Filters for visual observing

[jetstream]

lol!

It would be great to look through a good 2" Hb like yours...

My 1.25" Astronomik Hb does show a bunch of targets well though and was well worth the purchase. Once my little nebula grabber gets here I'll test things out some more- a good filter "captures" your attention in dark skies I find.

[Don Pensack]

On 8/15/2016 at 12:26, DRT said:

I have been looking into buying an H-beta filter to have a go at the Horsehead nebula and have a question about quality that I hope will elicit answers more helpful than "just buy the most expensive one"

H-beta filters seem to range in price from the Skywatcher 1.25" at around £28 to the Astranomik at £73 and the Baader at £89 and presumably upwards from there.

For imaging I can definitely understand why going for very high quality filters would improve your chances of bringing out the best from your telescope, camera and processing abilities - but my question is, how much difference would I see with my eye between the relatively inexpensive SW filter and the more expensive alternatives?

 

H-Beta filters work better the narrower the bandwidth.  But H-Beta is not a photographic filter, it is a visual filter.

All nebulae that emit hydrogen alpha energy also emit hydrogen beta energy at a substantially reduced level.

So a hydrogen alpha filter will record more nebula a lot faster than using a hydrogen beta filter.

Unfortunately for us, our eyes are particularly insensitive to the deep red wavelength of hydrogen alpha, so that is not a useful visual filter.

But our eyes are particularly sensitive to the 486nm blue wavelength of hydrogen beta, making it an excellent visual filter.

8 nanometers of wavelength seems to be ideal, but I have seen several inexpensive ones of up to 12nm bandwidths.  If wider than that, it wouldn't be very useful to enhance contrast on the already quite dim

hydrogen beat emission.