1. H-alpha narrowband 7nm CCD filter
- - is designed exclusively for imaging of emission nebulae, but it also works great for capturing luminance data of those nebulae with monochrome cameras.
- This filter provides 90% transmission at the H-alpha line of 656.3nm and has a very narrow bandpass of 7nm.
- Take high-contrast CCD images of emission nebulas in full moonlight or in extreme light pollution with the Hydrogen-Alpha Narrowband filter.
- 7nm H-Alpha Filter reveals subtle nebular details usually washed out by contrast-killing broadband light.
- Imagine capturing brilliant, high-contrast images of nebulas in full moonlight or in the thick of downtown light pollution.
- - The H-beta is a filter for visual observation, in particular with instruments of larger aperture.
- This filter should be used on telescopes with a diameter of 8 " (20cm) or larger.
- Visual observation (dark skies): Very good, but only suitable for a few objects.
- Visual observation (urban skies): Unsuitable
- Film photography: It depends, very long exposure time
- CCD photography: Good, when used with an additional IR-block-filter
- DSLR photography (original): Verry good, but only suitable for a few objects
- Webcam / Video (Planets): Unsuitable
- Webcam / Video (Deep Sky): Unsuitable
- This filter is so specialized, it is really only good for two objects; IC 434, the emission nebula surrounding the Horsehead Nebula in Orion, and the California Nebula.
- The filter emphasizes the glow of both of these nebulae, turning them red.
- In the case of IC 434, the red outline around the actual Horsehead itself (B33) is what makes it visible.
- The California Nebula is similar in that it is just barely visible without the H Beta. With it, the California "shape" becomes clearly visible.
4. O-III narrowband 8.5nm CCD filter
- - Delivers the absolute highest contrast views of many diffuse and planetary nebula.
- For many objects, the O-III reveals a level of intricate detail that rivals the best deep sky photographs.
- The majority of nebula, especially The Veil, Lagoon (M8), Swan (M17), Ring (M57) and Dumbell (M29). With a large scope, you can even view the famous 'Pillars of Creation' in M16 (Eagle).
- Combine with UV/IR filter for the ultimate in O-III deep sky imaging.
- - excels at delivering a high-contrast and natural view of emission nebula - without excessive dimming and loss of background star fields.
- The perfect filter for viewing emission nebula from light polluted skies, or for boosting the contrast of nebula from dark sky sites.
- - A minus violet filter to reduce chromatic aberration in achromatic refractors.
- Improves detail of almost all objects viewed through fast achromatic refractors
- Very high optical quality allows filter to be used anywhere in the optical path
- Additional blocking of infrared light makes this a good general filter for web cam and digital camera imaging
- Achromatic refractors, especially fast focal ratio models, suffer from significant amounts of "chromatic aberration" - false color.This is generally experienced as a violet halo around bright objects, particularly planets, bright stars and the Moon. The halo is caused by the fact that not all the wavelengths of light come to focus at the same point.
- Although it is possible to ignore the halo, the real problem is that the unfocused violet and blue light is spread all across the object you are viewing, robbing it of detail.
- The most common "cure" for this is to simply block the violet and blue light waves. The problem is, most minus-violet filters introduce their own resolution-robbing aberrations and they typically block significant "good" light, further reducing detail.
- Fringe-Killer filter - Almost all violet light (light below wavelengths of 450nm) is completely blocked, while blue light (450nm - 480nm) is attenuated by 50%.
- all other light is transmitted at higher than 95% efficiency
- suggests that the Fringe-Killer combined with Red filter is a good Hydrogen-Alpha filter. This combination has a 95% transmission rate at the H-Alpha wavelength and yet costs very little. H-Alpha filters are great for imaging emission nebula in great detail, though a smaller pass-band would produce better results.
- Conclusion
In short, this filter transformed the views through this f/5 achromatic refractor into what I would expect to see through an f/12 achromatic refractor. A fast achromatic refractor will never be the best choice for planetary views, but Fringe-Killer filter can certainly make it a good choice. If you've been looking for something to improve your achromatic refractor - this is it!
- - brings an entirely unique approach to planetary contrast enhancement and light pollution reduction.
- filters out a few specific wavelengths from streetlights as well as skyglow from the Moon.
- also boost color contrasts by isolating the Red, Green, and Blue regions (so-called RGB enhancement).
- The result is a filter that leaves natural colors mostly intact, but significantly enhanced.
- The filter's high efficiency preserves image brightness, and many Galaxies, Nebulae and Globular Star Clusters are improved due to the reduction of skyglow from artificial lighting.
9. UV/IR block (L filter)
- - This filter is a must for all digital imaging with Digital Cameras, CCD Cameras, and modified WebCams.
- Also useful for protecting valuable H-Alpha filters from heat stress and damaging IR (Daystar, etc).
- - Based on the popular Baader Moon&Skyglow filter, the Contrast-Booster takes contrast enhancement and skyglow reduction to the maximum level possible from a filter.
- Not only does this filter deliver a significant enhancement of planetary and lunar contrasts, but it is designed to also totally eliminate the damaging blue defocused haze present in achromatic refractors.
- Gone are the annoying blue halo and obscuring haze that surround and smear resolution and contrast. Subtle contrasts and colors are boosted, while displaying the full resolution your scope is capable of.
- The special coatings enable over 95% transmission across key portions of the visible spectrum (including H-Alpha).
- This results in a filter that retains the colors and color contrasts in tough subjects like Jupiter, without excessive image dimming. Cloud bands retain their ruddy red hues, but now become more striking in contrast. The Great Red Spot finally becomes easier.
- Planets and Lunarscapes are set against a jet black sky. The Contrast-Booster is a must for Solar observing.
- As many users have found, this is a great filter for Mars! The views of Mars with all telescopes (including reflectors and apochromats) benefit from the RGB filtration plus blue blocking.
- Combined with the UV-IR-Cut Filter, the Contrast-Booster makes the ideal filter set for digital imaging.
- - manufactured by Hutech Corporation
- is a thin-layered interference based light pollution suppression filter.
- is designed to suppress the various common emissions lines generated by artificial lighting, yet allow important nebula emission lines to pass.
- in the enhanced contrast of astronomical objects, especially emission nebulae such as the California nebula.
- are designed for balanced color transmission. This allows color photographs to be taken of broadband astronomical objects, such as stars, galaxies, and clusters, to be taken with minimal color cast.