EOS Clip-Filters

[NorthernLight (Max)]

Hi Guys,

a while ago I purchased an Astronomik CLS EOS Clip-Filter with the objective to get rid of the heavy Melbournian light pollution and allow for longer exposures under sub-urban skies.
I had good visual experience with the 1.25" Astronomik UHC eyepiece filter but wanted something that would be of more general use, not only for nebulae (and of course could be used with the EOS at prime).
Confusion regarding the wavelenghts of the majority of celestial objetcs (apparently they are all a bit different, so there can´t be a one fits all filter) led me to ask in a shop and they advised the CLS filter would be the best solution.
I purchsed and gave it a shot. The outcome wasn´t too great:
all picturs taken through the CLS clip come out blue and stars look out of focus and unnatural. It looks a bit as if the filter does nothing else than making the whitish sky-glow appearing blue (and all objects in the FOV) because the contrast of a galaxy e.g. is not really improved and the surrounding sky looks almost as in daylight.
I am now assuming that the CLS isn´t really a general purpose sky glow filter but a filter for special objects. If that is true:
Can someone please tell me what it is for?
If not:
am I doing something wrong?
And could you please advise what EOS Clip-Filter would be a better solution?
I am looking forward to your advice.

[rcheshire (Rowland)]

There is a new version - here. The performance graph off to the side provides an explanation and indicates the design performance of the filter - may assist with your question.

Reading further, the CLS is designed for black and white photography and CCD imaging. Reading between the lines, it's not really intended for colour work. I think that's where the CLS-CCD comes in - but I have yet to see the results.

Happy to post some daylight shots for comparison - no chance of AP at the moment.

[dugnsuz (Doug)]

Hi Max,
I believe the CLS filter is a visual light pollution filter. A better solution for photography is the CLS CCD filter - I've used it but found it a bit harsh compared to the Hutech LP filter.
I had the EOS clip filter in both models (Astronomik and Hutech).
The Hutech one caused reflection problems when using camera lenses (not sure if this would occur with a scope though), the Astronomik model was fine - just didn't like the colur shift.

I now use the Astronomik EOS clip in filters for narrowband work (fun!).
I have the Ha,OIII and SII filters - the work very well.
Cheers
Doug

[NorthernLight (Max)]

thanks guys for the instant reply!

following the link it becomes a bit more clear why the colours are shifted towards the blue. maybe it is worth to do some b/w exposures with the filter and add to them to some without to see if it brings out more detail.

But I will definitely check out an OIII clip in as soon as I get a hold of one.

Do you guys think a Ha-filter is of any use on an unmodded 450D?

Weather here sucks too, only clouds for the last 4 weeks

Cheers

[bmitchell82 (Brendan)]

no filter will be any good in a un modded camera as the standard terrestrial filter that canon have cuts the ha band pass in any case. To use true narrow band imaging you need to do 1 of 2 things.

Get the camera modified (removal of the factory filter)
get a astro CCD


your other pass's should work though

O3
maybe even S2

[NorthernLight (Max)]

thanks Brendan,

yeh, thats what I thought. so I stick to the cls and may get an o3 later on. for now Im pretty happy with the unmodded eos and need a couple of years more "return on investment" with it anyways before moving up into the ccd range.
I had the sensor replaced recently by canon as part of the warranty because it produced some nasty green lines and I hadn´t had a chance to test the new performance. I am very curious what it brings especially under my new, much darker backyard sky. If just the bloody clouds would disappear!!!!
till then...

[dugnsuz (Doug)]

The Ha and OIII produce quite nice results with my modded 40D - the SII is a work in progress...long, high iso exposures required to bring out any detail as expected. I tried a quick 'Hubble Palette' test on Eta recently...
http://www.iceinspace.com.au/forum/s...ght=eta+hubble
...and the SII on its own...
http://www.iceinspace.com.au/forum/a...se.php?a=79138

Doug

[NorthernLight (Max)]

Hi Doug,

looks nice! you´ve got a lot of detail in your images but I guess it is quite hard to get the colours look naturally with the different influences.
Attached is what I got so far and without filters.
I think I can ramp up with exposure time and need some sharpening but for a start I think it is not bad.
I have an old astroguide book here from 1989 and compared to the shots in this book mine are stunning

[Tandum (Robin)]

Originally Posted by dugnsuz

SII is a work in progress...long, high iso exposures required to bring out any detail as expected.
http://www.iceinspace.com.au/forum/a...se.php?a=79138
Doug

Have you tried another target with the S2 doug? What you have there looks great. I don't see enough of Eta from here to try it but this is a half dozen 20minute subs of helix binned X2 out of the qhy9/10" newt and it is truely crap For me S2 is the hardest to get anything at all.

[dugnsuz (Doug)]

Originally Posted by NorthernLight

Attached is what I got so far and without filters.
I think I can ramp up with exposure time and need some sharpening but for a start I think it is not bad.

Looks pretty good Max

[dugnsuz (Doug)]

Originally Posted by Tandum

Have you tried another target with the S2 doug? What you have there looks great. I don't see enough of Eta from here to try it but this is a half dozen 20minute subs of helix binned X2 out of the qhy9/10" newt and it is truely crap For me S2 is the hardest to get anything at all.

Haven't tried the SII filter out on anything else yet - gear changes and weather working against me.
I'm not convinced that my SII Eta image is really all SII emission!
The object is so Ha-heavy that there must be some spill from all that data.
It would be nice to source some book or online resource that provided the relative proportions of Ha, OIII and SII in various objects.
Doug