Hi. Help pls I need advice on purchasing a telescope?

[Spare Tyre Nebula]

Hi,

I'm interested in purchasing a telescope, and after some deliberation I've decided to buy a SW Skyliner 200P.

Firstly, I have some questions..

1. Do I need to buy a Collimator?

2. Do I need to buy a Telrad or Rigel?

3. Do I need to buy a right angle finder?

4. Will the Telrad/Rigel fit on 200P Skyliner?

I hope someone can answer these questions?

I am keen to get started but feel that without these items I will not enjoy astronomy; especially because the collimator will enable me to keep the mirrors aligned, and the Telrad/Rigel will enable me to star-hop easier along with the right angle finder that won't cause me spinal damage during observation.

Any help would be greatly appreciated!

Cheers

[dweller25]

A. Excellent choice - this is a great scope for deep sky and the planets/Moon.

B. For best results buy a wide angle eyepiece - this reduces the amount of knudging you have to do.

1. These scopes are easy to collimate - A collimator will help but just get a collicap with a central hole - you do not need an expensive laser jobby.

2. Personal choice - the Telrads are very nice.

3. Personal choice - try the straight one thats provided and see how you get on. Personally I prefer a right angled finder as I find them much more comfortable to use.

4.Yes

[vulcan]

1. Do I need to buy a Collimator?

Not necessarily at first but you will have to get one eventually. (unless the scope comes from the dealer out of collimation!)

2. Do I need to buy a Telrad or Rigel?

This is very much a matter of preferrence. Is there some way you can try before you buy? (Telrads are hard to come by at the minute). Luckily, they are not very expensive.

3. Do I need to buy a right angle finder?

That depends on what direction you are looking. Sometimes a straight through is better and sometimes a right angle is less neck breaking. With a Newtonian like this, I would say, go for it so that you have a choice. 90° and 45°-angle finders can give a corrected (not upside down) image and/or a corrected (left to right) image so if you are changing finders often, it can get a little confusing.

4. Will the Telrad/Rigel fit on 200P Skyliner?

They can be made to fit fairly easily. The 200P has a dovetail fitting. It just a matter of having the correct baseplate. Your dealer should advise.

[Si W]

Welcome to SGL...

With regards to buying a Collimator, as Vulcan said, you will need one eventually, the best way to find out if you need the Collimator sooner rather than later is to do the focus test, just centre a star and take it out of focus. if it looks like the image on the left you'll be Ok for a while, if however it's like the one on the right or similar, it's worth thinking of investing in one. Don't get me wrong, if it's out of Collimation is not going to ruin your day, or should I say night, it just degrades the image.

[umadog]

A cheshire/sight-tube tool will be sufficient for collimating your scope. You don't need to spend lots of cash on a laser.

[dweller25]

Welcome to SGL...

With regards to buying a Collimator, as Vulcan said, you will need one eventually, the best way to find out if you need the Collimator sooner rather than later is to do the focus test, just centre a star and take it out of focus. if it looks like the image on the left you'll be Ok for a while, if however it's like the one on the right or similar, it's worth thinking of investing in one. Don't get me wrong, if it's out of Collimation is not going to ruin your day, or should I say night, it just degrades the image.

If you see the out of focus star image as in the right picture then you don't need a collimator at all - just collimate the main mirror on the star until the circles are concentric. A collimator is only used when no star can be seen.

[umadog]

A good collimator is always useful, although a star test is the final proof that the procedure worked.

You need to adjust both the secondary and primary mirrors for axial collimation. The primary alone will not cut it. How do you know which to tweak based on a star test? Finally, it's not easy to do a star test if the seeing is poor.

[Si W]

A Cheshire Collimator will maxims the accuracy over eyeball collimation or a sight-tube, it has two parts to it, the Collimation eyepiece is a combination of sight tube and a Cheshire eyepiece.

The site tube portion of the Collimation eyepiece has cross hairs to centre the optical axis and is used to make sure the secondary mirror is centered by adjusting the screws on the back of the secondary mirror.

The Cheshire portion of the eyepiece has a polished metal 45 deg angled element, that reflects light from a cut out down into the optical path and forms a bright ring on the primary mirror, all you need to do is to adjust the Collimation screws at the back of the primary mirror.

They are an excellent choice, I have one and it was worth every penny, it will help you find that sweet spot and bring out the best in your new investment. There are also some excellent threads on Collimation and these are really in-depth and helpful and worth a good read.

Simon

[umadog]

Thus:

John Reed Home Page Collimation - Cheshire

[Maximillion]

it all depends on whether it is second hand or first hand. if it is first hand it will be unnecessary to buy equipment to help improve your optics. if it comes with a Barlow lens or not and eyepieces, this should get you going until you want to upgrade and buy more advanced equipment. but if it second hand you might want to buy the equipment you suggested after you have bought the telescope. buying the telescope first will then enable you to know what equipment you will need to improve your optics.

hope this helps

regards

[Si W]

it all depends on whether it is second hand or first hand. if it is first hand it will be unnecessary to buy equipment to help improve your optics. if it comes with a Barlow lens or not and eyepieces, this should get you going until you want to upgrade and buy more advanced equipment. but if it second hand you might want to buy the equipment you suggested after you have bought the telescope. buying the telescope first will then enable you to know what equipment you will need to improve your optics.

hope this helps

regards

To be honest, I thought that was the case when buying from new as well, oooooh no , i wont say who i got my Brand new Meade LXD75 sn10 from a couple of years ago, but my new scope was that far out on the primary and secondary mirrors, i thought someone must of been using the OTA as a bouncing bomb for the next re-make of Dambusters .

[umadog]

The OP's question has nothing to do with "improving optics" and its answer doesn't depend upon whether the scope is new or used. He was wondering about upgrading the finder and whether to buy a collimation tool. These are basic items of equipment, not "advanced" ones. Many people prefer a Telrad and it will fit on that scope quite happily. At F5.9, collimation doesn't need to be super-accurate, but he would benefit from a proper tool rather than using the cap which comes with most scopes.

[Capricorn]

You need a collimator. You have to collimate newtonians and you are getting a newtonian. You may get away without one for a while but eventually you will need a collimator. It is just a case of when not if.

A telrad is a finder, a right angle finder is a finder. They are both finders, and perform a similar purpose. The decision is which do you find easiest to use. To find that out (unfortunately) you will have to buy both and decide. So one of them is going to be a waste of money, just which one.

It should fit the scope. Although you may have to make it fit the scope if no convenient mounting points.

If the scope comes with a finder try it first, if you get along with it then stick with it. Saves money.

[Spare Tyre Nebula]

Thank you Dweller25; Vulcan; Si W; Umadog and Capricorn..I appreciate the excellent advice, it's very helpful and will definately get the 200P with collimator & Telrad.

I can't wait to start stargazing & wish you all clear skies!

Regards