Baader SunDancer II H-Alpha Solar Filter

The Baader SunDancer II (with heated H-alpha Etalon from SolarSpectrum) transforms an existing telescope quickly and easily into a professional H-alpha telescope! For telescopes up to 80mm aperture, you do not need any further accessories: The SunDancer II already includes an achromatic (!) 3x telecentric with T-2 connection; the entire SunDancer is simply plugged between star diagonal and eyepiece and connected to a power source. It then automatically heats up to the optimum operating temperature. No readjustment is necessary even during long observation sessions. Finetuning the transmission line e.g. to adapt to different telescope systems is possible via the control box; the micrometer screw can be used to quickly shift the transmission line into the blue wing of the H-alpha line to compensate for the Doppler effect during fast H-alpha events on the sun.

Features:

Silently heated H-alpha-Filter with integrated 3x telecentric system with 2nm block filter.
Half-width (FWHM) of 0.6±0.1Å at an effective focal ratio of f/30
Resistant to ageing: The dielectric coating of the blocking filter and the airtight storage of the SolarSpectrum Etalon filter in oil prevent the ageing process
The complete disk of the sun as well as prominences are visible in telescope with focal lengths up to about 600mm
shows prominences and solar surface details for visual observations as well as for photography and bino-viewers
For telescope with 80mm aperture or less, no additional D-ERF (energy rejection filter) is necessary
Userfriendly electrical temperature control; additional micrometer screw for observiong fast changes in the blue wing of the H-alpha-line
Nosepiece: 2″, 1,25″

An additional D-ERF energy protection filter in front of the telescope is necessary only on telescopes with more than 80mm aperture; alternatively, the telescope can also be stopped down to 80mm with an optional diaphragm in front of the lens.

Power is supplied either via the included power supply or via an optional PowerTank. A detailed description of the possible applications and the requirements for the telescope can be found in the operating instructions.

Solar disk and prominences
The H-alpha filter has a half width of 0.6 +/- 0.1Å on telescopes with f/10. The telecentric (corresponds to the soon separately available TZ3 #1363070, but additionally with integrated 12nm block filter) extends the focal length of the telescope by a factor of three, so that on telescopes with f/10 the ideal focal ratio of f/30 for H-alpha is achieved. The SunDancer II is recommended for telescopes up to about f/8 and is well usable up to about f/6.5; on faster telescopes the half-width increases. The half-width was chosen in such a way that both prominences and the solar surface are nicely displayed at the same time.

Visual, photographic and binocular
The complete solar disk can be seen in telescopes up to about 600mm focal length. A T-2 thread under the eyepiece clamp also allows the adaptation of larger cameras. Particularly appealing is the space-saving connection of a bino-viewer via the T-2 thread. In most cases, a glass path corrector is not necessary: the telecentric provides a parallel beam of light and at the same time shortens the necessary back focus.

Non-ageing
The dielectric coating of the block filter (instead of the usual silver coating) and airtight storage of the SolarSpectrum Etalon filter in oil prevent the ageing processes of simpler filter designs. With proper treatment, the SunDancer II will retain its performance for many years. Please note that the filter – just like any H-alpha filter with Fabry-Pérot Etalon – must be protected from frost. It must not be stored below 0°C, as otherwise the oil will become sulky and push the optical elements apart, damaging the filter. Thermal insulation is necessary for use at lower temperatures.

Specifications
SKU (#) 1363056
USAGE Visual solar observation and solar photography
INNER DIAMETER / CLEAR APERTURE (MM) 19
HBW (HALFBANDWIDTH) 0.6 +/- 0.1 Angstrom
FILTER MOUNTED? Yes
OPTIONAL ACCESSORIES Additional D-ERF only necessary with telescopes over 80mm
INCLUDED ACCESSORIES SunDancer II H-alpha filter, control box for temperature control, 12V power supply, sturdy hard case, Baader Utility Bag, detailed manual
SOLAR WAVELENGTH H-alpha

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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