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stargazer424
sage


Reged: 10/03/05

Loc: Central NJ
Orion XT8 questions...and more...
      #5559200 - 12/07/12 12:16 PM

So I started a thread a page back about getting a telescope for my 6 year old niece and decided against it at this time. However, all of this talk about getting a scope for her has reopened the case for getting a scope for myself. Maybe it will be a birthday present for myself in April...or sooner (holiday bonus?). I did research years ago, but wound up spending my $$ on a Canon DSLR at the time.

I have been an avid stargazer since I was about 9 (so around 25 years now) and I can name the constellations and most of the bright stars (and even point out at least 1 DSO [Andromeda]). I don't need a small, beginner scope to learn the sky.

I have read all of the "dobs give the best bang for the buck for your first scope" comments everyone else posts. I am focusing on an Orion XT8. One of my other hobbies is photography, but I am trying not to catch the AP bug. The XT8 can at least get semi-detailed moon and blurry planet photos, right? I don't think I need the XT8i since I have phone apps that show where objects are. I would love the XT8g for tracking, but it's just not in the budget.

Question 1: Orion XT8, is it easy to transport? I live in an apartment and would need move the telescope to a different location to use it.

Question 2: Could someone run down eyepiece/lenses in layman's terms. I am versed in cameras/photography so is it the same where the higher the mm the more "zoom" you get? Are there "must have" and "don't ever buy" eyepieces. And what is a Barlow? I wear glasses, does that affect eyepiece selection at all?

Question 3: How high up is the eyepiece on average when viewing. I'm 5'10", would I need to be sitting or bending over to view? I have a camping chair, but I don't know if it will be tall enough to use.

Question 4: Any thoughts on Orion's "Build a scope" to customize accessories VS getting the scope and accessories/upgrades separate? What about the Beginner Barlow Kit or the LE Bundles?

Question 5: Everyone talks about how easy a dob is to push around to find something. Can you tighten/loosen the mechanics? I think I am more worried about finding something and then accidentally moving the scope and losing it than not being able to move it at all.

Question 6: What will I actually see when looking at, say, a nebula? I know it won't look like Hubble images, but will it just look like a cloud, or will it be interesting. Anyone have photos that more closely represent visual experience.

Oh boy...this was supposed to be a quick post, but I kept thinking of more things to ask. More questions likely to come...


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Tank
Carpal Tunnel
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Reged: 07/27/09

Loc: Stoney Creek, Ontario, CANADA
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5559249 - 12/07/12 12:52 PM

1. 8" is pretty portable
2. 1200mm is you FL of the scope divide this by the EP FL give you the magnification.
1200/6mm EP gives you 200x magnification
3. its about only 4'-6" at zenith pointed straight up! You will be viewing mostly at about 3'-6" off the ground
4. Lots to choose from as far as accessories the ES 82 N2 eyepieces right now are the best value EPs out there!
5. Most DOBs have tension controls. If you view enough with the DOB you will get the hang of it quickly
6. Forget the Hubble images!!!! For instance M42 without a filter will look like this without a filter and a bit better with also will look more life like!:
http://www.flickr.com/photos/emiliokuffer/8028102484/


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JoLo
sage


Reged: 02/09/10

Loc: Highland, IL
Re: Orion XT8 questions...and more... new [Re: Tank]
      #5559272 - 12/07/12 01:07 PM

The 8" scope is a great one to start out on, and not difficult to move around. I would describe it more as awkward than anything; i started out with a 10" solid tube Dob, which is about the limits of what I would want to drag around...I subsequently bought a 12" truss tube, which although heavier, is easier to tote in pieces. An 8" solid tube will not pose a problem.

Yep, I got some very nice moon / planet shots with a Dob and a Canon 450D...they are bright enough that you can take fast exposures and not get too much blurring. An afocal or eyepiece projection setup is a great way to get your feet wet with AP.

Quality eyepieces make a difference, save some of your budget to get good ones, a spread of focal lengths to get you wide views and moon/planet closeups.

A few items i would consider...adjustable astro chair is the best, back saving investment I have made. A quality star chart and a Telrad / Rigel Quickfinder. The combination of an optical finder and a Telrad or QF is hard to beat with star hopping. A good chart combined with finder/Telrad will make you an expert star hopper in no time. Learning the sky and how to star hop is a great skill that will serve you well.


