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Equipment Discussions >> Refractors

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skywatcher101
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Reged: 07/13/10

Re: CA Reduction filters new [Re: azure1961p]
      #6115487 - 10/03/13 03:53 PM

Any test using the 495 long pass and a moon and skyglow filter to see if it brings out a more natural color?

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Jon_Doh
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Reged: 09/16/11

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Re: CA Reduction filters new [Re: azure1961p]
      #6115548 - 10/03/13 04:11 PM

The photos in the link I posted above clearly show astrophotography can be done with an achro and that the Longpass filter will remove all of the CA. The photos in that link show CA left with a semi apo filter, but none with the Longpass.

Skywatcher, I'm interested in that kind of test too. It would seem that it would help remove the yellow cast and be very useful on Jupiter. Curious too whether the combo would dim the viewing for stars too much.


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mikey cee
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Re: CA Reduction filters new [Re: azure1961p]
      #6115726 - 10/03/13 05:29 PM

Visually on a white surface that Longpass filter is a dead ringer for my Contrast Booster when compared with my #8 yellow. Has anyone checked the band pass characteristics between those two yet? They are probably different in some small insignificant way for us visuals but it still will turn the planets yellow just the same. No free lunch that's for sure. Mike

Edited by mikey cee (10/03/13 05:52 PM)


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russell23
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Re: CA Reduction filters new [Re: mikey cee]
      #6115896 - 10/03/13 07:05 PM

Quote:

Visually on a white surface that Longpass filter is a dead ringer for my Contrast Booster when compared with my #8 yellow. Has anyone checked the band pass characteristics between those two yet? They are probably different in some small insignificant way for us visuals but it still will turn the planets yellow just the same. No free lunch that's for sure. Mike




If you go to the Agena website both the longpass and the contrast booster transmission curves are published. The CB removes a lot of light that the 495 longpass let's through and would probably cause significant dimming - but might be better in light polluted areas.

Dave


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russell23
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Re: CA Reduction filters new [Re: azure1961p]
      #6115901 - 10/03/13 07:08 PM

Quote:

The white , or rather yellow elephant in the room with the Baader long pass is that strong yellow. I find the Fringe Killer is all the yellow I want on generalized targets before color shift begins to attenuate contrasts. That much yellow on Jupiter or terrestrial spotting or Saturn for that matter might be more hinderance than help. I'm impressed with the long pass on stars but I couldn't see carrying the baggage of that yellow on much else unless it waS to increase something like festoons in Jupiter or other bluer features.

Interesting filter though. I may get the Long Pass - just for limited use however. I'd be curious how it stacks with my Wratten 15 .

Pete




I suspect I may find the color shift a bit much for lunar/planetary, but for deep sky it seems to turn my scope into an APO-like performer.

Dave


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skywatcher101
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Reged: 07/13/10

Re: CA Reduction filters new [Re: russell23]
      #6118666 - 10/05/13 09:19 AM

Just checking in. Still has anyone stacked a moon and skyglow with the #8 or the 495 long pass ?

Just curious if it keeps the contrast and brings a more "natural" color.

Thanks


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Jon_Doh
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Reged: 09/16/11

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Re: CA Reduction filters new [Re: skywatcher101]
      #6118719 - 10/05/13 09:57 AM

Quote:

Just checking in. Still has anyone stacked a moon and skyglow with the #8 or the 495 long pass ?

Just curious if it keeps the contrast and brings a more "natural" color.

Thanks




I would like to know the answer to that too.


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skywatcher101
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Re: CA Reduction filters new [Re: Jon_Doh]
      #6118939 - 10/05/13 12:16 PM

Jon Doh.....yes interested indeed. I am trying to deside between a #8 or the 495 long pass and using a moon and skyglow.

Another question here is the moon and skyglow filter.....looking at the zhumell urban sky filter is it is comparable to the baader moon and skyglow.

Wondering if the baader is worth the 3x the cost to the zhumell. Anyone capare these two?


