How important is collimation accuracy?

[pevsfreedom]

Let me pre-face by saying that I'm a full blown sufferer of OCD, like clinically,

I have a 10" dob,

Things like collimation drive me nuts. I have a problem if things aren't 100%. How important is accuracy with collimation? I can get it to probably 85-95% of what I think would be 'perfect', should I just forget about it and point the scope at the sky, or is getting it right crucial?

Only concern I have is that whenever I look thru the eyepiece, I get a headache, but that's even on things that seem perfectly in focus, and I think that just might be a 'trigger' of mine (squinting my eyes = headache), but I was wondering if collimation can cause basically instantaneous headaches (from looking thru the EP?) or is it more of a 'personal problem'?

Thanks!

[kens]

Have you been able to use your scope yet? It bothers me that you've had it form some time without being able to enjoy it.

Personally, I don't advise novices to collimate as the first thing they do as it is just as likely they'll end up worse off.

But you are there now so the only way out is to fix it.

Having said that, I've still been able to see things even with a very poorly collimated scope and it doesn't give me headaches. I'd say it is the squinting that is the problem.

Do you wear glasses or do you know if you have any astigmatism? These could contribute.

Also, have you tried putting an eyepatch over your non viewing eye so you can keep both eyes open? That might help you to not squint.

Edited to add. It's also possible to view with both eyes open and no eyepatch but it takes some getting use to.

[pevsfreedom]

I've used it a few times, not to much success however. Only thing I've been comfortably able to find is Jupiter. I mean I got a cheshire collimator after realizing BOTH lasers I was sent by the company were way out, and I had no interest in collimating the collimator. So I think I'm pretty close now, was just wondering how severely collimation will really affect the view if it's not spot on. I wear contacts and have no astigmatism, but it's like an instantaneous headache as soon as I look thru any EP I have. I've used a hand over my other eye which kind of helps, but I still have to squint. I'm very prone to headaches though so this could just be one of those things. Haven't used an eyepatch yet though would be pretty cool. Truthfully after 2 months of mild/severe frustration I'm thinking of selling it and just getting a huge pair of binoculars, I loved my 10x50's and for some reason this telescope business is just like 'work' with no pleasure. 

[pevsfreedom]

Took her out again tonight. Best night so far, I went out and collimated it the best I could and forgot about it. 

Couple notes (not that anyone cares):

1) headaches definitely from squinting. if I use left eye and put right hand over right eye the headaches go away.

2) focusing issue wasn't collimation, I have to screw the 2" 30mm EP about 1/2 way into the focuser, if its all the way in in doesn't focus clearly, and if I use the XT tube it's even worse, 1/2 way into focuser was perfectly beautiful stars

3) is spring the worst season for stargazing (in terms of avg constellation magnitudes)? winter was very nice even here in LA and spring I can count literally.. 20 stars in the sky. not sure I'll find anything during this season in LA. I only 'know' the winter sky regardless, so I can't even find DSO's with my binoculars now that it's may. 

4) very curious to see jupiter jiggle at high magnifications, I take it it's the air. on 2nd note when I tried to star collimate (just to see what it looked like), it was 100% either the 'bad optics' identifier or simply 'bad seeing' identifier (when unfocusing on a star). I'm gonna go with bad seeing, since everything looked great @ 100x, at 200x I couldn't see a thang. I did manage to get jupiter @ 250x (super jiggly) but that was nice, again I used trick of sliding barlow only 50% into focuser, worked very well. 

[kalasinman]

I'm quite nearsighted with astigmatism. I don't know about contacts, but I only get good viewing when I take my glasses off.

[-Aldebaran-]

When the larger, brighter stars turned into coloured spheres, (they all looked like mars!)I knew it was time for a collimation! The primary was well out!

[Ouroboros]

Personally I can't see a difference in the quality of the view when my telescope is correctly or slightly off being collimated. Now maybe that's because it really doesn't make much difference or I don't know what to look for or my eyesight is too poor to see the difference.