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5559295 - 12/07/12 01:24 PM

so many questions so i'm going to answer what i can one a time

Question 1 : depends. if you live on the ground floor of the apartment or it has elevators transporting it as a single unit or split from the base will not be a problem. if you have to lug it up and down lots of stairs then i would think twice unless you get a carry bag or make handles/straps for the OTA. the base has a handle on it.

Question 2 : the shorter the focal length the greater the power/magnification. a barlow is basically a power doubler/tripler that can be put between any eyepiece and the telescope in the focuser to effectively double or triple their power depending on the barlow. there really isnt a eyepieces to avoid list per se. all but the cheapest ones you can find will produce good images and serve various purposes, as you wear eyeglasses if you want use wear them when you view you are going to want to make sure you get eyepieces that will have a longer eye releif. many cheaper esp high magnification eyepieces like plossl's will have a very short eye relief. even some higher end eyepieces can have very short eye relief. i have an older 16mm Televue Nagler type 2 that has very short eye relief. anyways this subject can be studied and discussed for ages. go check the eyepiece section on here sometime

Question 3: the scope to eyepiece is about 4-1/2 feet off the ground if pointed straight up. if pointed horizontally its about 3 feet off the ground approximately. folding camping chairs are terrible. i tried to use one when i first started. you will want a decent height adjustable observing chair. there are some that work well starting at around 100 dollars.

Question 4: build a scope is not necessarily a good deal. buying a used XT8 is the best deal. i got mine locally for 200 dollars!

Question 5: if anything the stock bearing are not smooth enough. I recently upgraded the surfaces the teflon rides on on my XT8 with FRP (fiber reinforced plastic) i had to make a counter weight to strap to the back of the scope to rebalance it but following objects and wait times for the scope to settle are greatly reduced. down side is yes if i bump the scope it will move. solution don't bump it!

Question 6: what you will see will depend on many factors. what type of object it is, your viewing conditions both as far as seeing and transparency goes as well as and more importantly how much light pollution you have at your viewing site. stars will be points with 4 spikes from the diffraction from the spider that holds the secondary. nebula will very from just a slight hazy spot to a detailed gas cloud but only the orion nebula shows a ton of detail from just about anywhere. galaxy's are going to often be super faint fuzzy's except for andromeda. its a larger faint fuzzy in light polluted skies. Globulars will look like faint fuzzys often. in good conditions without too much light pollution at higher mag you will be able to star resolving stars in the brighter globs. open clusters will look amazing in low light pollution areas and good even in high LP.


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Tony Flanders
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Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5559427 - 12/07/12 02:43 PM

Quote:

So I started a thread a page back about getting a telescope for my 6 year old niece and decided against it at this time. However, all of this talk about getting a scope for her has reopened the case for getting a scope for myself.




Sounds familiar. That's exactly how I ended up with my first scope, except it was a nephew, not a niece.


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stargazer424
sage


Reged: 10/03/05

Loc: Central NJ
Re: Orion XT8 questions...and more... new [Re: Tony Flanders]
      #5559438 - 12/07/12 02:50 PM

Thank you all for your responses.

@JoLo: Do you have example images you care to share? I see you have a 12”, so your exposures would probably be faster than with an 8”. I’ll definitely need to look into a chair. I already have a bad back.

@frito: I am on the first floor and my back door is close to the parking lot, so as long as it is easy to carry looks like that won’t be much of a problem. Ah so it's the opposite of camera lenses with the smaller number being more magnification.

So with the supplied 25mm eyepiece and an additional 2x Barlow would give me 96x, so I would probably need a barlow and at least a shorter focal length EP.

I just did a price comparison of the stock classic XT8 and a build-a-scope (adding the items that come with the stock classic XT8) and it came to $428.36 compared to $359.99, a $68.37 difference…that seems wrong…best go with the stock and spend the $68.37 on an extra eyepiece.

