Baader 3.5 / 4nm Ultra-Narrowband Filter-Set – CMOS-optimized (H-alpha / O-III / S-II)

The actual dimensions are 65mm length on each side with tolerance + 0 / - 0.2mm

You will see more contrast in the images because more of the unwanted light (straylight, out of band light) gets blocked. This way you can imagine even fainter nebulae and structure, like described here: https://www.baader-planetarium.com/en/downloads/dl/file/id/1712/product/0/baader_ultra_highspeed_f_2_filter_andreas_bringmann.pdf

The "normal" filters will work but you may experience a slight contrast loss at the edges of the sensors field.

Thank you for your nice comment, we are excited too! As soon as narrowband deliveries start, the 65x65x3 mm filters all will be available in all four filter families. At this time we are concentrating entirely on production and marketing of the new narrowband technology - also due to the fact that RGB-filters have a much wider spectral window and imaging results do not suffer so badly when comparing the s/n ratio of CCD-chips versus CMOS-chips. Eventually we will bring the new coating tech into the field of RGB-filters - but please understand that this still will take considerable time. The financial burden to enter into new technological fields are big. At this time we are concentrating entirely, to show that this new CMOS-optimized coating tech is really as good as our early testers confirmed. As soon as more people know about this and can confirm it with their imaging results, we hope this will pave the way to extend this tech into other fields. However - far more important than the RGB-filters are both families of photometric filters (SLOAN & UBVIR) which are in demand at this time - to be produced in the same quality grade and "to be available at all". We are working on this very hard and once the community can access SLOAN (u,g,r, i,z-s,y) filters at "down to earth prices" this will also open the field for totally new ways of "RGB-like" imaging, for new optics to work in NIR asf.

Our largest cell mounted filters measure 2" (50.8mm) in mechanical diameter (having a metric thread of M48). The optical clear aperture is 46 mm. In order to ease the adaptation of our 2" filters onto most camera lenses, we do produce a 2" filter-holder, to convert from the ASTRO-2" Standard (M48) into a more common photo-standard of SP54 mm ("SP"means this is not a metric thread). For adapting any cell mounted Baader 2 inch Filter onto a camera lens with 52mm front filter thread you will need: #2408166 Baader DSLR 2" Filter-Holder M48 / SP54: https://www.baader-planetarium.com/en/baader-dslr-2%22-filter-holder-m48sp54.html #2958052 Baader Lens-Adapter-Ring SP54 / M52: https://www.baader-planetarium.com/en/baader-hyperion-dt-ring-sp54m52-for-dtadapter-iiandiii-and-hyperion-eyepieces.html Based on the SP54 thread, we offer many more adapters for various camera threads, our so-called Hyperion DT-rings. https://www.baader-planetarium.com/en/catalogsearch/result/?q=sp54