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Which 8" dob would you buy?

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#1 Lane

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Posted 06 March 2013 - 04:53 PM

My brother and his wife were using my C8 a few weeks ago and now they are infected with the astronomy bug. They don't want to spend a lot and they want to learn how to star hop so they are not really that interested in a computerized scope.

I have suggested they start with an 8" dob. I was thinking Zhumell or Orion Classic. Which one of these would you choose and why? Or is there something else that might be a better starter scope for them? I think the Zhumell comes with a collimation tool, but is it any good and is a collimation tool really necessary for a small scope like this?

I am an SCT / Refractor guy, so not sure what to really look for here.

They will be carrying the scope about 100 yards to the open field behind their house. Their location is a Green Zone.

#2 KerryR

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Posted 06 March 2013 - 05:04 PM

I think either would be a fine choice-- I've had both. More similar than different. I think the Zhumells may come with more accessories.

They won't necessarily have to make a big deal out of super-accurate collimation, but they will need to be able to do it. A combination sight tube and cheshire will do the trick.

The only other thing I could mention is that there's nothing wrong with a 6" f8. These are nice because they (usually) fit in the back seat of a car with the base attached, and are easily carried with the base attached in one hand. This may or may not be of interest, but I find I use 'one handed' scopes more often than 'multiple handed'...

#3 JIMZ7

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Posted 06 March 2013 - 05:11 PM

Try Opticsmart.com. They sell Apertura Dobs which are nearly the same as Zhumells but you can get super upgrades on their Dobs. as I see in their videos.

Jim :dob:

#4 tezster

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Posted 06 March 2013 - 05:19 PM

I agree - if I were in the same position, I'd be looking at an AD8 :)

#5 BDS316

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Posted 06 March 2013 - 05:47 PM

Definitely one of the GSO's. Zhumell, Apetura or Astro Tech from Astronomics with a CN discount.

Reasons for choosing a GSO over the Orion are several:

Better Dobsonian motions. I know this from personal experience, which is why I upgraded to an aftermarket dob mount

Better eyepieces. The 2 inch GSO 30mm SV is pretty good at f/6.

Better accessories, like a finder scope, eyepiece rack, and a fan.

I'm not going to list "better focuser" as a reason although many like the GSO 2 stage focuser better than the Orion's Synta single stage. At f/6 it really isn't that big a deal. The reason I upgraded to a Moonlite is because I got an older XT8 that had a rack and pinion.

#6 kfiscus

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Posted 06 March 2013 - 05:54 PM

Avoid the tension springs if possible. I like the Zhumell (and related) adjustable alt bearings.

#7 Pinbout

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Posted 06 March 2013 - 05:59 PM

I would tell them to hurry up and buy the 8nf6 swayze refigured for 150 in the classifieds and send it to dobstuff to build the structure.

a custom doby with larger alt bearings make all the difference than those imports.

#8 Tophat3

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Posted 06 March 2013 - 06:04 PM

Yep, Zhumell or Apetura.

#9 Lane

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Posted 06 March 2013 - 06:34 PM

The Apertura AD8 looks like the way to go.

Thanks for your help guys :bow:

#10 RogueGazer

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Posted 06 March 2013 - 07:32 PM

As a Z8 owner I have no problem recommending them but there are a few issues I have had.

The supplied laser collimater is of poor quality IMHO. If they go this route they will need to verify the collimater is collimated. Even after doing that it wobbles around so much it is hard to get a repeat placement of the laser on the primary. It goes through batteries like crazy. I actually replaced the internal laser pointer with a more efficient model and the batteries last way longer now. I still plan on replacing it eventually but it gets me by for now.

The primary mirror clips were way too tight. I could not achieve proper focus until I figured out the problem. I bought it new so this was done at the factory.

A lot of the external hardware was too loose. The worker who installed the mirror couldn't be the same guy who installed the rest of the hardware. I have the tension spring model which doesn't bother me but the 4 bolts attaching the ALT bearing assembly to the OTA would never stay tight until I used some locktite.

The build instructions are not the greatest but there is a video on Youtube that will help.

Other than those fully correctable problems I really like the scope. If they are going to carry it that far I would get a moving dolly and a small ratchet strap to secure it to the dolly. A couple shower caps on both ends will help keep the mirror clean during storage.



#11 Ed D

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Posted 06 March 2013 - 07:53 PM

If they're going to be carrying the scope 100yd I think an 8" or 6" Dob is going to get old really fast, unless your brother is built like an upside-down pyramid or they plan to use a cart to take the scope and accessories out. You may want to talk to them about this.

