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RVO Horizon 12" f/5 Dobsonian Telescope

RVO Horizon 12'' f/5 Dobsonian Telescope
RVO Horizon 12'' f/5 Dobsonian TelescopeRVO Horizon 12'' f/5 Dobsonian TelescopeRVO Horizon 12'' f/5 Dobsonian Telescope
RVO Horizon 12'' f/5 Dobsonian TelescopeRVO Horizon 12'' f/5 Dobsonian Telescope
Price:  £879.00(Inc. 20% VAT)
Add Accessory Bundle (Moon Filter, Planisphere & Smartphone Holder)

Model:  RVOH12DOB
Brand:  Rother Valley Optics



Generally In Stock, Please Confirm Before Ordering

2 Year Warranty On All New Items
(Excluding Batteries & Globes)

The RVO Horizon 12" dobsonian is a superb, high quality, all round telescope. Ideal for the beginner and widefield observer! Incredibly easy to use, nice and portable and will provide amazing views of the moon, planets and bright deep sky objects. 

This model has 44% more light gathering than the Horizon 10" model resulting in brighter and more detailed views!

This is our largest classic dobsonian, immerse yourself with bright, widefield views, ideal for deep sky observing. Use the included 2" eyepiece for beautiful views. Still a reasonably portable system, you can take this dobsonian to any dark sky to get the full potential from the telescope.

We have chosen only the best components for our dobsonians including high quality parabolic mirrors, dual speed 2" crayford focuser, right angle finderscope, cooling fan and much more. All these features, plus our amazing customer and back up service, makes our Horizon dobsonians the best choice in the UK!

Each of our dobsonians are fully checked, tested and collimated prior to dispatch or collection for your peace of mind.

The minimum reflectivity of the BAK7 primary mirror on our dobsonian range is 94% as well as a protective silicon-dioxide coating provides a long lasting super clear and high contrast view. On the rear of the scope, you will find large, easy to use collimation knobs with a large cooling fan to reduce cool down time and keep the mirror at an optimum performing temperature. 12v battery box is included. Cool down time is almost twice as fast so you can start observing much faster.

We have selected a high quality CNC machined dual speed crayford focuser with a 2" and 1.25" fitting, 10:1 fine adjustment and tension adjusters for precise focus every time.

Improved Features

At Rother Valley Optics, we like to stand out from the crowd. We have added a couple of important features to our dobsonians making them easier to move around and therefore, more observing time! A handy CNC handle on the tube makes moving large tubes a breeze. Plus 3 eyepieces included as standard including a large 2" eyepiece and 2 x 1.25" eyepieces.

The telescope base is a classic dobsonian base, but with improvements. The mechanics of this base have been improved and also it features a special brake system side bearing for smooth tube movement allowing you to move the telescope tube far more precisely and also improves stability. The base also features a convenient eyepiece tray so you can house all your eyepieces in 1 place. The adjustable tension on the altitude axis provide a smooth movement thanks to the large knurled hand knobs on each side. 

3 quality eyepieces are included as standard, a 30mm 2" for amazing widefield views, 20mm 1.25" mid power eyepiece, plus a 9mm 1.25" premium plossl for higher powered views, ideal for the planets.  A handy 35mm extension is included with the kit to ensure focus can be reached with most eyepieces.

Our Horizon dobsonian models also come with a convenient right angled 8 x 50 correct image finderscope for ease of use and easy spotting for your next target!

Key Features:


Model:  Horizon 12" Classic Dobsonian
Aperture:  304mm
Focal Ratio:  F/5
Focal Length:  1520mm
Focuser:  2" CNC Crayford Focuser With 1.25" Adpator
Eyepiece 1:  9mm 1.25"
Magnification 1:  168.8x
Eyepiece 2:  20mm 1.25"
Magnification 2:  76x
Eyepiece 3:  30mm 2"
Magnification 3:  50.6x
Finderscope:  8 x 50 Right Angled Correct Image Finderscope

OTA Weight:  21kg
Base Weight:  15kg

Click here to view the instruction manual for the Horizon dobsonian range. These are generic instructions but will suit the full range of Horizon Dobsonian telescopes.

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Some items that are showing as in stock are in stock at our holding warehouses, not at the shop. To double check the stock levels at the shop, please contact us on 01909774369 or

The delivery times for most items is 1 - 2 days but again, please double check stock levels on important orders before placing an order via the website.

The delivery costs for courier next day are for mainland UK only. If you live in the Scottish Highlands/Islands, Channel Islands or Northern Ireland, then a shipping surchage will apply. please contact us for prices. Smaller items can still go 1st class via Royal Mail.

