Celestron Omni XLT 150mm Reflector vs Refractor

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Joshelerry
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Celestron Omni XLT 150mm Reflector vs Refractor

Post by Joshelerry »

Hi came across these 2 telescopes..
Almost same specs at 150mm aperture, f/5, only being one is reflector and the other a refractor.

Need to check except for the price difference and verastility of a refractor to be used in daytime as telescope, what other differences are there in terms of astronomy viewing?

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Gary
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by Gary »

Joshelerry wrote:Hi came across these 2 telescopes..
Almost same specs at 150mm aperture, f/5, only being one is reflector and the other a refractor.

Need to check except for the price difference and verastility of a refractor to be used in daytime as telescope, what other differences are there in terms of astronomy viewing?
Hi Joshelerry. Welcome to the forum!

If you do not mind, could you kindly state the brand and model of these 2 telescopes you are comparing so forum members can give better specific advise?

Also, what is your definition of "versatility"? Some telescopic accessory can make vertical and/or laterally inverted views upright again. Thus making them suitable for terrestrial observation during daytime.

Inch for inch, refractor gives the best view compared to a reflector. But inch for inch, reflector gives the best aperture value for money. Bigger aperture (diameter of primary lens/mirror) will give better astronomical viewing. But if the telescope is too heavy and bulky (i.e. non portable to you), you may be discouraged to set it up for viewing often. And with less use, see less stuff and after sometime giving up the hobby altogether.

Another important thing to consider is whether you want to do astrophotography (AP) with your telescope. If yes, mainly which type of astrophotography? The answer to these questions can greatly influence how you spend your budget on a telescope system.

In any case, do join as many free public stargazing sessions as you can and find out more the pros and cons of different types of telescopes before you purchase one. You can gain a lot of useful info from such face-to-face sessions with telescope owners in one evening than trying to figure out everything by yourself.

Lastly, lots of good books about telescopes and related accessories in the library. Borrow them and read it - e.g. Star Ware.

Good luck and enjoy the learning process!
http://www.astro.sg
email: gary[at]astro.sg
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"The importance of a telescope is not how big it is, how well made it is.
It is how many people, less fortunate than you, got to look through it."
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Hardwarezone
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by Hardwarezone »

The Celestron Omni XLT series comes with CG-4 mount, not convenient as ALT-AZ mount for "daytime use" as you mentioned.

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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by Davegn »

Hi Joshelerry,

Welcome to the forum and astronomy.

Generally, reflectors are best value for money. Refractors on the other hand are much shaper but at a price to pay, as it is a lens design, a 150mm F5 achro, would give you quite a bad Chromatic Aberration (CA).

If you don’t own your own transport, you would like to also take a note that the CG4 is also quite heavy.

No matter how big or small your telescopes are, the best telescope is the one that you use the most offend.

And I do agree with Hardwarezone that depending on what "daytime use" as you mentioned, an AZ will be more convenient.

Do drop by to one of our many free public stargazing sessions and have a look at difference in the telescope designs.
Dave Ng
Bishan Park SideWalk Astronomy
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Joshelerry
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by Joshelerry »

Hi all, thanks for the information.. Some clarification here

1) Brand is Celestron omni series, saw these 2 similar specs scopes but of course price is much different! So comparing refractor and reflector to know more about them. Read that at least refractor can be use as terrestrial viewing

2) I am into photography and so matching them will be good. Hence astro photography will be in the plan definitely! Do own a tripod and hence can be used for alt-az functions. While CG-4 for astronomy. Do own a car.

3) Found out Orion Astrograph 8" f3.9 which is good for photo taking. Knowing that the bigger objective will allows deeper space viewing. How do u compare Orion to Celestron?

4) B&H do sell Celestron telescopes and Orion from its own website. Is it alright to buy online from overseas? I use B&H often but for telescope not sure if shipment can damage parts.

5) Practically in Singapore how much deeper can we view? I mean on clear skies of course but knowing there is severe light pollution, can those remote spots which you people often go be good enough to view deep space objects beside solar planets and moon? ( of course with the right equipment)

Will join one of the viewing session someday

ggodetucsamoht
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by ggodetucsamoht »

3) Found out Orion Astrograph 8" f3.9 which is good for photo taking. Knowing that the bigger objective will allows deeper space viewing. How do u compare Orion to Celestron?

