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Last night I used a UHC filter for the first time in my ED 80. Whilst it gave a slight improvement on the Orion nebula and Andromeda it gave a funny red and green colour to the brighter stars. This was not evident with the filter removed.  Is this normal or do I have a rubbish UHC filter.

Cheers

Steve

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Mine makes the stars green too. It's Explore Scientific. It also gives me a slight improvement on the Orion Nebular. On the (big) plus side, I can see the Veil with it.

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I have a Lumicon UHC, supposed to be one of the best and mine also presents stars as green blobs with a tiny red dot in the bottom right, I call it the 'Christmas tree effect' I think it's fairly common with UHC filters, probably because different colours in the light spectrum aren't converging fully or something to that effect. I use my OIII mostly, so it doesn't bother me a lot but can get annoying if viewing with it for a long period. I've seen this green/red phenomenon discussed on one of the forums in more detail.

My next filters will be the DGM NPB set hopefully.

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It will depend upon the band pass of your respective filters to some extent.  Green I understand, because you want that part of the spectrum for your OIII and red for your Ha.  I have a 1.25" visual Astronomik UHC filter which is nothing short of spectacular on M42.  The filter produces no aberration at all and the stars dim slightly (obviously) whilst the nebulosity becomes granular.  Last week during our last event at LTO, the public commented on how the filter produced a '3D effect' on M42 (through my ED80). On the veil though my Baader OIII prevails due to the high proportion of OIII revealed.

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Thanks for the replys. I guess it's doing what it's designed to do.

Steve

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My explore scientific is the same, I just try to ignore the stars and concentrate on the gas.

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21 hours ago, domstar said:

Mine makes the stars green too. It's Explore Scientific. It also gives me a slight improvement on the Orion Nebular. On the (big) plus side, I can see the Veil with it.

 

1 hour ago, Pete Presland said:

My explore scientific is the same, I just try to ignore the stars and concentrate on the gas.

I too have the Explore Scientific, (1.25") ...I don't know if I even have noticed it. 

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I currently have the 2 inch Explore Scientific UHC and an older 1.25 inch Meade (Japan made) 4000 series UHC and both show a similar effect on stars to that described above.

 

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These filters make the stars blue-green because they pass O-III and H-beta light very efficiently, blocking much of the rest of the spectrum. They also pass H-alpha and S-II, but the dark adapted eye tends not to be very sensitive there. Sometimes I do pick up some red on bright stars

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