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russellhq

QHY8L - Good Idea/Bad Idea?

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Edit; I'd also like to have a play with a decent dataset from one of their colour cameras. I often feel QHY OSC images have a distinctive look, rather red-brown dominated, and I wonder if this is just from the processing or is inherent in the data. I'd be surprised if it were in the data. If anyone would like to throw some my way I'd be delighted. :grin:

Olly

You're right Olly - my QHY8 (old toaster shaped version) has a blue channel that you have to send out a search party for :-)

When I process in Nebulosity I have a choice of using "Auto Colour Adjust" and this levels the three channels out - but by killing red and green it also kills detail and introduces noise

So I preserver and try to boost the blue channel a bit as I process - dropping the red and green a bit right at the end

I could send you the data I captured on the Elephant Trunk nebula at Kelling this month if you'd like

David 

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You're right Olly - my QHY8 (old toaster shaped version) has a blue channel that you have to send out a search party for :-)

When I process in Nebulosity I have a choice of using "Auto Colour Adjust" and this levels the three channels out - but by killing red and green it also kills detail and introduces noise

So I preserver and try to boost the blue channel a bit as I process - dropping the red and green a bit right at the end

I could send you the data I captured on the Elephant Trunk nebula at Kelling this month if you'd like

David 

Very interesting. I really had a strong impression that this was so. Sure, I'd be interested in the data.

Olly

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Olly, I have some data as well from my QHY8L if you would be interested. Though I cannot guarantee it's decent! :D

It's 33 x 15min lights calibrated with darks, bias & flats.

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Olly, I have some data as well from my QHY8L if you would be interested. Though I cannot guarantee it's decent! :D

It's 33 x 15min lights calibrated with darks, bias & flats.

Great, I'd be delighted to have that via dropbox or whatever, in linear form. I'll PM you.

Thanks,

Olly

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My very old and cranky QHY8 finally packed in last week.  Encouraged by the feedback on this thread, and the fact that I liked the FOV and image scale the old QHY8 gave me, and the fact that I couldn't justify shelling out a large wad on something more exotic, an order went into Modern Astronomy on Saturday.  The camera arrived yesterday (thanks MA for a very quick delivery).

First impressions are excellent.  The build quality of the QHY8L compared with the old QHY8 is vastly superior - they've clearly got their act together and built upon their experiences.  The camera works well with my weapon of choice, Nebulosity (sorry OIly, but Neb & QHY suit me just fine :smile:).

Just need to get my head around the setpoint cooling - what setpoint would folks recommend?  Is a single setpoint the way forward or will I need to vary it for particular scenarios?

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Hi Mike,

I use -20 centigrade. Don't bother with darks.

cheers

Steve

Thanks Steve. :icon_salut:

Do you cool down in stages and at the end of the session reverse the process?  I read somewhere about doing this to avoid thermal shock.

Edited by r3i

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Thanks r3i!  :laugh:  :laugh:  :laugh:

Finally someone had seen the light!!  :grin:  :grin:  :grin:

I totally agree with you the QHY ccds have improved a great deal!!

And that's proof that someone as experinced it!!  :grin:

Good luck on the New QHY8L it's an awesome CCD!!  :grin:

So enjoy mate!!  :grin:

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My very old and cranky QHY8 finally packed in last week.  Encouraged by the feedback on this thread, and the fact that I liked the FOV and image scale the old QHY8 gave me, and the fact that I couldn't justify shelling out a large wad on something more exotic, an order went into Modern Astronomy on Saturday.  The camera arrived yesterday (thanks MA for a very quick delivery).

First impressions are excellent.  The build quality of the QHY8L compared with the old QHY8 is vastly superior - they've clearly got their act together and built upon their experiences.  The camera works well with my weapon of choice, Nebulosity (sorry OIly, but Neb & QHY suit me just fine :smile:).

Just need to get my head around the setpoint cooling - what setpoint would folks recommend?  Is a single setpoint the way forward or will I need to vary it for particular scenarios?

