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Bresser LER 8 - 24mm 9 Element Zoom Eyepiece 1.25"

Bresser LER 8 - 24mm 9 Element Zoom Eyepiece 1.25''
  Zoom
Price:  £225.00(Inc. 20% VAT)
+

Model:  4920320
Brand:  Bresser

Availability  

  

Generally In Stock, Please Confirm Before Ordering



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



Achieving the ideal magnification with a twist - a compact solution, especially when travelling and lacking space for bulky equipment. Deluxe version with larger field of view and even better field correction and sharpness.

Zoom eyepiece with stepless focal length adjustment 8-24 mm
Deluxe version with better field correction and sharpness
Large apparent field of view 40 up to 62 degrees
Stepless adjustment to ideal magnification
Comfortable eye relief of 20 mm (LER=long eye relief)
Adjustable rubber eyecup to set the ideal distance
Also very suitable for people with glasses
Made entirely of black anodised aluminium
Precise and robust zoom adjustment mechanism
All lens surfaces with full multi-coating for a bright and crispy image

One eyepiece for every occasion, with very good field correction and large field of view.
The BRESSER Zoom Eyepiece Deluxe covers the large focal length range from 8 to 24 mm. These are also the focal lengths most frequently used with most telescopes. Especially for instant observations, where you don't want to pack a whole suitcase full of eyepieces, the zoom eyepiece is a good choice. The Deluxe version offers with its particularly advanced optical design with 9 elements in 6 groups an even better field correction and sharpness, combined with a large apparent field of view of 40 up to 62 degrees.

Always the ideal magnification on hand
A quick turn and the ideal magnification for you is set. The adjustment is stepless from 8 to 24 mm focal length. This eliminates the need to always change eyepieces.

Comfortable viewing
The BRESSER Zoom Eyepiece Deluxe offers a large comfortable eye relief (LER) of 20 mm to the eyepiece lens. This means a comfortable view even during longer observation, an important criterion especially for people wearing glasses. The rubber eyecup can also be individually adjusted by a twisting movement.

Advanced optical design
To achieve the best possible image over the entire focal length range, a particularly advanced optical design with 9 lenses in 6 groups is used. The full multi-coating on all lens surfaces also guarantees maximum light transmission. To effectively suppress unwanted reflections, all lenses are carefully blackened at the edges. Thus, the image produced offers the maximum possible contrast and image brightness.

Compact and solid design
The BRESSER Zoom Eyepiece Deluxe is made entirely of black anodised aluminium. It has an extremely solid and high-quality material appearance and is long-lived, even with extensive use. The precise zoom mechanism can be adjusted safely through the rubberised adjustment ring. A white laser engraving with focal length and pointer arrow shows the current focal length setting even in low light.

Achievable magnifications with common telescope focal lengths
350mm: 44 - 15x
400mm: 50 - 17x
500mm: 63 - 21x
650mm: 81 - 27x
750mm: 94 - 31x
900mm: 113 - 38x
1000mm: 125 - 42x


FEATURES
Deluxe version with even better field correction and sharpness
Large apparent field of view 40 up to 62 degrees
Zoom eyepiece with stepless focal length adjustment from 8-24 mm
One eyepiece covers a wide focal length range
Stepless adjustment to ideal magnification
Quick adjustment of magnification without changing eyepieces
Comfortable eye relief of 20 mm (LER = long eye relief)
Adjustable rubber eyecup to adjust to ideal interpupillary distance
Also very suitable for eyeglass wearers
Compact and solid design
Made entirely of black anodised aluminium
Aluminium dust cap with thread
Very high-quality material appearance
Precise and robust zoom adjustment mechanism
Rubberised grip surface for zoom adjustment
White laser engraving with focal length and pointer arrow
Focal length range 8-24 mm freely adjustable
Optical design: 9 lenses in 6 groups
All lens surfaces have full multi-coating
Eyepiece sleeve diameter: 1.25 inches / 31.7mm
Filter thread in sleeve: M28 x 0.6 mm (standard 1.25'' filter thread)
Eyepiece weight: 315 g
Length of eyepiece: 102 mm
Diameter: 52 mm
Colour: black

SCOPE OF DELIVERY
Deluxe zoom eyepiece
Metal dust cap for eyepiece lens
Plastic dust cap for eyepiece sleeve

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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 sales@rothervalleyoptics.co.uk.

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.

https://www.rothervalleyoptics.co.uk/zygo-tested-refractors.html

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 sales@rothervalleyoptics.co.uk.

 


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