I guess since I am pretty sure I am going with the XT8, I really need to start focusing on eyepieces. I really don’t know where to start with that. They look like they can get really expensive. I see Orion sells long relief eyepieces for $99.99 each…


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Pharquart
sage
*****

Reged: 11/11/09

Loc: Southwest Minneapolis Metro
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5559503 - 12/07/12 03:36 PM

Eyepieces indeed can get very expensive. I think almost everyone agrees that Televues are the acme of the eyepiece options, and their top ones are $500. The F/6 ratio of the 8" scope is in the range that is more forgiving of eyepieces, so you generally won't have to spend as much as someone using a F/5 or F/4.5 scope like the bigger reflectors. At the lower ratio, stars at the edge of field can be blurry or streaked.

You'll want to start your search for eyepieces based on focal length to achieve a desired magnification. Don't fall into the trap of thinking you need super high magnification. 200x might be the highest usable magnification you'll get out of most nights because of atmospheric conditions (seeing). Many objects actually look better at lower magnifications than higher. In basic eyepieces, shorter focal length (higher magnifications) means less eye relief. You can probably take your glasses off and use the telescope focuser instead, meaning you can use low eye relief eyepieces, but if you have to keep taking off/putting back on your glasses, you'll tire of that quickly. So probably better to pick eyepieces with long enough eye relief, maybe 15mm or more. Any eyepiece that's about 15mm focal length or longer should already give you that. It's the shorter focal length models that make you get close. A Barlow allows an eyepiece with a long eye relief to keep it, even though the magnification doubles. In fact, most advanced eyepieces that are short focal length and long eye relief have a built-in Barlow-like lens at the front end.

Next comes field of view, or how wide a patch of sky you can see. A basic inexpensive Plossl gets you about 50 degrees. (That's what your eye thinks it sees in the eyepiece. The actual field of view in the sky is 50 divided by the magnification.) Wide angle eyepieces go to 60, 68, 82, 100, or more. The Explore Scientific line of 82 degree eyepieces seem to be very good and very reasonable, particularly compared to similar Televue, but they're still $100 or more. Wide field + long focal length usually means you need a 2" eyepiece barrel, which the XT8 may or may not have, depending on which configuration you buy.

The nice thing is that eyepieces, if cared for well, retain a good chunk of their value. Browse the classifieds on this site and buy a used one, maybe something in the 15mm range. Probably stay away from 12-13mm, as you can get that effective length by using the 25mm with a 2x Barlow. Use the scope and decide if you want more or less magnificaiton, more or less eye relief, and more or less field or view. Sell whatever eyepiece doesn't fit your needs. If you bought it used and didn't scratch it, drop it, or smudge up the glass, there's a good chance you'll get most of your price back, less shipping. Buy one that's better. I've "traded up" my eyepiece collection over the years with remarkably low loss in value along the way.

In the end, get used to the idea that this initial purchase of a scope and eyepiece (and any other accessories) is just an initial purchase. Dobs in general are very easy to modify and customize over time. Eyepieces are interchangeable and your collection will likely improve in size and quality over time. Don't fret too much about picking the best accessories to start. Just pick something and get started, then change stuff out as you learn more about what and where you like to observe.

Brian


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stargazer424
sage


Reged: 10/03/05

Loc: Central NJ
Re: Orion XT8 questions...and more... new [Re: Pharquart]
      #5559555 - 12/07/12 04:20 PM

The XT8 does have a 2" Crayford focuser that accepts 1.25" and 2" telescope eyepieces.

It also comes with a 25mm Orion Sirius Plossl eyepiece (48x magnification/96x with 2x Barlow). Your recommended 15mm would give me 80x magnification (160x with 2x Barlow). I guess that sounds like a good start?

As far as the Barlow goes, is the Orion Shorty 1.25" 2x Barlow Lens decent? Would a 3x be better to start with, or should that be a future purchase.

Is there loss of image quality through a Barlow? For example would you get a better view through a 15mm eyepiece vs. a 30mm with a 2x Barlow?

I guess I will start lurking in the Eyepieces section...so far I have been spending all of my time here.


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csrlice12
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Reged: 05/22/12

Loc: Denver, CO
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5559710 - 12/07/12 06:05 PM

"Is there loss of image quality through a Barlow? For example would you get a better view through a 15mm eyepiece vs. a 30mm with a 2x Barlow?)

Oh, the can of worms you just opened......

