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Orion XT8 questions...and more...

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#26 stargazer424

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Posted 10 December 2012 - 10:45 AM

@Dave74: That's good to know. As long as it wont go up $100+ after the holidays. I wont rush to get it.

@tedbnh & rick-SeMI: Great idea! While I don't have to worry about an elevator (I live on the ground floor of a 2 story apartment) moving it around would be easier with a hand truck.

I was thinking about the idea of putting locking castors on the mount so it can be rolled around. Has anyone done this?
http://www.homedepot...play?catalog...

@BDS316: So, if I go with the Z8 (with the 2" 30mm and 1.25" 9mm) would you suggest that the 2" 30mm should be the only 2" I should get (for now) and any additional starter EPs (like a 11 or 12mm) should be 1.25"?

I kind of wish both eyepieces were the same size so that I could use one Barlow for both and then have the combination of 40x/80x and 133x/266x magnification with a 2X Barlow. Or can I if I get a 2" Barlow and put it in the focuser first. So it would go 2" Focuser - 2" Barlow - 2" to 1.25" adapter - 1.25" EP? Where would a filter go? I don't quite get the sequence of putting it all together.

#27 Saneless

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Posted 10 December 2012 - 11:11 AM

@BDS316: So, if I go with the Z8 (with the 2" 30mm and 1.25" 9mm) would you suggest that the 2" 30mm should be the only 2" I should get (for now) and any additional starter EPs (like a 11 or 12mm) should be 1.25"?

I kind of wish both eyepieces were the same size so that I could use one Barlow for both and then have the combination of 40x/80x and 133x/266x magnification with a 2X Barlow. Or can I if I get a 2" Barlow and put it in the focuser first. So it would go 2" Focuser - 2" Barlow - 2" to 1.25" adapter - 1.25" EP? Where would a filter go? I don't quite get the sequence of putting it all together.

I like the 30mm 2" that came with the AD8 but I know there's better ones out there. Problem is, am I willing to spend $250 to replace it with something that is a bit better quality and larger FOV? Probably not. Not now, anyway.

As far as the barlow goes, I know GSO makes a 2" barlow that has a 1.25 adapter. I'm not sure if you can drop in the 2" barlow, then drop in the 1.25" adapter, then the 1.25 eyepiece. Never done it or thought about it until now :)

I already have a decent range of 1.25" eyepieces and instead of worrying about a 2" barlow to get the 30mm to 15mm, I'm just going to buy a very good quality 1.25" 14-16mm very wide view piece instead.

I'd say stick with the 30mm 2" and then just fill out some of the mid/lower range. The only other 2" ones you can get are as low as 24" (I think, maybe 18mm for 100 degree) and up to 50mm. I think 30mm at 68 degrees is enough to see bigger open clusters and that should be fine, for now. You will find out as you use it what you're lacking on the lower-powered end.

You'll probably be ok to get a 12-14mm and a barlow. 14mm is a great zone for this scope (gets it around 85-100x) and a barlow would get it to around 170-200x. Then the 9mm would take care of 133 and 266 if the conditions are right for it.

That's if you just want to add the minimum amount of extra eyepieces. Be sure to get a barlow that lets you remove the end piece to get you 1.5x. Then maybe you could think about getting something like a 24mm and you can go 24/12/15 and with the existing 9 you would do 9/4.5/6.

Again, that's a little more mucking around with unscrewing things and screwing them into other eyepieces a lot but it gives you a lot of versatility.

From there you can just get a good feel for what you like without wasting too much money on pieces you'll never use. And when you feel like upgrading your pieces you'll know that you like xmm better or plan to use ymm all the time.

TLDR Version:
Get a 12 or 24mm 1.25" piece and a barlow to complement your 2" 30mm until you get a better idea what more you want.

#28 BDS316

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Posted 10 December 2012 - 11:50 AM

BDS316: So, if I go with the Z8 (with the 2" 30mm and 1.25" 9mm) would you suggest that the 2" 30mm should be the only 2" I should get (for now) and any additional starter EPs (like a 11 or 12mm) should be 1.25"?


I would suggest a GSO rather than Orion (Synta). lower cost, better features and accessories, better mount, etc

The 30mm 2-incher is the same as the one I am using. At f/6 its not bad. This eyepiece you will not use barlowed. A 2 inch Barlow with a 2 inch eyepiece causes significant balance issues for small dobs.

You don't need a 15mm (30mm with 2x barlow) eyepiece with a 68 degree fov if you have an 11mm eyepiece with an 82 degree fov. The 11mm would show you almost the same amount of sky but with higher magnification, darker background, more contrast and a more favorable exit pupil for a medium power eyepiece option.

I always go right from low power to the 11mm Nagler, My 16mm Konig sees little use natively although it is useful when barlowed

#29 stargazer424

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Posted 10 December 2012 - 12:31 PM

Again, that's a little more mucking around with unscrewing things and screwing them into other eyepieces a lot but it gives you a lot of versatility.

Ha! Yeah...I don't think I would be comfortable taking apart a lens. Chances are I would A. Scratch it. B. Not be able to put it back together the same way.

