fringe killer filter

[Purplehayze104]

Hi All

just browsing FLO site and came across some fringe killer filter that apparently cuts down on C.A thru normal fractors, anyone had any use of them & are they any good ?

john

[Moonshane]

if for imaging why not use your CA free newtonian?

I tried a fringe killer once but it created a very obvious yellow tint which I like less than the CA.

[John]

I used a William Optics MV-1 filter with a 6" F/8 refractor for a short while. I did reduce the visible CA around bright objects but, as Shane says, it also introduced a tint to the image that I was not keen on.

[JG777]

I looked into these as well some time back and they did not seem to be that popular, maybe OK under some circumstances, thought about whether it would help out a ST120, then decided probably not from the replies. As said you have the newt. I have an APO as well so no sleep lost over the filter!

[m37]

I have a small Skywatcher refractor (achro) and I've found my Baader fringe killer very effective at greatly reducing (though not eliminating!) blue/violet halos, and without too much discolouration. If the clouds are elsewhere tonight I will post a side by side comparison for you tomorrow so you can judge for yourself.

cheers

[rwilkey]

For achromatic refractors I think they are useful, the Baader Fringe Killer is good but the Baader Semi-Apo is even better, also the WO VR-1 minus violet filter is also great. NB. that these are intended for visual use not AP.

[m37]

Dead cable, will try again tonight for you!!!

[Tonys]

I bought the Fringe Killer for my Evostar 120 and I find that while it does reduce the CA for the moon, Jupiter and Saturn considerably it doesn't help me to see any more detail or make for a more pleasing view, at least to my 50+ year old eyes. It works well on Venus though, sharpening it up. I think it's more effective with short tube refractors like the Startravels, as m37 has found. I don't find the yellow colour a problem but maybe that's because I'm a fan of Russian eyepieces!

[Macavity]

The transmission curves suggest that several of these filters have... commonality.

I always think it strange that the Fringe Killer only reduces the violet region to 50%

- Why not 25%... 10%? Live dangerously! Maybe even try "double stacking" them?

Though, as others suggest, there are perhaps more "interesting" filters to explore...

[JG777]

Dead cable, will try again tonight for you!!!

Be good to see some images, hope your in luck!

[Purplehayze104]

thanks for the replies

i do like to use my newt, but have found trying to focus my camera (Nikon 3100) bit of a challenge looks great in the image till you zoom in to see if they pinpoint but usually end up like lil doughnuts. DSS doesn't like em so stacking has been an issue.

[m37]

Be good to see some images, hope your in luck!

Yes it would!!! Pesky cloud...

[jgs001]

I have the Fringe Killer, the Contrast Booster and the Semi APO filters, they all work to a greater or lesser degree. Personally, like the others, I do not like the yellow colour tint the FK and CB filters produce, so opted to use the Semi APO filter. It's not as strong on the CA reduction as the other to, but produces a more natural colour which I found better, and could live with the CA that remained.

Take a look at http://stargazerslounge.com/topic/30187-baader-ca-filter-comparison/ for an attempt to capture the different colour casts. The Konus Vista 80 I have is basically the same optics as the ST80.

[m37]

It's cold and raining and I'm bored so I compared the FK with an unfiltered image in daylight.

Definite yellow colour cast due to the reduced blue but it balanced out more or less OK in PS. Decent reduction in CA too I think. 

I reckon a nice APO would reduce it even further; if anyone fancies buying me a 150 Esprit Pro I'll gladly post some comparison pictures of that too

[Donkeiller]

Nice comparison, M37. I have recently done a back-to-back with a Baader semi-APO and a Wratten #8 filter.

The £8 Wratten #8 (see curve here http://motion.kodak.com/motion/Products/Lab_And_Post_Production/Kodak_filters/wrattten2.htm#s1) removes allmost all C.A. and leaves on a slight yellow tint (much less than #12), whilst the £58 semi-APO

removed alot less C.A. and noticeably dimmed the image.

Also compared transmissions using a home-made spectograph.

#8 removed higher frequency blue/purple, whilst semi-APO had a marginal effect , but cut out the yellow wavebands. Maybe it is better as a L.P. filter?

[m37]

Nice one Donkeiller, might be worth a look...