I prefer to use separate focal length eyepieces. But will use a barlow on those nights of exceptional viewing....doesn't happen often. But, everyone who has a dob/newt should have a barlow. A barlow is essential if you use the barlowed laser technique to collimate your scope.

Edited by csrlice12 (12/07/12 06:09 PM)


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Tim D
super member


Reged: 10/08/10

Loc: Temecula, CA
Re: Orion XT8 questions...and more... new [Re: csrlice12]
      #5559996 - 12/07/12 09:32 PM

A zoom might also work well for you- I get great results with mine and my XT8
Tim


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kfiscus
Carpal Tunnel
*****

Reged: 07/09/12

Loc: Albert Lea, MN, USA
Re: Orion XT8 questions...and more... new [Re: Tim D]
      #5560105 - 12/07/12 10:49 PM

The eyepieces (EPs) you get with the XT8 are good and will give you low- and medium-power views, the views you'll use and enjoy more often. If you get a barlow, 2x is the most common magnification, you've just doubled your EPs' magnifications and you've effectively doubled your EP collection. The following is what happened to me...
I started out with decent stock EPs, years later upgraded to new wide-field $200 EPs, and now have upgraded to buying used but good-as-new Televue Type 6s for $250 each from reputable sellers here and Amart.

Edited by kfiscus (12/07/12 10:50 PM)


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JasonBurry
sage


Reged: 04/27/12

Loc: Cape Spencer, NB, Canada
Re: Orion XT8 questions...and more... new [Re: kfiscus]
      #5560124 - 12/07/12 11:02 PM

I observe with a telescope not terribly different from the XT8. I've found that I do the great bulk of my observing with 2 eyepieces and a 2x barlow. My mix is a 32mm plossl, and a 12.5mm plossl. Works for me.

With that, I get about 38x, 76x (32mm with and without barlow), 100x an 200x (12.5 with and without barlow). It's a rare day on which my 6mm sees use (400x with barlow), maybe a handful of times in the last 10 years.

The 3 main pieces, 32, 12.5 and 2x barlow can be had for maybe 150 easily enough, and maybe significantly less.

They've provided good value and some beautiful views. The 32mm shows some coma at the edge of field, but it's unobjectionable to me. I get 1.3 degree fov which ain't bad.

A decent chair will be nice too, but a rectangular box style seat can give a handful of height options on the cheap. You'll see more if your seat height is comfortable.

You're gonna have some fun!

J


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CosmoSat
Pooh-Bah


Reged: 07/24/09

Loc: India
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5560234 - 12/08/12 12:30 AM

Its kinda surprising the nobody pointed u to the Apertura AD8 dob...it has great value for money with excellent quality too..I would recomment u this one over the orionxt8. only if u want to hve the intelli feature..then go for the xti.

Clear Skies!


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Saneless
member


Reged: 12/03/12

Re: Orion XT8 questions...and more... new [Re: CosmoSat]
      #5560243 - 12/08/12 12:39 AM

Quote:

Its kinda surprising the nobody pointed u to the Apertura AD8 dob...it has great value for money with excellent quality too..I would recomment u this one over the orionxt8. only if u want to hve the intelli feature..then go for the xti.




The AD8 is definitely a much better buy. Most of the time.

Only real issue is its weight compared to the XT8. It has much better bearings (mount and tube) but this also adds about 12-14lbs of weight. The XT8 is about 40 vs almost 53 or so for the AD8. And of course the XT6 is only 34.

I guess it really depends how far you have to go. If it's not that far, the bearings, better finder, better focuser, fan, and the fact you get a 2" 68 degree 30mm and a 9mm plossl make it worthwhile.

The XT kinda rips you off really with its 25mm. They should have at least made the single eyepiece a 32.


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FlorinAndrei
scholastic sledgehammer


Reged: 09/28/10

Loc: California
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5560362 - 12/08/12 02:45 AM

Either the Apertura AD8 or the Zhumell Z8 would be a somewhat better deal than the XT8. Two eyepieces instead of one, magnifying finder instead of 1x finder, OTA with adjustable balance instead of fixed OTA, dual speed focuser instead of single speed, primary mirror fan instead of no fan, etc.