#30 Dave74

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Posted 10 December 2012 - 12:45 PM

I use the a GSO 2 inch 2x barlow all the time. They're around $60. Comes with a 1.25 adapter. Pretty simple and easy to use even in the dark. The view from the 30mm in the barlow is one of my favorites. It's true, you might need to counter balance your scope, though.

#31 Saneless

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Posted 10 December 2012 - 01:40 PM

Again, that's a little more mucking around with unscrewing things and screwing them into other eyepieces a lot but it gives you a lot of versatility.

Ha! Yeah...I don't think I would be comfortable taking apart a lens. Chances are I would A. Scratch it. B. Not be able to put it back together the same way.

It's not really taking apart a lens. Have you ever seen an eyepiece filter? That's basically what the bottom cell of the barlow is. It's just a 1/2" or so ring screwed into the bottom of a longer tube. If you screw that piece into an eyepiece (like a filter) then you get 1.5x. If you leave it as is and drop the eyepiece into the longer tube part, you get 2x.

The reason I bring it up is on some nights using a barlow on the 9mm might not work out so well viewing jupiter (266x), but at 1.5x it's at a usually always good 200x (meaning this scope can do 200x even on rough nights up above).

#32 stargazer424

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Posted 10 December 2012 - 08:36 PM

Oh boy! I just saw this on another post that the Z8 has ! I have been looking at the Z8 too. I wasn't going to get it just yet, but will the price ever be lower? I hate making rash decisions...

#33 nploop102

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Posted 10 December 2012 - 09:31 PM

I just ordered the Z8 and with the extra 25 bucks off, free shipping and no taxes, it's really a great deal.

#34 stargazer424

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Posted 10 December 2012 - 09:42 PM

Peer pressure!!

Did you order any accessories with it?

#35 stargazer424

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Posted 10 December 2012 - 09:59 PM

Ok, So I guess back to the Barlow question...

Zhumell 2in. 2x ED Barlow

Vs.

Astro-Tech AT22XB

Vs.

Any other Barlows?


Also 2" Barlowvs 1.25" Barlow?

#36 kfiscus

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Posted 10 December 2012 - 10:05 PM

I'd wait on the barlows. You won't use them as much as you'd think...

#37 nploop102

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Posted 10 December 2012 - 10:09 PM

Peer pressure!!

Did you order any accessories with it?


LOL. Peer pressure indeed.
No accessories. Just the scope.

#38 Dave74

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Posted 10 December 2012 - 10:09 PM

They're the same.

#39 stargazer424

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Posted 10 December 2012 - 10:23 PM

I'd wait on the barlows. You won't use them as much as you'd think...

Really? Even with only 2 EPs?

#40 Dave74

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Posted 10 December 2012 - 10:29 PM

I have a 2 inch barlow. It's great with the 30mm. I don't use it much with the 9mm. Things are mushy, and fly through the FOV. You can wait to buy it though. For sure. It's not a must have. A good chair would be a better accessory.

#41 kfiscus

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Posted 10 December 2012 - 10:40 PM

I have always given the advice to people starting to buy gear to start with 2 EPs, then a barlow, then a high-power EP if they still want to. If the OP is torn between brands of barlow, I'd say to wait, research, borrow and try, then buy. The nice thing is, barlows are cheaper than EPs.

#42 stargazer424

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Posted 10 December 2012 - 11:15 PM

Order Placed! Went without the Barlow, but I do think I will be getting one. Just need to find the right one at the right place...

#43 Shawn Garbett

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Posted 10 December 2012 - 11:35 PM

I recently got the Orion XT10g for my wife. She loves it. I can answer a few of these.

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.


You'll probably be alright in that regard. For the 10" we're talking about a bigger car, probably a mini-van already. Moving it around is easy. It's the room it takes up in car that can be a problem (got to put kids somewhere). The 8 is probably more manageable.

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?


Pay attention to the maximum and minimum effective magnification on the website. The range is 29-300X for the XT8. It has a 1200mm focal length. So eyepieces should never be outside of 41mm to 4mm in size. You want a wide field and a higher magnification. I would recommend something around 25-30mm for the wide field. Preferences for the higher mag run between 8-15mm for this size scope. We have the 25mm deep sky Orion and the 9mm ES 100. A 2X barlow would give you a 12.5mm and a 4.5mm equivalent with these two, a good range. Asking about barlows is a loaded question, opinions run the to all extremes about them. I think you have to try one for a year, and use several eyepieces before you make up your mind. If you wear glasses, eye relief is important. 17mm or larger is great. 15mm or less and the field of view will be reduced (I.e., if you get a 100 degree, can you live with only realizing 82 degrees?). Unless you have astigmatism, you can probably focus without the glasses. The package I got also had a 14.5 with illuminated cross hairs for alignment. It's irritating for anything but alignment on the goto, but I don't know how I'd live without it. If you don't get the goto, you won't need anything like it.

300X is for the rare day the weather is perfect, don't go for this to start.

Once you advance to seeing the limitations of your equipment in few years, consider a paracorr. At present, I've learned what the coma is, but haven't been bothered by it enough to drop the $$$. I've heard getting a paracorr, is like a scope upgrade for the dobsonians. So you can enjoy a better scope in years to come.

