Reddit reviews Orion 27194 XT8 Classic Dobsonian Telescope and Beginner Barlow Kit

Hi /r/pics!

I enjoy building stuff, and this won’t be my last telescope--I have three more planned over the next few years, plus a shipping container observatory! The last two times, I got a ton of questions (which I love to answer), but I’ll hit the most common questions that were asked on the previous telescopes:

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How much did it cost to make?

It’s difficult to put a number on it. More than $1000, less than $2000, but there were so many small components and wasted materials it’s hard to say exactly. The optics (primary mirror, secondary mirror, spider combo) I picked up for $600 from eBay two years ago, which was a steal at twice the price. I used around $100 worth of plywood, about $80 of steel for the mirror cell, about $60 worth of plastics for the baffles and bearings, about $60 of aluminum for trusses...and I forgot how much I paid for the focuser, maybe $70? I’m also not counting wasted materials (wood, plastics, aluminum that I screwed up), which is probably in the $200-$500 range.

Also, I had to learn to weld (with help from /r/welding) in order to make the mirror cell, and bought all the welding equipment, which put me back a few hundred. However, I’ll be using that in the future, so I’m not counting that as a material cost.

If this were a professionally made dobsonian from a company like Obsession Telescopes, it would be worth around $6000.

How much does it weigh?

The entire assembly is 85 lb. The heaviest part by far is the mirror box (the thing with handles), which is a 26 lb. mirror (a 1.68” thick slab of glass), 11 lb. of steel, and 24 lb. of wood. Next time, I’m going to make the mirror cell detachable from the box so I can walk more than 30 feet before having to set it down. :P

How do you transport it?

It breaks into components (secondary cage, trusses, mirror box, rocker box, base) and can store in the back of a hatchback. It’s just a little bit too big for my Civic, but I was planning on trading up to a hatchback next month anyway because transporting lumber and raw materials is starting to put some serious nicks in the upholstery in the back seat of my Civic.

How long did it take you to build?

I began drafting the project back in January, with most of my serious design work in the spring. I welded the mirror cell in May, worked and reworked the design off and on through the summer, and did the final stretch of construction and finishing in September.

Can you take pictures with it?

Not really, at least not without another platform that I’m going to build. I have some DSLR cameras I picked up off of eBay (at an INSANE PRICE, I got a Canon D60 and Canon 20D, no lenses or batteries, for $80!!). The camera mounts right onto the scope, and I will be trying astrophotography. However, the full moon is a few tens of thousands of times brighter than the Orion Nebula, which requires around 30 second exposures to pick up anything at all. The problem is, the sky moves about a quarter of the way out of frame over 30 seconds, so all you get is a blur. It needs a tracking mount (called an “equatorial platform”) to stay fixed to a certain spot in the sky, and I’m in the process of designing and building one now.

What’s the focal length and focal ratio of the mirror?

Honestly, I don’t really know, the eBay auction is expired and I bought the optics two years ago. I think it was 2000mm, but once I used the jig to measure the optimal distance between the secondary mirror and the primary mirror, I went with that and didn’t bother going back to calculate the FL.

What should I do if I’m interested in astronomy but don’t have a huge budget?

First, subscribe to /r/astronomy!!

My advice is to get a mini-dob like this one. Some people will advise binoculars, but I disagree; a mini-dob is much easier to handle and you don’t have to deal with hand jitter. After you’ve found a bunch of Messier objects and want more, get an 8-inch classic dobsonian like this one.

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Past projects, in chronological order:

• 12.5” dobsonian, and while I’m proud of it as a first attempt, I later recognized a number of structural and design flaws and it’s much heavier than it needed to be.
  
  
• 12” dobsonian, as it turns out, way too flimsy and vibration-prone, I used it a few times and disassembled it. I am planning a sturdier rebuild.
  
  
• A CNC machine
  
  
• Another CNC machine after the first one died a slow, sputtering death
  
  
• This telescope.
  
