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Optolong 2″ CLS Light Pollution Premium HT filter with data – 8540-4
Optolong 2″ CLS Light Pollution Premium HT filter with data – 8540-4Click images to enlargeDescription
We are delighted to offer for sale this superb quality 2″ CLS (City Light Suppression) filtermade byOptolong.
All filters arenotthe same.
Only Sky’s the Limit:Test every filter soldInclude an individual data graph for each filter (sent by email)Inform you of all the transmission and cut off frequencies before you buyCan provide a complete test result for your filter on request
Optolong 2″ CLS filter.
Our Optolong filters comewith their own individual data sheet of performance – guaranteed!
The filter is designed for visual and imaging use in areas of light pollution and by blocking the spectral lines of mercury and sodiumit lets the largest part of the visible light and H-alpha emissions pass. All the important emission lines, as well as the spectral region that the very well dark adapted eye can see, can pass through the filter. This makes it particularly useful in enhancing nebula viewing which can be a bit difficult at the best of times.
This filter is fine to use on smaller aperture telescopes where a UHC filter wouldcut out too much light making viewing almost impossible. The CLS filter has a much wider band pass which will not cut out so much light.
Genuine UK Stock and UK Business!Performance
Optolongfilters offer performance as good as, and in some cases better than, the top brands currently on sale. The listing shows the actual performance curve for the CLS filter (if you are unsure how to interpret the graph see our easy to read Glossary guide below). You can compare this to similar curves from the top brands and we are sure you will be pleasantly impressed.
However, to ensure that you will be impressed with your purchaseeach filter is individually tested and issued with its own performance data sheet. This is your guarantee that you are getting exactly what you paid for.
This is the curve of the actual filter for this listing:
You will get an A4 printout of this curve with your filter (less the watermark) sent by email.
And here are the important figures to back up the claims:Nebula’s light (nm)Transmission T%H- 478nm96.70%H- 479nm97.29%H- 480nm97.75%H- 486.1nm97.19%O- 495.9nm97.94%O- 500.7nm97.74%H- 656.3nm97.48%SII – 672.4nm98.60%Artificial light (nm)Transmission T%Hg 435.8nm0.54%Hg 546.1nm0.68%Hg 577.0nm0.31%Hg 578.0nm0.31%NA 589.6nm0.31%Na 615.4nm0.78%Na 616.1nm0.81%
Quality
Each filter is built upon a precision polished substrate of Schott glass. The specification speaks for itself and is supported by the data sheet. Thefilter will retain its ‘as new’ optical performance for more than 10 years. It is resilient to scratches, moisture, dew, and humidity.
Even the storage package was carefully developed to take the greatest of care of your filter so that it can be a long lasting companion to you and your hobby or profession.
Price
No silly RRPs but an honest price for an outstanding product.
Sky’s the Limit are pioneers in bringing exceptional value items to the astronomy market. Started in 2004 we have been importing and selling optical products at prices others only wish they could achieve. By dealing directly with the manufacturers and suppliers in China and keeping our overheads low in the UK we are at the forefront of the bargain price supply chain. We aim to be the lowest prices in the UK and we aim to offer the best service that you would get from anywhere.Manufacturers Information (with modifications)
The CLS (City Light Suppression) broadband filter is designed to improve the visibility of various deepsky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightingincluding mercury vapour lamps, both high & low pressure sodium vapour lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).Together with the highly transparent in main nebula emission lines at OIII (496nm and 500nm), H-beta (486nm), NII (654nm and 658nm), H-alpha (656nm) as well as SII (672nm), the filter is suitable for enhancing the contrast and details for both visual and photograghic purposes in rural areas.Main Use and PerformanceSuitable for colour CCD cameras and unmodified DSLRsCLS with wider pass-band than UHC and hence is more favoured when observing under mild to moderate light pollutionLight pollution filtersdo not eliminate the effects of light pollution or increase the objects brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.WARNING:The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.
Technical DataSchott substrate materialThickness 2.0 mm (1.25/2/36mm)Thickness 1.0 mm (Clip series)Surface Quality: 60/40 (Refer to MIL-O-13830)Fine-optically polished to ensure accurate 1/4 wavefront and
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Category: Cameras and Photography:Telescopes and Binoculars:Telescope Parts and Accessories:Filters
Location: Welwyn Garden City