The only thing I can say that might be of comfort is that YOU WILL get better at it.
It's just one of those strange things in life where you get better at it the more you do it ...
I can't explain it. One day, the penny seems to just drop.
But you do have to do it, and do it, and then do it some more. And aim for only small improvements if you don't feel that you are making giant leaps forward
Optics to me is a bit of a black art at the moment.
Yes, when I get around to it I've got some incantations to try and already have selected a virgin bottle of beer that I'm going to sacrifice to the collimation gods
Aligning my scope with the laser is a breeze, made even easier because I have motorised my primary collimation screws.
I Just stand opposite the focuser and press a few buttons until the ring binder shadow in the barlowed laser beam return lines up with the laser emitter. I love my gadgets
holy cow! That's awesome! I just had my 1st collimating attempt, I used a film canister and as I suspected, the primary AND secondar collimation was way out. I've had a fiddle now and everything looks nice and aligned, I was a little worried never having attempted it before but it all started to fall into place once everything started to look alined.
Ok, this is my first post and it is due to utter frustration if I sound weird. I just bought an 8" lightbridge and am totally confused about the collimation. Especially about this 'offset'.
A few questions,
1. Can a lightbridge be collimated well with a meade laser collimater?
2. Does the offset mean your eye will not be center of the secondary when properly collimated.
3. Can someone post a pic of a collimated lightbride from down the focuser?
Or am I asking the completely wrong questions. HELP
I've just taken a photo of my 12"LB through the focuser. This is how it should look.
There is a great site called www.andysshotglass.com he has a very good video on collimation amongst other things.
If you need further help, PLEASE ASK!!
Quote:
Originally Posted by a1120028
Ok, this is my first post and it is due to utter frustration if I sound weird. I just bought an 8" lightbridge and am totally confused about the collimation. Especially about this 'offset'.
A few questions,
1. Can a lightbridge be collimated well with a meade laser collimater?
2. Does the offset mean your eye will not be center of the secondary when properly collimated.
3. Can someone post a pic of a collimated lightbride from down the focuser?
Or am I asking the completely wrong questions. HELP
My point of view is that whatever gets you collimated, and if you have a scope you have to transport to use you WILL need to collimate, is fine with me.
Passive tools (non-electric tools that use ambient light) are generally easier to use and can correct more problems than a laser. Active tools (laser, Krupa) can work well, too, and MAY be easier to use at night for a "touch up" to collimation.
You have to :
--center the secondary under the focuser. This takes a sight tube, not a laser.
--rotate the secondary until it appears round. This is for even illumination of the field, NOT for collimation. This takes a sight tube, not a laser.
--adjust the tilt of the secondary until the reflected image of the primary's center mark lines up with the axis of the focuser. This can be done with a sight tube (center the dot behind the crosshairs) or a laser (adjust till beam hits dead center on primary's mirror centermark).
--adjust the tilt of the primary. This can be done with a cheshire or a "barlowed laser". It cannot be done with the simple return beam of a singlebeam laser unless you can accurately gauge the spot on the primary to a hundredth of an inch. Placing the laser in a barlow and centering the shadow of the return beam on the bottom of the laser (look up in Google: "Barlowed laser protocol" for multiple sites on how to do this).
--eliminate all residual errors. This can be done with an autocollimator, but no other tool. No matter how ell you've done the previous steps, there will be residual errors in your collimation. The autocollimator can eliminate those and give you perfect collimation. Other tools will get you close, but not quite to perfect.
Who makes the tools:
Laser: Only brand recommended: Howie Glatter.
Passive tools 2": Catseye Collimation
Passive tools 1-1/4": Tectron or AstroSystems (just ignore their instructions to center dot the secondary.....shudder ).
And, though I may regret this, send me a private e-mail if you would like help with an issue on collimation. I'll help if I can.
Thank you for all the help. No problems so far except one, I live in Adelaide where does everyone get their collimation tools from. I only have one retailer here who is small. I am aware of Bintel, who else would you recommend?
This is not a paid ad but I have dealt with Bintel for a number of years and have found them to be reliable, competent and friendly at all times.
The other supplier that is very good to deal with is Andrews Communication here in Sydney www.andrewscom.com.au
I bought a Catseye collimation tool set and obtained the image taken with the SDM in my solar system blog at Wartook Rise (latest entry). Truss dobs require collimation on each session. The collimation will be out if the truss is dismantled.
