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Bresser BinoViewer Deluxe 1.25"

Bresser BinoViewer Deluxe 1.25''
Price:  £414.00(Inc. 20% VAT)

Model:  4920300
Brand:  Bresser



Generally In Stock, Please Confirm Before Ordering

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

Observe astronomical objects with both eyes. Creates a three-dimensional-like view. Comes into focus with any telescope.

Enables binocular observations with telescopes
Relaxed and comfortable viewing
Additional detail seen when using both eyes to observe
Suitable for all telescopes with 1.25'' eyepiece connection
For observing moon, planets and deep sky objects
No additional light path required
No magnification factor at the binocular attachment
Original eyepiece focal length is retained
Even low magnifications with large fields of view are achievable
High-quality hard-shell carrying case included

You see better with two eyes
The BRESSER BinoViewer Deluxe makes it possible to observe astronomical objects in a relaxed way with both eyes and with considerably more detail than using one eye. The images created of the moon, planets and globular clusters are particularly impressive. But also with deep-sky objects such as the Orion Nebula the detection of details is much easier. At the same time this binoviewer is very easy to handle. Thanks to the newly patented optical system you can get into focus with any telescope. All you need is a pair of identical eyepieces to enjoy this dramatic and immersive viewing experience.

How to use the BinoViewer?
Since the BRESSER BinoViewer Deluxe does not require an additional light path (back focus), it can be used with any telescope - including Newtonians and short focus refracting telescopes, which traditionally suffered when using standard binoviewers. No light path corrector or similar accessory is necessary. If a standard 1.25'' eyepiece can be focused, the binoviewer will also work. The eyepiece focal length and field of view size of the eyepieces used are fully retained. As with binoculars one eyepiece is focused first using the telescope focuser. Then the second eyepiece can be brought into focus using the helical focuser on the binoviewer. The required interpupillary distance is then elegantly adjusted to a range of 58–74mm with the help of a linear sliding mechanism, with graduated marker, to help you find your ideal interocular setting quickly. Self-centring helical eyepiece grips, rather than side-mounted thumbscrew eyepiece retainers are used, decreasing the chance of offsetting collimation of both eyepiece to each other. The fact that this design of binoviewer uses a well-engineered linear slide mechanism to adjust interpupillary distance, rather than a cheaper-to-produce traditional hinged design also helps retention of collimation.

Which objects can be observed with this accessory?
Actually, all objects that were previously observed with the telescope in question, but only monocularly with one eye. Because there is no magnification factor at the binoviewer, even low magnifications can be achieved. This makes not only the moon, planets and globular clusters, but also the brighter deep-sky objects very interesting observation targets. The use of two eyes leads to a more relaxed view than using one eye alone. Although true depth of field viewing at infinity is a little beyond most telescopes and binoviewers, users will note how the human brain attempts to impose depth of field ("3d-like") effects on stereo views through binoviewers. The biggest difference that most observers comment upon when comparing views through binoviewers like these, as opposed to single monocular eyepiece views, is the extra detail that can be seen in most observable targets. Relaxed viewing and extra detail in objects are the two main benefits of binoviewing, which the BRESSER Bino Viewer Deluxe 1.25'' delivers in abundance.

Also ideal as an accessory for solar telescopes
A very special application is the use of the BRESSER BinoViewer Deluxe in combination with all solar telescopes. The spherical shape of the sun with all its surface details is shown very impressively. The depth of field effects of seeing filaments silhouetted against the solar surface are particularly enjoyable to observe.

Important note: Do not use the BRESSER Binoviwer Deluxe without a suitable solar telescope or a safe solar filter in front of the telescopes objective lens . Otherwise, there is an acute risk of going blind.

High-quality mechanics and materials
The entire BRESSER BinoViewer Deluxe is made of high-quality materials. Except for the outer plastic covers all components are made of anodised aluminium. Particularly remarkable are the low-backlash sliding mechanism for adjusting the interpupillary distance and the precise rotary clamping of both eyepiece adapters. The wide clamping surface holds the eyepieces in place securely and also centres them automatically on the optical axis. The one-sided dioptric adjustment has a backlash-free helical drive and enables the finest corrections. For safe transport a high-quality hard-shell transport case is included in the scope of delivery.

Which eyepieces can be used?
All eyepieces with a 1.25'' barrel and a field stop of up to 22mm. Depending on the interpupillary distance the outer diameter of the eyepiece housing should not exceed a value of approximately 50 mm.

Filter thread 1.25'' available
No 2nd filter sets are necessary to operate the BRESSER Binocular Approach Deluxe. The desired colour or nebula filter can be screwed directly into the 1.25'' nosepiece. in this configuration, when changing the eyepieces to affect a change in magnification, no swapping of filters is necessary.

Unique mirror-lens system with Ohara (Japan) lanthanum glass material
The BRESSER Binocular Viewer Deluxe is equipped with a unique mirror-lens system. This has the advantage of higher light transmission and less color aberration. The resulting image is simply brighter and sharper. To achieve this the exclusive Ohara (Japan) lanthanum glass material has been used and in addition all optical surfaces are equipped with a full multi-layer broadband coating. Finally the beam-splitting mirror has a 99% dielectric coating and completes the excellent optical design.

Enables binocular observations with all telescopes
Relaxed and comfortable viewing
Three-dimensional viewing experience
Suitable for all telescopes with 1.25'' eyepiece connection
No additional light path required
No magnification factor at the binocular attachment
Even low magnifications with large fields of view are achievable
For observing moon, planets and deep sky objects
Precise and robust mechanics
Sliding mechanism to adjust the interpupillary distance
Dioptric compensation via fine helical drive
Wide eyepiece rotation clamp with automatic centering
Filter thread 1.25'' (M28.5 x 0.6mm) available
Lens and mirror design made of finest Ohara (Japan) lanthanum glass material
Advanced broadband multilayer coating on all optical surfaces
99 % dielectric-coated beam-splitting mirror
High-quality hard-shell carrying case included

Bino Viewer Deluxe
Dust caps
Carrying case

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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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