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  #21  
Old 25-04-2010, 10:24 AM
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JohnH
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FWIW : My rig is tear down and mono.

If you would like to do NB imaging you will want a mono camera - not sure if there are any here getting success with OSC/NB but it would be painfull I am sure.

Also an automated filter wheel is essential - before I got that it was too much like hard work changing filters lost the focus and guiding and framing and also meant I was having to visit the scope every 30 mins or so all night. Now I have a script driven system (AA4) that can slew to a target, start guiding and the run the LRGB or Ha, Oiii sequences and this is supervised from the lounge beer in hand.......it is more complicated and sometimes causes me grief but works well and knocks the socks of what I was using before (an unmodded 20D), I would like a bigger sensor though - but that is another story....
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  #22  
Old 25-04-2010, 10:58 AM
Hagar (Doug)
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A Mono camera is not a definite requirement. OSC cameras perform very well with NB filters still only capturing the level of colour the filters pass. The overall processing is no harder than the normal RGB processing of a mono camera. Sensitivity may be a little less with the OSC using NB filters but this can be reduced using longer subs.
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  #23  
Old 25-04-2010, 11:06 AM
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multiweb (Marc)
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Quote:
Originally Posted by JohnH View Post
If you would like to do NB imaging you will want a mono camera - not sure if there are any here getting success with OSC/NB but it would be painfull I am sure.
I do NB with an OSC. Did I mention it is a pain? ... yes. But only because I have to change filters and I don't have a filter wheel, so the data acquisition is a pain, lenghtier, but... it wouldn't be any different with a mono. Although I have to admit I am still drooling to date on your Eta shot with the QHY9. That was an absolute corker.

I'm getting and SXV-AO with a lodestar shipped and I now have a Keller Corrector to fit on the C11. So I'll be using an OSC at 3m FL with an image scale of 0.5asp and hopefully a flat field. I will post bayer shots when I get a chance (which should be 8 weeks away now) and see if I can get any result out of it and if the bayer matrix is indeed a problem with details.
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  #24  
Old 25-04-2010, 11:23 AM
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Quote:
Originally Posted by Hagar View Post
...Sensitivity may be a little less with the OSC using NB filters but this can be reduced using longer subs.
I have not used a osc with nb but I would be surprised if it is only a little less sensitive. For a given pixel size a osc is going to need ~4 times the exposure length for the same result is it not?

Most bayer masks are GRGB thus, with Ha in line, the GGB sub elements will all get zero photons (ok 1-2%) and you get 1/4 of the signal per pixel and I do not think the debayer routines will help compensate for this.

And while you can compensate with longer subs the exposure lenghts required in NB are already long, typically an hour or more per filter for me so taking that out to 4 hrs would be unrealisitc. My scope is small though so if you are 200mm or more it might be useable.
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  #25  
Old 25-04-2010, 11:25 AM
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mill (Martin)
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In the end, this is what i would want to do if i had the money
Have the mono camera taking Luminance all night and the same camera but the color, taking color all night.
Both camera"s on the same type of scope so you dont have to stuff around later calibrating images.
Now that would be almost perfect
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  #26  
Old 25-04-2010, 12:18 PM
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Quote:
Originally Posted by Hagar View Post
There is a lot of hype about the difference between OSC and Mono CCD's but from my experience a lot of it is purely hype.
Doug I am just a little curious here and this is not an attack just a question. From memory you sold your QHY 9 mono and replaced that with a QHY8 pro OSC. Now you have bought another QHY 9 mono.....if you percieve the difference to be that small why pay 3K to get another one .

Mark
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  #27  
Old 25-04-2010, 05:48 PM
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Quote:
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Doug I am just a little curious here and this is not an attack just a question. From memory you sold your QHY 9 mono and replaced that with a QHY8 pro OSC. Now you have bought another QHY 9 mono.....if you percieve the difference to be that small why pay 3K to get another one .

Mark
I bought the QHY9 a second time for a few reasons.
1. I have purchased a FSQ106ED which left my images severely undersampled with the QHY8Pro and the QHY9 colour was not available in Australia at the time.
2. I thought I would make a conserted effort to see what all the hype was about as with the first I gave up pretty quickly and sold off the camera.
3. I wanted to do some narrow band imaging and needed a filter wheel and to get something which was fully integrated into the camera at a reasonable price was quite attractive.

