Astronomik MaxFR Sii Emission Line Filters

There is an ever growing demand for filters suitable for extremely fast optical systems like Celestron´s RASA the Epsilon Astrographs made by Takahashi.

Our novel MaxFR emission line filters are suitable up to very fast focal ratios. The new Astronomik MaxFR series of narrowband-emissionline filters are perfectly matched to the requirements of astronomical deep-sky imaging with fast optical systems. For the three most important emission lines of oxygen (OIII), hydrogen (H-alpha) and sulfur (SII) you may select your filters either with 12nm or 6nm Bandwidth (FWHM).

Highest transmission:
Our new MaxFR filters are made in a completely new way, designed to work perfectly with fast optical systems. The built-in well known MFR Coating technique gives you the best out-of-band blocking possible across the entire range of wavelengths from the UV up to IR! Your advantage of our new design is a extremly high contrast, minimized stray light, no halos and needle-sharp stars. The Astronomik MFR narrowband-emissionline filters give you the best quality of data: The best start material to be processed to a awesome final image!

For 12nm MaxFR filters this means a unlimited usability from f/1.7 to f/1:8 and about 85% of the maximum transmission at a f/1:1.4 as guaranteed.

For 6nm MaxFR filters this means a unlimited usability from f/2.2 to f/1:8 with about 90% of the maximum transmission at a f/2 as guaranteed performance data.
For maximum contrast the SII filter is carefully designed to block all light coming from H-alpha and NII (nitrogen).

Imaging with Narrowband-Emissionline Filters
If you have to observe from light polluted sites (like most of us...), imaging with narrowband-emissionline filters is the best way to take great images, as all kind of light pollution can be blocked very effective! Normally an H-alpha filter should be your first step into this amazing field of astrophotography! With an Narrowband H-alpha filter you will be able to take deep and contrasty images even with very heavy light pollution or with the full moon high up in the sky!
If you look at other astrophotos, an H-alpha is the best choice for all nebulas glowing red! An OIII filters expands your imaging possibilities, as you are able to image all greenish/blueish structures. Planetary nebulas and star forming regions are great targets! The SII filters completes your HSO-set of filters. With these three filters you are able to process your images like the ones from the Hubble space telescope!

Quality aspects of the new Astronomik MFR narrowband-emissionline filters:

MFR Coating: The 12nm Filters can be used on all instruments down to f/1.4, the 6nm filters down to f/2.
High-Quality substrate: Astronomik filters are made with stress- and striae free, optically polished glass. The filter itself is made of ultra thin layers on this substrate!
Parfocal filters: All Astronomik Filters are parfocal! Due to the very small thickness-tolerance the focal plane is not shifted when changing filters!
Coating: Astronomik filters are made of up to 170 layers which are coated on both sides of the substrate. These layers form the filter itself and act as a Anti-Reflection Coating.
Durability: Due to our coating technique all Astronomik filters are highly scratch resistant, not sensitive to moisture and do not degrade when getting older. Every Astronomik filter will deliver it´s full performance and meet the specs at the point of shipping even after lot´s of years.
Integrated Blocking: All unwanted light is blocked in the whole spectral range from UV up to the IR! (You will not need an additional UV & IR-Blocker when imaging with any of our new narrowband-emissionline filters with coating!)
Wide range of available sizes from 1,25" up to square 50mm x 50mm filters.
Delivered in a high-quality protection & storage box.
Due to our outstanding coating technique we do offer a 10 year guarantee on all of our filters.
You get the highest quality possible with every single Astronomik filter to be able to take perfect images with your instruments! Especially the filters against light pollution and the narrowband-emissionline filters will expand your imaging possibilities enormous! You are investing your money for an accessory which will work in lot´s of years in the same ways it did when it was brand new. Due to our special coating technique the filters do not degrade when getting older, and due to the new MFR coating you will be able to use the filter on nearly all instruments!

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.

Are you interested in this product but would like to speak to someone with some more information? Simply fill in the form below and we will get back to you as soon as we can!

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