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Badder Fringe Killer vs. 495 Long-Pass Comparison

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#1 Dave Lee

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Posted 09 February 2014 - 03:05 PM

I have a Vixen 'Neoachromat' (140mm refractor, 4 element Pertzval but no exotic glass, 800mm focal length). From what I understand the Pertzval design gives the optics the color correction of a 140mm traditional achromat of around f11 to f12 (and a pretty flat field).

Tonight was not much of an evening for anything (71% moon, high cirrus clouds wandering all over the place, etc). Not long ago I had purchased both a Baader Fringe Killer filter and a Badder 495 Long Pass (basically a yellow filter). I thought that I'd give them a try on Jupiter tonight as the evening was not good for much of anything else.

The scope had a good 90 minutes of cool down time and seeing was at least not horrible. However out of focus star images still had something of a 'boiling around' look. So clearly this was not great seeing by any means. I spent a good 30 minutes on Jupiter using a Televue 2.5x Powermate ("Barlow") and the following EP's.

1) 10mm Agena SWA (200x)
2) 8mm Baader Hyperion (250x)
3) 6.7mm ES 82* (298x)

Note that I AM NOT an accomplished planetary astronomer and have very little experience with refractors. The Vixen is my first refractor and I have only owned it a few months.

Obviously there were 9 combinations of EP's and filters (or no filters). My impressions in no particular order.

1) Over-all (on this evening with this equipment) I had a slight preference for the Fringe Killer (and 8mm Hyperion EP/Powermate). But the differences were not huge from my perspective other than the fact that the 495 'yellowing' was something that I did not care for. The Fringe Killer did this as well, but (from my perspective) to a much less objectionable extent.

2) A purple fringe was obvious without the filters (with all EP's). But to me the fringe itself was not important (the fringe does not bother me). What I was most interested in was if the filters might sharpen things up a bit (maybe removing some unfocused light from the target viewing area). My conclusion was that they both did sharpen things just a bit, but the difference was very small. Both filters pretty much removed all the purple fringing (but maybe not 100%).

3) From a 'what was seeable' perspective the two major belts were very obvious as you would expect. After maybe 10 minutes of viewing you could begin to see a hint of structure in both belts (not well defined). And a hint of 'stuff going on' outside the belts was showing up as well. My impression was that this was most viewable using the Fringe Killer. But the differences were small. From my understanding the GRS was not visible early evening (eastern US) on 2/8/14. However, I do believe that there was a shadow transit viewable at that time (easily visible filters or not). Ganymeade maybe?

4) This is the first time that I had really spent any serious time looking at Jupiter. My impression is that there is a skill involved here (one that I have not yet acquired). And maybe with better developed observing skills my filter preference would change. But I really didn't care for the yellowing created by the 495 long pass.

5) The view using the 6.7mm ES eyepiece (almost 300x) did not really break down, but it also didn't reveal anything that you could not see just as well with a lower power EP. And it wasn't obvious to me that the (less expensive) SWA EP (200x) was yielding views inferior to the 8mm (250x) Hyperion. But I somehow developed a preference for the 8mm, although for the first 10 minutes or so my preference was the 10mm SWA (for whatever reason).

The impressions of an 'unskilled planetary observer'.

dave

#2 Dave Lee

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Posted 10 February 2014 - 05:23 PM

An interesting review of several CA filters is documented here

http://tinyurl.com/kxjfjv4

I assume that the reviewer is of much higher observing (and experience level) than am I. And toward the end of the review is a very specific statement regarding the Vixen NeoAcromat and the FK vs. 495 filter (vs. what I stated in my review). And the results are basically opposite of my own stated results.

Given my lack of experience here I would tend to think that my review is totally wrong. OTOH, the quoted review says that the Vixen NeoAcromat becomes useless for planetary observations above 100x (without filters). This sounds completely wrong to me so maybe reasonable folks should ignore both what I posted and the link I provided. You are most welcome :foreheadslap:

dave

#3 Jim Curry

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Posted 10 February 2014 - 05:47 PM

Dave,
You reported what you saw. Thank you. There's nothing wrong with your report. After you've observed Jupiter for a while report back on this thread with any updates of your impressions.

#4 Vondragonnoggin

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Posted 10 February 2014 - 06:12 PM

If you like the effect of the fringe killer, but do not care for yellowed views (as with me, I do not care for them either), then try a semi-apo filter from Baader. this is a combo of the fringe killer and Moon and skyglow filter and returns the yellow view to white.

After trying the FK by itself and the semi-apo, I sold the FK filter for the more natural color view of the semi-apo. The Moon and skyglow features will dim the image slightly, but you already are at 140Mm objective and I would think that dimming would not be an issue with that much aperture already. the Moon and skyglow has a great reputation for contrast boost and is used by quite a few reflector owners on planetary already. As described by a CN review - It darkens the sky background without dimming the object viewed. But check out the reviews yourself first.

