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Baader 2" Colour Filter Set

Baader 2'' Colour Filter Set
Price:  £357.00(Inc. 20% VAT)

Model:  2458310
Brand:  Baader



Generally In Stock, Please Confirm Before Ordering

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

These Baader colour filters are carefully prepared for amateur astronomical use for contrast enhancement of lunar and planetary observations. Colour filters are often identified with a Kodak Wratten (W) number. Baader colour filters were developed and manufactured to correspond to the respective wavelength range following the Wratten nomenclature:

Baader-red filter ≅ W25,
Baader-Orange filter ≅ W21,
Baader-yellow filter≅ W12,
Baader-green filter≅ W58,
Baader-light blue filter ≅ W80A,
Baader-dark blue filter≅ W38A

The filters are screwed into the filter thread of eyepiece barrels or in planetary imaging camera nosepieces (e.g. Skyris). A thread at either end of the filter allows the filters to be combined (i.e. stacked) with each other or with other filters (for example with the Baader UV / IR infrared cut filter).

The glass are co-planar fine optically polished. These filters exceed the quality of the usual “raw polished” (hot flamed) coloured glass filters. As they are fine optically polished, these filters can be at any point in the mean path – far ahead of the focal point (for example, in front of a binocular approach!) without causing defects (astigmastism) or to degrade the image otherwise in any way! The parallelism of the optical surfaces is excellent to within 30 arcseconds meaning that “double images” are not present. The transmission curve for each filter colour is also supplied.

Red 610nm longpass filter with steep absorption edge.
Filters the H-alpha line from the visible spectrum.
Blue and Green lights is almost completely filtered blocked increasing contrast between the light and dark bands on Jupiter and Saturn.
Most interesting filter to use for observing the polar caps of Mars.
An optimum filter for daily observation of all the planets.

Orange 570nm longpass filter.
Contrast enhancement for lunar and planetary observations at dusk.
Improves the detection of dark areas on Mars and penetrates the hazy atmosphere of Mars.
Shows more detail in the cloud bands of Jupiter and Saturn.
Suited for daytime observations of the Moon, Mercury and Venus.

Yellow 435nm Longpass filter.
Suppresses the secondary blue spectrum when using achromatic and half-apochromatic refractors (increasing image sharpness).
For visual and photographic planetary observations.
Enhances contrast between the belts on Jupiter.
Increases contrast of the lunar and Martian surface.

Green 500nm bandpass filter.
Provides the sharpest images with achromatic and refractors (eg double star observations.
Improves the visibility of CO2 Hoarfrost and ground fog on Mars.
Increases contrast between red and blue regions on Jupiter and Saturn.
Provides the best contrast for lunar craters Tyco, Copernicus and Kepler.

Light Blue 470nm bandpass filter.
For visual and photographic planetary observations.
To observe high clouds on Mars, enhances contrast of hazes on terminator of Mars (Violet Clearing).
Displays reddish structures darker, ideal for observing the red spot on Jupiter. Also shows Saturn rings better.
To monitor the structures in the atmosphere of Venus.
Highlights the fine details in gas tails produced by comets.

Dark Blue 435nm bandpass filter.
For visual and photographic planetary observations.
Aids in better detection of Venus phase.
The Violet Clearing on Mars can be seen better.
Enhances the Great Red Spot on Jupiter and contrast between the belts.
Enhances the contrast between zones on Saturn.

Largest free opening of all colour filters on the market to elimante any vignetting.
CNC machined “grip crown” provides excellent handling and comfort.
Both sides 7-layer AR coating with only 0.25% residual reflection per surface. This is the most antireflective that has ever been undertaken with color filters.
Planeoptically polished to within 30 seconds of arc for a sharp image at high magnification with non-ageing sealed coating edges.
Multi-coated for max contrast – no reflections, scatter or dimming.
The most important criterion for any kind of light filtering is brigthness. Certain spectral ranges at high magnification will only work at the highest light transmittance.
The long-pass filter in this filter set offers 98% transmission and produces no flare. Unmatched by other brands. This can be seen in comparison with standard colour filters at once – the filter colour radiant downright.
The combination of our infraread (IR) cut filter 1¼” and the RG 610 red filter results as an extremely narrow-band H-α pass filter for the CCD photography of red emission nebulae – at a ridcidulously low price!
A wide range of adaptors allow the uses of T-2 photo threads (See: Baader Astro T-2 System™).
Baader Phantom Group Coating™ developed by Baader Planetarium the coating is a 7-layer broadband coating with extremely low residual reflection. The term “Group” indicates that the respective most effective anti-reflection layer system was calculated for each type of glass of the filter. This means that the anti-reflection layers of different colour filters are different. They are calculated to provide the mximum for the respective filtered colour transmission values. Both sides of the filter are coated with 7-layer AR coating with only 0.25% residual reflection per surface. This is the most that has ever been provided for colour filters. The filter discs are screwed into the blackened aluminium frames and are delivered within a filter. Each filter is designed for multiple applications.

MANUFACTURER Baader Planetarium
TRANSMISSION RANGE multiple bands (see spectral image)
AR-COATING Phantom Coating® Group, planeoptically polished
FILTER USAGE Color, Planetary
TYPE OF FILTER Bandpass, Longpass

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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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These Baader colour filters are carefully prepared for amateur astronomical use for contrast enhancement of lunar and planetary observations.