Jump to content

Orion SkyQuest XT4.5 or Zhumell Z130?


Recommended Posts

Okay, I think I've narrowed down my list for my first scope to be one of these two. It's going to be either one of these scopes for viewing our moon, planets and their moons. I'll be transporting it frequently up/down 2 flights of stairs regularly and then every couple of months will be bringing it in the car on an hour long ride to my parent's house for some viewing there. Will be viewing with 2 toddlers for as long as they sky has their attention which will be about 5-10 minutes.  No interest in using either of these for astrophotography.

  • The Zhumell Z130 is only 0.5" larger in aperture, but the focal length on the XT4.5 is quite a bit longer. Not sure how that translates to the performance of the scope. What should I be expecting out of a scope that has a slightly larger aperture but significantly shorter focal length? That should reduce the magnification drastically, but how does that affect clarity/detail and/or contrast/color if at all?
  • The price difference is around $60 which I feel is negligible considering the long term use of the scope I'm hoping to have for me and the two kids (and possibly wife if she wants to join us).
  • Though aesthetically, I think the Z130 looks nicer, the looks aren't going to be the deciding factor. It's all about the function. Is aperture really king if the difference is just 0.5"? 
  • I hear raving reviews about both and can't decide which. Lately, I've been hearing that the XT4.5 is so small in stature that I would still need that to be on a table top so the whole advantage of that possibly having a leg up over the obviously designed table top Z130 is out the door...for me. The kids looking through the XT4.5 standing up would be perfect. 2 and 5 year olds. 

I'm aware the collimating of the Z130 is a bit more difficult (not impossible like the Z114) with the screws over the thumb nobs which I'm fine with. I'm just looking for clarity. Totally okay with not seeing everything out there in the sky, but would be disappointed if what I am able to view isn't as crystal clear as possible for a sub $300 scope. I'll probably be buying a couple eyepieces eventually/immediately. 

Thoughts on the comparison other than to buy one of each? Haha.

Link to comment
Share on other sites

For planets and moon I would go with the longer focal ratio of the XT4.5, I won't dis the Z130 though I gave one to my niece last Christmas and she is very happy with it.

Link to comment
Share on other sites

1 hour ago, Constellasian said:

What should I be expecting out of a scope that has a slightly larger aperture but significantly shorter focal length?

Increased aperture means that more light is being collected and the image will be brighter. As a rule of thumb, square the diameter of the primary (this is influenced a bit by things like central obstruction). At this size, that equates to about 30% increase in light-gathering capability (1302/1142) with an equivalent increase in brightness at the same magnification.

Now a longer focal length results in higher magnification for the same eyepiece (magnification = scope focal length/eyepiece focal length). So a shorter focal length means lower magnification. One consequence of this is that all of the light (which is 30% more) is being focussed on a smaller area and so the image is brighter again.

You can get bigger magnifications on a shorter focal length scope - you just need to get a shorter eyepiece.

Contrary to what the departments stores would have you believe, more magnification on small scopes does not mean that you see more. You will always see more detail on a small bright image than a big faint image.  The largest useful magnification is generally reckoned to be about 2x the mm diameter of the primary. So for the 114mm that is 228x and for the 130mm that is 260x.

Bottom line: the larger mirror and shorter focal length will give you brighter images and will support more magnification than a small mirror with a long focal length. You just need to select your eyepieces accordingly. As an aside, it will also give you a wider field of view with the same eyepiece, so would be useful for more extended objects as well.

Link to comment
Share on other sites

Looking a little closer at the two scopes and what's included, yes .5" aperture will give a slight but visually unnoticeable increase in details observed but the XT4.5 will likely provide a better image with it's incuded 10 and 25mm plossl eyepieces and incudes a colomation cap and it's colomation hardware is better than the Z130. It also would be an easy upgrade to a 8x50 RACI and handle it's weight easily not to mention it's awesome ota carry handle and inclued dobknob. 

Between the two packages the XT4.5 clearly from a what you get standpoint is the better package as well at f8 the cheaper eye pieces that are included will work quite well.

https://www.highpointscientific.com/orion-skyquest-xt4-5-classic-4-5-dobsonian-telescope-10014

     Either choice I think you will be more than happy with though.

