Telescope Comparison

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  • Member since
    May, 2008
Telescope Comparison
Posted by Cassini on Wednesday, May 28, 2008 12:39 PM

HI all, Just one last telescope question, sorry for all the questions,

  Seems maybe there is a problem with stock on the Celestron omni xlt 150.(http://www.telescopes.com/telescopes/reflecting-telescopes/celestronomnixlt150reflector.cfm)

So, I was wondering what you all thought about this Omni XLT 150 when compared to the Celestron Nexstar6 SE, (http://www.telescopes.com/telescopes/catadioptric-telescopes/celestronnexstar6se.cfm)

 

                       Celestron omni xlt 150 VS Celestron Nexstar6 SE

Planets, as far as size, clearity?

DSO Objects?

Tripods

Mounts

????

 

Would the Celestron Nexstar5 SE compare to the 6SE?

Thank you ALL VERY MUCh in advance. TY

-Cassini

 

 

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  • Member since
    July, 2002
  • From: Texas
Posted by chipdatajeffB on Wednesday, May 28, 2008 2:04 PM

I think you would like either of the NexStar telescopes better than the 130 XLT, especially since you are interested in seeing the planets well.

The 150XLT has  focal length of 750mm, whereas the NexStar 5SE is 1,250mm and the NexStar6SE is 1,500mm. The focal length is important for two reasons:

  • With the same eyepiece, a longer focal length gives you a larger image (more magnification). Since planets require about 150X, minimum, for good detail, you're better off with more focal length.
  • At nearly the same aperture, a longer focal length will give you a narrower field of view. So, targets that are "wide" (like M45, The Pleiades, or M31, The Andromeda Galaxy) may not "fit" in one eyepiece view, so you'll have to move the scope around to get the complete picture.

Given that your earlier post said you were primarily interested in getting a good view of Saturn, the the 6SE would be the best choice. However, I noted your other post asking about the dual-drive kit for the 150XLT ... if you add that kit to the 150XLT it would come to almost the same price as the NexStar5SE. I think you would be happier with the 5SE.

The NexStar mounts are rigid enough for this size scope. They are also GoTo mounts, so you need not add the motor kit (it's already there) and, in addition, the scope's controller can aim the scope automatically at objects in the sky for you. You must first align the scope and mount each time you set it up, but it's a simple process and only takes about 5 minutes once you have some practice.

In any case, you're going to need either a barlow or an additional eyepiece, or both, with any of the above scopes if you want good views of planets.

In a direct comparison to the 150XLT:

  • The view in the 6SE will be only a little dimmer, but with the same eyepiece will provide twice the image size (since it's focal length is double that of the other scope).
  • The view in the 5SE will be noticeably dimmer, but will actually be better for planets (since the focal length is almost doubled and the planets are bright enough for the dimming not to matter much).
  • Both NexStar mounts will seem more solid to you, and easier to use.

If you are interested in DSOs, then the larger aperture of the 6SE will make it a better scope for you. If you are interested primarily in planets and the Moon, then consider getting the 5SE and an eyepiece/filter kit -- for roughly the same price as the 6SE.

You will get reasonable DSO performance from the 6SE as long as you're not expecting the views to be like photographs. A good minimum aperture for DSOs is an 8-inch to 10-inch scope, but these two SEs will do acceptably well on globular and open star clusters, for example.

The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane

Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.

www.3rf.org

  • Member since
    May, 2008
Posted by Cassini on Wednesday, May 28, 2008 2:33 PM

Thank you for that very detailed explination. That was awsome of you. This is such a hard descion. The OMNI XLT150 is HALF the cost of the 6SE. But dam that 6SE looks awsome and has the XLT coating.

I may be going out of my budget if I go with the 6SE. The 5SE I can manage easily. But fear that maybe I would be "forced" to JUST seeing planets and not much else. I'm not sure, as I am still new to this. Although I believe ALL 3 telescopes with be a HUGE improvment over my Used Meade DS-2114.

