Explore Scientific O-III 1.25″ filter review

The O-III light filter (read as “o-three”) is an astronomical accessory designed to improve the visibility of gas nebulae, namely planetary nebulae, supernova remnants and regions of active star formation. The O-III filter passes the green region of the spectrum around the doublet of the spectral lines of doubly ionized oxygen O2+ (or O III), highlighting these lines (495.9 and 500.7 nm) against a darker background of the rest of outer space. Perhaps this is one of the most useful filters for visual observation of nebulae.

Explore Scientific O-III 1.25

Explore Scientific O-III 1.25″

The filter comes in a colored cardboard box with a magnetic lock. Inside the box there is a filter in a plastic box and a bag, sealing material, as well as a filter bandwidth graph.
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Venus in false color, February 14, 2020.

Venus visibility conditions are getting better every day. The brightness of the planet is so high that under favorable conditions it can be found with the naked eye during the day. The angular size at the time of the capturing was 16.72 “, the angular distance from the Sun was 42 degrees. It is interesting that the distance from the Earth to Venus was exactly 1 astronomical unit (150,000,000 km).

Venus in false color, February 14, 2020.

Venus in false color, February 14, 2020.

-telescope Celestron NexStar 8 SE
-NPZ Barlow lens 2x cell
-camera QHY5III178m
-filter Meade green CCD (red channel)
ZWB2 + NPZ SZS-22 filter stack (blue channel)
Stacking 1500 frames with Autostakkert, wavelets with Registax 6.
Location: Russia, Anapa, backyard

Details of Venus’s cloud cover are best obtained when shooting with a light filter that transmits only ultraviolet light. There are special filters for shooting Venus (for example, Baader U-Venus), but they are very expensive. As a budget solution, I decided to use a bunch of ZWB2 filters with a diameter of 20.5 mm and a NPZ SZS-22 1.25″.

ZWB2 transmits ultraviolet radiation with a maximum at 365 nm. I bought it without a rim – an inexpensive 1.25″ filter perfectly fit as a housing. The disadvantage of the ZWB2 filter is that it also transmits infrared radiation, to which the camera is also sensitive. To reducing it, a second filter is used – the NPZ SZS-22.
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Optolong L-eNhance filter review

Every year, the illumination from cities is becoming stronger and stronger, creating difficult conditions for shooting deepsky objects. However, progress does not stand still – various filters have appeared that make it possible to cut off spurious light. Narrow-band filters that allow only a specific wavelength (hydrogen H-alpha, oxygen OIII, sulfur SII) have been used by astrophotographers for a very long time and make it possible to capture gas nebulae even under the conditions of strongest exposure. The hero of today’s review is the Optolong L-eNhance filter, passing only the H-alpha, OIII and H-beta lines. In combination with a color camera, it allows you to get a full-color image at once with one frame. Optolong L-eNhance will be of interest primarily to owners of color cameras and aperture telescopes. I immediately warn that it is not suitable for shooting objects of stellar nature (galaxies, star clusters, dust nebulae).

График пропускания фильтра Optolong L-eNhance, заявленный производителем

Filter bandwidth declared by the manufacturer

Packaging, appearance
The filter is delivered in a cardboard box. Inside it is a transparent plastic box for storage and transportation. Filter weight 5.4 g, thread diameter 28.5 mm, filter thickness with thread 7 mm, without thread 5 mm, light diameter at the inlet and outlet – 26 mm.
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