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Omegon 9mm Illuminated Crosshair Eyepiece 1.25"

Omegon 9mm Illuminated Crosshair Eyepiece 1.25''
Price:  £72.00(Inc. 20% VAT)

Model:  49760
Brand:  Omegon



Generally In Stock, Please Confirm Before Ordering

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

Product description:

Cross-hair eyepiece with adjustable double filament - great for an off-axis guider

Omegon crosshair eyepiece - for perfectly guided astrophotos

The Omegon crosshair eyepiece is ideally suited for guiding astrophotos when used in off-axis guiders or guide scopes. The extremely fine, illuminated double crosshairs make tracking the guide star much straightforward for you. Instead of having to cover the star, as with single crosshairs, you can keep it precisely positioned in the centre of the eyepiece. Any deviation from this position is noticed immediately, and in time to be able to react.

Making the crosshairs visible

The eyepiece has a red LED light source for illuminating the crosshairs. This is steplessly adjustable via a knob on the side of the eyepiece. There is also a separate dioptre adjuster for you to be able to bring both the star and the crosshairs into focus simultaneously.

It is the magnification that matters
The 9mm eyepiece provides magnification that is sufficiently high for allowing good precision guiding. This Ploessl design 1.25” eyepiece has four multi-coated lenses, providing a 40° low-reflection field of view.

And not just for astrophotos

There are also other uses for your crosshair eyepiece. These eyepieces are also very useful for determining the field of view, aligning a mount, or for finding the position angles of double stars.

Perfectly guided astrophotos are no secret, but rather the result of using the right accessories.

The advantages in a nutshell

  • double crosshair 9mm eyepiece
  • adjustable LED illumination
  • 1.25“ barrel diameter
  • multi-coated
  • comfortable eye relief
  • filter thread provided
  • batteries included (3x LR54)

The advantages in a nutshell

  • adjustable double crosshairs - particularly suitable for an off-axis guider
  • dimmable lighting, battery powered
  • eyepiece with clear optics for using faint guide stars
  • lens focusing - sharp focusing of the cross-threads for your vision
  • 2x LR44 batteries included

Steplessly adjustable cross-hairs

Sometimes the guide star is not in the centre but rather at the edge of the field of view. This is especially tricky when using an off-axis guider. Adjusting the image field is out of the question. But this model lets you move the cross-hairs in any desired direction.

Dimmable LED lighting with battery

The cross-hairs are illuminated with red LED lighting which can be dimmed by means of a rotary switch on the side. The eyepiece has adjustable dioptre compensation in order to be able to have both the star and the cross-hairs in focus.

9mm Ploessl design

The 9mm Ploessl eyepiece offers a very high magnification. This is good for a fast reaction in case of any tracking deviations with the guide star.

The four lens element design provides a clear and sharp image. Multi-coating ensures high transparency, so that you can make out faint guide stars too.

Photos are not everything

Discover other applications for your cross-hair eyepiece. These eyepieces can also be used measuring fields of view, for the polar alignment of a mount, or for getting the positional angles of double stars.

Perfectly tracked astronomy photos are no secret, but the result of using the right accessories

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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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