{"title":"Explore Scientific Light Pollution \u0026 Broadband","description":"\u003cp\u003eExplore Scientific light pollution \u0026amp; broadband. Part of \u003ca href=\"\/collections\/explore-scientific-filters\"\u003eExplore Scientific Filters\u003c\/a\u003e.\u003c\/p\u003e","products":[{"product_id":"uhc-filter-2","title":"Explore Scientific 2-inch UHC Nebula Filter","description":"\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003eOne of the most important obstacles for the exploration of the night sky is the brightening of the night sky by artificial lights, such as streetlights. The night sky is not really dark in the vicinity of towns or cities, which reduces the visibility of objects bejond the solar systems enourmously. Depending on the type of the celestial object it is possible to increase the contrast dramatically by blocking the annoying artifical light. \u003c\/span\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003eThe Explore Scientific UHC filter uses a characteristic property of the so called emmission nebulae. Those objects glow in special colors, the so called emmission lines. Those emmission lines are linked to chemical elements - in this case hydrogen at 486nm and 656nm, plus oxygen at 496nm and 501nm. \u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003eThe Explore Scientific UHC nebula filter blocks all other colors (and thereby nearly all of the artificial light) and only the emmission line of the hydrogen and oxygen can pass the filter. The result is astonishing: suddenly nebulae are visible at locations that were completely empty without filters. In suburbian skies for example the Owl-nebula M97, the Veil-nebula Ngc 6992 or even the bright Dumbell-nebula M27are not clearly visible.\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\n\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003eBy using this filter you can see the nebulae and their structures without problems. A must for every visual observer. The Explore Scientific nebula filters come with a individual test certificate - your guarantee to receive a premium filter.\u003c\/span\u003e   \u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"color: rgb(50, 50, 50); font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 16.2px; background-color: rgb(255, 255, 255);\"\u003e UHC Nebula Filter. Range from 458nm to 508nm with peak at 488nm. Peak transmission 96.7%\u003c\/span\u003e\u003c\/div\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44013255852143,"sku":"310210","price":184.2,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/0310210_PAC_small__35622.jpg?v=1766550360"},{"product_id":"cls-fliter-2","title":"Explore Scientific 2-inch CLS Light Pollution Reduction Nebula Filter","description":"\u003cspan style=\"background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"font-size: 13px; font-family: 'Source Sans Pro', sans-serif;\"\u003eOne of the most important obstacles for the exploration of the night sky is the brightening of the night sky by artificial lights, such as streetlights. The night sky is not really dark in the vicinity of towns or cities, which reduces the visibility of objects beyond the solar systems enormously. \u003c\/span\u003e\u003c\/span\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: \" source sans pro sans-serif font-size: background-color: rgb\u003eThe Explore Scientific CLS nebula filter blocks those colors and thereby increases contrast - the light ot the celestial objects can pass the filter. The result is astonishing: suddenly objects are visible at locations that were completely empty without filters. In suburban skies for example the large galaxy M101, the Veil-nebula Ngc 6992 or even the bright Dumbbell-nebula M27 are not clearly visible. By using this filter you can see the nebulae and their structures. \u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\n\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003eThe Explore Scientific nebula filters come with a individual test certificate - your guarantee to receive a premium filter.\u003c\/span\u003e  \u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: 'Source Sans Pro', sans-serif; font-size: 13px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"color: rgb(50, 50, 50); font-family: Arial, Helvetica, sans-serif; font-size: 12px; line-height: 16.2px; background-color: rgb(255, 255, 255);\"\u003eExplore Scientific 2\" CLS City Light Pollution Reduction Filter. Range from 436nm to 536nm with peak at 488nm. Peak transmission 98.3%\u003c\/span\u003e\u003c\/div\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44013257850991,"sku":"310220","price":162.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/0310220_PAC_small__15891.jpg?v=1766550373"},{"product_id":"explore-scientific-1-25-inch-cls-light-pollution-reduction-filter","title":"Explore Scientific 1.25-inch CLS Light Pollution Reduction Nebula Filter","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThe Explore Scientific CLS Nebula Filter is a 1.25-inch light pollution reduction filter intended for general deep sky observing from skies that are not truly dark. Explore Scientific describes it as a general-purpose light-pollution reduction filter for a broad range of deep sky objects, and publishes a wavelength range of 436nm to 536nm with peak transmission at 488nm and a transmission rate of 98.3 per cent. That passband sits directly over the blue-green region where the strongest visual emission lines of nebulae live, so the light you want arrives with very little loss while a good deal of the sky glow around it is held back. It is item 310225 and threads into the barrel of any standard 1.25-inch eyepiece.