Collimator and few more questions

[luka]

I just got a 10” SkyWatcher solid tube dob from gumtree. This was not planned but the deal was too good to pass. I am coming from AP, refractor-only background (and GOTO mounts) so this is all very new to me.

I cleaned everything and washed the primary mirror as per instructions on IIS as it was covered in (dog?) hair. The next step is the collimation. I tried with a film cap but I am not sure what I am doing and I don't think I did a good job. I am looking at getting a tool for this. I read lots of positive about the Orion Collimating Eyepiece (https://www.bintel.com.au/product/orion-collimating-eyepiece/).
Is this still a good choice for collimating both mirrors?
Is there any advantage in also getting a cheap laser collimator at the same time (to save postage)? I assume that the cheap laser collimators may need collimation themselves but that does not look too difficult.

What other "essentials" should I be looking at?
Fan for cooling down the mirror?
Observing chair?

Thank you in advance
Luka

[Merlin66]

IMO I'd stick initially with the film cap and spend the time (Google) learning and understanding what you should be looking at during the Newtonian collimation process. Once you can get your head around it - you'll find it very easy and you'll be able quickly to do it when required.
The Cheshire eyepiece and laser collimator can help - but the basic understanding is still needed.
Save the money at the moment.....

[gaseous]

I'm not sure if it's just me, but I collimated my laser collimator on the weekend for the first time, and it's orders of magnitude harder to get the laser properly aligned than it is to align the mirrors on a dob.

[sharptrack2]

I found this resource to be the one that made it all click. Once through and I was amazed at the difference. Then I read up on fine tuning using a star and even a cheap 5" consumer Newtonian was showcasing Saturn and Jupiter.

www.astro-baby.com/collimation/astro babys collimation guide.htm

Another good resource is our own Projects and Articles...

http://www.iceinspace.com.au/63-390-0-0-1-0.html

For fine tuning using a star...

http://garyseronik.com/no-tools-telescope-collimation/

and...

http://www.backyardastronomy.com/Backyard_Astronomy/Downloads_files/Appendix%20A-Testing.pdf

Good luck!

[mental4astro]

The Astro Baby link that Kevin gave is a very good one. I would have posted that link too if Kevin hadn't.

Just a word on laser collimators. They are designed to collimate the primary, they won't look after the proper setting of the secondary mirror. That is what is at the heart of the Astro Baby article. That is why I have both a Cheshire eyepiece for the secondary and a laser for the primary. The Cheshire can do it all, but the laser makes tweaking the primary easier. The Cheshire will help you get the positioning of the secondary correct for the focuser, both up and down and laterally, and square with the focuser. A laser won't do this.

I keep a photo canister collimator in my kit as a "just in case" measure should I forget to pack the other stuff... :rolleyes:

Not all lasers collimators are made the same way. Some need to be collimated themselves! Below is a link to an IIS thread I started on how to collimate some of these. Very easy to do, and taking the time makes all the difference. The divergence could be small or large, and only by testing the laser can you actually know how true it is:

http://www.iceinspace.com.au/forum/showthread.php?t=75601&highlight=pimp

Collimating isn't a big deal. The hardest part about it is just the word "collimating". Just remember that it is just tweaking the alignment of the mirrors so the scope can give you the optimal image that it can. Like any new process it takes a little to get the hang of it, but then becomes second nature and you don't even think about it, you just do it. Knowing that the three minutes that it takes to do will give you the best the scope has to offer is incentive enough, and it just becomes part of the set up ritual.

How often to do it? Depends on you, the scope and how you use it. Remember that a Newt has several parts that are only really lightly held in place. These parts are often spring loaded, so movement does happen. If you haul your scope long distances in your car, then there will be more of a shift than if it's just at home. Going bush I check it every time. The dob I have set up at home I check every second or third time. The better the scope is made the less movement there will be - just don't over tighten anything! This will only cause damage.

Most cooling fans are incorrectly implemented. The wrong thing to do is have the fan blow directly on the primary. This will only cause a cold spot on the mirror. Best practice is to have the fan pull air away from the mirror, and hence also down the tube of the enclosed OTA. This will give a more uniform flow of air over the entire mirror, and helps cool any thermal currents from inside the scope. It also means that the rear cell of the OTA needs to be closed off leaving just the fan exposed so that the correct movement of air can be achieved. Leave the rear cell open and air will just reticulate around the fan, and not the mirror.

Have a read of the article I wrote about this if you would like a little more insight about mirror cooling. It was written with much peer review from fellow IIS'ers, and the final article is the product of this reviewing, :)

http://www.iceinspace.com.au/63-771-0-0-1-0.html

Obs chair is up to you. Depends pretty much on the range of movement the eyepiece has from zenith to the low horizon. Use your dob a few times first with the chairs and stools you have handy and then make a decision.

Maybe a filter or two, OIII and/or UHC type. They help a lot with nebulae, especially under urban skies.

Only other thing is, be patient. It takes a little while to retrain our eyes to see in low levels of light. A quick glance at something just to tick off a bucket list ain't gonna do much. You've picked up this new scope to supplement your imaging gear. Be patient. The details are surprisingly there. Just take your time and let your eyes do their thing, caressing every square inch of the image, like a lover does their partner's body, ;) - it's a sensory thing.

Alex.

[luka]

Just wanted to say thank you for all the comments.
The life events took over and the new dob is sitting sadly in the corner :(.
But I will follow your recommendations as soon as I get a bit of spare time.