Star alignment& collimation

[Vali x]

Finally ! i went to my first stargazing party and i got the answers that i was looking for ! amazing ! but, talking with some people there, it was brought to my attention that every time that i want to use a Newtonian, i need to perform a star alignment AND a collimation! is this true? do i have the same situation with a schmidt cassegrain ? please let me know . thank you

[Tyr]

Vali,

Collimation is something that needs doing quite frequently to Newtonian reflectors (as I understand) but not (so often) with cassegrains or refractors.

By Star Alignment I think you're most probably talking about setting up the mount,

If you were using an equatorial mount you would need to polar align it each time you set it up. This (normally) involves pointing one axis of the mount at the star polaris, often using a small scope built into the mount itself.

If you were using a computerised "GOTO" mount you need to align these using stars as reference points so the computer chip in them knows which direction the mount is facing. This is usually done by pointing the scope using the hand controller up down left right controls at several bright stars one after the other in a simple setup procedure. Something which takes me about 5 minutes.

There's a good article about telescope types in the Primers and Tutorials section you could look at, which described the various types of telescope and goes into the pro's and con's of each design.

http://stargazerslounge.com/primers-tutorials/37999-primer-telescope-types.html

Hope that helps,

Tyr

[RikM]

It is best that you 'check' the collimation of a Newt every time you use it, to be sure you are getting the best views out of it. You certainly don't need to adjust it every time, or if you do, it is just a matter of twiddling a couple of knobs. It really is just a 2 minute job and nothing to be worried about. It also depends a lot on which Newt you have. Bigger / faster Newts need more attention than small / slow.

I star test mine as well, just as a double check that I have got the collimation right. That's just a case of pointing it at a star and putting it slightly out of focus. If the dark dot is in the centre of the white rings it's okay, if it's not, re-check the collimation.

SCT's also need to be collimated to give the best views but I am afraid I don't know how to collimate an SCT. Being generally longer focal length / slower f/ratio I would suspect that they are more tollerant of slight mis-collimation than an f/5 Newt, but I don't know for sure.

[NGC 1502]

Hi Vali x in Montreal.

I would agree with Rik in post #2. Both my newtonians hold collimation well,

although they are checked most times they are used, and just need an occasional

tweek, no big deal.

But a SCT is probably better in that regard, and there is just the secondary to

adjust, the primary being factory set. I will try to find an online 'what scope'

article, and come back with a link.

By star alignment, perhaps you are refering to setting up a goto scope (one that

uses an onboard computer and motors to find objects ?) Then yes, they will

require setting up each time you use it.

HTH, Ed.

Edit : useful article here http://www.cloudynights.com/item.php?item_id=1887

It is part 3 of a 3 part article, with links to part 1 & 2.

[lukebl]

Collimation is pretty easy once you get the hang of it. It takes me 2-3 minutes every now and then. Sometimes I go for weeks without needing to collimate my Newtonians.

[Vali x]

wow ! nice advise guys ! it will take some time for me to feel confortable ! so, i need also to buy the collimation item, right? i will not assume that it will come included ! for sure i will stick with my option as a telescope, an C10-NGT. i rather to have a little "chalenge" than pushing a button

PS: my browser is in french, so pls excuse me if i am missing some letters !