Using a barlowed laser in conjunction with the Catseye tools will provide the best collimation you have ever had.
I've seen the cats eye page but was unsure what I needed. The "kit" you mentioned would seem like the best idea and can be used on any other Newts I may get in the future. The next question is price and delivery time.
BTW I'm green with envy, I just looked at your blog.
I was surprised that that shop Steve went to advised mainly to adjust the Secondary when collimating, since the Secondary is held rigid by Spider vanes, whereas the primary mirror is 'floating' on rubber and therefore has some play. Our club taught us the basics of collimation using a cheshire eyepiece and stressed that the secondary should hardly ever be touched once correctly aligned, whereas the Primary should ideally be collimated every time the scope is moved. Collimation is certainly easier using scopes where the primary has the centre marked.
I also understand that a laser collimator will itself need colimating every now and then. The blind leading the blind? One guy in the club that used both a laser and cheshire ended up ditching the laser.
So how do I know if the laser is collimated, this seems like it goes round in circles. My retailer assured me the best way to go is laser, probably more so to his profit margin than the good collimation of my scope. I think I'll start with a chesire and sight tube all in one first and see how I go. Adelaide optical said the lasers he has are made my meade but rebadged, anyone confirm if this is the case. He's asking $120 for them which is $50 more than Bintel's, my head is starting to spin.
I think all retailers I have spoken to have suggested a laser first.
Get the chesire/sighttube. Next step after that is the Catseye system I reckon. A laser on its own won't do all that is required but may be useful in conjunction with the cheshire.
Re-read Don's post, he has covered the major points nicely
Thanks Don for your help, It would seem that a laser is not the way to go first off. I think I'll be getting the chesire. I think I could use the practice this will give me. Then when I can afford the laser I can use it to double check the chesire collimaton.
So how do I know if the laser is collimated, this seems like it goes round in circles. My retailer assured me the best way to go is laser, probably more so to his profit margin than the good collimation of my scope. I think I'll start with a chesire and sight tube all in one first and see how I go. Adelaide optical said the lasers he has are made my meade but rebadged, anyone confirm if this is the case. He's asking $120 for them which is $50 more than Bintel's, my head is starting to spin.
First don't go to him, he is way too expensive and not trustworthy. I and several others here in SA have had bad experiences with him. He always adds 30% onto everything and sometimes as much as 50%.
To check if you laser or a laser is collimated. Make a jig with two "v's" and use these as a craddle to hold the laser. Then turn the laser on and about 15 feet away have a door with some white paper stuck to it. Point the laser at the paper and rotate the laser a little at a time. Go and make it after each rotation. You will see if it is collimated. Most lasers for this type of thing have collimatino screws.
However, I recommend getting a barlowed laser as this is more accurate and will present the centre dot image at the face of the barlow. It will not shift when you rotate the laser, thereby removing the need for great collimation of the laser.
Location: Tucson, before that Wisconsin, before...
Posts: 231
collimation gear
I have a glatter laser, also, and the Catseye triad of tools. A barlowed laser serves the same function as the Chesire, so if you want to avoid duplication, then you can avoid buying a Chesire.
A sight-tube and an autocollimator complement the Laser + barlow attachment nicely. Each has a purpose not served by the other two. So, if you want a high quality sighttube - one with a telescoping inner tube so as to make secondary placement very simple, get a sight-tube from him...it's quite nice, really, and easily adjusted for different scopes.
The autocollimator is great for fine tuning collimation by adjusting the secondary screws. It's really valuable for faster f-ratio scopes, and less noticeably beneficial for f6 and greater scopes. But if you dial in the AC, you'll be spot on. When using the AC, the fine adjustments you make to the secondary often require you to repeat the primary collimation a bit, then again to the AC. 2-3 iterations at most is necessary for this, but then you are about as perfect as you can be. Assuming your center dot is centered!
if you get the Catseye autocollimator, I'd suggest requesting the WHITE reflective triangles rather than red. Red is fine, but in truth, it's harder to see depending on lighting conditions. If it's daylight, the red is harder to see in the eyepiece, whereas the white reflective is visible in all conditions.
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