                    Freddie ?

Link to comment
Share on other sites

I was thinking of buying from them too based on their list of reasons why. Seemed to be good support. I also feel like I owe it to them after watching all the free videos on YouTube by that Ken guy. I don't live far away from Orion's shop south of the SF Bay Area. If I was getting the XT4.5, I figured I should just drop by their to pick one up in person and get all the support needed there. Yelp has mixed reviews but from what I'm hearing on these forums, Orion seems to be known for excellent customer service.

If I ended up with the Z130, I'd probably get it at HighPointScientific. 

Link to comment
Share on other sites

1 hour ago, Demonperformer said:

Increased aperture means that more light is being collected and the image will be brighter. As a rule of thumb, square the diameter of the primary (this is influenced a bit by things like central obstruction). At this size, that equates to about 30% increase in light-gathering capability (1302/1142) with an equivalent increase in brightness at the same magnification.

Now a longer focal length results in higher magnification for the same eyepiece (magnification = scope focal length/eyepiece focal length). So a shorter focal length means lower magnification. One consequence of this is that all of the light (which is 30% more) is being focussed on a smaller area and so the image is brighter again.

You can get bigger magnifications on a shorter focal length scope - you just need to get a shorter eyepiece.

Contrary to what the departments stores would have you believe, more magnification on small scopes does not mean that you see more. You will always see more detail on a small bright image than a big faint image.  The largest useful magnification is generally reckoned to be about 2x the mm diameter of the primary. So for the 114mm that is 228x and for the 130mm that is 260x.

Bottom line: the larger mirror and shorter focal length will give you brighter images and will support more magnification than a small mirror with a long focal length. You just need to select your eyepieces accordingly. As an aside, it will also give you a wider field of view with the same eyepiece, so would be useful for more extended objects as well.

You spooked me out a bit with your Avatar, but perhaps people are thinking the same of mine! Thanks for your well thought out response. The math is getting away from me a bit, but I think I understand your point. Good point about seeing more detail on a small bright image vs a big faint one. Even as such, I can't quite tell from your response if you'd be more likely to recommend the XT4.5 for the clearer image or the Z130 for the brighter image. Is it a no brainer for you or would you say I'd be alright with either one and it's not a huge difference particularly for a newbie like myself?

Link to comment
Share on other sites

There is one last caviat in advantage the Orion offering has  that I somehow forgot to mention, the included eye pieces due to the 900mm fl will produce higher magnifications out of the box for planets and moon, planets require  higher magnification.

So I guess for planets and moon the XT does come ahead slightly and for extended objects the Z does the same, out of the box at least ?

 

 

Link to comment
Share on other sites

6 hours ago, Constellasian said:

 I can't quite tell from your response if you'd be more likely to recommend the XT4.5 for the clearer image 

How have I suggested that the xt4.5 would give a clearer image?

Link to comment
Share on other sites

Both kits are nice, and will perform to your expectations.  The Orion XT4.5 has the same Newtonian OTA as that of my Meade kit...

kit4c.jpg.8b4eafc2fdac0500a7e53a31ddc587f0.jpg

...although the XT4.5 is perhaps more staircase-friendly.  Both have a focal-length of 900mm.

At f/8, it is a "planetary" telescope, and for the medium-to-high powers.  You might find the need for a 2x barlow eventually with the XT4.5.  The primary-mirror, at the bottom of the tube, is a lesser spherical, but a spherical performs quite well at f/8, as my own does.

The Zhumell Z130, with a 650mm focal-length, at f/5, is also a Newtonian, and intended as a low-to-medium power telescope; however higher magnifications are certainly possible, via its superior parabolic primary-mirror, and with a 2x barlow definitely required, if not a 3x.  The barlows will, in effect, extend the focal-length of the Z130.  I have a 150mm f/5 Newtonian...

