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Skywatcher 200p dobsonian


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Hi All. I’ve used a refractor for a number of years, but am thinking of buying a SW 200p. Now my question is, what do I need to buy along with it in terms of collimating tools. I’m guessing I’ll not be able to use it straight out of the box without collimating it first. There is an ‘essentials laser collimator’ for £45 on FLO site which says that I also need a sight tube as well. Any advice would be greatly appreciated. Many thanks in advance.

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I've found a laser collimator best for aiming the secondary at the center of the primary.  It's also handy to align the primary back to the secondary with a truss Dob while crouching at the back of the primary mirror.

A sight tube or cheshire is best for centering and squaring the secondary below the focuser.

I prefer to use a Rigel Aline to align the primary back to the secondary/focuser, assuming it is center marked with a donut ring.  It also makes for a handy focuser cap, leaving just a small vent hole to allow the OTA to breath in storage.

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OK thanks for the reply. So I need a laser collimator and a Cheshire? Mm beginning to sound more expensive. I’ve used a Celestron 102HD for a number of years and have been quite happy with it until it suffered an err accident. The reason I’m thinking of a 200p is because it’s about the same price as replacing the 102 with a SW equivalent, but buying both collimator and a Cheshire is going to add about another £100 to the cost so  maybe I’ll have to rethink. 

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You can use just the Cheshire for all steps of collimation, which will save on costs. However, I would advise spending your money on a good quality device rather than a cheap one, either the FLO premium Cheshire or a concentre would be my choices. 

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It may also be worth considering https://www.firstlightoptics.com/stellalyra-telescopes/stellalyra-8-f6-dobsonian.html as an alternative to the 200p

It's standard equipment such as finder etc. is a step up from the basic 200p

As for collimation, I'm no expert but I got a cheap laser one from amazon, checked it was collimated itself and that's been fine for me, haven't tried other methods though

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My 200p from FLO was perfectly useable for visual out of the box. I assume the only issue could be if it gets knocked in transit.

I bought the FLO premium Cheshire and a Rigel Aline collimation cap for just over £40.

Never used a laser - I've read that they themselves can go out of alignment.

Andy

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I've got the essential laser collimator from FLO along with a collimation cap for my 200P. I used the cap to center the secondary through the focuser, then the laser to aim the secondary at the centre of the primary and finally align the primary. The laser collimator arrived slightly out of collimation itself so I had to use the method found on youtube to collimate that first.

Edited by KP82
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Thanks a lot for all your replies. Some great info there and I’m a lot clearer now about what I need. I guess using refractors for years, I’ve been kind of anxious about the collimating process but doesn’t seem too bad. The Stellalyra 8” looks good but I can’t find any reviews. Does anyone know how it compares with the SW. in terms of the optical quality?

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5 minutes ago, YogSothoth said:

Thanks a lot for all your replies. Some great info there and I’m a lot clearer now about what I need. I guess using refractors for years, I’ve been kind of anxious about the collimating process but doesn’t seem too bad. The Stellalyra 8” looks good but I can’t find any reviews. Does anyone know how it compares with the SW. in terms of the optical quality?

The Stellarlyra Dobs are made by GSO, so if you search up GSO dobs (e.g. GSD 200C), you should be able to find some info on them. AFAIK the optics are about the same between GSO and SW dobs, but the mechanically the GSO is slightly more superior. You could also have a look at the Bresser Dobs. They are pretty decent.

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I use a Cheshire eyepiece and sight tube combination tool. I have a laser but only use it for final tweak of the secondary. My blog below has a “down the eyepiece” page you may find useful as I also own the 200P.

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On 12/10/2021 at 17:48, YogSothoth said:

I guess using refractors for years, I’ve been kind of anxious about the collimating process but doesn’t seem too bad.

Understandable, like most folk (myself included) you've quite possibly read several articles on it and decided it's complicated and best avoided. The first time you try it you'll probably spend a couple of hours faffing about but then things fall into place (not literally, hopefully) and you'll also realise that most of the time you'll need a small tweak of the primary, worst-case. Subsequently it'll be a couple of minutes tops, or even just a quick check-only thing. I thoroughly recommend this no-nonsense guide that doesn't over-complicate things:

https://garyseronik.com/a-beginners-guide-to-collimation/

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Mine didn't need collimating out of the box either.

