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General Astronomy => Beginners Forum => Topic started by: Jan Giri on December 30, 2017, 08:00:55 PM

Title: Battle of the 8" mass-produced dobsonians
Post by: Jan Giri on December 30, 2017, 08:00:55 PM
This is an hypothetical question, but I can really use your answers and opinions.

So, if you had a Telrad (or your favorite finder) stored, and barlows, but absolutely no sweet eyepieces, ¿which one of the following scopes would you get at these prices, and why?

$1.334 SW 8" goto. Pros:Tracking, transportability. Cons: Weight, needs $69 Light Shroud,lacks top dust cap
$1.057 Orion XT 8i. Pros: DSC, RACI finder.
 $784 XT8 Plus. Pros: weight, dual speed focuser. Cons: lacks navigation knob
 $775 SW 8" Collapsible: Pros: transportability, Cons: needs $69 Light Shroud, lacks top dust cap
 $736 Z8 Solid. Pros:Dual speed focuser, 30mm 2", Laser collimator
 $627 SW 8" Solid.Pros: weight

... assuming the money difference could be spent at US prices in more gear (sweet eyepieces, a binoviewer, or whatnot).

Keeping in mind:
<ul class="bbc">The prices seem odd because they are the final cost for me after international shipping to my country, plus customs/taxes. I'm trying to see how you'd perceive value at these rates.
The more inexpensiveAperturas are out because Highpoint Scientific won't sell to me, while Zhumells are in because telescopesplus had no problem selling me my Z114.
Orion XT Classics are out becaise I don't like their spring mechanism.
Discovery 8" F7 scopes are out because of theirdeterioratingcustomer service (http://www.astronomyforum.net/dobsonian-telescopes-forum/223452-discovery-telescope-10-inch-dob-9.html#post1058525067).
Explore Scientific ultracompact dobs are excluded because they don't come in 8" size
So, which would you pick and why?
If you picked a lower cost one, what would you spend the "saved" of the money in?
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: vuicapathvie on January 08, 2018, 05:21:12 PM
Is this out too??https://explorescien...ght-8-dobsonian (https://explorescientificusa.com/collections/firstlight/products/firstlight-8-dobsonian)
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: tradunjuwa on January 09, 2018, 11:45:31 PM
I find that ease-of-use means more than almost anything else. If a scope is cumbersome in some way to set up or use, then it tends to get used less and less. Now all your examples are 8" so thermal acclimation time will be similar. However, that SW collapsible is quite small and easy to either move around or transport, plus when you put a binoviewer in it you can just collapse it a little way so you can get to focus without the need of an OCA on the binoviewer.

Now strut-type dobs do have their issues compared to solid tubes in that collimation does not hold as well and body heat can go right through the middle of the light path and through the shroud affecting mostly planetary and tight double observations. But on the other side with solid tubes you need to wrap them in a bubble after use to keep dust from accumulating on the mirror reducing transmission and adding scatter, whereas with the strut design it is easy to use/make a cap for the mirror and place it right on it. Overall IMO the SW Collapsible's advantages trump and disadvantages.
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: rarisata on January 10, 2018, 12:09:05 AM
Quote
I have to disagree that the collapsible dobs have clearly more advantages.

<p class="citation">Quote
But on the other side with solid tubes you need to wrap them in a bubble after use to keep dust from accumulating on the mirror
That's a new one to me, after years and years of solid tube dobs. "Wrap them in a bubble"?
Just use the provided end caps. Easily improvised if the scope lacks them (shower caps, say). Very effectively reduces dust accumulation.
The SW collapsible dobs are shorter when collapsed to be sure, but don't take up any less floor space and don't weigh any less (in fact, they weigh slightly *more* than their solid tube counterparts).

Unless you *really* need the shorter tube (very tiny car?), I don't see any significant advantage to collapsible dobs in the 8--10 inch aperture range (well, maybe the binoviewer thing, can't speak to that myself).
Unless you really desire tracking/goto, I think the plain Z8 is clearly the best deal here. Optically these are all going to be more or less the same, the Z8 presents the best value.
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: tiogeroligh on January 10, 2018, 07:04:17 AM
$799 - Orion XT8i push-to is another choice.
Pros - ease of use. 35lbs. 2 EPs. Computerized star finder. Includes navigation knob.
Cons - starting to get long for narrow vehicles.
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Leon Vale on January 11, 2018, 04:43:00 PM
http://www.discovery...overy/pdhq.html (http://www.discoverytelescope.com/discovery/pdhq.html)
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: John Jefner on January 12, 2018, 12:45:24 PM
Quote
$799 - Orion XT8i push-to is another choice.
Pros - ease of use. 35lbs. 2 EPs. Computerized star finder. Includes navigation knob.
Cons - starting to get long for narrow vehicles.