Initially I was also looking at this Orion 8" Astrograph reflector but after coming to understand some pointers from the guys here i dropped the idea instantly, why? Firstly f3.9 means it is much faster scope comparing to common f5 reflector but with its wide view one do need to factor in high quality eyepieces to bring out its true potential of the performance on the visual, Televue eyepieces works closely with such scope specs and i am not ready to pay 600-800 bucks on just one eyepiece. More stringent on the collimation as compare to the f5 reflector.

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cloud_cover
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by cloud_cover »

Hello Josh and welcome to the "club" :)
The debate between a 6" Achro vs. a 6" Newt (or SCT for that matter) is an often raised question.
I'd like to point out that firstly, a 6" REFRACTOR is a heavy and bulky object. To wit, it will be effortful to deploy it to do terrestrial viewing unless you are always viewing from 1 fixed spot. Of course, a 6" Newt is a no-go unless you are able to read upside-down :)
Also, the scope itself weighs 7.5kg, without associated rings, accessories and eyepieces so unless your tripod or Alt-Az mount is heavier duty, you will find that it will strain the system.
Regarding chromatic aberration: a fast achromat is not really meant to look at bright objects such as the Moon, Jupiter or bright stars like Vega or Sirius, to name a few. However, for dimmer DSOs this is much less of an issue. Personally i think that sometimes CA makes stars look prettier because I sorta like the blur border that makes them really look like diamonds. Sometimes :) I strongly suggest you look through one of these scopes, if possible, before deciding if the degree of chromatic aberration is acceptable for you.
a CG-4 is not really an ideal platform to image with such a heavy scope: The CG-4 may not be able to deal with the weight and the result is streaky stars, which are frustrating.
Regarding Orion vs. Celestron: Virtually the same with some minor design differences. Meade, Celestron, Orion, Explore Scientific, Skywatcher, , Antares, GSO, Astro-Tech, Stellarvue are all China made scopes so the lenses are mass produced to variable quality, although of late the quality has been fairly good. The main producers of such scopes in China are Synta (PRC), JOC (PRC) and GSO (Taiwan). Astro-Tech and Stellarvue are owner-operator shops in the USA who also do some QC on the units they sell so they are considered a step above.
The Orion 8" f/3.9 is a fine scope and will produce many fine images certainly at a beginning or intermediate level. Collimation may be an issue photographically but visually it will be relatively simple to do with a Barlowed laser (cheap - can be made for less than USD$60 and the barlow component can be used as, well, your regular observing barlow lens). I routinely take less than 5 mins to collimate my f/4.7 Truss-Dob very satisfactorily. What you will have to deal with, at f/3.9 is Coma. Lots and lots of it. To this end a coma corrector may be desirable so do factor that in your costs. These range from the cheaper GSO/Astro-Tech/Baader MPCC to the expensive Televue Paracorr.
Regarding suitable eyepieces: Its not true that you "need" $600-$800 Televue eyepieces for an f/4 scope. To start, Televue Plossls can be routinely had, used, for under $100 each or new for about $150 from the USA. Explore Scientific 82degree eyepieces start at USD99 and people have reported being very satisfied with them. Of course you can buy new Televue Ethos eyepieces for between $700-$1250 each but that would be a personal choice :) Even if you did use lower end eyepieces, its the edges of view that suffer. Generally the center of view is well preserved in all but the cheapest eyepieces. To this end, its probably useful asking for specifics either here or in the cloudynights forums :)
So, what can a 6" see? I observe from a slightly darker part of Singapore in the North and with my 50mm Binos I can routinely see down to mag 6+ stars to the north but only Mag 4+ when looking south into the CBD's light dome. In my 4" Refractor I can expect to see at least Mag 10 stars (although they are faint - perhaps Mag 9+ for easy seeing) I can easily see the Orion nebula and sometimes the Lagoon nebula, not to mention bright planetary nebulae like the Ring and Dumbbell. In my 8" SCT (which has roughly the light gathering power of a 6" refractor due to reflectivity losses) I can definitely see down to at least Mag 11+, resolve Omega Centauri somewhat. Of course when we go for a short 2 hr drive up to Johor when everything is thrown out of the window: my 4" refractor there will outperform my 8" here. Hence perhaps the most important tool in visual astronomy is actually the ability to seek darker skies!
Personally I suggest that if you intend to go visual first, then get a dobsonian. An 8" will provide very decent aperture and locally Skywatcher (I'm not advocating the seller!) sells them for a reasonable price (or you can import from the USA but be aware shipping is expensive since they calculate by volume and a telescope is mostly empty air). You have your choice of computerized goto or not based on pricing. Then when you feel you want to delve into astro-photography, get a smaller 80mm or 4" refractor to start to minimise the effect of overloading your mount or higher magnification, which increases the camera shake caused by motor/gear irregularities in the mount or inaccurate polar alignment, which you can also use for daytime duties.
DON'T PANIC