I am also prone to headaches, but I doubt they're caused by poor collimation. Any combination of other factors could be the cause. Stress caused by worrying (probably unnecessarily) about minor things like collimation, the cold, tiredness (it is usually late when we observe), or lifting and setting up heavy mounts.

I recommend taking a couple of paracetamol and drinking a large mug of tea ..... but above all relax and enjoy your astronomy.

[pevsfreedom]

Relax" is probably the key word here! I try. Had a good night tonight, helped everything was in focus and I wasn't starring at fuzzy blobs like I usually did with my miscollimated laser collimators. 

[kens]

Took her out again tonight. Best night so far, I went out and collimated it the best I could and forgot about it. 

2) focusing issue wasn't collimation, I have to screw the 2" 30mm EP about 1/2 way into the focuser, if its all the way in in doesn't focus clearly, and if I use the XT tube it's even worse, 1/2 way into focuser was perfectly beautiful stars

That doesn't sound right. If you are only putting the eyepiece half way in then you need an extension tube. Maybe you need a shorter extension tube. Another possibility is that when you collimated you moved the mirror too far forward. You could try CAREFULLY easing off all the collimation screws equally so the mirror moves back a bit

3) is spring the worst season for stargazing (in terms of avg constellation magnitudes)? winter was very nice even here in LA and spring I can count literally.. 20 stars in the sky. not sure I'll find anything during this season in LA. I only 'know' the winter sky regardless, so I can't even find DSO's with my binoculars now that it's may. 

Could be due to more moisture in the air creating a fine haze. That's the problem we had here for many months. Now its just plain cloudy

4) very curious to see jupiter jiggle at high magnifications, I take it it's the air. on 2nd note when I tried to star collimate (just to see what it looked like), it was 100% either the 'bad optics' identifier or simply 'bad seeing' identifier (when unfocusing on a star). I'm gonna go with bad seeing, since everything looked great @ 100x, at 200x I couldn't see a thang. I did manage to get jupiter @ 250x (super jiggly) but that was nice, again I used trick of sliding barlow only 50% into focuser, worked very well. 

Bad seeing is likely. Could also be vibration from wind or just general wobblyness but you'd probably be aware if that was the problem. More magnification increases all the problems.

[brantuk]

Poor collimation will result in oblong or mushy stars and planets - "just off" collimation they will be less distorted - but at the end of the day you're either collimated or you ain't. What's important to getting it right is having the right tool - which for me is the one you get on with best. I use a Hotech laser and the barlow technique - others use a cheshire and swear by it. You'll need to try several methods over time I guess to find what suits yourself.

One good recommendation that helps enormously is to change the secondary collimation screws for "Bobs Knobs". They make it so much easier to collimate and they do obviate the possibility of dropping an allen key on the primary. Make sure your tube is horizontal when collimating with a tool, until you change them.

Once you're proficient at collimation and know what you're looking for it'll be a thirty second tweak at the start of a session and maybe a tweak here and there during the session (depending on weather conditions). And do get a demo from a local club member - you'll be surprised how easy it is. HTH

[Paul73]

I collimate at the start of every session (primary only). It takes about 30 secs. I find it quite reassuring that the scope is about right. I check the secondary every couple of months.

As said above. Relaxing is the key. Observing while seated is a key aid as you eye is much stiller at the eyepiece.

Paul

[jetstream]

Glad you have your collimation sorted out, it's fine. Do you get headaches when panning (searching)? Some eyepieces can really make a person feel funny....

[spaceboy]

My personal experience has found that you can't achieve 100% perfect collimation simply because you are going to use your scope by swapping out various sized eyepieces, moving it to different elevations causing sag, etc, etc. It is going to be in an environment with ever changing temperature, humidity, seeing, transparency, etc, etc. Your optics are always in varying states of flux due to temperature, sag, dew forming, etc and can even have dust gather on the surface.

If I can see colour in an object I am happy. If I can split close doubles with nice round stars I'm happy. If I can see GRS, clouds, icecaps, rings, small craters, vallis, on planets and the moon I'm happy. if I can resolve globular to the centre I'm happy. I guess what I am saying is if the telescope shows me what I want to see I am happy and don't care about collimation unless I'm seeing two of everything or the stars are no longer points of light in the centre of view.

