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Old 17-03-2010, 09:16 PM
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pmrid (Peter)
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QHY8 and filters

I'm looking at extending the capabilities of my QHY8 and wondered what others are doing about replacing the nosepiece filter element with something else. I'm in an area where I am not overly constrained by light pollution and my prime interest is in imaging nebulae and galaxies.

Peter.
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Old 17-03-2010, 11:23 PM
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mldee (Mike)
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Quote:
Originally Posted by pmrid View Post
I'm looking at extending the capabilities of my QHY8 and wondered what others are doing about replacing the nosepiece filter element with something else. I'm in an area where I am not overly constrained by light pollution and my prime interest is in imaging nebulae and galaxies.

Peter.
I've got a similar setup and located 26K west of Brisbane, with good hills/trees shielding in that direction as well, so not too worried about light.

I bought a used 2" Astronomik Ha 12nm filter and my "plan" is to try that plus the QHY8 OSC pics, using my C8/6.3FR and f5 8" Newt with MPCC.

Also want to do the same with the Ha on my DSI III OSC and 3.3FR on the C8.

Sorting that lot out should keep me busy for a while.
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Old 18-03-2010, 12:30 AM
Hagar (Doug)
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Hi Peter and Mike, I have used a QHY8 quite a bit with NB filters. It is not only possible it delivers quite good results. To use NB filters you have a couple of options to process the images.
When capturing Ha images the initial image at 1 x 1 bin will be captured at full RGB and will be quite red when debayered. This red image can be blended with the red channel after your initial RGB images are split into separate colours or it can be desaturated or converted to greyscale and used as a normal NB filter image would be or used as a great luminance layer.
Some strange star colour can be included into the the blended images but this can be corrected by removing the stars after image registration and before blending.
The camera can be used similar to a mono camera just by converting the NB images to greyscale for normal NB image processing.

Good luck with it you should have fun. It's really quite easy.
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Old 18-03-2010, 09:11 AM
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mldee (Mike)
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Hi Doug,
Thanks for the helpful comments, I actually got the urge to try Ha from reading some of your earlier posts.

One small question; apart from Ha is there any "simple" role for other wavelength filters (Hb, OIII, etc) to help augment the OSC RGB, again, for nebs and galaxy type work.

And finally; Should I keep the existing IR cut filter in place when using Ha, etc?
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Old 18-03-2010, 10:07 AM
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Thanks Doug. I'll be interested in your responses to Mike's question also.
Peter.
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Old 18-03-2010, 02:20 PM
Hagar (Doug)
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Originally Posted by mldee View Post
Hi Doug,
Thanks for the helpful comments, I actually got the urge to try Ha from reading some of your earlier posts.

One small question; apart from Ha is there any "simple" role for other wavelength filters (Hb, OIII, etc) to help augment the OSC RGB, again, for nebs and galaxy type work.

And finally; Should I keep the existing IR cut filter in place when using Ha, etc?
You can use the QHY8 with any NB filters just as you would with a mono camera. These images after debayering and converted to grayscale can be used just the same way to compile NB images such as Hubble pallet etc. You simply need a set of Ha, OIII, and SII filters and a bit of time to capture the images and process them. You may need to take a few more or slightly longer exposures to get the same result as a mono camera but it is quite reasonable to expect good results despite what some will tell you.

In most cases the IR filter can be removed as most filters these days have a built in blocking filter. I always left mine in place due to the fact that my IR filter was the seal on the camera, and I just screwed the NB filters on the front of the camera adapter with the IR filter already in place.

The biggest problem to overcome is the repositioning of the camera after removing it to change filters. I used a pencil to mark the camera and focuser tube so the images were pretty close to aligned.

Hope this helps.
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Old 18-03-2010, 03:25 PM
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Well, I'm going to have a crack at this. I've been offered a couple of good Lumicon filters (a Night-Sky Ha and an OIII) to get me started.

So it's game on. Here we go merrily skipping up that old learning curve again.

