Takahashi FSQ-85EDX F/5.3 Petzval Quadruplet APO Refractor OTA Package

This is the brand new 2018 version complete with 1.01x flattener and n°50 extension tube. 

With the success of short refractors and improvement of the performances of CCD and DSLR cameras, Takahashi introduces the FSQ-85ED, more itinerant than the FSQ-106ED model, and intended for deep-sky and wide field photographers.

The FSQ-85ED is based on the same ED glass Petzval quadruplet design as the FSQ-106ED model, but offering a focal length of 450mm and a photo field of 5.6°, which is ideal for photography. It is equipped with an oversized rack-and-pinion focuser and an independent camera angle adapter. An optional focal reducer is also available in order to transform the refractor into a true astronomical teleobjective with a focal length of 328mm and with a focal ratio of 3.9, providing a field of view of 7° and a 40mm image circle.

Weighting only 4kg without accessories, you will not need a heavy mount. It becomes easy to take pictures of the deep-sky while transporting your telescope under the best skies.

The FSQ-85ED modified Petzval quadruplet design is the same as the FSQ-106ED one. It has a built-in flattener inside the optical tube, offering a field of 5.6°, essential for taking quality pictures. It is thus not necessary to add any other optional accessory. With a focal length of 450mm, the image circle is 44mm width. The addition of a 0.73x focal reducer makes it possible to change the focal ratio from 450mm (F/5.3) into 328mm (F/3.9). It then becomes a true teleobjective for the deep sky.

The FSQ-85ED is equipped with an oversized rack-and-pinion focuser, just like the 106ED. However, the camera angle adjuster has been taking apart from the focuser to come back to a more traditional position where accessories are screwed on focuser tube.
The rack-and-pinion has been oversized on purpose to gain in precision and effectiveness. This focuser is a model of precision. It is driven by two focus wheels with a 1/7 microfocuser.

Although its design resolutely directs it towards astrophotography, the FSQ-85ED can be equipped with various accessories including those for observation. Please go to the system-charts section to see the different possible options. With a 220mm back focus, no matter which accessory you will pick up, you will have different choices of uses and assemblies.
The FSQ-85ED has a specific focal reducer (see the Accessories section) that deep-sky astrophotographers, wishing to have a very large field, will enjoy.

As on the FSQ-106ED, the built-in field flattener, perfectly designed and manufactured, gives an almost homogeneous flat field of 44mm diameter. At prime focus, at the edge of field (22mm from the optical axis), stars remain pinpoints, including on pixels of 7µ width. The addition of the Reducer-QE 0.73x, specifically designed for this quadruplet, makes it possible to gain in field of view on the widest deep-sky objects while preserving the initial optical performances.

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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