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis filter is for the observer whose sky is the limiting factor rather than the telescope. If you are working from a driveway in a town or a suburb, the problem is rarely resolution or aperture; it is that the background of the field is grey instead of black, and faint extended objects simply do not have enough contrast against it to register. A CLS filter attacks that directly. Rather than making the object brighter, it darkens the field around it, and the object separates from the background because the ratio between the two has changed.\u003c\/p\u003e\u003cp\u003eIt is also the sensible first filter for someone who is not ready to commit to a narrowband set. A dedicated O-III or H-beta filter is a far more aggressive tool and will show you a small number of targets spectacularly while making most of the sky unusable. The CLS is deliberately broader. You can leave it in the eyepiece and star hop, work through an evening of Messier objects, and keep enough field stars visible to know where you are.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003ePublished wavelength range of 436nm to 536nm, covering the blue-green band where the brightest visual nebula emission occurs\u003c\/li\u003e\n\u003cli\u003ePeak transmission at 488nm, close to the O-III doublet that carries most of the visible signal in planetary and emission nebulae\u003c\/li\u003e\n\u003cli\u003ePublished transmission rate of 98.3 per cent at peak, so very little of the wanted light is given up to the coating\u003c\/li\u003e\n\u003cli\u003eStandard 1.25-inch filter thread, compatible with the great majority of 1.25-inch eyepieces and diagonals\u003c\/li\u003e\n\u003cli\u003eThreaded cell that stacks with other standard 1.25-inch filters if you want to combine effects\u003c\/li\u003e\n\u003cli\u003eBroadband rather than line-specific behaviour, so field stars remain visible and star hopping stays practical\u003c\/li\u003e\n\u003cli\u003eWorks with any focal ratio and requires no power, batteries or adapters\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFilter Design\u003c\/h2\u003e\u003cp\u003eA light pollution reduction filter is an interference filter, not a piece of tinted glass. Alternating thin layers of material with different refractive indices are deposited on the substrate, and their thicknesses are chosen so that reflections within the stack cancel at some wavelengths and reinforce at others. The result is a transmission curve that can be shaped, in this case to pass the 436nm to 536nm region efficiently and to reject a good deal of what falls outside it. The wavelengths that mercury and older sodium street lighting throw into the sky sit largely outside that window, while the emission lines that make nebulae visible sit inside it. Because the filter subtracts rather than adds, the whole field including the target does get dimmer in absolute terms; what improves is contrast, and contrast is what the eye actually uses to detect faint extended detail. It is worth understanding that this is a physical wavelength selection, which is also why the filter cannot help with light that arrives at the same wavelengths as your target.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eVisual observing of emission and planetary nebulae from suburban or town skies\u003c\/li\u003e\n\u003cli\u003eGeneral deep sky sweeping where you want a darker background without losing field stars\u003c\/li\u003e\n\u003cli\u003eOutreach and public nights under compromised lighting, where the improvement is easy for a newcomer to see\u003c\/li\u003e\n\u003cli\u003eA first light pollution filter for an observer who is not yet ready for narrowband\u003c\/li\u003e\n\u003cli\u003eReducing the visual impact of moonlight-brightened sky on brighter nebulae\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThe filter uses the standard 1.25-inch filter thread found on the barrel of most 1.25-inch eyepieces, and it can equally be threaded into many 1.25-inch star diagonals and camera nosepieces. A small number of eyepieces have unusually deep or recessed barrels and can be awkward to thread by hand, and a very small number of older or specialised barrels are not threaded at all. If you are unsure whether it will thread into a particular eyepiece, contact our team in Bolton with the model and we will confirm it before you order. If you also observe with 2-inch eyepieces, note that this filter will not fit them and a 2-inch version is a separate item.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eExplore Scientific publishes no shipping weight for this item, so we are confirming it on our own scales before the listing goes live. That is why it is currently unpublished. Contact us and we will give you a shipping figure for your address. Beyond that, set expectations honestly on performance. A CLS filter gives its best results on emission and planetary nebulae. Galaxies, globular clusters and open clusters shine by broadband starlight, and any filter that removes part of the spectrum removes part of their light too, so the gain on those targets ranges from slight to none. The filter also cannot do anything about modern broad-spectrum white LED street lighting, which puts energy right across the visible band including inside the passband. Nothing is included beyond the filter itself in its case; eyepieces, diagonals and adapters are separate.