Don't apologize! The sreen stretch drives me crazy and has done so every clear night for nearly two years, but if it works for you then that's a good reason to stick with it. I'm often imaging very faint things and in Artemis Capture I can see them in 10 seconds when in Nebulosity I need 2 minutes and an incessant amount of jackassing with the black and white point sliders. Who knows, it may be just with the camera I'm using in that rig. I sincerely hate it. Voila!

Olly

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Hi Mike,

I use -20 centigrade. Don't bother with darks.

cheers

Steve

I use -20C as well. it gives a nice balance of low temps and low power consumption.

If you use the supplied ezcap software, which is more than capable, then it will look after cool downs and warm ups to avoid thermal shock.

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Great, I'd be delighted to have that via dropbox or whatever, in linear form. I'll PM you.

Thanks,

Olly

Olly, did you ever get a chance to process David's data? Would be very interesting to see how it came out :)

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Don't apologize! The sreen stretch drives me crazy and has done so every clear night for nearly two years, but if it works for you then that's a good reason to stick with it. I'm often imaging very faint things and in Artemis Capture I can see them in 10 seconds when in Nebulosity I need 2 minutes and an incessant amount of jackassing with the black and white point sliders. Who knows, it may be just with the camera I'm using in that rig. I sincerely hate it. Voila!

Olly

Horse for courses -  our operating circumstances, expectations, and expertise are a tad different.  A bit like comparing a team in the Premiership and one in the Evo Stick Frirst Divsion North League :D

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Horse for courses -  our operating circumstances, expectations, and expertise are a tad different.  A bit like comparing a team in the Premiership and one in the Evo Stick Frirst Divsion North League :D

No no, we both need to be able to see what we're doing and in Nebulosity I can't. That's really it. In Artemis I can go into Bin 6 and out again in a click when I need to pick up faint traces quickly. 

Olly

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Glad to hear the QHY8L is comparable to the original design

Mine is still working great thankfully but when it dies I will either buy another one of the same design or the 8L - mine has worked so well.

The thermal shock element of the threads has me concerned :-) Haven't taken that into consideration at all - and I run mine at 12v (well..usually 11.7) all the time.

Not going to change that practice now as I feel I've got my money worth out the camera and if it goes bang I'll worry about that with the next one.

I was interested to read the debate/discussion about Nebulosity and the QHY8 above - I've found it to me extremely easy to use (Nebulosity). There are many useful tools and processes to explore in it - but then I've not used anything else. I have to admit I don't do any processing in it although it is possible - when I've tried I've found it can be a lot easier and quicker than Paint Shop etc - but I always get the feeling some of the processes are killing data - not because the program does it but because my understanding of the program does it :-)

I understand Photo Shop better I guess.

Olly - I'm afraid I've dropped the data off dropbox now - I figured you were too busy to get to it and I needed the space :-) Thanks for the offer though

On that note though I have to say I've discovered a way of processing these heavy red nebulosity shots - as discussed early it involves boosting the blue channel but i've found doing that in the very early stages of the Levels process has worked much better. Every time the blue falls away on a Level step I boost it - seems to be working - well at least better than it used to.

David

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I use -20C as well. it gives a nice balance of low temps and low power consumption.

If you use the supplied ezcap software, which is more than capable, then it will look after cool downs and warm ups to avoid thermal shock.

Thanks Russell,

I'm currently sticking with Nebulosity for now as I'm just so familiar with it.  It does have facilities for controlling the cooling of the camera, although they're admittedly not as sophisticated as the ones in EZCAP.  Once I've got a few sessions under my belt with the new camera, I really should give EZCAP a try.

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Hello everybody,

I am impaciently waiting for my QHY8L camera to arrive these days and i wanted to ask you guys a couple of things:

- since this is an OSC camera, you can't use HA,OIII or SII filters (although it is possible..i saw an image on flickr).

My question is : would it not be then possible to use Binning 2x2, which would be grayscale and then use the Narrowband filters ?

You would also benefit of a greater SNR, which is great, also the readout is Progressive Scan for 2x2 binning so no amp glow.

The only negative i see is the smaller resolution (half), which for QHY8L would be ~ 1500x1000, which is quite reasonable imo..

