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UHC filter Question

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#1 Ken Watts

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Posted 16 September 2019 - 06:29 PM

Do UHC filters change the visual color of stars and nebula?  I am asking this because I bought a "Nebula filter" about 40 years ago because everything was tinted a light pink/purple and I had difficulty focusing.

 

 



#2 DLuders

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Posted 16 September 2019 - 06:52 PM

They're not supposed to.  Here's a good article about "Useful Filters for Viewing Deep Sky Objects" -- the UHCs are discussed halfway down the webpage  https://www.prairiea...ep-sky-objects/      smile.gif 


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#3 macdonjh

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Posted 16 September 2019 - 07:12 PM

My Tele Vue Nebustar filter turns everything blue, my Lumicon UHC gives things a reddish tint, but more subtle and easier to ignore than the blue from my Nebustar.



#4 noisejammer

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Posted 16 September 2019 - 07:30 PM

I've noticed that some UHC filters produce a red ghost image of stars. I think this is caused by a pass band around the H-alpha line (656.3 nm) . It's a bit weird and may sensitise the observer to the blue light from the rest of the field.

 

Not all UHC's do this - my Lumicon does not but my NBP does. My old Meade oxygen filter used to do something similar.



#5 MitchAlsup

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Posted 16 September 2019 - 07:36 PM

Do UHC filters change the visual color of stars and nebula?  I am asking this because I bought a "Nebula filter" about 40 years ago because everything was tinted a light pink/purple and I had difficulty focusing.

Once a UHC filter takes out most of the stelar light, what is left arrives at the eye.

So you loose, the orange, yellow and most of the green part of star light.

This will make the far green, blue, and red portions* appear brighter.

 

In my 20+ YO Lumicon, most stars take on a red hue.

 

(*) some UHC filters let red through, others do not.


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#6 Starman1

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Posted 16 September 2019 - 10:09 PM

If the only wavelengths that pass the filter are blue-green, it shouldn't surprise you that stars appear to be blue-green.

Some UHC narrowband filters pass reds as well, so you could see a faint trace of reds mixed in with the blue green.


Edited by Starman1, 16 September 2019 - 10:12 PM.

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#7 Jon Isaacs

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Posted 16 September 2019 - 10:33 PM

If the only wavelengths that pass the filter are blue-green, it shouldn't surprise you that stars appear to be blue-green.

Some UHC narrowband filters pass reds as well, so you could see a faint trace of reds mixed in with the blue green.

 

:waytogo:

 

This what H-Beta, O-lll and UHC (= H-Beta + O-lll) do, they only pass specific narrow bands of green light.  Some pass a bit of red as well. This greatly enhances the contrast of appropriate nebulae.

 

Brighter stars will show the color. 

 

Jon



#8 Ken Watts

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Posted 16 September 2019 - 11:02 PM

Thank everyone for the input.  Right now, I will sit tight and not get a filter.   There are at least 3 astronomy clubs in the area and I plan on visiting them.  Maybe at a star party or public outreach some one will let me look through one.  Then I will be able to make a decision.

 

Everone,

 

Clear Skies and steady seeing!

 

Ken W



#9 Starman1

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Posted 16 September 2019 - 11:07 PM

Be prepared to be shocked how much of a difference a filter makes.


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#10 macdonjh

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Posted 17 September 2019 - 06:20 AM

Be prepared to be shocked how much of a difference a filter makes.


+1, if you want to see nebulae, buy the filter now. If you want to just dip your toe in, buy a 1-1/4" Ultrablock from Orion. After your socks are blown off, you can start a thread asking which is the best premium UHC. Or... do a search for one of the existing threads.

#11 Mike W.

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Posted 17 September 2019 - 07:27 AM

A word of caution when purchasing a filter from a private party, some are absolute dud's like the Lumicon I purchased, granted it was an older one.

The seller claimed great views, I included it with a batch of filters I recently had checked, it was pathetic.

My Celestron LPR put it in the dirt performance wise.

 

If you're going to get one, get the new Gen Farpoint UHC, very good quality control with them.


Edited by Mike W., 17 September 2019 - 07:37 AM.


