Levenhuk Ra 250N Dobson Telescope

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Newtonian telescope with a built-in primary mirror cooling fan. Aperture: 250mm. Focal length: 1250mm

Reflector

Optical design

9.8

Aperture – the diameter of the light-collecting lens or mirror that the telescope uses to collect light

49.2

Focal length – the distance from the primary lens or mirror to the point at which the light is focused

Availability

Product ID	50749
Brand	Levenhuk, Inc., USA
Warranty	lifetime
EAN	5905555002613
Package size (LxWxH)	55.5x22.4x19.3 in
Shipping Weight	86.3 lb

Description

Levenhuk Ra 250N Dobson is a Newtonian reflector with a 250mm diameter primary mirror. Its optics allow for observing thousands of deep-sky objects in detail that cannot be observed with small-aperture telescopes. You can also use this telescope for outer space exploration. For example, you can observe small structures on Mars's surface, details in the atmosphere of Jupiter, the Encke gap within Saturn's rings, and even a satellite of Neptune, Triton. It is an excellent optical instrument for visual observations of space that is best suited for trips to the countryside.

Parabolic primary mirror with active cooling of the optics

The parabolic primary mirror creates a clear image free from optical distortion, even at extreme magnification. Its surface is covered with an aluminum coating that reflects 92~96% of light improving image quality. Due to the dual-speed Crayford Focuser, the focus can be smoothly adjusted.

The primary mirror features a cooling system that runs on batteries (purchased separately). If any telescope is moved from a warm room to a cold street and vice versa, the optics will take several hours to “cool down”. The built-in fan speeds up temperature stabilization almost twofold.

Stable and reliable Dobsonian mount with a brake system side bearing for smooth tube movement

The Dobsonian mount is easy to assemble and handle. It reliably holds the optical tube and allows you to carry out long-term observations with maximum comfort. The mount mechanics has been improved. Now, the movement of the tube is smooth so that tracking objects at high magnification is much more comfortable.

A special brake system side bearing for smooth tube movement allows you to move the optical tube a few centimeters up or down. There are scales on the mount sides for convenient balancing. In addition, the bearings have a more robust design (compared to conventional ones), and so they will run smoothly throughout their entire service life.

Quick start kit

The telescope kit includes base accessories that allow you to start observations right away. 9mm and 30mm eyepieces are ideal for your first introduction to deep space. An 8x50mm optical finder is used to search for objects.

Features:

Reflector with a high aperture, ideal for deep space observations
Parabolic primary mirror - no distortion even at extreme magnification
Special aluminum coating with a reflectivity index of 92~96%
Active cooling of optics for faster temperature stabilization
User-friendly and easy-to-assemble Dobsonian-style mount
Dual-speed Crayford focuser, brake system side bearing for smooth tube movement

The kit includes:

Telescope optical tube
Dobsonian mount
Plössl 9mm eyepiece
Super View 30mm eyepiece
Finder 8x50mm
Finderscope base
Cooling fan
User manual and lifetime warranty

specifications

Product ID	50749
Brand	Levenhuk, Inc., USA
Warranty	lifetime
EAN	5905555002613
Package size (LxWxH)	55.5x22.4x19.3 in
Shipping Weight	86.3 lb
Optical design	reflector
Optical scheme	Newtonian
Optics material	BK-7
Optics coating	aluminum
Primary mirror diameter (aperture), in	9.8
Secondary mirror obstruction, in	2.5
Lens (mirror) shape	parabolic
Focal length, in	49.2
Highest practical power, x	508
Aperture ratio	f/5
Resolution threshold, arcseconds	0.5
Limiting stellar magnitude	14.7
Eyepieces	Plössl 9mm (138x), Super View 30mm (41x)
Eyepiece barrel diameter, in	1.25/2
Objective lens obstruction: by area	0
Objective lens obstruction: by diameter	25
Finderscope	optical, 8x50
Focuser	2", Crayford, dual-speed
Accessory tray	✓
Telescope control	manual
Mount	Dobsonian
Mount material	wood
Additional	primary mirror cooling fan
Operating temperature range, °F	23...+95
Optical tube material	metal
User level	experienced users, professionals
Assembly and installation difficulty level	complicated
Observed object	deep-sky objects

References
and downloads

User manual: Levenhuk Ra Dobsonian Telescopes (pdf)

(PDF, 2.33 Mb)

High-resolution images (zip)

(ZIP, 49.07 Mb)

click to
download

Questions and Answers

Ivan Ayers (2015.01.06)

Does the difference in dimensions between Levenhuk Ra 300N Dob and Levenhuk Ra 250N Dob have any importance?