The optics are similar, however. So if you get the XT8 as a Christmas present, keep it, don't throw it away, it's not a bad scope.

Quote:

is it easy to transport?




Any 8" dob can be easily carried in a sedan. Chances are it will fit on the back seat, unless your car is pretty small.

For carrying it down the stairs and so on, they split in two: base and OTA. You can carry the two parts separately, they are a little bit voluminous, but aren't too heavy at all.

Be VERY careful with the door frames, they hate focusers for some reason and are looking for every opportunity to ruin your scope.

Quote:

Could someone run down eyepiece/lenses in layman's terms. I am versed in cameras/photography so is it the same where the higher the mm the more "zoom" you get? Are there "must have" and "don't ever buy" eyepieces. And what is a Barlow? I wear glasses, does that affect eyepiece selection at all?




F = focal length of telescope

f = focal length of eyepiece

M = magnification

Then:

M = F / f

For the XT8, AD8 and Z8, F = 1200mm.

The shorter the eyepiece focal length, the greater the magnification.

For a scope like this, the useful range of eyepiece focal lengths is 3mm ... 36mm, although the extremes will be used very rarely (6mm and above will be used more often, and you may never need an eyepiece longer than 30mm if you get a wide angle 30mm like the 30mm Explore Scientific 82 degree).

You "must have" 3 or 4 eyepieces spaced uniformly within the range of focal lengths indicated above.

"Don't ever buy" many cheap eyepieces. Rather get a few better quality ones.

A barlow is a multiplier for magnification. A 10mm eyepiece plus a 2x barlow is the same like a 5mm eyepiece alone.

If your glasses are spherical, you can just remove them and adjust the focus on the scope until you see clearly (but it may look de-focused for other people). Or you could keep the glasses on and adjust focus like everyone else. If you must keep the glasses on, make sure your eyepieces provide plenty of eye relief, 12...15mm ER at minimum, ideally more like 20mm ER.

If you wear glasses for astigmatism, you may find that you must keep the glasses on. Then look for eyepieces with decent ER.

Quote:

How high up is the eyepiece on average when viewing. I'm 5'10", would I need to be sitting or bending over to view? I have a camping chair, but I don't know if it will be tall enough to use.




Excellent question.

The eyepiece on a dobsonian varies in height as the scope moves up and down. Therefore it's best if you have some kind of adjustable height chair. In the beginning, a rectangular box would suffice, it will provide 3 different heights. Or just any fixed chair will do, but you will do some gymnastics while bending over to the eyepiece.

Google "observing chair", it's the most comfortable solution. You could even build one if you have any DIY skills at all.

Quote:

Everyone talks about how easy a dob is to push around to find something. Can you tighten/loosen the mechanics?




Excellent question. Looks like you're doing your homework.

The tension in the altitude bearing should be adjusted for best push-to performance - when the motion is effortless and buttery smooth, it begins moving without jumping, and stops immediately, that's best. It takes some trial and error until you figure it out, after that it should be fine.

With the AD8 and Z8, don't adjust tension to compensate for a very heavy eyepiece; instead, take advantage of the OTA balance mechanism and move the OTA until it's balanced again. With the XT8, you can't do that, you'll have to sacrifice perfect friction to keep it from stooping down.

Quote:

What will I actually see when looking at, say, a nebula? I know it won't look like Hubble images, but will it just look like a cloud, or will it be interesting.




Not like Hubble, indeed.

It will look "just like a cloud", yes, but it will be interesting nevertheless. You're seeing light that has traveled thousands of years to reach you. Are you kidding me? Of course it's interesting!

Only one way to find out.

Buy this book, it will tell you what objects to observe in the beginning:

http://www.amazon.com/Turn-Left-Orion-Hundreds-Telescope/dp/0521153972/

Edited by FlorinAndrei (12/08/12 02:59 AM)


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phillip
professor emeritus


Reged: 11/26/05

Loc: Sterling, Illinois
Re: Orion XT8 questions...and more... new [Re: FlorinAndrei]
      #5560416 - 12/08/12 05:24 AM

My experiences with my XT8. Fun catching some of the brighter Deep Sky, Orion Nebula are hints of a Green Color, companions to the Trapezium cluster let me know if I'm in for a good night.

