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ZWO 1.25" SII 7nm Narrowband Filter - Mark II

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Model
Z263-SII7nm1.25MkII
Weight
0.20 kg
Our price:
£129.00
including VAT 20.00 % ( £21.50 )
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d6a3-11

ZWO 1.25" SII 7nm Narrowband Filter - Mark II

(Since mid 2018 ZWO supplies a new, improved version of their narrowband filters. The difference is visible when shooting night sky "landscapes" with very bright stars in the field of view, especially with the H-alpha and SII filters, the difference is very-very subtle when using the new OIII filters...)

The ZWO SII 7nm narrowband filter passes light at 672nm wavelength with a bandpass of 7nm which is designed for nebula observation and imaging. It is suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants, use it with H-alpha and OIII narrowband filters (SHO Set) for tricolor CCD astrophotography or use it with a H-alpha filter to create bicolor images of nebulosities.

Narrowband filters are used to create high contrast deep sky images of certain objects, mainly emission and diffuse nebulae (i.e. Veil Nebula, M42 Orion Nebula, North America Nebula, Horsehead Nebula) or planetary nebulae (i.e. M27 Dumbbell nebula, M57 Ring Nebula, Helix Nebula), just to mention few of well known nebulosities. Narroband filters are sometimes used instead of LRGB filter sets and sometimes in combination with them...However, if you don't yet want to commit to full narrowband H-S-O imaging, you might just buy them one-by-one and still be able to use them, i.e. a SII filter could be used together with a H-alpha for bicolor astrophotography for certain deep sky objects, usually nebulosities...

Some amateur astronomers would use narrowband filters when the Moon is out or if they live in heavily light polluted areas as these filters would practically eliminate the effects of light pollution as a side effect. By applying longer exposure time you will increase the brightness of the nebulosity whilst stars will still apear much fainter (thus smaller and sharper) than if they were imaged with LRGB filters. The sky's background will also stay darker hence contrast will be increased.

We would recommend to use narrowband filters with fast imaging telescopes with f/8 and faster focal ratio.

Technical Specifications of ZWO SII Narrowband Filter
Size: 1.25″
Fine-optically polished to ensure accurate 1/4 wavefront over both surfaces
FWHM:7 ± 0.5nm
Thickness of glass: 1.9mm ± 0.03mm
Total Thickness: 9mm = 5.5mm + 3.5mm (thread)
Optical Length: 5.5mm
Thread: M28.5*0.6 male thread (standard 1.25" filter thread)

The optional ZWO H-Alpha filter has a bandpass of 7nm and passes light at 656nm wavelength. The light transmission rate comes up to appr. 90% (min 80%). A 7nm type is a very good choice for narrowband H-alpha astrophotography for high-contrast imaging and revealing rich details of a nebula even in areas with strong light pollution, so prepare to have lots of fun with it!

The ZWO narrowband S-II 7nm filter passes light at 672nm wavelength with a bandpass of 7nm which is designed for nebula observation. It is suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants, use it with H-alpha and OIII narrowband filters (SHO Set) for tricolor CCD astrophotography.

The optional ZWO narrowband O-III 7nm filter is designed for nebula observation allowing the 7nm bandwidth of light centered on a wavelength of 500nm through,  which corresponds to OIII emission lines, blocking out all other light.  Adding the ZWO O-III Narrowband filter to your imaging collection will help you go beyond the RGB imaging and will help capture your favorite nebulas in a totally new light, no matter how polluted your skies may be!

After installing the filters in the EFW, make sure that the correct side of the narrowband filter faces to telescope and camera.

 

Reviews of the NEW ZWO narrowband filters

https://www.cloudynights.com/topic/627187-review-of-the-new-zwo-narrowband-filters-comparison-to-the-old-zwo-and-astrodon-filters/

Transmission Curve

Comparison of New (Mark II) and Old Narrowband filters:

The New (Mark II) Ha filter is based on a new base glass, resulting in less reflection (i.e. less halo around bright stars).

The New (Mark II) SII filter is based on a new base glass, resulting in less reflection (i.e. less halo around bright stars).

The New (Mark II) OIII filter is based on the same base glass, but with a new standard coating, resulting in improved blocking of off-band light.

Here is a sample image of a test comparison of the old and new ZWO narrowband Ha Filters (ASI1600 mono camera, single frame, 300s, DDP in MaximDL). 

The difference is subtle, but visible, especially when there are really bright stars in the field of view:

 

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