Will the 5SE show me atleast a few dozen DSO objects that I would be happy with?

I may just have to bite the bullet and pay the extra $400-$500 for the 6SE. Such a Hard decision, and I REALLY appreciate you helping me out.Thanks

-Cassini

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  • Member since
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  • From: Texas
Posted by chipdatajeffB on Wednesday, May 28, 2008 2:52 PM

I don't know how difficult it will be for you if you stretch your budget to get the 6SE. So I would be tempted to say go with the 5SE and add another eyepiece, or a barlow, and save for the rest. I think you would be happier with the 5SE than with the XLT150.

However, if you're expecting any decent DSO performance then you're really looking at the wrong size and type of scope, in my opinion.

A good 8-inch newtonian on a dob mount will "blow away" any of the scopes you've mentioned so far when it comes to DSOs. With Orion's summer sale, you could even afford a 10-inch scope of that type, plus a couple of nice eyepieces, for what you would pay for the 5SE. Hmmm, as a matter of fact, you can get the 10-inch dob equipped with object locator for what you'd pay for the 5SE!

Or, you could save $170 by getting the 8-inch with object locator!

I have had nice views of Saturn, for example, with Orion's 6-inch dob, and likewise with their 10-inch dob. At 150X the planet is not that hard to track with a dob. You simply move the planet to the edge of the field of view, let go, and watch as the planet drifts through the field.

There are a few dozen DSOs that will be offer acceptable views through the SEs. There are literally hundreds that are within reach of a 10" scope. A good rule of thumb is that decent view of planets require at least 4 inches of aperture and 1,000mm of focal length, whereas "good" views of DSOs start with 8-inch apertures.

In my experience, observers who want to see DSOs quickly tire of the brighter star clusters that are within reach of smaller apertures. It would be far better to start out with a larger-aperture scope if DSOs will be a primary target.

The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane

Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.

www.3rf.org

  • Member since
    May, 2008
Posted by Cassini on Wednesday, May 28, 2008 3:14 PM

Well I know I dont want a DOB due to portability issues, i understand there not that bad to move, but I cant image wanting to lug that around with me.

I may go with the 5SE and Hope I am happy with it. As I cant get it out of my head that a "larger: image of Saturn is for sure what I want. And If I can see 2 dozen or so interesting DSO's then I will be happy.

Will the 5SE have the power to show me M51, or M81?

As far as Ep are concerned I had in mind, the Celestron X-cel 5mm, and X-cel 2x-barlow. they are supposed to be great for planetary viewing. I hope also decent for DSO.

What do you think of that? (plus telescopes.com offers 90-day money back program, so that could help).

Thanks

-Cassini

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  • Member since
    July, 2002
  • From: Texas
Posted by chipdatajeffB on Wednesday, May 28, 2008 8:48 PM

Cassini

Well I know I dont want a DOB due to portability issues, i understand there not that bad to move, but I cant image wanting to lug that around with me.

There are different parts of the "lug around with me" problem. With a dob like the ones mentioned, you move the base to where you want to observe, you go get the OTA and plunk it down into the base, you attach a couple of springs, and you start observing. If you get the object locator, you also do a two-star alignment very similar to what you'd do with either of the NexStar mounts, then you start observing. Any newtonian (such as your previous DS2114) also requires periodic collimation.

With the 150XLT, you put the tripod in place, then you mount the CG-4 to it, then you attach the counterweight, then you attach the OTA, then you swing the OTA and mount around both axes to ensure you've balanced it right, then you check your polar alignment, and then you start observing. The 150XLT may be light enough that you can move it all at one time, but that's a bit risky. In any case, you'll be doing a polar alignment -- at least a casual one -- each time you set up the mount.

With the NexStar mounts, you set up the tripod, attach the mount/scope combination, do a rough North alignment, do a two-star alignment, and start observing.

You can compare the relative weights of the various pieces and decide which is "easiest" overall.

