Hydrogen-Beta Filter Question(s)?

Question

can someone explain why hydrogen-beta filters are best suited for 8" telescopes or larger? does it only work on 8" scopes (or larger)? will this filter work on a celestron nexstar 6 se, which obviously has an aperature of 6 inches?

Answer 1

It may be that this particular filter transmits so little light that a smaller telescope may not provide a bright enough image. If you don't mind a little dimmer image there is no reason it won't work with a 6  inch.

Answer 2

H-beta filters block everything but the blue light of ionized hydrogen, leaving nothing else. That means they darken the sky and everything else tremendously. I own one of these filters and they're very useful for nebulae that emit mostly H-beta light, but they render everything else invisible. Without it, I would have never seen the Horsehead or the California Nebula. You can use them on a 6-inch telescope, but you still need dark skies to use them, or at least one not in the middle of a city because the objects they work on are really faint. Most nebulae are not helped by these filters, but they do work wonders on the Cocoon, Horsehead and California Nebulas. Unless you already have one, I suggest you buy a Lumicon UHC, Orion Ultrablock or some other narrowband nebula filter first before buying an h-beta filter. They are specialized and do not work on most nebulas.

Answer 3

These are mostly used for long exposure photography-- not for visual.

There is a special solar Ha filter (very expensive) to look at the sun -- visually or via photographs--

it darkens the field a LOT---  try an O3 filter and or an ultra contrast filter instead-- and these work better in larger scopes -- but a 6 inch should be OK.

Answer 4

this is such a funny question!

i have studied hundreds of HB filtered photos and never once did i wonder what a HB filter actually looked like or was!

off to Google it!

most likely the first answer was correct, as HB is only a TINY fraction of the spectrum of light.

Answer 5

Hydrogen Beta filters are pricey additions which you should acquire after you have purchased OIII and UHC filters, that are the most-used visual filters.  (I was $20k into amateur astronomy before I broke down and bought an H-beta.)    These filters come in two inch and 1.25" formats.  Generally speaking you're chasing nebulae and you want a wider field so you're going for the wide view and a two inch format is best.

The H-beta is basically known as the "Horsehead" and "California Nebula" filter.  Those are really the only two amateur class objects (for non-photography) that it works on.  You have to want to see them real bad.  The other two filters are good on hundreds of objects.  H-beta can be profitably employed on more objects in astrophotography.

Now, the Horsehead is hard to pick off in a small aperture scope so you'd want a real clear sky and 8 inches or more of aperture. Fortunately for us it is a small object so you can put some power on it.  It is a winter constellation object, in Orion, just above the Sword.  You'd want a chart to go chasing it; even in 14 and 15" telescopes you are not guaranteed to "bag" this object visually.  I've seen it, but only sometimes.  (It can be seen in white light, meaning without a filter, but that's unusual)

The California Nebula (ngc 1499) is a different ball of wax.  It is a very cool object in Perseus, you can see it now, later in the evening.  But in order to take in the effect you need a large field of view.  It's 2.5 degrees on its major axis, about seven times larger than the 20 arc minute region that affords a reasonable view of the Horsehead (the Horse is small, but you need some framing to "get" what you're looking at).  A lot of larger scopes won't be able to fit the California nebula in and you won't get the California effect.  To see the whole thing a five or six inch refractor is pretty good.  Your nexstar 6" doesn't take 2 inch eyepieces and has a long focal length.  So unfortunately you're not going to have the field of view to make the California nebula look worthwhile.  And you won't have the aperture to make the Horsehead look good.   I experienced great satisfaction when I finally bagged the California Nebula.  It's just not something one sees often because of the required filter and combination of large-ish aperture (five to six inches) but not too small (because you need light) but not too big (because you need field of view).

So this filter is probably not for you, not yet, but you could look for one on Astromart to try out if you absolutely must.  A 2 inch h-beta runs around $200 and a 1.25 inch about half that.  It's just not the best way to spend your money unless you're really obsessed.   For your C6 I think a better investment would be a 24mm Pan Optic which will give you optimal wide field views in 1.25 inch format--consider the difference between spending $100-$200 on a filter that will get use on two objects at most, versus an eyepiece you'll use all the time.

On the other hand an OIII filter and a wide field eyepiece--such as the 24 Pan Optic or, to save money, a 32mm plossl--will knock your socks off if you turn it on the Veil (NGC 6995) or the Crescent nebula (NGC 6888) or the Swan Nebula (M17) or any of a number of different objects. UHC is also nice but I always reach for OIII first.

And what the heck are you asking this question here for?   You should join a group of people who are totally into astronomy.  You own an SCT so try this one:

http://groups.yahoo.com/group/sct-user

This is a yahoo discussion group and membership is free.

Hope that helps,

GN

p.s.  With OIII and UHC filters you can get positive results with binoculars.  I've seen them work fine in 90mm to 120mm scopes.  So don't think that all filters require a large scope.

Answer 6

they block so much of the light that hits them that you need *lots* of light to begin with to see anything at all. i have a narrow-band o3 filter that is the same sort of thing, amazing on a 12 or 18 inch scope, but you see nothing at all on a 5 inch.

everybody should have a broadband nebula filter. if you have to ask about others, you don't need them. in particular, there are only about 3 objects a hydrogen beta filter is useful on.