Ok, I'll add it, but after international shipping and taxes it's final cost is $1057. ¿Do you still prefer it to the others at that price?
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Brandon Hughes on January 13, 2018, 03:30:10 AM
Quote
Is this out too??https://explorescien...ght-8-dobsonian (https://explorescientificusa.com/collections/firstlight/products/firstlight-8-dobsonian)


I forgot about that one, but I just checked and I can't find the shipping information (box sizes and weights) I'd need to calculate the international shipping cost, do you happen to have one?
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Nathan Sorgaard on January 15, 2018, 09:47:56 PM
Quote
http://www.discovery...overy/pdhq.html (http://www.discoverytelescope.com/discovery/pdhq.html)

That 8" F7 would be $1505. Let's add it to see what happens
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Michael Washington on January 18, 2018, 05:25:17 AM
+1 for the Z8. Plus you can pick up a higher power EP with the $$$ you save. My two cents...

STARKID2U
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Marlin Riewer on January 20, 2018, 10:04:28 PM
I wouldn't let myself be swayed by the Navigation Knob. It's a good idea. But it is easily replicated with a cabinet knob from the local hardware store and about 10 minutes work (although it does require a drill and this makes some folk squeamish).
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Derrick Jones on January 21, 2018, 07:48:49 AM
I just recently bought a used Orion XT8i, and it's a good choice. I used to have a Zhumell Z8, but I sold it and left the hobby for a couple of years like a dummy.
You can get the XT8i as a "2nd" on Orion's website for $525 plus $10 shipping with the warranty. I don't know what your cost would be.My favorite things about the Z8:
• The bearings are so smooth! I like them a lot better than the XT8i's.
• The OTA just drops into the mount without any parts, so you have nothing to lose.
• The OTA can slide back and forth to adjust for balance. I had to do this when I added a Telrad in addition to the finderscope.
• It comes with a right angle correct image finder!
• The included 30mm performs decently in the scope.The things that are nice, but not deal-makers:
• The dual-speed focuser is really good, but it's not as big of a deal on a F/6 scope. Faster scopes benefit more from it.
• The laser is useful for collimating the primary mirror without having to look into the eyepiece. Be sure to keep the laser itself is collimated. Also, it's more accurate to use the laser in a barlow for the primary. It's still best to use a collimation cap or cheshire on the secondary.
• The fan works, but it's a little close to the mirror and doesn't have a shield to force the air all around it.Dislikes:
• It weighs 52lbs, so it's not easy to move in one piece.
• The primary collimation knobs are not recessed on the bottom, so that's not good for setting it on the ground upright.
• It isn't computerized, but that's always a personal opinion.Okay, my favorite things about the XT8i:
• It weighs 42lbs (Not 35lbs like posted above) and has slots in the side of the mount which makes it easier to carry in one piece.
• The Intelliscope feature really works and allows me to spend more time observing.
• It also has a right angle correct image finder.Things that are nice, but not deal-makers:
• The primary collimation knobs are recessed.
• Navigation knob.Dislikes:
• The bearing system is not as smooth as the Z8. I mean, it's good to have some stiction, but it's a little more than I like.
• The bottom of the mount is a triangle, so combined with the stiction when pointed near zenith, it can be possible to tip the whole scope over if you are not careful.
• The OTA is bolted in the mount with hand knobs.
• Can't adjust ballance without weights or tightening the knobs.
• No fan included.
• No 2" eyepiece included.
So for me, I personally consider it a tie. I like the Orion XT8i for the computer and weight, but I like the Zhumell Z8 for everything else. But between the XT8 Plus and the Z8, I definitely recommend the Z8.
I think all the scopes you mentioned are good, so you can't really go wrong.
Edit: I hope this all makes sense! I typed this on my phone, so I probably missed some stuff.
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: belmadeasus on January 23, 2018, 04:43:34 AM
Quote
You can get the XT8i as a "2nd" on Orion's website for $525 plus $10 shipping with the warranty. I don't know what your cost would be.
Yeah, those "2nd" can be good deals, just recently there was an XT8 plus for like $375, sometimes I wonder if I should have taken it.
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: szenawahle on January 25, 2018, 04:04:20 PM
One of my Dobs is a 10" Sky-Watcher Collapsible. The shorter tube definitely makes it easier to transport than a traditional OTA. I don't have a shroud and have never felt the need for one. My scope came with two caps.