What do you guys think, is this doable ?

P.S.: I will keep you updated about the camera when it arrives (also firstlight), also it is not QHY8L, it is from the German manufacturer AstroLumina but it's the same thing.

Perhaps build quality is better since it's manufactured in Germany, not China etc .. :D

Thank you and clear skies !!

Andrei

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- since this is an OSC camera, you can't use HA,OIII or SII filters (although it is possible..i saw an image on flickr).

You should be able to use narrow band filters. You won't get the same efficiency as you would if you used them with a mono camera, as the filters will attenuate some of the wanted light amplitude. Also the resolution will be lower as the narrow band light will only get through to 1 pixel in each group of 4 (or 2, if the O3 light is passed by the green filters over the pixels).

But it's better than nothing.

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I'm not sure whether binning or "super pixel" stacking would be better. I would think the latter as the former may introduce more noise.

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Greyscale does not recreate monochrome, which is a bad term as I'll explain. You can remove the colour data in software but the point is this; nothing you can do in software alters the fact that the physical RGGB filters are in front of your pixels, each one obscuring about 2/3 of the incident light. Green blocks red and blue, blue blocks red and green, etc.  A monochrome camera would be far better renamed an omnichrome camera because that's what it is. It collects all visible light. Seen in these terms, it is OSC cameras which really have monochrome pixels!

So Ha filters pass a specific wavelength of red. OSC chips only let 1 out of 4 pixels see red so your Ha is 25% efficient. Discarding the colour data from G and B doesn't alter this. They still can't see red, and you'll have to ditch all the info from those filters anyway because their pixels are effectively dead. Yes, you can shoot narrowband with an OSC camera and, yes, it can enhance your images. But anyone wanting to shoot narrowband should chose an omnichrome camera at the start. That is, a monochrome camera which collects all the light but cannot distinguish between wavelengths. The filters and software do the distinguishing later on.

Olly

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You CAN use narrowband filters with a OSC camera. The resolution won't be as good in comparison to a monochrome camera of the same sensor size. However the QHY8L is a 6 megapixel camera. so 1.5 megapixels will still be collecting data. Which is the same as an Atik 314 (for example). I know that this is a very simplified comparison to make, as the sensor sizes are totally different. However, the QHY8L pixels are a lot larger than the 314s, so, in theory, would be more sensitive. IIRC, Mike Wilson of this here parish got a QHY8L mono image on a S@N coverdisc.

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Ok, thank you all for the information; probably in the future, i will get an mono ccd with all the filters required, but at the moment, i don't seem to have that time available...

Anyway, thank you and will come back with some first images taken with the QHY8L soon !

Kind regards,

Andrew

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You CAN use narrowband filters with a OSC camera. The resolution won't be as good in comparison to a monochrome camera of the same sensor size. However the QHY8L is a 6 megapixel camera. so 1.5 megapixels will still be collecting data. Which is the same as an Atik 314 (for example). I know that this is a very simplified comparison to make, as the sensor sizes are totally different. However, the QHY8L pixels are a lot larger than the 314s, so, in theory, would be more sensitive. IIRC, Mike Wilson of this here parish got a QHY8L mono image on a S@N coverdisc.

I can see your logic. I'd be interested in a shoot out...

Olly

Edited by ollypenrice

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You CAN use narrowband filters with a OSC camera. The resolution won't be as good in comparison to a monochrome camera of the same sensor size. However the QHY8L is a 6 megapixel camera. so 1.5 megapixels will still be collecting data. Which is the same as an Atik 314 (for example). I know that this is a very simplified comparison to make, as the sensor sizes are totally different. However, the QHY8L pixels are a lot larger than the 314s, so, in theory, would be more sensitive. IIRC, Mike Wilson of this here parish got a QHY8L mono image on a S@N coverdisc.

Finally found the post :) 

http://stargazerslounge.com/topic/104010-first-light-with-qhy8l-in-ha/

The images look ok and it is exactly an QHY8L OSC with the ha filter...so i think i'll get some narrowband filters soon and try it out to see what i get..

Cheers,

Andrew

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