Customer service:

Levenhuk Ra 300N Dob Telescope features large objective lens diameter then Levenhuk Ra 250N Dob Telescope. Therefore, the maximum useful magnification of the first model will be higher.

Ivan Ayers (2014.12.10)

Hello! Tell me please what is the objective lens diameter of this telescope? Is it 254mm or 250mm?

Customer service:

The objective lens diameter of the Levenhuk Ra 250N Dob telescope is 254mm.

Walter Carson (2014.09.10)

Hello. Is it in stock?

Customer service:

Unfortunately this model is currently out of stock, we expect Levenhuk Ra 250N Dob to be back in stock in February, 2015. In the meantime please consider the Levenhuk Ra 300N Dob telescope: http://www.levenhuk.com/catalogue/telescopes/levenhuk-ra-300n-dob-telescope/

Bruce Hodge (2014.08.16)

Hello, how is this model different than Levenhuk Ra 200N Dob ({{ {{ http://www.levenhuk.com/catalogue/telescopes/levenhuk-ra-200n-dob/.link.link }} }})? Which one is better?

Customer service:

The main difference between Levenhuk Ra 250N Dob and Levenhuk Ra 200N Dob is primary mirror diameter (aperture). The Levenhuk Ra 250N Dob is a preferred choice due to larger primary mirror diameter.

Amy Larson (2014.08.08)

Hello! I wanted to ask you which eyepiece would allow me to achieve the highest practical power of this telescope?

Customer service:

To achieve the highest practical power of the Levenhuk Ra 250N Dob telescope we recommend using 2.5 mm eyepiece. Unfortunately such accessory is unavailable in our store at the moment.

Gerry Bauman (2014.07.11)

{{ {{ http://www.levenhuk.com/reviews/ra_250n_dob_telescope_review/.link.link }} }} - it's one helpful detailed review!

Customer service:

Thank you for your feedback on Levenhuk Ra 250N Dob!

Gerry Bauman (2014.07.11)

Despite the fact that I did not make telescope adjustment, I haven't notice any effect of coma. Well, we'll see, maybe I just got lucky.
I started my observations with The Ring Nebula (M57) in the constellation of Lyra. I could clearly see a misty ring, with a noticeable dark hole in the middle.
Then I found M13 - great globular cluster in Hercules. The star cluster was seen pretty well, individual stars could be seen throughout the area of the cluster up to the center. Yet I couldn't see The Veil Nebulae, I only saw the central star but not the nebulae itself... have to wait till August I guess.
I didn't have much more time cause the skies started to light up... and I chose the wrong spot to observe - part of the sky on the south was blocked by a building.
I observed with both standard eyepieces that come with this telescope. I especially liked the 2 inch eyepiece - wide angle of view allows observing vast star fields. Wide angle eyepieces are very useful tools indeed! I heard that with Levenhuk Ra 250N Dob you can discern colors of stars and some very bright nebulae. I'm not sure about nebulae (maybe it's true for Orion, I will definitely try it out) but I really can see difference in colors of some bright stars.
In general, I'm really happy with my Levenhuk Ra 250N Dob. Even without adjustment and with such a bright sky image quality was still very good.
The telescope's quite heavy... Thought I think I can handle even 300 mm ota, but it's not really convenient to carry such a monster around in the city. Plus it's more expensive. So I think I chose wisely. But when I read that with 300 mm you can see colors in deep-sky I feel a bit of jealousy, so maybe one day I'll go for it, but for now I'm quite happy with 250 mm.

Customer service:

Thank you for your feedback on Levenhuk Ra 250N Dob!

Ramon (2014.06.16)

When will the telescope be in stock? Which similar models (not less than 250-300mm) would you recommend?

Customer service:

We expect it in September 2014. Please, take a look at Levenhuk Ra 300N Dob Telescope - http://www.levenhuk.com/catalogue/telescopes/levenhuk-ra-300n-dob-telescope/ .

Warren Swanson (2014.06.11)

Greetings! I bought this telescope, which eyepieces are better for planetary observations? Someone recommended me to buy wide-angle eyepieces... is it a good advice?

Customer service:

Yes, the use of wide-angle eyepieces is preferred.

Daniel (2014.06.09)

I can see there is some kind of a cross inside the tube... will I see it when observing?

Customer service:

Don't worry, you won't see it, only high-quality image of observed object with no distortions.

Jeff Parker (2014.05.21)

I apologize for this silly question, but why it is needed to cool the telescope mirror?

Customer service:

Cooling the telescope mirror significantly reduces time of optics thermal stabilization. Thanks to the built-in fan the primary mirror quickly reaches thermal equilibrium with the environment.

