20 inch Dobsonian Design, Build and Observing

A big 'scope tour! Lots of ideas, tips and advice on building and using a big telescope. Amazing views through an amazing bit of kit.
A tour through Alan Marriott's homemade 20-inch / 505mm telescope at Kelling Heath Star Party, England.
My thanks to Alan Marriott for showing us his wonderful telescope and also for letting us view through it. We had a wonderful view of the Orion Nebula in the early hours of the morning.
00:00 Star Party Observing
00:41 Telescope Design and build
02:44 Scope Dog: Tracking and GoTo
04:41 Filter Wheel
06:03 Improved Secondary Collimation
08:04 Wheel Barrow Handles for Portability
09:18 Scope weights and balance
09:44 Power System
10:55 Painting and Finishing
12:59 Fitting Truss Connectors
14:09 Fitting Scope Dog: GoTo & Tracking
20:11 Observing with a 20-inch
23:10 Favourite Deep Sky Objects
26:34 Improved Front Collimation
26:48 Lightweight Mirror Cell
28:25 Dew Heater for Primary Mirror
29:15 Rain / dew drain holes
29:45 Scope Cover & Tying Down

[@astronomycrazyman2940]

I must say, just an amazing build and well thought out. I own a 15" Obsession and there are things that he has done that I think all manufacturers could learn from.

[@RefreshingViews]

You're right, it's a great build isn't it?

[@cannibalholocaust3015]

Could listen to that man talk about his build all day. Maybe the best astronomy video I’ve watched in KZbin and this channel is really excellent. Despite having little experience I can relate to the aperture hunger, once you catch a glimpse of something cool you simply must see more.

[@RefreshingViews]

Couldn't agree more, Alan is a true gent with an amazing set up.

[@lightbridge1695]

Hello from Australia. I personally think there's nothing better than a dobsonian telescope and wow has this telescope been engineered incredibly well. Thanks for a great video.

[@RefreshingViews]

I agree with you - it's a great set up and gives such amazing views.

[@ColdWarWarriors]

Always love seeing a big dob!! Thankyou for bringing this to us and keep up the great work.

[@RefreshingViews]

Thank you! We’re off to UKs Ewuinox star party next month so hopefully another big dob to visit.

[@AdirondackAstronomy]

I love seeing the mods people do to their scopes. This is just an amazing build. I take back what I said about not wanting anything bigger than a 12"

[@RefreshingViews]

You'll love the views through a big scope - even if your back doesn't!

[@jackfrost4033]

Proud like a child 🤗

[@Sergey_Sergeev]

Thank you very much. It is very interesting! Especialy many thanks for the time table of content.

[@RefreshingViews]

Glad you enjoyed it, Sergey.

[@FarFromOxygen]

Thank you for the knowledge provided in the video.

[@RefreshingViews]

Glad it was helpful. It was great fun to see and use.

[@jamesw5713]

Great engineering, views must be amazing!

[@RefreshingViews]

The views of the Orion nebula in the pre-dawn sky were amazing. The nebulosity looked like cotton wool!

[@tinyartguy]

What a machine!!

[@RefreshingViews]

It's a beauty isn't it? Alan was so nice as well!

[@tullyfisher]

Interesting instrument. Nice!

[@RefreshingViews]

Not quite a grab and go but beautiful set up isn't it?

[@MicroscopyShorts]

Sweet vid!

[@RefreshingViews]

It's great isn't it? And the views weren't too bad either.

[@editbalazs349]

Dobson telescopes are the very BEST!

[@RefreshingViews]

Yes they are - especially if they have tracking.

[@nman2563]

That guy who jumped in towards the last third derailed the interview. I was getting annoyed. Alan is a patient man

[@RefreshingViews]

It’s probably the way I edited it. No harm no foul as they say.

[@Beaver-be8vk]

I would love a 14 inch version of this. And do it in gray and black. Amazing design.

[@RefreshingViews]

Glad you enjoyed it - and let us know if you make your own model.

[@daveatkinson4774]

Great video Mark! and what a scope! I was out last night with Amelia looking at Jupiter :) Clear skies!

[@RefreshingViews]

Glad you enjoyed it! And nice to hear you are out under the stars again. Stay safe buddy!

[@yoshito8912]

It's a great Dobsonian telescope!

[@RefreshingViews]

I think so too!

[@Landjet]

The best planetary telescope ❤

[@RefreshingViews]

It’s not bad is it?

[@t3avelos]

this is a massive job of a scope. Looks like the builder got all corners covered and Nichols is as good a mirror maker as they get (at least in Europe). Just one (reserved) comment: from the video it seems that the secondary cage hasnt been made oversized relative to the mirror box. if this is true, then due to the 3 (vs 4) sets of struts, the shroud cuts into the light path so deep that, mathematically, you are losing 4% of aperture, which is about 1 full inch of light gathering capacity.

[@brentj7564]

Is this scope sold somewhere or is this a one off custom implementation?

[@RefreshingViews]

It’s homemade Brent - although there are companies who supply such a scope if you wish.

[@brentj7564]

@@RefreshingViews Beautiful scope, appeared to be really well thought out. If you were making a recommendation for an 18-20 inch DOB in todays market that was giving you maximum quality with maximum portability, what is it you would be rcommending (for purposes of this discussion, let's say, price was no object)?

[@RefreshingViews]

@@brentj7564 not sure I can give you a recommendation, simply because I don't have such a scope. I would suggest reading the feedback on the reflector section of the Cloudy Nights forums and, if appropriate, visiting a star party or 2 so you can see a variety of big scopes first hand. A chap in our club has a 22" compact Obsession and that seems to work well but there are alternatives. I must admit I like the idea of a Skywatcher dob simply because it comes with a drive system. As to its quality, I simply don't know as I have never used one! Conscious I haven't answered your question but I hope that helps!

[@user-lb9gw5kn9d]

나보다 나이가 많아 보이는데 20인치 도전해보고 싶네요

[@RefreshingViews]

go for it - you will love it!

[@MissCV]

Does he have a KZbin channel at all? Or a website?

[@RefreshingViews]

Afraid not, Cora. It's a generational thing :-) 😀

[@MissCV]

@@RefreshingViews NOOOOO! Well, that's just too bad. He seems like a wonderful person and I'm happy he shared this with you and you with us. Thank you

[@MissCV]

@@RefreshingViews I guess I'll have to bite the bullet and dish out 549.00 for that book. Unbelievable pricing...

[@RefreshingViews]

@@MissCV ouch! Is it worth putting a post on Cloudy Nights or StarGazers Lounge asking if anyone has a copy? You could buy a whole telescope for that price!