QHY8 and narrowbanding

[afesan]

I saw in this forum some nice examples of images in Ha taken with the QHY8..Does anyone tested this CCD with OIII and SII filters?..
I saw some nice examples in Ha+OIII+SII with some DSLR´s (Canon 20D)..but no one with QHY8..
Of course a monochrome is far better..but I have a QHY8 and Ha filter and would like to purchase OIII+SII if someone give me an example..? 
Clear skies¡¡
Antonio
(Vargas,Spain)

[Gama]

Yes you can do narrow band imaging, but of course it comes at a price.
You lose sensitivity due to the debayer filtering, so you will need much more time on exposures.


theo

[afesan]

I know,Theo..
Anyway I´m very patient¡¡¡     .Next future I would like a monochrome CCD but not 11Mpixel..I´m looking something like QHY8 (4-6megapixel)..a CCD in the mean between IC285AL and KAI-11002...
I think it could be a good idea or project..Artemis is proporsing one in 2 months ..with KAI4021 sensor..

I love my QHY8 as "one-shot" and my idea is using it mainly as LHaRGB CCD,...but for "city" people like me,with suburban backyards..narrowbanding is the final solution against light polution...and a second CCD monochrome could be nice..

This summer I´ll dedicate some hour to Ha with QHY8 and OIII also..¡¡
Best regards¡
Antonio

[QiuHY]

Hello,

       Last year Mr.Randy(The first user of QHY8) use narrow banding Ha filter gets many nice image. Here is some of his image. Since the OIII is green and the QE is better than Ha postion so I think it has no any problem for OIII narrow banding.

Here is some Ha narrow banding image he captured

[afesan]

Thanks Qiu..
As usually said (proverb): "one image is more than 1000 words".Nice image,indeed.Thanks for the explaantion about OIII possibilities.
I also think Ha+OIII is possible when into the city with the QHY8 CCD..
I suppose bin 2x2 ,of course better than 1x1..?
 Best regards¡
Antonio

[MMys]

I think so using Astronomik UHC filter could be good solution.

It allows to pass only OIII+H beta lines to blue/green pixels and H-alpha to red pixels. You will have both narrow band images at one exposure. But bandwith is not as narrow as with any dedicated narrow-band filters. If light pollution is not such heavy, it must work.

I'll test it sometimes.

[afesan]

MMYs ¡
Thanks for remember me the "forgotten" UHC filter¡¡..I´m agree with you about this possibilty and,if you tested it before..sure it must work.¡¡,,Unfortunately,light pollution is present in my suburban backyard in a moderate way.Always using here an IDAS-LPS when imaging.But UHC it´s a real possibility..
I have a dedicated Astronomik OIII CCD 2" filter  and 13nm Ha 2" filter..also a narrower Baader 7nm Ha 2" filter :-)..I only need a good night to test it.
I used before an SXV-H9 monochrome CCD and the IC285AL sensor (what a nice camera,indeed)is excellent in reds (Ha response)..Looking in the market for a similar 4 - 6 Mpixel monochrome CCD (like SXV-H16,STL-4020..etc) now..but at lower price.I heard rumours and an official announce of one of 4 Mpixel in another forum.I would be delighted if QHY produce one¡.....Hopefully soon I´ll find one..¡¡: I feel very happy in this segment..---more comfortable  than in the  11Mpixel one :-)) ..¡¡

Just one more question..
What is better in order to collect Ha and OIII ?:

Take images in bin 2x2..,as most are ding or... or:
Take images in 1x1..,make flats,process as RGB..then split and choose only the red channel as Ha ,discarding green channel (noise) and blue channel if no signal present...?,Sure second option request more exposing time but,...¡
This topic is actually being discussed in ither forums related to one-shot-colour CCD`s  with different approaches and sugestions and I want to know your ideas and opinnions about QHY8 and Ha experiences...
Best regards,
Clear kies¡¡
Antonio

[MMys]

I think so best way would by to take image at full res. (no binning), perform calibration and separate R, 2x G and B images. Unfortunatelly, I haven't found any SW for separation of RGB components directly from RAW full resolution FITS.

neither of methods you explain is optimal.
1) Binning will sum noise from unused G a B pixels  into usefull R channel
2) Interpolation to RGB and separation of R has disadvantage of resampling and interpolation of R channel once again

I think so some SW might be useful e.g. original QHY application, which saves 16bit RGB TIFF with half resolution (if I remeber it well). I think so there is not interpolation here. Simply R,G and B components are copied directly from bayer matrix data (B averaged probably from two B components). If you separate channells, do this same with darks, flats etc... taken by same method, you can work directly with single components in grayscale, with anyl astro-imaging program, which accepts 16-bit TIFFs.

Can QiuHY confirm this ?

When using with OIII, signal will be divided into G and B components roughly equally.  (OIII is blue/green color)

[afesan]

Thanks for the detailed explanation,Mmys...
I would like to take the most of detail in my images,so not binning is a better option for me..But I don´t know which are the better techniques and software...
My usual soft is MaximDL 4.58 and DeepSkystacker..PS CS2 for post-processing..
Thanks for the OIII explanation (about I can use both channels (G,B) for OIII )..it`s an excellent advice.The only dude now is Ha ..It seems that 1x1 and 2x2 have different approaches and the advantage in one case  is disadvantage in the other..
Well..let`s try 1x1..that`s my idea...Suggestions ??.I´m prepare to take HOURS of Ha along several nights .I´m very patient¡¡.
 
Anyone have more ideas?..All are wellcome¡¡
Clear skies¡¡
(Here it´s raining/cloudy since May 10th) :-((
Antonio

 

[QiuHY]

Hello,

      Yes the 16bit TIFF is only put alll red pixel into red channel, blue pixel to blue chanel and average two green pixel into Green channel so the outpput is 1550*1050.  This is better than BIN or debayer for narrow banding.
The data is original and not be effect by other channel, Files size is small and it do not need take time to do debayer.

      For narrow banding and color sensor 1*1 is better than 2*2. Because 2*2 bin will bin the dark noise. And the signal is not really increased(for R,or B, only one pixel effective in 4 pixles) So it is no advantage for 2*2bin.
and 2*2 bin may have some shadow after brght stars also.


Best regards,