those pesky mirror lock screws rip them out and throw them away there useless ( why would you colimate your scope only to throw it out when you tighten them things up).

And as said check the collimator itself.

Hope it all works out.

Cheers Kev.

PCH (Paul) · #9 31-01-2011, 03:24 PM

Craig,

for my two bobs worth, nobody has yet mentioned the poxy primary mirror springs that come as standard with the 12" LB. You'll find that if you get the stronger ones from bintel, the main mirror will be rock solid once adjusted.

At the moment, the weak springs will be allowing it to slosh around all over the place, and the locking nuts only prevent it from moving in the one direction - ie they don't prevent movement and sagging caused by weak springs.

I had this problem with mine and it sorted it out.

Hope it helps

barx1963 (Malcolm) · #10 31-01-2011, 05:04 PM

Yeah thats why I said get the complete set of Bobs knobs includes springs, primary knobs and secondary knobs
You save a few $$$ by buying the complete kit not each item one at a time.

Malcolm

Jason D (Jason) · #11 01-02-2011, 07:15 AM

Quote:

Originally Posted by Kevnool

Those pesky mirror lock screws rip them out and throw them away there useless ( why would you colimate your scope only to throw it out when you tighten them things up)

These lock screws could be useful. You are not suppose to tighten them blindly. You are suppose to tighten them while checking the cheshire or barlowed laser to maintain collimation. That is, use them the maintain collimation the same way you would use the main knobs to collimate.
Jason

Robh (Rob) · #12 01-02-2011, 10:45 AM

Craig,

I have the 12 inch LightBridge and it is a great scope. The locking screws should be next to the collimating screws. However, all 6 screws are evenly spaced at 60 degree intervals. So, effectively, the locking screws act as another set of collimating screws with less play. At first, provided the collimation was not too far out, I actually used the locking screws to fine tune the collimation. The springs that come with the scope are too light. As you move the scope around, the mirror will shift. If you replace them with a Bob's Knobs spring kit, you will find less issue with collimation and the collimating screws will work properly to hold the mirror in place. The locking screws can be ignored or just done up very lightly.
You will still need to collimate, every time you set up the scope.

Regards, Rob

steve000 (Steve) · #13 01-02-2011, 01:26 PM

Hi Mate,

Not being familiar with the laser mate, the differences could be caused by the way the collimator is inserted. if its attached by a thumbscrew there will be movement. on my 2" scope every time i use my 1.25" collimator using the 2" adapter its different. cause the 2" adapter attaches using thumb screws.

For me close enough is good enough, I dont expect the laser to be exactly center every single time if its out just slightly viewing will still be reasonable. I have found only uber expensive super tight tolerance equipment will give it aligned every single time. 1-2mm of difference should not be a real big deal. Check out the HOTECH SCA collimator, its expensive but more perfect then a thumbscrew attached collimator.

Kevnool (Kev) · #14 01-02-2011, 08:04 PM

Quote:

Originally Posted by Jason D

These lock screws could be useful. You are not suppose to tighten them blindly. You are suppose to tighten them while checking the cheshire or barlowed laser to maintain collimation. That is, use them the maintain collimation the same way you would use the main knobs to collimate.
Jason

Sorry Jason i disagree if that is so then why have six collimating knobs my newt has had the original gso springs replaced a couple of years ago with industrial compession springs and there tight as.

So there just useless except for the 1/4 threads they occupy which are now used to hold counterweights solidly inplace.

Collimation dont move during the night but as allways i colimate every time i set up.

Cheers Kev.

Kevnool (Kev) · #15 01-02-2011, 08:12 PM

[QUOTE=steve000;683131] For me close enough is good enough QUOTE]

Hey Steve that quote you say there i reckon you will change in time as theres objects that need perfect collimation or you just wont see detail.

Binary systems are an example some such as Antares you will never see its green little companion.

Sorry but for my $4000 newt i really need to see $4000 views.

Cheers Kev.

Jason D (Jason) · #16 01-02-2011, 08:38 PM

Quote:

Originally Posted by Kevnool

Sorry Jason i disagree if that is so then why have six collimating knobs my newt has had the original gso springs replaced a couple of years ago with industrial compession springs and there tight as.

So there just useless except for the 1/4 threads they occupy which are now used to hold counterweights solidly inplace.

Collimation dont move during the night but as allways i colimate every time i set up.

Cheers Kev.

I said they "could" be useful. In your case, you have strong springs installled -- but not everyone has strong springs installed in their primary mirror cell.