#12 aeajr

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Posted 17 September 2019 - 07:29 AM

Thank everyone for the input.  Right now, I will sit tight and not get a filter.   There are at least 3 astronomy clubs in the area and I plan on visiting them.  Maybe at a star party or public outreach some one will let me look through one.  Then I will be able to make a decision.

 

Everone,

 

Clear Skies and steady seeing!

 

Ken W

Generally, outreach events are set up to show the showcase items like a planet or the Moon.  Unlikely someone will be set up with nebula filters unless it is a really dark site.

 

My suggestion is to contact the President, ask when they might have a club event that you could visit where you could ask people to bring their filters and to have a discussion.   Or ask to be directed to someone in the club who is focused on this kind of stuff.

 

What you are asking is not something that would necessarily be available at a public outreach event. But I am sure you could find someone to discuss it and perhaps set up an observing session for another time. 


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#13 Mike W.

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Posted 17 September 2019 - 08:20 AM

If you want a better understanding of how filters work, the different types, ad so forth, go to Searchlight and start working the graph,

click the box next to the filter you're interested in to toggle it on or off the graph, you can stack as many as you want on top of each other for comparison.

He just added most of mine on the main page.

 https://searchlight....9d-153d7e7c0eb8

 

Take your time and learn how to use the system, and on this link you'll see the Lumicon UHC I mentioned.

https://searchlight....bd-5235228cb75a

 

And when the page first comes up you'll see the two NPB's in my collection.

 

Personally I love to use filters, they seem to change a bit each time I use them, but that's due to seeing conditions and what light the atmosphere is blocking at the time, lots of pollution up there above our heads,,,,,,,shocked.gif


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#14 Miranda2525

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Posted 17 September 2019 - 10:07 AM

Do UHC filters change the visual color of stars and nebula?  I am asking this because I bought a "Nebula filter" about 40 years ago because everything was tinted a light pink/purple and I had difficulty focusing.

Yes, they do, but it isn't a concern because the filter is to bring out more detail of the nebula. Stars are of no concern. As long as you can get a sharp focus on a star nearby, the filter is of use. 

 

But, that depends on the type of filter used. The Celestron UHC-LPR isn't really a "UHC" filter. It is more like a "broadband" or "deep sky" filter.

 

Some good filters below:

 

Lumicon UHC (newer type)

DGM NPB

Astronomik UHC

Orion Ultrablock


Edited by Miranda2525, 17 September 2019 - 10:10 AM.

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#15 Miranda2525

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Posted 17 September 2019 - 10:15 AM

If you want a better understanding of how filters work, the different types, ad so forth, go to Searchlight and start working the graph,

click the box next to the filter you're interested in to toggle it on or off the graph, you can stack as many as you want on top of each other for comparison.

He just added most of mine on the main page.

 https://searchlight....9d-153d7e7c0eb8

 

Take your time and learn how to use the system, and on this link you'll see the Lumicon UHC I mentioned.

https://searchlight....bd-5235228cb75a

 

And when the page first comes up you'll see the two NPB's in my collection.

 

Personally I love to use filters, they seem to change a bit each time I use them, but that's due to seeing conditions and what light the atmosphere is blocking at the time, lots of pollution up there above our heads,,,,,,,shocked.gif

Awesome graph !!! Thanks for the link!  



#16 Mike W.

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Posted 17 September 2019 - 12:59 PM

The second link is to the batch I sent him of my personal filters, the DSO filters, save for the poor Lumicon UHC, are all very good, and as I expected them to be.

But what I find most interesting are the specialty planetary filters. 


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#17 Mike W.

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Posted 18 September 2019 - 07:59 AM

I was just clickin' filters on and off and noticed that the Lumicon UHC has almost the same pass but on a different band-wave as the continuum, it will be a different view to use in my solar scope, should be a bit closer to blue than green, might turn out to be a winner after all laugh.gif

 

It's the opportunity that that site and Oggie's efforts that has afforded me the knowledge, thanks LunarFox!


Edited by Mike W., 18 September 2019 - 08:01 AM.



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