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.


You'll probably be fine standing. However, some folks like a right-angle finder upgrade to save their neck. Personally, I couldn't do without it--I'm physically fit, but had a back injury years ago that doesn't allow certain positions.

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?


Decide and try different configurations. Buy the minimum possible to get started--this is the best advice I got a few months back. To balance it if you get a bigger finder and heavy eyepieces, get a couple 1lb magnets and wrap them in duck tape.

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.


After a few nights with it and a copy of "Turn Left at Orion". I can find things quite rapidly. Never tried to tighten or loosen. If you bump it, you find it again. It's part of the experience, and I find it relaxing. Each to his own.

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.


A nebula will look like a wisp of grey cotton in an odd shape, unless it's Orion. They are more difficult to see, and nebula filters help. They are still fascinating. I did a public telescope party recently. Setup the dumbbell nebula with a filter. When you tell a 6 year old that's an exploded star, their jaws drop. I personally, having a background in finding resonances in 3-d spaces, found the shape fascinating. Orion, is the only one you can really see the color, and it's jaw-dropping.

Read up on dew. Get a hair dryer. I've been looking into 12V ones to run off a marine battery.

Jupiter is incredible right now, if it weren't for the d*** clouds.

#44 Allan...

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Posted 11 December 2012 - 12:32 AM

I have an XT8 and was wondering if I should buy an ES11 or not. I already have a good Agena 20mm (70 deg) which I like very much; barlow it down with a 2x to 10mm. Will I see much benefit in getting the 11mm (other than wider view)? Or should I go for something like an 8.8mm ES? I dont have anything in that range as yet, though I do have a 14mm that I sometimes try to barlow down to 7mm but often its too much, with my seeing conditions. thanks, Clare

#45 CosmoSat

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Posted 11 December 2012 - 03:25 AM

with ur f/6 scope for highpower planetary viewing I would recommend atleast one eyepiece giving u something around an 1mm exit pupil like this Agena 1.25" Enhanced Wide Angle Eyepiece - 6mm to be used whenever the conditions allow.

Clear Skies!

#46 Billytk

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Posted 11 December 2012 - 07:14 AM

I have a Baader zoom eyepiece and a 2x barlow. The zoom ranges from 24mm to 8mm. It's like having a case of eyepieces in one package. I love it!

#47 nploop102

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Posted 12 December 2012 - 12:40 AM

Order Placed! Went without the Barlow, but I do think I will be getting one. Just need to find the right one at the right place...


Sweet!

#48 stargazer424

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Posted 12 December 2012 - 02:42 PM

with ur f/6 scope for highpower planetary viewing I would recommend atleast one eyepiece giving u something around an 1mm exit pupil

Ok so I understand Focal Length, Field of View and Eye Relief. What is the exit pupil?

#49 pogobbler

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Posted 12 December 2012 - 03:29 PM

with ur f/6 scope for highpower planetary viewing I would recommend atleast one eyepiece giving u something around an 1mm exit pupil

Ok so I understand Focal Length, Field of View and Eye Relief. What is the exit pupil?


The exit pupil is basically the diameter of the light exiting the eyepiece. You can calculate it by dividing the focal length of the eyepiece by the focal ratio of the telescope... for example, a 30mm eyepiece in an f/6 scope would give an exit pupil of 30/6 or 5mm. Lower powers have larger exit pupils and higher powers have smaller exit pupils. Since the pupil of the dark adapted eye is going to be around 7mm (the "entrance pupil") for most people, an exit pupil of greater than that is "wasting" light, reducing the effective aperture of the scope, so a power that gives a 7mm exit pupil is generally given as the lowest effective power for the particular scope. People's maximum pupil size will vary, and tends to decrease with age, but 7mm is a decent rule of thumb. At small exit pupils, the floaters in the eye become more prominent-- think of the sharp shadows produced by a concentrated light source, equivalent to a small exit pupil vs. diffuse shadows produced by an extended, diffuse light source. These floaters can be an issue with high powered planetary or lunar observing, bothering some observers more than others. Doing a little math, the 1mm exit pupil the poster recommended would be a 6mm eyepiece (6mm/6 = 1mm), or, of course, a 12mm eyepiece with a 2x Barlow. The magnification would be 200x, which is a good reasonably high power, though, with scopes about 6-8" and up, I like being able to hit around 300x, too, for those nights of very good seeing. I've used such powers on my own XT8 on Jupiter this fall and it was still a very useable power and I could track manually just fine.

#50 Allan...

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Posted 12 December 2012 - 05:51 PM

Great (and easy to understand for a newbie) explanation of exit pupil, Tom. My eyes arent that young anymore and I think mine are likely less than 5. How do you find that out? From an Optomestrist/eye exam? I have witnessed the floaters, too; not a big problem though; I learn to ignore them. In the Summer, when I had just got my XT8, I thought that I was looking at insects flying across the scope but when Fall and Winter hit, and they were still there, THEN I knew what was happening...lol. As I said, its no biggy. thanks, Clare






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