1034416590_6f5w2.jpg.a72159da8a5138bd5f33932d2e1c73e4.jpg

...but you wouldn't want to haul that one up and down a flight of stairs.  I've regularly used a 3x barlow with it, as its focal-length is only 750mm. 

The Z130 would be the more versatile of the two, for magnifications ranging from a binocular-like 20x, to 150x and beyond with, again, 2x and 3x barlows.  A 32mm Plossl inserted, at 20x, would show you a larger part of the sky, to aid in the hunting of objects.  Once an of object of interest is found, you then begin switching out eyepieces and ramping up the power for a closer look.

This illustrates the field-of-view when observing the Moon through the XT4.5(red) and the Z130(yellow), and with a 32mm Plossl at 20x inserted into both...

114 f8 vs 130 f5

As shown, you can see a larger part of the sky at that lowest power with the Z130.  With longer-focus telescopes, owners of those oft lament that they cannot realise low-power wide-field views.  With the Z130, you can have your cake and eat it too.

Link to comment
Share on other sites

23 hours ago, Constellasian said:

Is it a no brainer for you or would you say I'd be alright with either one and it's not a huge difference particularly for a newbie like myself?

I think you are right that it will not be a huge difference.

7 hours ago, Constellasian said:

I’m not certain I understand your conclusion from the assessments you’ve made between the two. 

Without trying to be patronising, let me try to remove the math:

Bigger mirror (Z130) > more light collected > brighter image > can support more useful magnification (in discussing magnification, "useful" is a vital word - always missing from department store scope hype. A 60mm f15 refractor with a 3.5mm eyepiece and 5x powermate will give you over 1260x magnification, but the image would be so faint it would be an utterly useless combination).

Shorter focal length (Z130) > wider field of view for same eyepiece (but a shorter eyepiece will still give you the higher overall magnification, while remaining in the "useful" bracket).

I think Alan sums it up very nicely:

3 hours ago, Alan64 said:

With the Z130, you can have your cake and eat it too.

 

Link to comment
Share on other sites

Alan64: Wow! Impressive response! Thanks so much for taking the time to show me this and for that diagram too of the field of view. If I'm understanding you right, the Z130 can have the same magnification as the XT4.5 by just adding a barlow or other lens. That package would be more versatile b/c it would have the advantage of a wider field of view from this shorter focal length of the tube compared to the XT4.5 which has a much tighter field of view which I can't really widen. Your response may have just made my decision on the Z130! Thanks again! 

Link to comment
Share on other sites

2 minutes ago, Constellasian said:

If I'm understanding you right, the Z130 can have the same magnification as the XT4.5 by just adding a barlow or other lens. That package would be more versatile b/c it would have the advantage of a wider field of view from this shorter focal length of the tube compared to the XT4.5 which has a much tighter field of view which I can't really widen.

Correct.

Link to comment
Share on other sites

Demonperformer: No offense taken. I'm totally okay with you guys talking to me like a 7th grader. I'm totally new at this and can use all the help I can get. The older I get, the more I realize how little I know. Thanks again for your feedback and taking the time to respond. Much appreciated. The forums I'm typically on are car ones where a lot of the times, it's tough to get away from the hot heads who are less helpful. This forum has been great thanks to the members here, you included. 

Link to comment
Share on other sites

Thank you for everyone's feedback regarding their input on the two scopes. I've decided that a table top scope would work best for me. Final decisions were due mostly to the compact size of the the Z130. It gives me the flexibility to mount on a tripod on an AZ mount and if needed more immediately, keeping the dobsonian mount and putting it on a tripod platform. Short term would be just to view it sitting on the ground from my backyard or putting it on a table or ottoman that I already own. 

In general terms, I'd rather have a more superior table top scope (compared to the 100mm or 114mm ones) than an inferior floor mounted dobsonian scope. I did consider the Orion Starblast 6 for a moment, but am admitting that it's too large for me. I'm projecting that the Z130 would last me longer than the XT4.5. The XT6 was just out of the question due to the sheer size. Not knowing at this time how involved my kids will be in this despite my confidence in being able to gauge their interest, the Z130 has the benefit of more flexibility. Although I can appreciate the slower XT4.5 scope and amount of detail it would provide, it would still require me to take it apart (not difficult, I know) before putting in the trunk of my smaller car which I may take out on my own. I can maintain the wider field of view the Z130 has to offer while still having the option to use a barlow or other eye piece to increase magnification. 