I don't check mine very often, it's stood stationary in the shed most of the time.

Unless you are very heavy handed getting the 'scope out and putting it away, it should be fine for a good while.

But there will come a time when you just can't resist a twiddle!

As others have said, the first time can be a bit overwhelming until you understand why you are adjusting the various screws and which ones make things tilt or swivel in which direction.

Have fun! :)

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I have only just picked up on the thread and am surprised nobody has asked about your eyepiece collection. If it exists.

If you use the stock 25mm EP, it gives OK views.
Most people find the 10mm eyepiece is next to useless.

More money to spend! But ask first for recommendations.

On collimation. Don't get worried about it unless you have obviously funny shape stars.
We all have our favourite tools and methods.
The benefit of the tools is you can do the job in daylight!
A visit to a local astro club will be worthwhile. A hands on demo rather than reading books works wonders.
The old hands will also quickly spot serious problems - if there are any.
I had such a scope in 2003 and fortunately the wise people at a local club helped out the newbie.

Keep posting questions, and the 200P is a cracking scope.

David.

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4 hours ago, Carbon Brush said:

I have only just picked up on the thread and am surprised nobody has asked about your eyepiece collection. If it exists.

If you use the stock 25mm EP, it gives OK views.
Most people find the 10mm eyepiece is next to useless.

More money to spend! But ask first for recommendations.

On collimation. Don't get worried about it unless you have obviously funny shape stars.
We all have our favourite tools and methods.
The benefit of the tools is you can do the job in daylight!
A visit to a local astro club will be worthwhile. A hands on demo rather than reading books works wonders.
The old hands will also quickly spot serious problems - if there are any.
I had such a scope in 2003 and fortunately the wise people at a local club helped out the newbie.

Keep posting questions, and the 200P is a cracking scope.

David.

As far as eyepieces go, I’ve got the original 25mm that I got with the Celestron 102 and a couple of Celestron plossls- 9mm + 15mm, so OK for those, although I might replace the 25mm at some stage. I hear that BST are quite reasonable eyepieces that aren’t too expensive? I know what you mean about a hands on demo. Much better than reading instructions. Just looking forward to getting my new scope now.

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In my early years of collimating newts, I used collimating caps, made from film canisters and Cheshires. Lasers were very expensive.
Having said that. Unless you drop the scope down the stairs 😲, it tends to hold collimation quite well.

Nowadays I tend to still use the 'low technology' tools for mirror alignment. Finding a laser useful for identifying movement or bend.

For example you might see the laser return move if you apply a small sideways force on the focusser. Does it need any screws tightening?
Does the retun dot move as you rack the focus in/out? This might be a focus tube not aligned to the scope axis. Often a simple adjustment.
However, these are hopefully 'final tweaks' rather than major movements.

You have chosen well. Enjoy the scope now and worry about performance issues later.

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A word of warning on Lasers the cheaper models almost always need collimating themselves very tricky for someone who hasn't done it before.  If you intend to use a laser get a very good one like the Hotech, myself I have had two cheaper ones both needed collimating the first one was impossible and went in the bin.

Saying that even a cheap out of collimation laser can be used to collimate the primary using the Barlow method,   https://astromart.com/reviews-and-articles/reviews/beginners/show/barlowed-laser-collimation-made-easy

I used a Cheshire/ Sight tube mostly I did use the Barlowed method in the field as its quick and easy once learned.

Edited by wookie1965
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Thanks again for all of the replies and great information. My 200p arrived today and is now all set up. Looks to be well collimated as far as I can see, so just waiting for some clear sky now. It’s currently grey and drizzly. Oh well…….

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I acquired a 16” SW Dob a while back and after a bit of research went with the Hotech laser Collimator. It’s not the cheapest option, but as the optics get disturbed every time I wheel it out, I wanted a quick, reliable and easy method.

A much bigger problem is getting the clear nights to use it, alas no device available that works to fix that one.

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