Viewing nebula with a ha filter

[newbie alert]

Hi all, I'll start by admitting I'm more of an imager than visual astronomy ...

I'm currently away in Gran Canaria and doing my normal up the mountain sky tour with Astrotours GC .. They use a couple of large 16 inch dobsonian scopes on various targets of interest, one of them being the mighty M42, where a O11 filter was used for higher contrast, seemed to do the trick but to my mind M42 emits more hydrogen alpha than Oxygen, so my question is, are Ha filters used for visual are would they make it too dim?

[pipnina]

I've never heard of someone using a Ha filter for visual successfully, maybe with night vision scopes it could be effective.

The problem is that while the colour vision of humans is relatively sensitive to 656nm, our night vision is not.

Our cones (colour-seeing cells) are not very sensitive in general, and become useless below a certain light level. To allow us to maintain some night vision, we evolved to have rod cells too. These are much more sensitive but only see one colour, which turns our vision black and white.

Note also, how the grey curve (the rod cell response spectrum) loses all sensitivity above 600nm, this means any Ha object would need to be bright enough to be visible to our cones if we were to observe it with our eyes! An object of such brightness does not exist besides bright stars/sun.

However most (all?) objects that emit Ha also emit Hydrogen Beta, which is around 480nm. While this band is only 1/3 as bright as Ha, it falls in our rod's most sensitive wavelength band, which means some hydrogen nebulae can be observed much easier with a HB filter! M42 is likely to be one of these nebulae.

[newbie alert]

20 hours ago, pipnina said:

I've never heard of someone using a Ha filter for visual successfully, maybe with night vision scopes it could be effective.

The problem is that while the colour vision of humans is relatively sensitive to 656nm, our night vision is not.

Our cones (colour-seeing cells) are not very sensitive in general, and become useless below a certain light level. To allow us to maintain some night vision, we evolved to have rod cells too. These are much more sensitive but only see one colour, which turns our vision black and white.

Note also, how the grey curve (the rod cell response spectrum) loses all sensitivity above 600nm, this means any Ha object would need to be bright enough to be visible to our cones if we were to observe it with our eyes! An object of such brightness does not exist besides bright stars/sun.

However most (all?) objects that emit Ha also emit Hydrogen Beta, which is around 480nm. While this band is only 1/3 as bright as Ha, it falls in our rod's most sensitive wavelength band, which means some hydrogen nebulae can be observed much easier with a HB filter! M42 is likely to be one of these nebulae.

So would the results from using a hydrogen beta filter be better than using a O111, O111 was ok but I've seen  it just as prominent in broadband in in bottle 5 ..

Is the done thing to use O111 filter for contrast or would a hydrogen beta filter be superior?

[Guest]

I have hit M42 with a narrowband and a O3 filter as well as without.  Never used a H alpha or beta on it.  I can't really say one is better then the other.  Everyones observing preferences are different and what looks good to you may not look good to the next guy.  I actually norefer M42 with no filter 

[Littleguy80]

I believe the DGM NPB was designed to include a Ha pass as well as OIII and HB. I think it’s the only visual filter that does it.

It’s pretty popular as UHC type filter. 

[jetstream]

On 10/05/2023 at 05:02, Littleguy80 said:

I believe the DGM NPB was designed to include a Ha pass as well as OIII and HB. I think it’s the only visual filter that does it.

It’s pretty popular as UHC type filter. 

I believe the new Astronomik UHC does as well whereas the Astronomik made Televue UHC does not. I have the NPB and new TV filters- the TV filters are the best I own.

[Deadlake]

The photo multiplication available by the intensifier tube makes the use of H-Alpha ‘s filter to view emission nebulae’s possible. Even so, NVD really flies from a dark site, here are some examples.

 

 

It’s just like looking thru an EP, just monochromic, however this is for DSO’s, no great loss.

[jjohnson3803]

I believe H-β, 486.1 nm (cyan), would be better for visual.

 

[PeterW]

H-beta is good, works on more nebulae than people sometimes believe. I’ve used a pair on my binoculars to see hydrogen nebulae from a suburban location. Need to shield your eye from all stray light as the filter blocks a lot.

 

peter

[Mark SW]

I asked that question about H-β August 2021 and the response was not what I expected.

S&T editors (Steve) (deepskyforum.com)

from the same source

"j.gardavsky here are some of my H-Beta nebulae as observed through my 6" F/5 achro and through the binoculars, but still not included the LBNs and the nebulae from the HII surveys from my last observin projects."
 

Thank you 

Mark

 

Edited May 6 by Mark SW
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[PeterW]

Jiri also used decent sized bino handheld with filters too. Many of the objects are quite big and better hydrogen beta filters (Baader ccd 5.5nm) have become available since then.

Peter

[Highburymark]

On 06/05/2024 at 11:16, Mark SW said:

I asked that question about H-β August 2021 and the response was not what I expected.

S&T editors (Steve) (deepskyforum.com)

from the same source

"j.gardavsky here are some of my H-Beta nebulae as observed through my 6" F/5 achro and through the binoculars, but still not included the LBNs and the nebulae from the HII surveys from my last observin projects."
 

Thank you 

Mark

 

He also uses exceptional eyepieces for faint nebulae hunting - the very best Leica and Zeiss microscope EPs.