I may go with the 5SE and Hope I am happy with it. As I cant get it out of my head that a "larger: image of Saturn is for sure what I want. And If I can see 2 dozen or so interesting DSO's then I will be happy.

The larger image of Saturn (or other objects) that you see comes as a result of focal length. Just for comparison, here are the focal lengths:

  • DS 2114 = 1,000mm
  • 150XLT = 750mm
  • NexStar 5SE = 1,250mm
  • NexSTar 6SE = 1,500mm
  • Orion XT8 = 1,200mm
  • Orion XT10 = 1,200mm

The difference in the views of Saturn through the 5SE and the Orions will be primarily in brighness and amount of detail. They will be, effectively, the same size with the same eyepiece. Resolution (appearance of detail) is primarily a matter of aperture and contrast of the optical system.

Will the 5SE have the power to show me M51, or M81?

It will not have the light-gathering power to give you a "good" view. You can offset that somewhat by traveling to a truly dark-sky site. Doing so is like adding another inch or two to your aperture. The same is true for M81: you want a clear, dark sky, and as much aperture as you can bring to bear.

Again, a lot depends on your expectations. Any of the above scopes will give you a better view of such objects than your current scope, but (again, relative to a DS2114):

  • 150XLT will be lower-magnification (not really a problem here) and a little brighter
  • NexStar 5SE will be very nearly the same, perhaps a tiny bit brighter
  • NexStar 6SE will be a bit larger and a bit brighter
  • Orion XT8 will be a little larger and a good deal brighter, and you'll be able to make out the basic shape (although it will still be a grayish fuzzy object)
  • Orion XT10 will be obviously brighter and will show some detail to the shape, although not much detail overall.

As far as Ep are concerned I had in mind, the Celestron X-cel 5mm, and X-cel 2x-barlow. they are supposed to be great for planetary viewing. I hope also decent for DSO.

You won't want to use your 2X barlow with any of the supplied eyepieces for DSOs, in general. A few may benefit. You want an eyepiece/barlow combination that avoids going over about 150X for most DSOs within reach of the above scopes. You want to avoid a combination that goes over about 300X for any object most of the time (since most of the time atmospheric seeing effects won't permit sharp views above that power).

But, for lunar and planetary observing, you can pair the 2X barlow with the eyepieces supplied with the above scopes, and you can use the 5mm eyepiece without the barlow.

The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane

Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.

www.3rf.org

  • Member since
    May, 2008
Posted by Cassini on Thursday, May 29, 2008 8:50 AM

Thanks again Chip.

However, I just got the email late last night that my telescope WAS shipped. So It says it will be here on Saturday. I will have to atleast try it out and if I am not satisfied, It is going right back for a Nexstar6 SE. (most likely lol). Thanks alot, I hope this gives me a nice Saturn image. Now the more I look at the comparisons the 750mm FL is kind of a let down on paper. Hopefully not though. I am going to place the order for the 5mm now. And maybe wait on the Barlow for now atleast. (asa i have one already, just an older one)

 

-Cassini

  • Member since
    May, 2008
Posted by Cassini on Monday, June 02, 2008 9:05 AM

Well as my luck would have it. I waited like a little kid on x-mas ALL day Saturday for my telescope to come. Around 6:30pm Fedex pulls up and gives me one box that weights maybe 10lbs. I tell him that my "tracking #" says 65lb box. He says "thats all i got sorry".

So of course, They sent me the OTA and NOT the mount. The package even says "package 1 of 2", i really wish they would have read that or atleast knew what they were doing. I am completely unhappy with the situation. and I am waiting for the customer service rep to get into the office and I am going to tell him to not bother sending out the mount, as I am going to return the OMNI XLT 150 and purchase the Nexstar6 SE.

I feel this scope will be more "portable" and give me "larger" images of Saturn, Jupiter, etc. Now I just have to come up with the diffrence in price, although I know they will give me a better deal after all this....

 

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