  Software and math:
  
  
• An unpublished plugin for Sketchup that turns sketchup geometry into “gcode” instructions for a CNC machine (available upon request, no guarantees for functionality, I still have to tweak it every now and then)
  
  
• A math model for a spring cam that I ended up not needing.
  
  
• An unpublished balance plugin that allows me to define weight, density, and calculate center of mass of any Sketchup group or component, used to balance this 16” telescope so the center of mass was ¼” separated from the center of axis rotation. (Available upon request.)
  
  Future projects (in planned order):
  
  
• Disassembling the 12.5” scope and building a steel-frame, fork-mount astrograph (astrophotography telescope).
  
  
• Remaking the 12” scope as a single-piece, quick-unfolding scope that can assemble in two minutes. Will have a heavy steel backbone, the cage and mirror box will fold up into the backbone so the whole thing can load up into the car without disassembling.
  
  
• Building a large scale, 4’ x 8’ leaning bed CNC machine with rack and pinion bearings, a manufacturing-grade spindle, and a high-powered vacuum tube assembly. This monster will have about a 12’ x 4’ footprint, and the bed will be mostly vertical and lean at a 30 degree angle. I will probably have a used conex shipping container hauled in to house it. The shipping container will run me about $3000, the machine itself will cost $2000-$3000. In comparison, an equivalent bed professionally made CNC machine will cost upwards of $20,000.
  
  
• A conex shipping container observatory with a geodesic dome top, housing the 12.5” astrograph.
  
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  If you have more questions, fire away! I’ll be happy to answer them!
  

Too bad you didn't post this a couple of weeks ago. I got my XT8 + Barlow kit for $369. Now it's $420.

Get an Orion XT8. Big enough to see cool shit, small enough to be transportable. That'll cost you 350, or 400 bucks if you get the version with a barlow lens. Barlows are great for planet viewing, as they make everything 2x bigger.

Haven't used that one, but it's 5.1 inch, so that's plenty big enough to see Saturn. Good eyepieces are key, though, to getting a good image. I had a cheap Meade 4 inch and it did okay. The model you link to included 1.25" eyepieces, so that's a good start. I haven't been into that stuff in years, though, so I don't know what else is available on the market.

EDIT: This one might be a better choice: http://www.amazon.com/Orion-Classic-Dobsonian-Telescope-Beginner/dp/B003ZDEUS2

I would recommend an 8-inch dobsonian. You will see the planets very nicely in them, and you'll be able to see deep sky objects at a dark sky location.

You won't be able to do much astrophotography with this though, because dobsonians can't track, you could buy a GoTo dobsonian, which are more expensive but will move to and track an object as long as it is aligned.

A new 8 inch dobsonian from Orion is currently $400 on Amazon.

But keep in mind, when viewing deep sky objects, you won't see beautiful, colorful nebula like you do in pictures. It will appear grey, and you will see less detail. The pictures you see from people's telescopes are stacked and post-processed, bringing out colors and making it look nicer.

Also, go to /r/telescopes, which is a subreddit made for the stuff you're looking for .

I've heard from a lot of other people as well to start with an 8". I think I'll take everyones advice on that I saw one like the 10" you sent me, but an 8" instead.

http://www.amazon.com/Orion-SkyQuest-XT8-Dobsonian-Telescope/dp/B001DDW9V6/ref=sr_1_1?s=electronics&ie=UTF8&qid=1369432158&sr=1-1&keywords=orion+skyquest+xt8

Also, for $30 more they have this option which to me sounds like it might be worth it?

http://www.amazon.com/Orion-Classic-Dobsonian-Telescope-Beginner/dp/B003ZDEUS2/ref=sr_1_2?s=electronics&ie=UTF8&qid=1369432158&sr=1-2&keywords=orion+skyquest+xt8

It seems like it's cheap enough to do what I want and I still have leftover money to get some accessories with it. Filters and such? I'm not sure of everything that I would need.

Also an owner of the the XT8 dob. It is my first telescope and has been great fun so far. Setup and calibration was easy too. You can also get it with a beginners barlow kit.

Possible con: It weighs around 40 lbs, so if you want a really portable scope it may not be your best option.