Planetary viewing is among my favored, more than one moon of Saturn not just Titan pop into view. Division in Ring is more than obvious. Several views of Mars during a close encounter was demanding to catch favorable sky conditions for details. One of those very rare steady sky's here in the Midwest released increadible details. Observation was over a 3 month period and highly rewarding teaching loads of patience viewing. Magnifications varied from just over 100 to over 350 latter those rare steady sky's. Mediocre sky's still release fleeting detail with continual focusing. Skills with higher power are rewarding with practice as shared 400 power group viewing putting the target just off edge of the scope and let it drift for just under a minute for the onlookers, they loved the huge image.

New Celestron only one night with an above average sky caught the Snowball Nebula rather sizeable puffy star stood out well at 60X, sure even better in the XT8.

Andromeda Galaxy is huge, brighter companion nice rather bright compact comet view, other more spread out companion sometimes elusive, but when there larger with averted vision hints of detail, nice indeed!

Sorry so lengthy, wish you the best.

ETX90
5 inch Short Tube
New SE6 Celestron
XT8
Nagler, and prized Clave 8MM Eyepices Planetary Views

Edited by phillip (12/08/12 05:46 AM)


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stargazer424
sage


Reged: 10/03/05

Loc: Central NJ
Re: Orion XT8 questions...and more... new [Re: phillip]
      #5561525 - 12/08/12 09:21 PM

Ack! Apertura AD8 and Zhumell Z8 VS Orion XT8!!!

@Saneless
Quote:

The AD8 is definitely a much better buy. Most of the time.


What are the exceptions?

Quote:

Only real issue is its weight compared to the XT8. It has much better bearings (mount and tube) but this also adds about 12-14lbs of weight. The XT8 is about 40 vs almost 53 or so for the AD8.



I guess this doesn't matter much. Chances are I will be transporting it in 2 pieces.

OK so running down the specs, the Apertura is only $40 more than the XT8. It replaces the 1.25" 25mm Plossl eyepiece with a 2" 30mm SuperView eyepiece and has a 2 speed focuser. And comes with the additional:
- 1.25" 9mm Plössl eyepiece (high-power) with 52 degree field of view
- 35mm Extension Tube (used to provide extra back-focus for eyepieces that need it)
- 1.25" Moon Filter
- Laser Collimator (1 battery included)
- Battery operated primary mirror cooling fan
- 4-slot eyepiece tray
- 35mm Extension Tube

I added up the cost of buying those items separately and it came to over $250!!! I don't think I can consider the Orion model anymore, unless someone were to tell me that the mirror or eyepiece that came with the Orion were vastly superior (which doesn't seem to be the consensus).

Also, I'm confused about the 35mm Extension Tube. The description says it is used to provide extra back-focus for eyepieces that need it.
What does that mean exactly?

Now, I have seen other people posting that the Apertura and the Zhumell are clones of each other. Are there ANY differences/advantages of one over the other? It looks like they come with the same accessories (not sure if Zhumell has the 35mm Extension Tube as I don't see it listed anywhere).

Also, since they come with a 1.25" and a 2" eyepiece, does that mean that I would need 2 different Barlows and a moon filter for the 1.25?


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FlorinAndrei
scholastic sledgehammer


Reged: 09/28/10

Loc: California
Re: Orion XT8 questions...and more... new [Re: stargazer424]
      #5561801 - 12/09/12 01:44 AM

Quote:

I don't think I can consider the Orion model anymore, unless someone were to tell me that the mirror or eyepiece that came with the Orion were vastly superior (which doesn't seem to be the consensus).




The consensus is that they are all made in similar factories in China, following similar industrial processes and standards.

Quote:

Now, I have seen other people posting that the Apertura and the Zhumell are clones of each other. Are there ANY differences/advantages of one over the other?




Just get the one that has the best discount for Christmas, or something. These scopes are almost identical.

Quote:

Also, since they come with a 1.25" and a 2" eyepiece, does that mean that I would need 2 different Barlows and a moon filter for the 1.25?




Somewhere on that list of accessories for either scope, there is a 2" / 1.25" adapter for eyepieces. Get any 1.25" eyepiece, plug it into the adapter, and now you could plug it into 2" focusers, 2" barlows, 2" coma correctors, etc.