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antares2063
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by antares2063 »

cloud_cover wrote:Of course when we go for a short 2 hr drive up to Johor when everything is thrown out of the window: my 4" refractor there will outperform my 8" here. Hence perhaps the most important tool in visual astronomy is actually the ability to seek darker skies!
Cant agree more with cloud_cover on this point...any scope does alot better in dark sites..my 80mm scope feels like gem under clear dark skies :)

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Junwei
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Davegn
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by Davegn »

antares2063 wrote:
cloud_cover wrote:Of course when we go for a short 2 hr drive up to Johor when everything is thrown out of the window: my 4" refractor there will outperform my 8" here. Hence perhaps the most important tool in visual astronomy is actually the ability to seek darker skies!
Cant agree more with cloud_cover on this point...any scope does alot better in dark sites..my 80mm scope feels like gem under clear dark skies :)

Regards
Junwei
Agree with cloud_cover and Junwei. You can even enjoy with a 7x50 bino in dark sites. Unless you want see veil nebula in 3D. (=

Anyway back to the topic on CA. it's really depending on user.

A 6" f5 refactor, as cloud_cover said it to rather heavy to be use on photography tripod. For birding and wildlife photography, I use a 80mm f6.3. Ed double at 2.7kg with a gimbal head and a strong tripod which is more then enough more me.
Dave Ng
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Joshelerry
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Re: Celestron Omni XLT 150mm Reflector vs Refractor

Post by Joshelerry »

Hi Guys, thanks for the many comments and advise here.. really appreciate.

1) CG4 mount was sold as a complete set with the 150mm both Refractor & Reflector series of the Celestron omni versions. Hence I suppose they should have consider this? I might not be really sure what it mean by getting "streaky stars" due to tripod mount capability because I thought there will not be much movement unlike photography?

2) As for the 6" series to be too heavy.. well, its not that we will be moving too much but of course almost most of the star gazing will be outdoor. I do forsee probably sometime to be overseas like Ubin, St John island which requires travelling by boat (therefore I cap at 6" to 8"). Malaysia maybe will requires drive in and hence with the boot should not be a big issue.

3) Brand wise, based on remarks here shouldn't be an issue with Celestron, Orion etc...

4) Refractor vs Reflector .... understand that reflector is not usable on daylike due to the reverse images which refractor can double up as some spotting scope. In this case it makes the refractor more versatile. But mainly I will use telescope for astronomy as it will be too heavy to luge around for bird/wildlife photography which I also am doing

5) The main point here is even though I will be a beginner but I know that I will be interested in this as this is something I like since young. Budget wise will not of course wan to blow out too much (maybe within $1.5k the most roughly). And based on experience with photography, I don't want to get the entry level and later on try to sell it and upgrade, this lose more money actually. And hence I want a scope that can not just view planets but also some deep sky objects (of course I know location matters but for me I will say over 95% of the time I will be viewing in locations in Singapore mainland). Therefore I suppose getting a f/5 6" scope will be quite around the mark?? Of course do take note that I will not be buying until I did some trying and testing....

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