Jump to content
  • Join the online East Midlands astronomy club today!

    With active forums, two dark sites and a knowledgeable membership, East Midlands Stargazers has something for everyone.

Collimation- How often?


Guest Trickydicky
 Share

Recommended Posts

Guest Trickydicky

Hi all


 


I have recently upgraded to a 200mm Dob and initially the scope will be used at home, so no long car journeys. I have not purchased a collimation kit as I was initially advised by the retailer that as long as I'm careful it will not need collimating for at least a year. However, I have now read that it is recommended that a newtonian/dob is checked every time it is used!!!.  Conflicting opinions.Whats the general consensus? 


 


Also, if I do buy a collimation kit any suggestions on manufacturer etc? 


 


 


cheers


Link to comment
Share on other sites

The smaller scopes under 200mm tend to hold collimation quite well if not interfered with (they're factory set quite firmly). But 8" and above it's best to do a star test at the beginning of each session and if it needs doing then go right ahead. The very large dobs - particularly truss dobs to tend to need collimating every time.


 


To test on a star - get the star central and well focused. Then take it slightly out of focus by turning inwards or outwards. You will see "airy" rings of light which should be perfectly circular and concentric. Then do the same thing in the other direction and you'll see the same thing. If the rings aren't circular and concentric in either direction then it needs collimation. :)


Link to comment
Share on other sites

They will take a good amount of abuse without grumbling. Mine has done a four hour road trip, and on checking it, it didn't need any adjustment.


 


Have a look on Astronomy Shed, there are excellent tutorials by Dion on collimation, with explanations that are easy to understand. 


 


http://www.astronomyshed.co.uk/forum/viewtopic.php?f=19&t=102&sid=89d25e59b3c2d51c8eac9ea19239844f


 


Collimation doesn't have to be a nightmare, but it can be. Just make one adjustment at a time, if you don't, and make an error, moving more than one thing can quickly compound any errors. But don't worry, if it goes pear shaped it's recoverable.


 


Iam down at J26 of the M1, if you need any help your'e welcome to pop down and we can go through it for you.


Link to comment
Share on other sites

Guest Trickydicky

They will take a good amount of abuse without grumbling. Mine has done a four hour road trip, and on checking it, it didn't need any adjustment.

 

Have a look on Astronomy Shed, there are excellent tutorials by Dion on collimation, with explanations that are easy to understand. 

 

http://www.astronomyshed.co.uk/forum/viewtopic.php?f=19&t=102&sid=89d25e59b3c2d51c8eac9ea19239844f

 

Collimation doesn't have to be a nightmare, but it can be. Just make one adjustment at a time, if you don't, and make an error, moving more than one thing can quickly compound any errors. But don't worry, if it goes pear shaped it's recoverable.

 

Iam down at J26 of the M1, if you need any help your'e welcome to pop down and we can go through it for you.

Thanks for the advice/offer Martyn,

Link to comment
Share on other sites

Having used various collimaters, I would say without a doubt the Hotech 2" is the best! It is self centring so is in the same place each time and rock steady! Not the cheapest but certainly the best!


 


Cheers


Ron


Edited by Ron Clarke
Link to comment
Share on other sites

Guest Trickydicky

Having used various collimaters, I would say without a doubt the Hotech 2" is the best! It is self centring so is in the same place each time and rock steady! Not the cheapest but certainly the best!

 

Cheers

Ron

Thanks Ron, I will have a look at them

Link to comment
Share on other sites

Well that didn't seem to painful.  The secondary mirror was way out. looking through the collimator it is pretty clear what needs to be lined up.  It is just a case of gradual adjusting of the screws for the secondary first then a slight adjustment for the primary.  This was more fiddly as it was a bit of a stretch to reach the adjusters and look through the collimator at the same time.  


 


I actually enjoyed the tweaking and now feel suitable chuffed.  Clear skies will tell if I have got it right though.  


Link to comment
Share on other sites

I agree with Ron, the Hotech is very good indeed and very easy to use.


 


With larger dobsonians I would check collimation every time it's used, you will find they do need a tweak. Truss tubes dobs will always need a tweak every time as they are dismantled or slid down after every use.


Link to comment
Share on other sites

Guest Tweedledum

Hi Richard,


 


Good advice above, when I had my newt, the first time I had it collimated by RVO who charged a tenner. If you don't wish to do it yourself RVO aren't far away.


Link to comment
Share on other sites

I have the 200p dobsonion as well and mine gets carted around in the car and too and from the garage to the patio, in a 12 month period I checked my collimation 7-8 times and only Collimated twice. If you are carefull and don't plonk it on the ground or throw it around, the 200p holds collimation for ages.

Link to comment
Share on other sites

Guest Trickydicky

Hi Richard,

 

Good advice above, when I had my newt, the first time I had it collimated by RVO who charged a tenner. If you don't wish to do it yourself RVO aren't far away.

Hi Damian, I bought the scope from RVO and they have offered to do the first collomation free of charge and its £15 thereafter. Will probably get a kit and have a go myself once I manage to get the scope out on a regular basis!!! Just need this cloud to jog on!!!

Link to comment
Share on other sites

Guest Trickydicky

I have the 200p dobsonion as well and mine gets carted around in the car and too and from the garage to the patio, in a 12 month period I checked my collimation 7-8 times and only Collimated twice. If you are carefull and don't plonk it on the ground or throw it around, the 200p holds collimation for ages.

Thanks Darren, lovin your SW mods links also. Will definatly give them a go. The rotation of the bottom plate feels a bit clumbsy... or that might just be me!

Link to comment
Share on other sites

Guest Tweedledum

hi Richard,


 


If RVO will do it for free, take it in and watch how they do it. Once you know how its done its not so daunting! There are also plenty of guides on the 'net and youtube.


Link to comment
Share on other sites

Guest Trickydicky

Well that didn't seem to painful.  The secondary mirror was way out. looking through the collimator it is pretty clear what needs to be lined up.  It is just a case of gradual adjusting of the screws for the secondary first then a slight adjustment for the primary.  This was more fiddly as it was a bit of a stretch to reach the adjusters and look through the collimator at the same time.  

 

I actually enjoyed the tweaking and now feel suitable chuffed.  Clear skies will tell if I have got it right though.  

Thanks for the update Doug, Like you, Im keen to collumate myself

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 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.