Just my two cents.

#5 Vondragonnoggin

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Posted 10 February 2014 - 06:21 PM

An interesting review of several CA filters is documented here

http://tinyurl.com/kxjfjv4

I assume that the reviewer is of much higher observing (and experience level) than am I. And toward the end of the review is a very specific statement regarding the Vixen NeoAcromat and the FK vs. 495 filter (vs. what I stated in my review). And the results are basically opposite of my own stated results.

Given my lack of experience here I would tend to think that my review is totally wrong. OTOH, the quoted review says that the Vixen NeoAcromat becomes useless for planetary observations above 100x (without filters). This sounds completely wrong to me so maybe reasonable folks should ignore both what I posted and the link I provided. You are most welcome :foreheadslap:

dave


I wouldn't say that. remember that personal preferences can vary as does the physiology of individual eyes in both color perception and a detail. This is why you'll find that some complain loudly about CA levels while others aren't bothered too much by it.

I'm going to quote a member of another forum (thanks JFD from Astronomy Forums)on this same type of discussion as I thought his post quite meaningful:

"1.
...there is no general agreement on the illuminance level that effectively inactivates cones or rods. Estimates vary by tenfold...''
2.
''Being bio-engineered, eye optics is far from (the) high standards of a quality telescope. However, due to its small aperture and
low magnification, significant aberrations generated by it generally do not have much of an effect on the perceived image quality.
3.
''Eye spectral response is directly related, and influenced by light intensity...''
4.
''...there are two basic types of retinal photo-receptors, cones, responding to bright-light conditions, and rods
responding to low intensity light...''
5.
''By combining their inputs the brain creates color.''
6.
''(The) human eye generates significant chromatic aberration, in the form of primary spectrum and lateral chromatism.
While most of the false color is filtered out during neural processing, negative effect... ...on image contrast remains.''
7.
''Perception of chromatic error is also somewhat attenuated by the retinal cone distribution.''

1. http://www.telescope....l_response.htm
2. The human eye
3. http://www.telescope....l_response.htm
4. same as 3
5. same as 3
6. http://www.telescope..._chromatism.htm
7. same as 6
8. same as 6

Conclusion:
So, the brighter an object, and the more centered it is in the eye or eyepiece, the more prone it is to chromatic aberration - if
your eye 'switches' to color. The number and 'health' of your rods / cones determine what level of CA is passed on back
for neural processing. And you brain filters it some more.
Since our eyes color response differs, (think color-blindness, see: figure 232 @ 8.) the level of perceived CA changes
from person to person, as does color perception. It seems every object in the chain
of perception requires correction - the objective, the eyepiece, the eye and for some, the brain."

#6 Dave Lee

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Posted 10 February 2014 - 06:23 PM

If you like the effect of the fringe killer, but do not care for yellowed views (as with me, I do not care for them either), then try a semi-apo filter from Baader. this is a combo of the fringe killer and Moon and skyglow filter and returns the yellow view to white.

After trying the FK by itself and the semi-apo, I sold the FK filter for the more natural color view of the semi-apo. The Moon and skyglow features will dim the image slightly, but you already are at 140Mm objective and I would think that dimming would not be an issue with that much aperture already. the Moon and skyglow has a great reputation for contrast boost and is used by quite a few reflector owners on planetary already. As described by a CN review - It darkens the sky background without dimming the object viewed. But check out the reviews yourself first.

Just my two cents.


Thanks for the suggestion. Being an engineer my instincts are to 'follow the numbers'. But the more I get into this the more 'the right decision' seems to be a very personal kind of thing. So maybe the semi-apo will be my 'thing' where others will prefer the 495 Longpass. Only I can make that determination.

Thanks.

dave

#7 Dave Lee

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Posted 10 February 2014 - 06:26 PM

Von, most interesting input (and worthy of serious investigation). Thanks!

dave

#8 ohioalfa64

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Posted 10 February 2014 - 07:52 PM

Thanks for posting this. While inconclusive, it provides more first hand experience from use of the Vixen 140 NA and the popular filters. While there may be no single answer, and individuals will view things differently. I enjoy reading your preferences with specific eyepiece selections. The ES 6.7 mm is my shortest FL eyepiece currently.

#9 Jay_Bird

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Posted 10 February 2014 - 07:54 PM

Informative review with lots of method and observation details in best scientific spirit Dave, thanks.

I alternate between seeking filters to control CA on my achromat -- or not looking at brightest stars, Venus, and Jupiter...

