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Imager turned observer


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After selling all my imaging equipment a while ago I've been using my binoculars to view the nights sky. I've never really been an observer but for some reason my interest has been piqued.

I've just ordered a 8" Skywatcher Dob from FLO but I know very little about collimating the scope. What do I need, laser or Cheshire collimator and which one is recommended?

Anyway, it's good to be back....cheers all.

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imager to observer, now that does not happen to often! why the change of direction? i have been tempted myself, during the "dark" hours of trying to guide

It was just down to time. I found myself not getting out doing any imaging so decided to sell up but I can see myself returning to it at some point in the future.

The Dob will be stored outside so will already be cooled down and I can spend a nice half an hour or so finding objects that would have been used setting up an imaging run.

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For a solid tube, unless you are going to take your scope all over the place and throw it around, collimation should hold for ages, so I would think a quality laser would be overkill price-wise and would go for a Cheshire.

I normally use a HoTech laser, which I like for being able to use it in the dark, but that's with a flextube that I collimate every time. It's been one of my best birthday presents ever!

I like both visual and imaging and always thought I'd be more into the imaging, but some fantastic views at star parties and new gear have made it 50/50 for me now. Without an obsy, it's a pain to set up my imaging kit. With a dob, it's almost no effort. We hope to get a shed sorted out so that there's not even the hassle of cool down!

Anyway, welcome back! :)

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I use a Cheshire. More accurate than most lasers and the batteries don't run out.

I'd probably go for Cheshire myself in this case as it's a solid tube, but my original battery is still going strong one year on in my HoTech! Battery life is stated as 65+ hours, and I use it every time I set up my flextube.

You can get a pack of two Cr123 batteries for about £3. But with the current weather conditions, the original battery will last a lifetime at this rate! ;)

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You don't need a collimation cap but If you feel you need one then they can be made at home with a 32mm fim canister(?)

You know the covers for the EP holder? (It has 3 gaps on the base so the screws can go through it) If you punch a small hole in the centre of that then I think you can use that as a collimation cap but I just use a chesire myself.

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You don't need a collimation cap but If you feel you need one then they can be made at home with a 32mm fim canister(?)

You know the covers for the EP holder? (It has 3 gaps on the base so the screws can go through it) If you punch a small hole in the centre of that then I think you can use that as a collimation cap but I just use a chesire myself.

Ah thanks, I was reading AstroBabys guide and they suggested the collimating cap.

Is there any video guides for using a Cheshire Collimator out there?

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Unfortunately, no. But you could look at these:

Collimation Website

Collimation Video

Excellent, many thanks.

The Dob and Cheshire Collimator arrived at the office this morning (many thanks to FLO again for the excellent service) and I don't want to tempt fate but the forecast is for a clear night tonight so it may get a run out.

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i used astrobaby's guide too so recommend that. just take your time and don't rush it. good luck!

Thanks......luckily the scope turned up yesterday and collimation looks to be pretty much spot on but I'll give it a more detailed going over at the weekend when I have more time.

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I'm trying to get my head around collimation and the manual that came with my scope has a section that deals with it. One thing that puzzles me is in the section Aligning the Secondary Mirror. It says "You will have to alternately loosen one and then compensate for the slack by tightening the other two. Make sure that all the three small alignment screws are tightened to secure the secondary mirror in place"

So if I use the 3 adjustment screws to align the secondary mirror, what if I have to loosen one to get it aligned?? How do I re-tighten without messing up the alignment?

I'm obviously missing a major point about how the screws work here. :Envy:

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...but to answer your question...

If you loosen one and it aligns everything, you then need to tighten the other 2. in theory. Never quite works like that :)

Just use a bit of patience and take it slow; concentrate on only using 2 screws if you can. It'll come :)

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...but to answer your question...

If you loosen one and it aligns everything, you then need to tighten the other 2. in theory. Never quite works like that :)

Just use a bit of patience and take it slow; concentrate on only using 2 screws if you can. It'll come :)

ahh, so I don't have to re-tighten the one that I have loosened :embarrassed:

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The three screws work in a push-pull arrangement (a bit like the alt adjustment bolts on an EQ mount only there are three of them) If you loosen one bolt, they will all be loose but then you tighten back up using the other two and everything is tight again, just you have moved the mirror a bit.

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