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Old 26-10-2013, 08:01 PM
stevous67 (Steve M)
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Astronomik CCD LRGB VS Astrodon Tru-Balance LRGB

Hi all again,

Still on filters...I've been using Astronomik CCD LRGB filters since I began imaging, but are growing frustrated with colour reproduction. It could all have to do with how I process the colour channels, but I am now thinking "no".

If others have made the transition from Astronomik filters to Astrodon, can I get some feedback on colours after making the transition. Did you notice the difference? Was it a positive experience?

Thank you for any feedback,

Steve

Last edited by stevous67; 27-10-2013 at 06:55 AM.
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Old 27-10-2013, 05:31 AM
stevous67 (Steve M)
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After feedback from Rick and Dave, I realise I need to expand this question. I have the STL11k (KAI) chip, and understand there are two versions of the Astrodon filters to consider. Apparently the I Series is the correct type, designed for the KAI chip.

To show my issue, I have linked below a recent shot of M20, with the suspect colours:

M20 - with suspect colour of the Ha

I do not change colours on processing, other than altering saturation and setting the range, and this washed out look of the Ha is as it was when looked at the colour data prior combination to the luminance data. I can blend the colour data without saturation loss.

This image contained 300sec subs at F8, binning 2x2. Looking at Peter wards last M20, the colouring is vastly different. I am guessing he uses Astrodon?

Another image that exhibits the same issue was a M42, having a washed out look and browny dust areas:

M42 with same browny dust and light Ha

What am I asking, should I consider moving to Astrodon filters to achieve better colour results? And has anyone made the change from Astronomik filters to Astrodon?

Thank you for having a look,

Steve
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Old 27-10-2013, 03:28 PM
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PRejto (Peter)
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Hi Steve,

There are so many variables to your question that I'm sure there is no clear answer! Certainlty there are absolutely terrific non-washed out images taken through Astronomik filters. Just look at Mike Sidonio's for example! In my opinion changing your filters is not the answer.

A more likely explanation is that it comes from the way you are procesing your data, or the amount of colour data that you collect (or both!). I'm fairly new to imaging but have found colour combining one of the hardest things to get right. It depends so much on the software. I had horrid results trying to use CCDSoft and vastly better results using CCDStack. One very helpful book you might want to read is by Ron Wodaski "Zone System For Astro Imaging." It contains terrific advice for colour balancing. Also, if you use CCDStack (from CCDWare) Adam Block's tutorials on CCDStack and Photoshop are great and well worth the price.

I think you might try boosting your colour using "lab colour" in photoshop. Perhaps you have tried this technique already (?). I find that it certainly makes for a vibrant image if used properly. Here is a non-astro imaging tutorial that ought to work very well:

http://digital-photography-school.co...with-photoshop

(If you don't like using curves to bring out the colour in the Lab colour channels you can try adjusting contrast instead.)

Peter
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Old 27-10-2013, 05:41 PM
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I have both. I used Astronomiks for a little while. At first I had a lot of trouble as they are very thin - about 1mm. My filter wheel was designed for 3mm thick so they were loose. As a resulta couple got damaged. Then Astronomik released a packer for them. That cost $100 for something that should have been released with the filters as they were unuseable for their intended use so that was not cool.

At that time filter wheels that could take thin filters did not exist as far as I know, they came later. So my opinion of Astronomik was negative right from that - they were very unprofessional to be selling filters that could not be used and when told ask for more money to make the defective filters work.

However imaging with them I found I could get a pleasant image without any hassles and I think they produce nice star colours in particular. These were Gen 1 without antireflection coatings and it was a while ago but I don't recall having too much of a reflection issue but there was some. Usually its the green filter that has worst reflections. If you are using a flattener or reducer then anti reflection latest versions of whatever brand are vital.

Astrodons though are the best. They fit. They are parfocal as claimed (Baader is not despite marketing nor are they 1:1:1 colour balance as they claim).

So I think its buyer beware in the filter industry with more than a little bit of marketing BS. But I have found Astrodon Gen 11 to not cause reflections, to be easier to colour balance and to be quite parfocal.

They are expensive but in my opinion worth it. Mike loves his Astronomiks so there is the other view. I was turned off Astronomik by the above and felt gouged and let down. But Mike's experience no doubt is very positive.

Astronomiks are also quite a bit cheaper, so perhaps that is an important point.

Greg.
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Old 27-10-2013, 08:18 PM
stevous67 (Steve M)
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Peter and Greg, thanks for your frank opinions. It could be due to my process. I calibrate to the letter of Adam Block's guide for CCDStack, I combine 1:1:1 and do not edit colour channels individually beyond noise reduction in CCDStack. I used PS to set my RGB white and black points, and that's about it. I do use saturation, LAB, and HP filter, but never any colour mixing. If you see my raw RGB from CCDStack, the dark cloud already exhibits the reddish tinge [like attached image].

I don't like that, and don't like the thought to have to manually edit it out to blacky/ charcoal. These images have been taken in a dark sky site.

I can edit my images so the cloud and general sky background is nice a neutral, but that is not what has been captured. Frustrating. It may be me; I'd hate to blame my tools if they weren't to blame.

I may just buy the I Series and see what the case is. I'm sure I can sell one or the other afterwards.

Thank you for your detailed answers,

Steve
Attached Thumbnails
Click for full-size image (M20 - 2013-09-02 LMDSS_PI_IIS.jpg)
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Last edited by stevous67; 28-10-2013 at 05:34 AM.
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Old 28-10-2013, 09:01 AM
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naskies (Dave)
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Even if your filters are 1:1:1 combine in a laboratory, that doesn't mean you don't need background subtraction or slightly different ratios in practice...

There's no such thing as a purely black sky background. At a minimum, you're shooting through airglow, atmospheric conditions can pick up and scatter light pollution from hundreds of kilometres away, and shooting through the atmosphere will cause extinction effects (especially for the blue channel).

Have you tried G2V calibration (e.g. see here)? eXcalibrator seems to do a pretty good job of figuring out combine ratios empirically, but you'll still need to subtract background gradients (even at a dark site).

http://bf-astro.com/eXcalibrator/excalibrator.htm

Good luck
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Old 28-10-2013, 07:11 PM
stevous67 (Steve M)
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Hello Dave,

Thanks for the good information, I have the G2V offsets for the Astronomiks for my system. In any case, I have now bought the Astrodon I Series LRGB's, and I will see for myself the difference, if any.

If its interesting, I will post a comparative image. I need to prove its my lousy processing skills, or something else.

Thanks again,

Steve
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