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWill this make faint objects brighter?\u003c\/strong\u003e No, and no filter can. It removes unwanted light, so the whole view including the target gets slightly dimmer. What increases is the contrast between the object and the sky background, and that is what determines whether you can see faint detail at all.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it for astrophotography?\u003c\/strong\u003e You can thread it into a 1.25-inch camera nosepiece and it will help under light pollution, though it is designed and specified as a visual filter. Imagers working seriously under light pollution usually move to narrowband filters matched to their sensor and optical train.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work on galaxies?\u003c\/strong\u003e Only marginally. Galaxy light is broadband continuum, so it is attenuated along with the sky glow. The honest answer is that this filter earns its place on nebulae.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it fit my 2-inch eyepieces?\u003c\/strong\u003e No. This is the 1.25-inch version and threads only into 1.25-inch barrels. Ask us about the 2-inch size if that is what your eyepieces use.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eIf your observing site is bright and your nebula views are washed out, a broadband light pollution filter is the least expensive change that will visibly help. The CLS is an easy filter to live with because it is gentle enough to leave in place all evening. Contact our team in Bolton if you would like help deciding between this and a narrowband filter for your sky and your telescope.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53958533185647,"sku":"310225","price":117.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/0310225_PAC.jpg?v=1785960458"},{"product_id":"explore-scientific-77mm-slim-dark-sky-filter-for-camera-lenses","title":"Explore Scientific 77mm Slim Dark Sky Filter for Camera Lenses with 4mm Low Profile Mount","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThe Explore Scientific Dark Sky Filter, item 310260, is a 77mm screw-in filter made for camera lenses rather than telescopes. Explore Scientific describes it as a universally applicable dark sky filter for photo lenses, particularly suited to increasing contrast in aurora and deep-sky photography. The substrate is a special optical glass containing neodymium oxide, which absorbs strongly in a narrow band centred on the 590nm sodium line while passing 550nm green and 630nm red at over 90 per cent. The frame is black anodised aluminium with a construction height of just 4mm, a slim profile chosen specifically so the filter does not vignette on wide-angle lenses.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis is for the photographer shooting nightscapes, aurora and wide-field Milky Way frames from anywhere within reach of town lighting. The problem it addresses is specific and quite different from what a telescope filter deals with. A camera sensor records colour through red, green and blue channels, and the yellow of sodium vapour street lighting and greenhouse lighting lands across both the red and the green channels at once. Once that has happened, the skyglow is entangled with exactly the colours you are trying to record, the red of hydrogen emission and the green of aurora, and no amount of work in post-processing separates them cleanly. Blocking the sodium line at the point of capture keeps the channels distinct so the red and green in your image mean something.\u003c\/p\u003e\u003cp\u003eIt is also the practical answer for anyone who does not want to modify their camera. Clip-in interference filters that sit between lens and camera body mean disassembly, careful handling near the sensor, and a filter that only fits one body. This one threads onto the front of the lens like any other 77mm filter, goes on and off in seconds, and moves between bodies freely, which makes it realistic for time-lapse work and for travel where you are shooting on the move.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eBlocks the 590nm yellow sodium line, suppressing sodium vapour street lighting and greenhouse lighting\u003c\/li\u003e\n\u003cli\u003eTransmits over 90 per cent at 550nm green and 630nm red, the bands that carry aurora and hydrogen emission signal\u003c\/li\u003e\n\u003cli\u003eSlim 4mm construction height, chosen to avoid vignetting on wide-angle lenses\u003c\/li\u003e\n\u003cli\u003eStandard 77mm filter thread, so it fits directly on the front of a 77mm lens with no camera modification\u003c\/li\u003e\n\u003cli\u003eSpecial optical glass with neodymium oxide, an absorption glass rather than an interference coating\u003c\/li\u003e\n\u003cli\u003eBlack anodised aluminium frame, which resists handling wear and limits internal reflection off the ring\u003c\/li\u003e\n\u003cli\u003eNatural night sky colour reproduction, with the correction confined to a narrow band rather than a broad cast\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFilter Design\u003c\/h2\u003e\u003cp\u003eThe important engineering decision here is absorption rather than interference. An interference filter builds its passband from stacked thin-film layers, and