Baader Alan Gee Telecompressor Mark II

A common limitation that plagues owners of most popular Schmidt-Cassegrain telescopes is the narrow field size and high magnifications produced by their slow optical system (typically, f/10). Until now, owners of SCTs have lacked a truly versatile and high-quality method of reducing their f/10 (or slower) systems for faster, wider, photographic/CCD and visual fields. (note: the telecompressor is not intended for use with the Meade native f/6.3 SCTs). Using the Alan Gee with 1¼” eyepieces can yield actual fields of view that match or exceed what you could only achieve with expensive 2" eyepieces!

Baader Planetarium has developed a truly unique and extremely versatile telecompressor system that delivers the finest wide flat fields your SCT is capable of. The key to the Alan Gee Mark II Telecompressor is its innovative optical and mechanical design. Unlike the commonly available and simple single-purpose solutions, the Alan Gee Telecompressor Mark II has been engineered specifically to work well with SCTs in a wide variety of visual and imaging configurations. The unique design of the Alan Gee Telecompressor positions the lens elements several inches inside the telescope's central baffle tube (see the C8 Cutaway, which shows the lens mounted in the standard imaging configuration). The result is a sharp, wide, flat field, at a fast focal ratio of f/5.9 – and it even works superbly with Baader Planetarium, Zeiss, and Celestron Binocular Viewers! That's right. The Alan Gee Mark II is designed to function with many popular binocular viewers. At last, you can use your large aperture SCT to produce stunning wide field binocular views.

The Alan Gee Mark II is made with typical Baader Planetarium attention to detail and flexibility by design. Designed by Roland Christen, the optical configuration consists of a matched, wide air-spaced doublet, utilizing lenses that are precision polished to the very edge, and anti-reflection coated with the finest 7 layer multi-coatings available today (reflections per surface are less than 0.2% !). The lenses are individually centered and painstakingly mounted into the precision cell. The extra-large 35mm clear optical aperture and lens cell design maximizes the field size. The cell itself is unique. The long thin-wall aluminum tube surfaces are sharp V-threaded and blackened, to reduce stray light reflections. The telecompressor assembly actually consists of 4 threaded pieces; the lens cell, two 19mm long removable spacer sections, and a flanged end-ring (plus a thin spacer ring used in some configurations). By using combinations of these pieces, along with varying the placement in the optical path, you can now utilize the Alan Gee in a wide variety of visual and imaging configurations that have never been possible with any other telecompressor (see the section below for suggested configurations).

Until now, SCT focal reducers were designed primarily for imaging or single eyepiece use, and lacked the necessary focal length and positioning flexibility to work with binocular viewers. The Alan Gee Mark II has been designed to work perfectly in concert with the Celestron and Baader Planetarium Binoviewers * (including the Baader/Zeiss Giant Binocular Viewer). Now, you can turn your SCT into the ultimate large aperture wide field binocular telescope! Imagine the stunning wide field binocular views that your telescope will deliver (up to a 1.2º field in a C8 or 0.7º in a C14 - using the Baader/Zeiss Giant Binocular Viewer, that's almost a 3X improvement in field area!). Now, not only will large deep sky objects now fit within the field of view, but even the entire Moon can be comfortably viewed with two eyes.

* Please Note: The close coupling required for the telecompressor to reach focus with binoviewers limits it's use to only the Baader/Zeiss and Celestron binoviewers.

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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