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Vixen BT ED70S Angled Binocular Telescope

Vixen BT ED70S Angled Binocular Telescope
Price:  £1,706.00(Inc. 20% VAT)

Model:  X014305
Brand:  Vixen



Generally In Stock, Please Confirm Before Ordering

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

Large binoculars with ED glass 70 mm objectives, for aesthetic observation of the starry sky, nature and landscape

Large binoculars with 70 mm objective lenses with ED glass
31.7 mm (1.25 inch) eyepiece sleeves for interchangeable eyepieces
Very colour-free, high-contrast and sharp images
Moon, nebulae, galaxies, star clusters and nature observations
Individual eyepiece focusing, 45-degree viewer
Interpupillary distance of the eyepiece adjustable
GP rail, tripod thread, carrying handle and viewfinder shoe
Travel binoculars can also be used with photo tripods
Dimensions: 400 × 190 × 155 mm , Weight: 4 kg
High quality product - Made in Japan

Large binoculars with 70 mm ED glass objective lenses
Observe the beauty of the starry sky at night and distant objects in nature during the day. By customer request, we have succeeded in producing a new edition of these legendary binoculars. The ED glass lenses guarantee enormously high sharpness, contrast and colour purity even during the day. Globular clusters, luminous gas nebulae, the moon with its craters and even planets can be observed wonderfully on a clear night. But also all other distant things in nature and landscape, even ships, aircrafts and animals can be seen in detail at long distances. With the binoculars of the Vixen BT series, you can bring everything up close. The large, fast ED lenses in combination with the ultra modern magnesium fluorite coatings on all lens surfaces enable maximum light transmission. Thus, these binoculars produce bright, sharp and high-contrast images even at night and dusk, allowing for a particularly aesthetic viewing pleasure.

Comfortable travel binoculars can also be used with photo tripods
The comfortable 45-degree viewer enables comfortable viewing even when the binoculars are tilted towards the zenith. The BT-ED70S-A large binoculars are 4 kg light and particularly portable. An attached metal carrying handle ensures easy transport and a secure grip during tripod mounting. The binoculars have a standard Vixen dovetail rail as well as a standard 1/4 and 3/8 inch photo tripod thread. They can therefore be used on almost all common photo tripods and telescope mounts.

The ideal binocular mount
However, we recommend the Vixen HF2 fork mount for mounting. Thanks to its sophisticated design and precision mechanics, it offers perfect viewing comfort and practically zero vibrations. Especially for astronomical observations, a solid mount with tripod is one of the most important accessories. This guarantees observation without shaking and allows you to see even the finest details.

Interchangeable 1.25-inch eyepieces
Stay flexible and use your favourite eyepieces and ideal magnification. The BT-ED70S-A has standardised 1.25-inch eyepiece holders, allowing you to change eyepieces at any time.

Which eyepieces can be used?
All eyepieces with a 1.25'' barrel. Eyepieces with focal lengths of 8 to 26 mm are particularly recommended. The magnification can thus be varied from approx. 15x to 50x (focal length of binoculars : focal length of eyepiece = magnification). The eyepieces are held in the binoculars by a precise brass ring clamp and guarantee a tilt-free position. Depending on the interpupillary distance, the outer diameter of the eyepiece housing should not exceed a value of approx. 50 mm. Of course, two identical eyepieces of the same series should always be used.

Use of colour and nebula filters for astronomical observations
Increase the contrast and visibility of objects and details by screwing the appropriate filters directly into the thread of the eyepiece sleeves. Of course, colour and nebula filters must always be used in pairs. All EXPLORE SCIENTIFIC screw-in filters with 1.25''/31.7 mm diameter are suitable (see Art. No. 03102xx).

Comfortable 45-degree viewer and single focusing
The 45-degree viewer enables a relaxed observation position even when the binoculars are heavily tilted. The individual interpupillary distance can also be adjusted within a range of 58 to 102 mm. The fine helical focusing system makes precise focusing simple and effortless.

Retractable dewcaps
The integrated dew caps can be pulled out in high humidity and cold conditions. This prevents fogging of the outer objective lenses and effectively shields from additional stray light coming in from the side.


Objective lenses: 70 mm / ED apochromatic
Full multi-coating on all lens surfaces
Focal length 400 mm (F = 5.7)
Resolving power: 1.66 arcseconds
Limiting magnitude: Mag 11.0
Dimensions: 400 × 190 × 155 mm
Weight: 4 kg
Adjustable interpupillary distance: 58-102 mm
Integrated and retractable dew caps
Viewfinder shoe: Vixen Standard
Eyepiece mount: 1.25 inch / 31.7 mm barrel diameter
Single eyepiece focusing
Tripod mount: GP dovetail rail, 1/4 and 3/8 inch photo tripod threads.

BT-ED70S-A Large Binoculars (without eyepieces)
Vixen finder shoe
Integrated dew caps
Dust cover
Carrying handle

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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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