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Jon_Doh
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Reged: 09/16/11

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Re: CA Reduction filters new [Re: skywatcher101]
      #6119129 - 10/05/13 02:41 PM

All the Zhumell filters are reasonably priced, but I have no experience with them. I do have the Baader Skyglow and the Zhumell can't be any worse as the Baader by itself doesn't do very much.

In looking at what light these filters cut and what light they allow it would seem, at least on paper, that the Skyglow and Longpass would be a good match. CA would be eliminated and stars would be very close to their natural colors.


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skywatcher101
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Re: CA Reduction filters new [Re: Jon_Doh]
      #6119494 - 10/05/13 07:16 PM

( Jon Doh ) This is my thought as well. Think I may just get the long pass and the Zhumell filter combo.

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Niklo
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Reged: 03/29/13

Loc: Bavaria
Re: CA Reduction filters new [Re: skywatcher101]
      #6119575 - 10/05/13 08:23 PM

I'm curious how the yellow longpass filter of Baader performs compared to the fringe killer. It's probably darker. That could help to remove more purple but that could be bad for a 4" achromat because the view get's too dark.
I have a light yellow, filter, a fringekiller and a skyglow filter and a minus violet filter which has the least yellow but so far I haven't done a test series.
Clear skies,
Roland


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russell23
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Re: CA Reduction filters new [Re: Niklo]
      #6119685 - 10/05/13 09:46 PM

Quote:

I'm curious how the yellow longpass filter of Baader performs compared to the fringe killer. It's probably darker. That could help to remove more purple but that could be bad for a 4" achromat because the view get's too dark.
I have a light yellow, filter, a fringekiller and a skyglow filter and a minus violet filter which has the least yellow but so far I haven't done a test series.
Clear skies,
Roland




Roland,

As I summarized, the Fringe Killer knocks down the CA ~50-60% whereas the 495 longpass wipes it out on the blue end (I saw no CA on Vega and Altair with the 495 longpass) and leaves the faintest red CA.

For deep sky I did not see a dimmer view with the 495 longpass. If anything, it was even easier to pick out fine details and faint stars because of the increased sharpness that came with the elimination of the violet CA.

Vega and Altair looked white with a deeper purple fringe with the Fringe Killer and a beautiful golden yellow with the 495 longpass. For deep sky the color shift is of no real consequence, but I haven't yet had a chance to use the longpass for lunar/planetary yet so I will report back when I see how it does there.
Dave


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De Lorme
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Re: CA Reduction filters new [Re: russell23]
      #6120021 - 10/06/13 03:24 AM

Dave, What you said about the long pass filter is exactly
what I saw tonight! Even though the weather was bad{so I was only looking at open clusters }m29 and m39 looked very much improved. Stars were pinpoints of light. But what really amazed me was when I turned the CR6" on the Double
Cluster. The back ground sky was much blacker and the stars
were pinpoints of bright light;really good.
Thanks for going through the trouble of checking these filters out! I'm like you and others here, what's it going to be like on the Moon and Jupiter? I can handle a color
change if I get better contrast and clarity.
I'm going to wait on the Fringe Killer and Moon and Sky Glow
combination{ their not cheap like the Longpass} until I hear from others how the LongPass compares
to them on the Moon and Jupiter. This is a real improvement. Thanks again.
De Lorme


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Niklo
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Reged: 03/29/13

Loc: Bavaria
Re: CA Reduction filters new [Re: De Lorme]
      #6120075 - 10/06/13 05:29 AM

Hello De Lorme,
I tried the fringe killer on Jupiter and it removes the small purple fringe in my 4" f/11 but even the fringe killer makes a light yellow view on Jupiter. The contrast improves only a little bit. I think the more CA a refractor has the more helps the fringe killer or even the longpass. In my Vixen 80L f/15 the fringe killer is too much (I haven't tested it yet) and for a 6" f/8 a yellow longpass might be better than the fringe killer. That are my expectations. But I'm curious to hear your reports.
By the way is it the BA2458301 for 1,25 "?
I found it e.g. at
http://www.teleskop-express.de/shop/product_info.php/language/en/info/p521_Ba...
That's quite cheep so I can buy and test it. If it's too much the costs do not harm.
Clear skies,
Roland