the wavelength at which those layers cancel depends on the angle at which the light crosses them. Light entering the corner of a fast wide-angle lens arrives at a very different angle from light down the centre, so an interference filter mounted in front of such a lens shifts its passband across the frame and produces uneven colour. Neodymium oxide glass works differently. The neodymium ion has an absorption band that sits over the yellow region near 590nm, and because that absorption is a property of the material itself rather than of a layer structure, it behaves the same regardless of the angle of incidence. That is what makes the filter usable in front of a 14mm or 24mm lens where an interference filter would not be. The 4mm frame height serves the same goal from the mechanical side: a standard filter ring intrudes into the field of a very wide lens and darkens the corners, so the mount is cut down to keep clear of it.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eAurora photography, where separating green and red emission from yellow skyglow is the whole battle\u003c\/li\u003e\n\u003cli\u003eWide-field Milky Way and nightscape work from suburban or semi-rural sites\u003c\/li\u003e\n\u003cli\u003eNight sky time-lapse sequences, where a screw-in filter can stay on the lens for hours unattended\u003c\/li\u003e\n\u003cli\u003eWide-field imaging of emission nebulae with a camera lens on a star tracker\u003c\/li\u003e\n\u003cli\u003eGeneral night photography where sodium lighting is casting an orange wash over the scene\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThe filter fits any lens with a 77mm front filter thread directly. Lenses with smaller threads can use it with an inexpensive step-up ring, though on the widest lenses a step-up ring reintroduces the very intrusion into the field that the slim mount was designed to avoid, so test for vignetting at your widest focal length and largest aperture before you rely on it. Some ultra-wide and fisheye lenses have bulbous front elements with no filter thread at all and cannot take a front filter of any kind. Slim frames also vary in whether they carry a front thread for stacking or for a lens cap, so if you need to keep a cap or hood on top, contact our team in Bolton and we will confirm what this frame will accept before you order. It works with any camera body, mirrorless or DSLR, modified or unmodified.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eExplore Scientific publishes no shipping weight for this item, so we are confirming it on our own scales before the listing goes live. That is why it is currently unpublished. Contact us and we will give you a shipping figure for your address. On performance, be realistic about what a sodium-line filter can and cannot do. It is aimed at one specific pollutant. Broad-spectrum white LED street lighting, which now dominates in many municipalities, emits right across the visible band and cannot be notched out this way, so under LED-lit skies the improvement is modest. Under older sodium lighting it is substantial. The filter also removes some light, which means slightly longer exposures, and like any front-mounted glass it can produce ghosting if a bright lamp is in or just outside the frame. Custom white balance is worth setting with the filter fitted. The filter is supplied on its own; step-up rings, caps and hoods are separate.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWill it vignette on my wide-angle lens?\u003c\/strong\u003e The 4mm slim frame is designed specifically to avoid that, and it is the reason to choose this filter over a standard-height one. On extremely wide lenses, and particularly if you add a step-up ring, test a frame at your widest setting to be sure.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it need a modified camera?\u003c\/strong\u003e No. It threads onto the front of the lens and works with any standard camera body, which is the main practical advantage over clip-in filters that sit in front of the sensor.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it help under white LED street lights?\u003c\/strong\u003e Only a little. Neodymium glass targets the yellow sodium line near 590nm. LED lighting is broadband and there is no narrow band to remove, so the honest answer is that this filter is at its best where sodium lighting still dominates.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it on a telescope?\u003c\/strong\u003e Not directly. It is built around a 77mm photographic thread for camera lenses. For telescope work, ask us about the light pollution filters made in 1.25-inch and 2-inch astronomical cells.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eIf you photograph aurora or wide-field night skies near sodium-lit towns, this filter fixes a problem at capture that is genuinely difficult to fix afterwards, and the slim mount means you can use it on the wide lenses that matter most for that work. It is a simple screw-in accessory with no camera modification involved. Contact our team in Bolton if you would like help matching it to your lens set or choosing step-up rings.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53958629032047,"sku":"310260","price":186.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/310260_1.jpg?v=1785960691"}],"url":"https:\/\/ontariotelescope.com\/collections\/explore-scientific-light-pollution.oembed","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}