A 1.25" eyepiece with an adapter is like a 2" eyepiece.

Many adapters are also threaded to allow you to use 2" filters with 1.25" eyepieces. Therefore you could get only the 2" version of any filter and use it with any eyepiece. If the adapter is not threaded, chances are it's one of those flimsy cheap ones which may or may not hold the 1.25" eyepiece exactly on axis, and you should get a better adapter - threaded, solid, well centered. But it's not an emergency, you could use the existing adapter for a while.

Most commonly used (and cheaper) barlows are 1.25". That means you can't use it with a 2" eyepiece. That's okay, since most of the time you would use it with the 9mm eyepiece anyway, when seeing is good, to give it a power boost. There are 2" barlows available for purchase, but they are more expensive, and it's less likely that you'll use it with the 2" eyepiece (but it's definitely doable).

Moon filters are over-rated. A telescope cannot increase the surface brightness of an extended object like the Moon. In fact, the Moon's surface brightness in a scope is lesser than in reality. The greater the magnification, the less surface brightness on the Moon. Keep the magnification rather high (which is how you should look at the Moon anyway), do not observe the Moon from a dark place, and filters will be unnecessary.

When I look at the Moon, I place the scope in front of the house; across the street there's a street light, there's enough light I could read a book. I observe at pretty high magnification (exit pupil is 1mm or less). I share the view with neighbors, passersby, etc. I can't remember when I used the Moon filter last time (in fact, I'm not even sure if I still have it).

Quote:

Laser Collimator (1 battery included)




Collimating with a laser is very intuitive, easy, quick, and precise. Here's a primer:

http://www.cloudynights.com/documents/primer.pdf

But there's a catch: It assumes that the laser itself is very precisely centered. That is indeed the case with high end models, but may or may not be the case with cheap lasers.

Not to worry. Just verify the laser if it's centered or not. If it's not, fix it. It's easy:

http://www.stark-labs.com/craig/llcc/llcc.html

After a while, when you acquire some experience, you could do some star testing, to verify your laser collimation. The star test is the ultimate authority for scope performance, but it's difficult to do and requires good conditions:

http://legault.perso.sfr.fr/collim.html

Quote:

Battery operated primary mirror cooling fan




This is why you need it:

http://www.garyseronik.com/?q=node/55

http://www.garyseronik.com/?q=node/69

Edited by FlorinAndrei (12/09/12 01:48 AM)


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Orion XT8 questions...and more... new [Re: FlorinAndrei]
      #5561816 - 12/09/12 02:02 AM

the Z8 and AD8 they are more or less the same scope but have a different name on them they are made by GSO in Tiawan. they offer more bang for your buck currently in just what comes with them than the XT8. now if you can find a used XT8 at the right price like i did (200 dollars!) then by all means get it instead. the XT8 is made by Synta in china, the company that now owns Celestron. Most of Orion's stuff is made by Synta but not everything.

out of the extra features/stuff included in the GSO scopes i would say the eyepiece rack, dual speed focuser and better bearing system are probably the biggest things. the XT8's bearing system can be made to work just as good if not better if your a DIY kind of person with just a 30 dollar sheet of FRP and some time spend cutting a disk for the base to ride on and two strips to wrap around the alt bearings. i did this to mine and love it but it has also required me to make a counter weight i have to attach to the mirror end of my scope so it stays balanced with heavy eyepieces and the 8x50 finder i got on it now.

no matter what you can't go wrong they are all great starter scopes. i already want a bigger scope but i will not get rid of my XT8 simply because of its portability and ease of setup. the easier it is to get out and observe the more likely one is to actually go out and do it often.

Edited by frito (12/09/12 02:04 AM)


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stargazer424
sage


Reged: 10/03/05

Loc: Central NJ
Re: Orion XT8 questions...and more... new [Re: frito]
      #5562452 - 12/09/12 01:20 PM

Here is an important question...is the $379.98 "sale" price a holiday time price or is that the normal price? http://www.telescopes.com/telescopes/dobsonian-telescopes/zhumellz8deluxedobs...

I wasn't looking to buy right away, but if the price is going to go back up after Christmas, maybe I will have to...


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