#10 Dave Lee

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Posted 10 February 2014 - 08:19 PM

An interesting review of several CA filters is documented here

http://tinyurl.com/kxjfjv4

I assume that the reviewer is of much higher observing (and experience level) than am I. And toward the end of the review is a very specific statement regarding the Vixen NeoAcromat and the FK vs. 495 filter (vs. what I stated in my review). And the results are basically opposite of my own stated results.

Given my lack of experience here I would tend to think that my review is totally wrong. OTOH, the quoted review says that the Vixen NeoAcromat becomes useless for planetary observations above 100x (without filters). This sounds completely wrong to me so maybe reasonable folks should ignore both what I posted and the link I provided. You are most welcome :foreheadslap:

dave


In retrospect the review linked above represents (a very extreme version of) what I thought the difference between a skilled vs. unskilled observer's impressions might be. The commonality is that there is an improvement available (via the filters) beyond just removing the obvious fringing.

dave

#11 Vondragonnoggin

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Posted 10 February 2014 - 09:19 PM

FWIW - All my observations of Semi-Apo and Fringe killer use were on an Explore Scientific AR127 F/6.5 achro, which is a bit smaller than the 140 and less corrected for flat field.

I believe that useful planetary observations can be had from an achromat in high mags if the focal ratio and quality/correction of the optics is good to start off with. the Vixen NeoAchro is no slouch when it comes to quality. It has good reviews and many happy owners.

here is my observations on Mars with ES AR127 and Semi-Apo Filter

#12 ohioalfa64

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Posted 11 February 2014 - 03:15 PM

For reasons I do not fully understand the Vixen 140NA people here do not prefer the Semi-APO filter for planetary viewing. I have only heard one in the past year mentioning using the Semi-APO. That person left it in the diagonal, and used it 100% of the time for all viewing. the 495 Long-Pass gets much more attention by writers here.

#13 russell23

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Posted 11 February 2014 - 04:01 PM

For reasons I do not fully understand the Vixen 140NA people here do not prefer the Semi-APO filter for planetary viewing. I have only heard one in the past year mentioning using the Semi-APO. That person left it in the diagonal, and used it 100% of the time for all viewing. the 495 Long-Pass gets much more attention by writers here.


Several reasons:

1. The Semi-APO filter is no better at CA reduction than the FK. And both reduce CA by 50-60%. But the Semi-APO cuts into the middle of the visible part of the spectrum to re-establish a neutral tone. The cost of this neutral tone is a dimmer image and lost information. So why not just go with the FK or a #8 light yellow? The FK also works for deep sky with very little detectable dimming.

2. The 495 Longpass eliminates violet CA completely - not just 50-60%. It removes the defocused light while leaving 95+% of the focused light. It is more effective than the FK and semi-APO at sharpening views. It is also effective for deep sky because it does not cut deeply into the 500-700nm part of the spectrum like the semi-APO.

I used to leave a FK on my diagonal. Now I leave the 495 Longpass on my diagonal. The difference between the two filters is like the difference between just sweeping a floor vs vacuuming then mopping.

Hope that helps.

Dave

#14 Kon Dealer

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Posted 11 February 2014 - 06:18 PM

I think the semi-APO is rubbish.
I see no evidence of CA removal, just a general dimming of the view. :mad:
Now a light yellow filter kills any CA stone dead and only imparts a slight yellow cast- which you soon get used to.
Alot cheaper too :grin:

#15 *skyguy*

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Posted 11 February 2014 - 09:40 PM

But the Semi-APO cuts into the middle of the visible part of the spectrum to re-establish a neutral tone. The cost of this neutral tone is a dimmer image and lost information



This "blocking out" of the middle part of the visible spectrum is distinctly seen in the spectrograms of the Semi-APO and other CA filters on this German site:

CA Filter Tests

A comparison spectrogram of the Baader 495 Long-Pass filter can been be seen ... HERE

I've seen some dramatic improvement in image sharpness and CA reduction in the limited photographic tests I've done using the Baader 495 Long-Pass filter versus no filter on achromatic refractors. The "blue fog" that permeates and reduces resolution in the unfiltered images is completely removed when using the 495 Long-Pass filter ... resulting in a significantly sharper image with greater contrast. The yellow color imbalance can be corrected fairly easily using Photoshop. I'm patiently waiting for the warmer spring weather to get out and try some deep-sky imaging using my achromatic refractor and the 495 Long-Pass filter.

#16 Vondragonnoggin

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Posted 11 February 2014 - 10:36 PM

I would encourage others to look at those spectrograms, then read some reviews on the M&SG filter. Very similar cuts to semi-Apo, but much more blue cut in the semi-Apo. Clearly shows how it can return a more neutral view (compared to FK filter). The Longpass has much deeper cut in blue.

My eyes don't have photoshop built in and not an imager, so yellow is out for me. Couldn't get used to it.