Life is just too short and to strive for perfection in an imperfect world.

HTH

SPACEBOY

[pevsfreedom]

That doesn't sound right. If you are only putting the eyepiece half way in then you need an extension tube. Maybe you need a shorter extension tube. Another possibility is that when you collimated you moved the mirror too far forward. You could try CAREFULLY easing off all the collimation screws equally so the mirror moves back a bit

Could be due to more moisture in the air creating a fine haze. That's the problem we had here for many months. Now its just plain cloudy

Bad seeing is likely. Could also be vibration from wind or just general wobblyness but you'd probably be aware if that was the problem. More magnification increases all the problems.

Interesting point regarding #1. I might try the mirror thing, but yeah the only way to get focused on anything was to have the EP's not all the way in the focuser, the extension tube made it worse, and without one it was 'just off'. Manually moving the EP made everything crystal clear, I suppose it could be the mirror. Before I spent some time collimating the other day it was 'way, way off' because my laser collimators were junk. I made a similar thread to this about how to fix it (where I got recommended the cheshire) after a local shop wanted to charge me $200 to collimate my scope! I spent the $20 and did it myself - pretty accurately I think! But the mirror might be in a weird spot like you mentioned, I'll try to see if that's why. 

Glad you have your collimation sorted out, it's fine. Do you get headaches when panning (searching)? Some eyepieces can really make a person feel funny....

Basically if my eye is at the focuser I have a headache. Panning was definitely making it pronounced. Only way it went away was if I covered one eye (but kept it open). 

My personal experience has found that you can't achieve 100% perfect collimation simply because you are going to use your scope by swapping out various sized eyepieces, moving it to different elevations causing sag, etc, etc. It is going to be in an environment with ever changing temperature, humidity, seeing, transparency, etc, etc. Your optics are always in varying states of flux due to temperature, sag, dew forming, etc and can even have dust gather on the surface.

If I can see colour in an object I am happy. If I can split close doubles with nice round stars I'm happy. If I can see GRS, clouds, icecaps, rings, small craters, vallis, on planets and the moon I'm happy. if I can resolve globular to the centre I'm happy. I guess what I am saying is if the telescope shows me what I want to see I am happy and don't care about collimation unless I'm seeing two of everything or the stars are no longer points of light in the centre of view.

Life is just too short and to strive for perfection in an imperfect world.

HTH

SPACEBOY

Good points. I saw bright red stars and bright blue stars, and thinking back they were astounding to look at. Now I just gotta find some DSO's in my insanely polluted sky. I refuse to set-up my own guitars for the most part because I get so particular with measurements it drives me nuts, but we all have our quirks I guess.

[xtreemchaos]

ive got to have my glasses off,its a waste of time with them on,im blind as bat without them but when looking through any of my scopes everythings clear.

[Odd Thomas]

Have you tried using binoviewers?

I use them with my 10" dob, as well as my other scopes. I find it not a pleasant experience using one eye.

[laser_jock99]

Collimation slightly off.

Same scope/target laser collimated to sub millimetre accuracy

Spot-on collimation is essential for imaging at least!

[Ouroboros]

Spot-on collimation is essential for imaging at least!

Goodness! Looking at your first image I'm surprised it's that bad. Not least because I'm pretty lousy at collimation. The extent to which my telescope is collimated probably ranges between a bit iffy to approximately OK - and I've never ever seen aberrated images anything like as bad as that. Did you point the collimation way way off?

[Ouroboros]

PS I've sometimes wondered whether imaging a star field might be a way to check collimation. Or is star image quality dependent on too many other factors like coma and tracking?

[laser_jock99]

Did you point the collimation way way off?

No- that was before I had the joy of using a nice quality laser collimator.

 

PS I've sometimes wondered whether imaging a star field might be a way to check collimation. Or is star image quality dependent on too many other factors like coma and tracking?

The most severe test of any telescope is imaging. It shows up the slightest of flaws that the human observer either can't see or just chooses to ignore.