Ed D

#12 Lane

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Posted 07 March 2013 - 04:05 PM

He likes to build stuff and when I told him about the wheelbarrow handles used on the big dobs, he started planning how he is going to build a custom wheelbarrow just to haul the scope back and forth.

#13 Pinbout

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Posted 07 March 2013 - 04:25 PM

if he likes to build stuff he can buy a kit from astro sky. He's having a spring sale also.

just think a custom dob with smooth movements...

and 8in's is easy to throw around.

Posted Image

or he can get a tube from HD or Lowes and make a tube dob and get a rocker box kit from astrogoods and still have that custom feel...

Posted Image

if he can make it why buy it. :foreheadslap:

and while he's building it he can get the companion 4" refractor... :grin:

#14 Jarrod

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Posted 07 March 2013 - 04:42 PM

if he can make it why buy it.


A biologist and a physicist go to a pristine white sand beach. The biologist exclaims, "Look at all that beautiful sand! I'm going to make a sand castle!" The physicist exclaims "Look at all that beautiful sand! I'm going to make a telescope!".

Spoken like a true physicist.

:grin:

#15 csrlice12

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Posted 07 March 2013 - 04:49 PM

For the scope itself, I'd go for the Zhummel or Aptura. But as foar as the laser collimater that comes with it--just heave it as hard as you can....that's as close as it should ever get to collimating your scope...you're cat will get better mileage out of it...Outside of the laser, they are great scopes, and they have a better mount system then the Orion classic (God, when are they ever going to bring the teflon friction pads to the classic??)

#16 kfiscus

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Posted 07 March 2013 - 06:45 PM

Troll alert...
Buy the one that has a 12" mirror.

#17 Pinbout

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Posted 07 March 2013 - 08:03 PM

Spoken like a true physicist.



it more like a designer, I don't like this...I don't like that. Oh god why don't they do this. I guess I'll have to find a way to do it myself... :foreheadslap:

#18 bob irvin

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Posted 08 March 2013 - 11:14 AM

The supplied laser collimater is of poor quality IMHO. If they go this route they will need to verify the collimater is collimated. Even after doing that it wobbles around so much it is hard to get a repeat placement of the laser on the primary. It goes through batteries like crazy.


I agree on the above points. I purchased a Glatter TUblug to "nullify" the inability of the laser to snugly seat in the focuser for the primary mirror adjustment. I do like the scope, mine's a Z10.

bob

#19 csrlice12

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Posted 08 March 2013 - 11:54 AM

It also doesn't go above the "no damage" setting......No heating rocks to stay warm, no stun setting, you can't even set it to overload.... :lol:

+1 onthe Glatter/Tublug system......

#20 SteveG

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Posted 08 March 2013 - 12:22 PM

I recommend the AstroTech version (same as Zuhmell only white). Much better motions than the Orion XT series. Nice, usable scope right out of the box.

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#21 Lane

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Posted 08 March 2013 - 09:37 PM

Yes the Astro Tech the Aptura and the Zhumell all apear to the be the same scope with slightly different accessories. I am going to recommend that they buy the Astro Tech since I can purchase it for them and get the CN discount, they are not on the internet so they can't join CN themselves.

The Astro Tech does not come with any collimation tool, so I am trying to figure out what if anything they will need to collimate the scope. Again they are trying to keep cost low on this so they are not going to spend hundreds on collimation tools. What would you guys recommend that isn't too expensive and also is it really necessary to have anything to collimate with? I had an 8" dob I built when I was a kid and used it for 10 years and I collimated it using a bright star and a high power eyepiece.

#22 TexasRed

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Posted 09 March 2013 - 02:46 AM

A Cheshire/sight-tube combo is cheap, realiable, easy to use and gives better results than most people could manage without using some sort of collimation tool.

#23 Starman1

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Posted 09 March 2013 - 11:45 AM

A Cheshire/sight-tube combo is cheap, realiable, easy to use and gives better results than most people could manage without using some sort of collimation tool.

Agreed, and these can be found for $30-$50 from many many sellers, including Astronomics:
https://www.astronom...ting-tool_p3...

#24 Lane

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Posted 10 March 2013 - 01:28 AM

:thanx:

#25 George N

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Posted 12 March 2013 - 11:58 AM

If you want to go ‘hi-end’, consider this “New Moon Telescopes” 8-inch F/4.5: web page and video: YouTube

I’ve seen one, but not used it. However, a friend has one of their 12.5” re-builds, and it is an excellent telescope.






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