Now blue/green stars from a UHC I can live with for some reason, but the yellow is not to my taste.

#17 dbowlin

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Posted 12 February 2014 - 07:13 AM

I have used the 495 filter for solar with the Baader film and wedge, it works great. I have not tried it at night. I will when weather and time permit. I expect similar results, no ca and sharper views.
Dale

#18 jgraham

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Posted 12 February 2014 - 07:37 AM

I've used both the Baader Fringe Killer and Semi-Apo filters in my 6" f/8. I didn't like the yellow cast from the Fringe Killer, but found the Semi-Apo to be very nice. I observe under red-zone skies and the modest light pollution suppression of the Semi-Apo is a bonus. The Semi-Apo lives in the star diagonal of my scope. You should be able to get a similar result by combining a minus violet filter with a light pollution filter like the Hutech IDAS LPS2. I did this for a while, but migrated back to the Semi-Apo for simplicity.

#19 Jon Isaacs

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Posted 12 February 2014 - 09:16 AM

Dave:

I read your Astromart article. I thought the images were quite informative, they definitely show the differences in color balance. I am not exactly sure how they translate to the night sky but I have to think that the strong yellowing of that some of the filters show would be seen on brighter targets.

Jon

#20 russell23

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Posted 12 February 2014 - 10:04 AM

Dave:

I read your Astromart article. I thought the images were quite informative, they definitely show the differences in color balance. I am not exactly sure how they translate to the night sky but I have to think that the strong yellowing of that some of the filters show would be seen on brighter targets.

Jon


You are correct Jon. As described in the article, the Moon, Jupiter, and bright stars are yellow. Instead of white with a purple halo bright stars like Vega appear a beautiful golden yellow. I also described what the 495 Longpass did with Albireo. Instead of blue and gold, Albireo appears white and yellow orange. For deep sky observing there color shift isn't noticeable. The improved sharpness is what the filter really does that matters.

Dave

#21 SStoffer

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Posted 08 August 2014 - 11:51 PM

I'm having a really hard time trying to decide which of these two different filters to try for my ES AR102 refractor.  As of the moment I am leaning towards the Baader Fringe Killer. 

 

I hope that it removes some of the scintillating rainbows of light surrounding close binary stars. 

 

 

Stephen



#22 russell23

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Posted 09 August 2014 - 08:18 AM

Stephen,

 

I would go with the #8 light yellow over the fringe killer.  I compared the Lumicon #8 with the Fringe Killer and 495 Longpass filter.  The #8 performed exactly the same as the fringe killer and costs a lot less.  Both filters reduce the CA about 50-60%.  The 495 LP completely eliminates the purple CA.  I've moved on to the 495 LP for my vixen 140NA but with your scope the #8 might be sufficient.

 

Dave

 

I'm having a really hard time trying to decide which of these two different filters to try for my ES AR102 refractor.  As of the moment I am leaning towards the Baader Fringe Killer. 

 

I hope that it removes some of the scintillating rainbows of light surrounding close binary stars. 

 

 

Stephen



#23 stevew

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Posted 10 August 2014 - 07:38 PM

Is there any filter for reducing c/a that does not turn the subject object yellow?

 

steve



#24 Sarkikos

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Posted 10 August 2014 - 07:46 PM

SemiApo or Baader Moon & Sky Glow. 

 

Mike



#25 russell23

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Posted 11 August 2014 - 07:21 AM

Steve,

 

I would recommend you take a look at the transmission curves for the Baader filters posted on the Agena website.   Restoring a neutral color is achieved by taking significant cuts to the visible part of the spectrum that an achromat does focus.  The FK leaves the 500-680nm wavelengths alone for the most part.  So doesn't the 495 Longpass.  The only way to remove the <500nm defocused light and maintain color neutrality is to also remove light that is normally focused by the achromat.  That will lead to some dimming of the image.  The reason I recommend the 495 LP for a large achromat is that it completely eliminates CA while keeping the 500-700nm wavelengths at 95% or better transmission rate.  If you really can't take the color shift then a #8 light yellow will cut the same amount of CA as the Baader Fringe Killer ~50%.

 

Incidentally, when I tested these filters on the Moon with my Vixen 140 NA, the moon was lavender colored without the filter - not just purple fringed, but lavender across the surface.  The #8 restores a white appearance to the Moon's color.  So depending upon your scope and eyes you might find a light yellow filter does give a reasonably neutral color.  

 

If your eyes are so sensitive to the color shift that you cannot adapt then you might want to consider an APO or the light loss that goes with the semi-APO filter.  But I think the color shift may be one of these things that people run away from before they have really given themselves a chance.  I rarely notice the color shift of the 495 LP filter for DSO unless the stars are really bright in which case the are a beautiful golden color like Capella.

 

Dave








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