When you have the collimation right - then there are other problems to overcome like coma, CCD spacing, CCD orthogonality,guiding accuracy etc.

[Ouroboros]

Mmmm. I'm sceptical. But I have to say you're probably far more experienced in this than I am.

My problem is not having any measure of how un-collimated my telescope is nor having the time or inclination to do a systematic study of the effects of poor collimation on image quality.

I suppose like a lot of people I try and set up the telescope as best I can, reasonably speedily, and work with that. Being too obsessive could mean one spends all night fiddling around and not doing any observing or imaging.

[laser_jock99]

Mmmm. I'm sceptical. But I have to say you're probably far more experienced in this than I am.

My problem is not having any measure of how un-collimated my telescope is nor having the time or inclination to do a systematic study of the effects of poor collimation on image quality.

I suppose like a lot of people I try and set up the telescope as best I can, reasonably speedily, and work with that. Being too obsessive could mean one spends all night fiddling around and not doing any observing or imaging.

Collimation is not difficult and having the right tools makes things a lot easier (I struggled using Cheshire eyepieces and cheap laser collimators for months- they simply aren't good enough for the collimation accuracy required in imaging at F4 and faster).

Collimation before an imaging run takes me less than 2 minutes and is a simple process:

1) Adjust the secondary first so the laser beam hits the centre spot on the primary.

2) Adjust the primary so the laser beam goes exactly back up it's own path.

Job done.

[kalasinman]

I'd venture to say you could have collimated a cheap laser and your scope in less time than you have invested at this point. It's not hard. I did mine, and it's stayed rock solid. You have to dig the goo out of the three adjusting screw holes, make something to hold the laser (v-blocks or one of many homebrew substutes elsewhere on SGL) tape a piece of paper to the wall at least as far away as the FL of your scope. Turn on the laser and make a spot where the beam falls, then rotate the laser and adjust till it no longer makes a circle, just stays in a spot as you rotate. Maybe an hour?

[laser_jock99]

I'd venture to say you could have collimated a cheap laser and your scope in less time than you have invested at this point. It's not hard. I did mine, and it's stayed rock solid. You have to dig the goo out of the three adjusting screw holes, make something to hold the laser (v-blocks or one of many homebrew substutes elsewhere on SGL) tape a piece of paper to the wall at least as far away as the FL of your scope. Turn on the laser and make a spot where the beam falls, then rotate the laser and adjust till it no longer makes a circle, just stays in a spot as you rotate. Maybe an hour?

All the cheap e-bay laser collimators are 1 1/4" fit which is already a "no no" in my books. You need the beam to be as dead centre in the focuser as possible to start with (I don't even recommend tightening the eyepiece clamp screw for collimation).

The whole principal of collimation is to align the optical path of the mirrors to the centre axis of the focuser tube. If the beam is in the wrong position to start with you are never going to be really well collimated. 

Clamp your 1 1/4" ' collimated laser collimator into a 1 1/4" to 2" eyepiece adaptor and then rotate this in a vee block if you want to see what I mean...... 

EDIT- of course if the focuser tube is 1 1/4" fit only then you are fine! 

[kalasinman]

All the cheap e-bay laser collimators are 1 1/4" fit which is already a "no no" in my books. You need the beam to be as dead centre in the focuser as possible to start with (I don't even recommend tightening the eyepiece clamp screw for collimation).

The whole principal of collimation is to align the optical path of the mirrors to the centre axis of the focuser tube. If the beam is in the wrong position to start with you are never going to be really well collimated. 

Clamp your 1 1/4" ' collimated laser collimator into a 1 1/4" to 2" eyepiece adaptor and then rotate this in a vee block if you want to see what I mean...... 

EDIT- of course if the focuser tube is 1 1/4" fit only then you are fine! 

It is always possible to provide increased precision (with extra money). I would question the need for an expensive collimation device in an F5 Newtonian. Yes a degree of extra care is required. I rotate my cheap laser in place during a collimation and see no movement of the laser spot. Good enough for my f5. This is one reason I opted for an f5 instead of something faster.