Dave MitskyAttached Thumbnails
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Jack Jefferson on January 25, 2018, 10:06:58 PM
Quote
I have to disagree that the collapsible dobs have clearly more advantages.

<p class="citation">Quote
But on the other side with solid tubes you need to wrap them in a bubble after use to keep dust from accumulating on the mirror
That's a new one to me, after years and years of solid tube dobs. "Wrap them in a bubble"?
Just use the provided end caps. Easily improvised if the scope lacks them (shower caps, say). Very effectively reduces dust accumulation.[/quote]

Orion scopes sure do not come with air-tight caps, and they come with no bottom cap, and there are plenty of air gaps around the focuser. I don't think there is any argument that a cap that directly fits over the mirror or mirror box is much more effective than trying to plug all the holes in a typical solid tube Dob...after decades with my solid tube Dobs. With my XT10, keeping it capped with what was supplied and positioned so the mirror is facing side ways to not collect dust, after a mirror cleaning let about 2-3 weeks go by and easy enough to see all the micro dust that has collected on the mirror adding to scatter. And strong light pointed at the mirror right after cleaning and 2 weeks later will show it well. So for me, being sensitive to scatter, mirrors take extra care, which is a bit more problematic with solid tubes...as is cool down and internal thermals. Choose your poison. I weight portability, ease of use, ease of accessibility for cleaning/maintaining as higher factors. Everyone is different. And last thing I want is to see a bunch of shower caps all over my scopes
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Kyle Montes on January 25, 2018, 10:15:30 PM
Quote
One of my Dobs is a 10" Sky-Watcher Collapsible. ...... My scope came with two caps.

They no longer do.

Quote
...And last thing I want is to see a bunch of shower caps all over my scopes
When I found out the newer SkyWatcher collapsible Dobs came with only one dust cap for the primary half, and just a shower cap for the secondary half, it was kind of a turnoff for me
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: ebalared on January 31, 2018, 12:06:29 AM
I hardly ever use the top cap to begin with, basically only when the scope is in storage, so for me that would be a very minor issue.

Dave Mitsky
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: Jerry Ridl on January 31, 2018, 02:55:23 AM
Dave is doing it right... a scope in use gathers no dust!

Just sayin'...

CB
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: ceusesugua on January 31, 2018, 04:43:17 AM
Quote
Humm..

Have you ever actually used a scope with "correction tension springs?"

Of all the systems on commercial Dobs, it's my favorite, it mimicks the large altitude bearings of the premium Dobs. My 14 year old GSO Dob uses the system.. I use it at magnifications up to 822x with good results..

Jon
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: ceicomfeara on January 31, 2018, 09:14:56 AM
Quote
Dave is doing it right... a scope in use gathers no dust!


Nothing in my house can ever claim to gather no dust. It might be a disadvantage of the "all windows open"tropical environment is the amount of dust I get inside my home. I store My Z114 reflector stored with its cap in a plastic bag in a closet in the 2nd floor, and laid horizontal, still collects dust!!
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: jingdilenma on January 31, 2018, 01:01:00 PM
Quote
<p class="citation">QuoteOrion XT Classics are out becaise I don't like their spring mechanism.

Humm..

Have you ever actually used a scope with "correction tension springs?"

Of all the systems on commercial Dobs, it's my favorite, it mimicks the large altitude bearings of the premium Dobs. My 14 year old GSO Dob uses the system.. I use it at magnifications up to 822x with good results..

Jon[/quote]

No, I haven't. I've only used Zhumell altitude bearings on a mini-dob (Z114).
Title: Re: Battle of the 8" mass-produced dobsonians
Post by: trapoutampub on February 04, 2018, 11:40:03 AM
Quote
Quote

Quote
<p class="citation">QuoteOrion XT Classics are out becaise I don't like their spring mechanism.

Humm..

Have you ever actually used a scope with "correction tension springs?"

Of all the systems on commercial Dobs, it's my favorite, it mimicks the large altitude bearings of the premium Dobs. My 14 year old GSO Dob uses the system.. I use it at magnifications up to 822x with good results..

Jon

No, I haven't. I've only used Zhumell altitude bearings on a mini-dob (Z114).
I have, and I found them to be horrible!
Another vote for the Z8 from me. I had one of these, and it was almost great right out of the box. With all of these scopes, you'll need to replace the primary springs. As mentioned, the knob is no big deal, and you can build your own dustcap.