I have yet to try narrow band imaging with this camera as work and weather have been against me for the last 6 months but I will get arround to it sooner or later. Even RGB imaging is yet to convince me that there is much if any gain to be made for all the extra effort. The fact that dark frames are a must, imaging times still seem longer to me and processing/combining time also is significantly longer I still question the value.
I intend to spend a reasonable period testing this camera in both RGB and NB so only time will tell whether I still own this one in a year or so.

From where I sit at the moment (Pixel size and sampling aside), the QHY8Pro is the easiest and best value for money camera a run of the mill imager like me can look at.

I hope this answers your question. Maybe I should look at a bigger sensor with higher QE, and better sampling figures for my scope but would still consider a OSC even in the 11000 series. (At least at the moment) $3K i'm loaded just pocket money.

The 2 images below may shed some light on my sentiments.

First image; 15 X 60 second exposures with VC200L 8" and QHY8 OSC
Total imaging Time = 15 minutes total exposure

Second image; 15 X 2 minute Lum + 10 X 2minutes each RGB filter = Total imaging time 1.5Hrs Exposure TAK FSQ106ED at f8 and QHY9 with LRGB filters

The last image is an example of NB imaging with QHY8Pro
80 minutes each Ha, OIII and SII.

There is a difference in telescopes of course. Tak FSQ106ED 106mm at F8 , VC200L 203mm at f9
Attached Thumbnails
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Click for full-size image (NGC5139-21-4-2010-web.jpg)
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Click for full-size image (M42-HST.jpg)
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Last edited by Hagar; 25-04-2010 at 07:54 PM.
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  #28  
Old 25-04-2010, 08:44 PM
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Goodo, that makes sense. Here is a dodgy M42 through a 80mm apo using the qhy9. Ha,L,R,G,B for a total of about 2 hours. Scuz the core and brighter stars (cant be bothered) but the dust is pretty clear. I always had a hard time getting that with the OSC, absolute breeze with the mono.

Mark
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  #29  
Old 25-04-2010, 09:04 PM
Hagar (Doug)
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This is M42 with QHY8Pro and FSQ106ED at f5 20 X 2 minute exposures.

I think the difference with most DSLR's is the sensitivity to Ha wavelength. Traditionally DSLR's are quite sensitive to OIII but reject Ha with a vengence.
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  #30  
Old 25-04-2010, 09:25 PM
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Yes I have noticed how much brighter the images from 100-110mm scopes are then the 80mm. Will have to invest in one soon me thinks.

Mark
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  #31  
Old 25-04-2010, 09:25 PM
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Here's 30min with the QHY8 OSC. No drama getting dust and details. ... and that's 3asp.
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  #32  
Old 25-04-2010, 09:28 PM
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and that's 3asp.
Cah . What scope did you use Marc?
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  #33  
Old 25-04-2010, 09:41 PM
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Cah . What scope did you use Marc?
C11 + Hyperstar but aperture is irrelevant because the image scale is 3asp similar to 2.87asp for an ED80 (80mm aperture). You just collect more light at F/2. Point was that OSC still get some good definition in details.
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  #34  
Old 25-04-2010, 09:50 PM
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C11 + Hyperstar but aperture is irrelevant because the image scale is 3asp similar to 2.87asp for an ED80 (80mm aperture). You just collect more light at F/2. Point was that OSC still get some good definition in details.
Hmmm 3 1/2 inches at F6 vs 11 inches at F2 ...bit like taking a knife to a gun fight me thinks .

Mark
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  #35  
Old 25-04-2010, 10:04 PM
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Hmmm 3 1/2 inches at F6 vs 11 inches at F2 ...bit like taking a knife to a gun fight me thinks .

Mark
Not at all. We're talking about details on an OSC vs. a Mono right?

ED80 + QHY8 at prime focus:
206.265/600mm * 7.8um = 2.68 seconds of arc per pixel.