Please note that if you are wanting to take advantage of our Saturday and Sunday timed services or next day pre 12 or pre 10:30 services, you MUST check that the stock is here at the shop before placing orders. Also, orders using the Saturday and Sunday services must be placed before 1pm the previous working day. Also, please remember to check that the stock is here at the shop before placing orders. If the stock is not at the shop, we won't be able to ship on any of the timed services. 

Please note International customers will need to contact us for a shipping price prior to ordering via the website. We don't ship all items internationally. It is at our discretion what we ship outside of the UK. This all depends on the size and weight of the items. Please get in touch with us for any postage costs. Please note we do NOT ship telescopes or heavy items outside of the UK. This is due to massive postage costs and problems regarding returns.

If you have any questions regarding stock levels or delivery, please get in touch.

Zygo Interferometer Testing For ED Refractor Telescopes!

We are extremely pleased to announce our Zygo Interferometer is now installed and ready for use! Our experienced staff can test refractor lenses up to 120mm aperture and provide a comprehensive 2 page report showing the optical quality and Strehl ratio, plus much more information. We are using the very latest Zygo MX software to provide a more detailed report compared to other standard reports.


The interferometer is essentially a measuring instrument. Within the interferometer is a calibrated laser that is pointed through the optical test surface, then onto a high quality reference sphere, then back through the test subject then to an internal camera which gives us the measurement on the screen. From this, we can adjust the position of the test optic and the reference sphere to obtain a perfectly calibrated system. The more central the laser to the test optic and then on return, the better and more accurate reading and measurement we can take. This takes a lot of adjustment to get the best results from the optical surface. Once the measurement has been taken, we are provided with a series of results that show the optical quality of the surface plus other information. Continue reading for an explanation of the individual values and you can also see a test report that was done on one of our RVO Horizon 60 OTAs. 

We are offering certain telescopes with a Zygo test at an extra cost. Mainly ED doublets and triplets. All available telescopes with a Zygo test report are listed here. Just select Zygo Test Report from the drop down box at the top of the listing and we will test the optics in house and provide a full 2 page report with your scope. This will show you the optical quality of your telescope optics. We can also offer this service on your refractor telescope. Please get in touch for more details about this. 

At Rother Valley Optics, one thing we pride ourselves on is customer service and quality of our equipment. When we test your telescope, we will ensure that it is of the highest quality otherwise, we will reject the scope under our strict quality control and test another model for your peace of mind. One of the main values to look at when testing a refractor is the Strehl ratio. The higher this number, the higher quality lens you have. At Rother Valley Optics, we will guarantee the highest possible Strehl ratio for your telescope.  We will aim to provide 0.95 Strehl or higher on Takahashi, RVO Horizon, William Optics and many more! Generally, the higher the Strehl ratio, the lower the Astigmatism and Coma meaning a better image quality from your instrument. 

Other measurements such as the PV and RMS are important too. With these measurements, the lower the number the better as it shows less curvature on the lens. The flatter an optical lens, the better it will perform. The PV rating (Peak To Valley) is a measurement from the highest point (Peak) to the lowest point (Valley). From this we get the RMS (Root, Mean, Square). This is a similar figure to the PV and measured exactly the same way. The RMS is basically an average height difference from the PV so again, the lower the better. As you can see form the example below, we measured an RMS of just 0.027 wave which is a very good value.

We also measure the Power with our systems which is essentially the error from the reference sphere to the test optic. The reference sphere we use on our system is a very high quality sphere so the closer to zero the Power, the less error between the 2 elements thus ensuring a higher quality optical surface. 

You will also see some more values such as Astigmatism and Coma. Again, these are measured by the interferometer when we take measurements of the optical surface after adjustment. These are values which ideally would be at 0 but as our test optics are all curved lenses, there will always be astigmatism and coma present. The lower the number, the less of these aberations you will effectively see but with most refractors, you can buy field flatteners which will compensate for the coma anyway. The astigmatisms value is explaining the error between the symmetrical curvature of the lens. Basically, no lens will be perfectly symmetrical, the lower the astigmatism, the more symmetrical the lens surface is. 

Once the Zygo test report has been completed, the optical alignment is thoroughly tested and tuned to ensure they are spot on before they leave us. 

All available telescopes are on the website at the link below and ones we've tested already that are available straight away are also listed.

Here is an example of the test what we provide. This was a test on one of our Horizon 60 ED OTA's.

For any questions about this amazing new service, please either call 01909774369 or email


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