Peter.
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Old 18-03-2010, 05:03 PM
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Peter,
I agree wholeheartedly with Doug, the QHY8 can do Ha without too many issues. Nope, it possibly isn't as good as a dedicated mono, but it does work, and I have quite a few images that will attest to this. Didn't get as far as trying the O3 though.
Think about 20 minute exposures though, I routinely did 20, and often 30 minute shots.
Great fun.
Gary
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Old 18-03-2010, 05:37 PM
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multiweb (Marc)
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Quote:
Originally Posted by pmrid View Post
I'm looking at extending the capabilities of my QHY8 and wondered what others are doing about replacing the nosepiece filter element with something else. I'm in an area where I am not overly constrained by light pollution and my prime interest is in imaging nebulae and galaxies.

Peter.
I have a null adapter now and got rid of the standard nosepiece. I put the filters further away from the sensor as to minimise reflections. the QHY8 works very well in Ha and even better in Oiii. Bit of a struggle in Sii: very long exposures needed in excess of 20min on an F/5 system.
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Old 18-03-2010, 05:48 PM
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pmrid (Peter)
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Peter,
I agree wholeheartedly with Doug, the QHY8 can do Ha without too many issues. Nope, it possibly isn't as good as a dedicated mono, but it does work, and I have quite a few images that will attest to this. Didn't get as far as trying the O3 though.
Think about 20 minute exposures though, I routinely did 20, and often 30 minute shots.
Great fun.
Gary
G'day Gary. How much contribution to an image can I expect from a SII filter? You can see how green I am with this NB business. But I'm keen to give it a run to at least get a taste.
Peter.
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Old 18-03-2010, 05:59 PM
gbeal
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Hi Peter,
heck, ask someone else who knows more than me, LOL.
From the recent mono camera I had (OK, getting slightly off topic but it is relevant) I found that most objects sprang to view with Ha, and to a slightly lesser extent with O3, and were less than appealing with S2. Mind you I shot that "Pencil Nebula" in the Vela SNR and it fair hummed with O3, more than Ha, go figure.
Can't hurt to try, just give it a go. Try Ha and possibly O3 first, then worry about S2 (or H Beta?).
Gary
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Old 18-03-2010, 06:20 PM
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Bassnut (Fred)
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Originally Posted by pmrid View Post
and my prime interest is in imaging nebulae and galaxies.

Peter.
Well, they are quite different filter wise. There is a trend to Ha RGB instead of LRGB for nebs, but galaxies are broadband scources, so traditional LRGB is still (and only) the go for them.

At a minimum, a set of LRGB and Ha would serve well, then OIII and SII together really to do neb NB properly.
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Old 18-03-2010, 09:59 PM
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Thanks Fred and Gary. That'll get me started.
cheers.

Peter.
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Old 19-03-2010, 10:20 AM
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Post is this filter any good

Astronomik H-Alpha 12nm CCD Filter - T Threads

  • The Astronomik H-Alpha 12nm Filter has T-threads on both sides, allowing you to attach it to a T-adapter, etc. and still present a T-thread on the other side.
  • The Astronomik H-Alpha 12nm Filter has a transmission of up to 99%.
  • The full width at half-maximum (FWHM) of 12nm is optimized for the use with common CCD cameras and allows the use of very fast optics.
  • The Astronomik H-Alpha Filter may NOT be used for solar observation.
Astronomik H-Alpha 12nm CCD Filter - T Threads

The Astronomik H-alpha filter is a narrow band filter for CCD photography. The filter lets the H-alpha light of emission nebulae pass and blocks nearly the whole remainder of the spectrum where the CCD is sensitive.

The full width at half-maximum (FWHM) of 12nm is optimized for the use with common CCD cameras and allows the use of very fast optics. It should be noted that the filter has a transmission of up to 99%. Another advantage of the 12nm filters is the availability of guiding stars for cameras with a built-in-autoguider (SBIG). If you use a very strong filter like our 6nm filter you often won’t find a usable guidestar.
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