Tim Suarez (2014.04.11)

Where can I fing user manual in english for this model? I haven't found it in the box.

Customer service:

You can download the user manual in the 'References and Downloads' section.

Warren Mann (2014.02.13)

what's the eyepiece to get the maximum magnification?

Customer service:

Please pay attention to Levenhuk Ra LER 3 mm Eyepiece: http://www.levenhuk.com/catalogue/accessories/telescope-accessories/telescope-eyepieces/levenhuk-ra-ler-3mm-1-25-eyepiece/

Eric Chang (2014.02.02)

Is it okay if I store this telescope in a larder where the temperature is the same as outdoors, what happens to the instrument in cold weather?

Customer service:

You can store Levenhuk Ra 250N Dob telescope in a larder, nothing bad will happen to it.

Yvonne Turner (2014.01.29)

What are the telescope's dimensions?

Customer service:

The dimensions of the Levenhuk Ra 250N Dob telescope (LxWxH): 57.1?19.7?19.7 in.

Gary Palmer (2013.12.13)

Hello!
Which Barlow lens you would recommend me to buy additionally?
How to achieve the maximum useful magnification?
What objects can I observe at this magnification?
Thank you.

Customer service:

To achieve the highest practical power we recommend you to use the eyepiece with 2.5 mm focal length. Barlow lenses in this case are not required. Here you can find a list of celestial objects you can see with a telescope based on its aperture - http://www.levenhuk.com/blog/knowledge-base-telescopes/things-you-can-see-with-a-telescope-based-on-its-aperture/

Dawn Sandoval (2013.11.14)

Can I mount this telescope on Levenhuk Ra EQ5 GoTo? Or equip it with the auto guidance system somehow?

Customer service:

Levenhuk Ra 250N Dob telescope doesn't have fasteners required for it to be installed on Equatorial mounts. Currently we don't have motors for automatic guidance for dobsonian telescopes.

Irene Sherer (2013.09.03)

Good evening! I don't understand anything in telescopes and astronomy, but I'm craving this telescope! I've been looking and comparing all day long and chose two models: this one and the Levenhuk SkyMatic 135 GTA. Which one would you recommend only for celestial observations (astrophotography is not needed), as I understand, with the first one I will be able to see more, but with the second - less, but without any problems.

Customer service:

The main advantage of Levenhuk Ra 250N Dob is larger objective lens diameter: the greater the aperture the more detailed images a telescope provides. On the other hand Levenhuk SkyMatic 135 GTA has an advanced auto guidance system, which with no doubt will be of a great help when navigating to and tracking celestial objects.

Paul Rouser (2013.07.16)

Hello! I really like this telescope! Tell me, in theory, is it possible to see Jupiter's moons (Ganymede, Callisto) in detail? In astro forums I read that there's a possibility with this kind of telescope under good atmospheric conditions and in the countryside. Is it true?

Customer service:

Yes, it is true; under favorable weather conditions you can observe Jupiter’s Moons.

Joan Kenner (2013.06.10)

Testing at the North Star under not calm atmospheric conditions allowed us to see the central disk and not less than 5 Airy's rings.
The first observations. Saturn - under a relatively peaceful atmospheric conditions we observed Cassini gap and 3 satellites. Leo Triplet . Nebula Bode, Cigr galaxy, M106, Whirlpool galaxy (and both parts separately), Pinwheel Galaxy ( M101 to the extent possible), globular cluster M3 (and it was resolved into individual stars in 9mm plessl, very nice), M90. Scorpio: M4, M80, M19, Coma: M53, M64 (black eyes), Hercules: The M13 (Great Hercules Cluster ), M92, Chanterelles: M27 ( the Dumbbell Nebula ), Lyra: M57 (the Ring in Lyra ), Sagittarius: NGC 6530.
Conclusions . The telescope requires calm atmospheric conditions with low turbulence. Good for deep-sky objects . Useful for planetary observations, but its main purpose - Deep-Sky Objects .

Customer service:

Thank you for your feedback!

Gina (2013.05.30)

Hello! Tell me, what accessories should I buy with this telescope for observing planets, as well as deep-sky objects (including The Sun) so I wouldn't have any problems and I could get maximum satisfaction right away?

Customer service:

Please, pay attention to the following eyepiece http://www.levenhuk.com/catalogue/accessories/telescope-accessories/telescope-eyepieces/levenhuk-ra-ler-3mm-1-25-eyepiece/ . The set of filters: http://www.levenhuk.com/catalogue/accessories/telescope-accessories/telescope-filters/levenhuk-solar-system-f4-filter-set/

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