Once I get my scope up and running, I'll make a first pass at a review. Thanks again everyone. 

 

Link to comment
Share on other sites

Cool you have decided, It seemed you were leaning twoard the Z. Its always a good thing to weigh your choices carefully in this hobby, a lot of money can easily be misappropriated.

                   Freddie ?

Link to comment
Share on other sites

Figured I'd have to make a decision eventually. With all the help I've been getting and all the hours online reading up on this and other models, it was time to order. Hoping to catch a glimpses of the upcoming red moon on 1/2/19 at the western hemisphere. Should be exciting. 

Link to comment
Share on other sites

Yes it will (weather permitting), I'm out now observing the Quadrantids and it's cold but catching a few per hour here at 52°, hoping to see Venus and the Cresent Moon by sunrise...no scope needed for some great astronomy. Look forward to your next inquires as you move along and some first light info too...

Link to comment
Share on other sites

There will come a time when you'll be tempted to ramp up the power, but all of your little "ducks" will need to be lined up in a row, and to ensure sharp and pleasing images.  For one, the collimation must be accurate, as precise as possible.  A Newtonian cannot be collimated to a 100% accuracy, but you can get very close, and the alignment must be adjusted on occasion as the telescope is used, and moved about when travelling.  Sharp and pleasing images are also dependent upon the atmospheric conditions.  The quality of the telescope's mirrors, the eyepieces, and optical accessories also play a part in that.  In addition, the drawtube of the focusser must rack in and out straight and true, along its entire length.  If it does not, there is a reliable and enduring fix for that, one that I developed, and due to my own experiences with my kits.  At the lower powers, the collimation needs only to be "good enough". 

At the higher powers, you will see a smaller portion of the sky, highly magnified.  As a result, the object of interest will want to zip out of sight, requiring you to manually track it by bumping and nudging the telescope, and often.  To extend the time, and to see more of the sky, that's where wide-angle eyepieces come into play.  That's also where barlows are advantageous.  For example, here is a 12mm wide-angle eyepiece...

https://agenaastro.com/agena-1-25-dual-ed-eyepiece-12mm.html

...and for a power of 54x.  When combined with a 2x barlow, you then have a simulated wide-angle 6mm(108x).  You can use that combination for awhile.  Later, you can get a 3x barlow, combining that with the 12mm, and for a wide-angle 4mm(163x).  Barlows should be of the same quality as the eyepieces with which they're used.  I would suggest these...

2x... http://www.scopestuff.com/ss_eba4.htm

3x... http://www.scopestuff.com/ss_eba3.htm

I have both of those myself, and they've performed wonderfully with my telescopes, including a 6" f/5 Newtonian.

163x is about as high as practical with your kit, at first.  The Earth's atmosphere, through which we observe, is also magnified as you go up in power, and along with its. at times, soup-like nature.  Per the 50x-per-inch "maxim", a 5" aperture can realise 250x at times, particularly on the Moon which is so very near to the Earth.  Indeed, the Moon can take a lot of magnification.  150x or so is considered the minimum at which to enjoy the planets.  There are also "planetary" eyepieces, and with somewhat wider views over Plossls...

https://agenaastro.com/eyepieces/1-25-eyepieces/shopby/bst.html

Those eyepieces have barlowing lens elements built in, and with no need to combine them with a dedicated barlow.  They also have nice, large eye-lenses through which to observe.  To find the power of each, you simple divide 650mm, the focal-length of your telescope, by the focal-length of the eyepiece...

650mm ÷ 2.5mm = 260x...

https://agenaastro.com/bst-1-25-uwa-planetary-eyepiece-2-5mm.html

Now, I'm not suggesting that you run out and purchase that particular one.  It is only to let you know what's out there on the market.  There are more eyepieces out there than you can shake a stick at, at different levels of quality, lens-polishing, and prices.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.