C11/Hyperstar + QHY8 at prime focus:
206.265/504mm * 7.8um =3.19 seconds of arc per pixel.

Yes you collect more light with 11" aperture and 500mm of FL but image scale being similar a star will still cover the same number of pixels in both rigs. Point is the QHY8 OSC even debayered is still looking pretty good compared to your QHY9 shots. Exposure time or photons collected being irrelevant.
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  #36  
Old 25-04-2010, 10:29 PM
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Sorry Marc I cannot agree. The C11 will always pull in more light than a 80mm apo and also has a greater capacity to resolve. It stands to reason 40 mins of data is going to provide a brighter image. The image I have posted is pretty much as is, stacked with noise filter run over it. You have been far more aggressive in your processing. FYI my image scale is 2.3 arcsec/pix and obviously I cropped the image as it was taken before I got a flattener. My point being that with the QHY8 on the back of my little apo with similar exposure time the detail and smoothness was far less then the 9.

Mark
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  #37  
Old 25-04-2010, 10:47 PM
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Sorry Marc I cannot agree. The C11 will always pull in more light than a 80mm apo and also has a greater capacity to resolve. It stands to reason 40 mins of data is going to provide a brighter image.
Yes, Mark, I agree - the C11 pulls more light in than the 80mm. Yes it has a greater resolving power. Yes the image is brighter as a result.

Quote:
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The image I have posted is pretty much as is, stacked with noise filter run over it. You have been far more aggressive in your processing.
No at all- Actually, no noise reduction or deconvolution was applied to this image which consist of approx. 15 subs of 120s. Just stacking and STD sigma reject. It was taken under very dark skies. I had enough signal to overwhelm any noise, but brightness is not the point here.

Quote:
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FYI my image scale is 2.3 arcsec/pix and obviously I cropped the image as it was taken before I got a flattener. My point being that with the QHY8 on the back of my little apo with similar exposure time the detail and smoothness was far less then the 9.
With an image scale of 2.3asp vs. 3.1asp on my shot you should have room to get finer details than the shot I posted. The shot I've posted has a similar or very close screen resolution (dpi) as the shot you've posted.

Not criticising any of your shots guys, don't take me wrong. I'm advocating the use of an OSC here and trying to show it stands on par with a similar size chip mono sensor.

My reasoning is based on image scale and details extracted within the same image scale.
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  #38  
Old 25-04-2010, 10:55 PM
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Fair enough Marc but the brighter the image (more photons on the sensor) the more detail you will see and this can make a sensor look better. My image was taken from my back yard in suburban Perth. I would really like to see a mono shot taken through your C11 with hyperstar as I think it would be very special indeed. I still think we are comparing apples with pears here.

Mark

Last edited by marki; 26-04-2010 at 03:00 PM.
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  #39  
Old 25-04-2010, 11:08 PM
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Fair enough Marc but the brighter the image (more photons on the sensor) the more detail you will see and this can make a sensor look better.
As in you guys get all the photons in each channel and I get only 1 out of 4 for red and blue and 2 out of 4 for green? I'm still looking good then hey? But I won't hold that against you for making your sensors look better.

Quote:
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My image was taken from my back yard in suburban Perth. I would really like to see a mono shot taken through your C11 with hyperstar as I think it would be very special indeed. I still think we are comparing apples with pears here.
Mark
Fair enough. I don't know how dark Perth burbs get. Maybe one day I get a mono, who knows? Probably down the road. No we're comparing apples and smaller apples. Smaller apples are sweeter.
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  #40  
Old 25-04-2010, 11:57 PM
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Maybe taking all the stacking and stetching and scopes out of the equation will make it easier to see the difference. These are single 300sec subs of m20 through the same scope on the same night, one is from a mono and the other from a osc.

If you look at the hystograms rather than the images, the monos show more data. I also found a couple of 434 shots using a different mono camera and these also show more data captured. However I miss my OSC and plan to get another sometime.

The original question was is there any difference combining planetary to deep sky lrbg images, probably not, I've found maxim has corrected stacked and aligned all my mono images without a problem.
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Last edited by Tandum; 26-04-2010 at 03:41 PM. Reason: Clean up text and update images.
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