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De Lorme
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Reged: 12/30/08

Re: CA Reduction filters new [Re: Niklo]
      #6120766 - 10/06/13 03:01 PM

Hi Roland, The BA2458301 is the Baader LongPass filter.
Really worth the price! I suspect that what Tommy5{under Filters Against Chromatic Aberration For Achromats} said
"even if you can't see ca, it is still smearing away low contrast planetary detail" is true. I'm waiting to see {reviews}if the Moon and Sky Glow{or some other filter}coupled with the LongPass will give better detail,contrast while taking away the yellow tint.
Does anybody know what combination will work?
Thanks for the info. De Lorme LONG LIVE CLOUDY NIGHTS!


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russell23
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Loc: Upstate NY
Re: CA Reduction filters new [Re: De Lorme]
      #6125729 - 10/08/13 07:35 PM

I just got in from a quick comparison of the Fringe Killer, #8 light yellow, and Baader 495 longpass on the Moon. The scope is my Vixen 140 Neo-achro. I used a 2.4x Dakin barlow and a 20mm ES68 so the magnification was ~96x.

The sky was not fully dark and the Moon is still low to the horizon so this was not the best conditions because of some turbulence near the horizon.

But as with the deep sky last week the Baader Fringe Killer and #8 light yellow had essentially identical performance. There was a residual purple fringe on the Moon's limb and some hints of CA on the disk. The color of the Moon was not yellow, but still a natural grayish-white with these two filters.

With the 495 longpass the Moon was yellow, but lunar features were sharper and ther was no purple fringe at all - just some faint traces of red CA - which I noted on the stars the other night.

Dave


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azure1961p
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Re: CA Reduction filters new [Re: russell23]
      #6126018 - 10/08/13 10:39 PM

I find the #8 wratten far too obtrusive to deny its there while the Fringe Killer lends a warm feel - almost like summertime haze yellowing. I can't see how the wratten 8 wouldn't make the moon anything but yellow.

Pete

Edited by azure1961p (10/08/13 10:39 PM)


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De Lorme
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Reged: 12/30/08

Re: CA Reduction filters new [Re: azure1961p]
      #6126221 - 10/09/13 12:57 AM

Looking at the Moon{very low in the sky almost setting} tonight with the Longpass and like Dave the yellow was there but not intrusive. What really caught my eye was how
the mountain ranges and craters stood out. A week from now the Moon will be high in the sky for most of the night.
With the weather getting much better I expect it will be great. Looking at Ngc 7009,7088 at almost zenith
with the filter on the stars were pinpoints of light;
so much better. I'm really glad I bought this filter.
I read somewhere the Moon and Sky Glow with the LongPass
took away the yellow on the Moon; is this true? If it is true would it dim the Moon/Jupiter?
Thanks De Lorme


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grzybu
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Reged: 10/09/08

Re: CA Reduction filters new [Re: De Lorme]
      #6126325 - 10/09/13 03:35 AM

If you want to experiment with rather extreme CA removal for Moon you should try Solar Continuum filter. Moon will be green, but sharpness and image stability will be much, much better. It works only for Moon or Sun, because SC filter is quite narrow band compared to FK or other filters. But it makes huge difference in my 4" F/5 achromatic refractor.
To use SC on Jupiter bigger aperture will be needed. I've tried it once with 11" SCT when Jupiter was low and views were great, with much better stability and sharpness.


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russell23
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Re: CA Reduction filters new [Re: azure1961p]
      #6126649 - 10/09/13 10:02 AM

Quote:

I find the #8 wratten far too obtrusive to deny its there while the Fringe Killer lends a warm feel - almost like summertime haze yellowing. I can't see how the wratten 8 wouldn't make the moon anything but yellow.

Pete




I think this is a great example of differences in sensitivity of people's eyes. I assure you that to my eyes when I put the # 8 in the optical chain it performs identically to the Fringe Killer. The moon looked no different to me in color than with the #8 than with the FK. The 495 longpass did give a yellow color. But I absolutely believe you when you say you see a yellow color with the #8. This is just more anecdotal evidence that everyone's eyes are different.

Dave


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