M42 - first attempt with QHY8L

[Carole]

Well I bought this OSC camera hoping to use it to replace the DSLR because of reduced noise, but I must say this is noisier than I expected, but perhaps I stretched it too much, or maybe I need more subs.

This is also anticipated to be part of my dual set up.

What I am concerned about is the horizontal lines accross the image and just wondered whether any-one has any idea what has caused that, or is this usual for a QHY8L? (Not sure if any-one in the group owns one). 

This is taken from my very light polluted back garden with no LP filter as I hadn't acquired one when I took this. Basically I guess this image was really for practice but I was hoping for less noise.

9-1-13
No light pollution filter used (not acquired one yet)
10 x 600sec
24 x 30secs
ED80 (I think?? it was sitting on my dual set up and can't remember which scope I used !!!)
QHY8L, guided with PHD also my first attempt with the Finderguider.
Captured in APT
Processed in Photoshop CS3
Couldn't get layers mask to work (normally I can), image wouldn't paste into the mask, just kept making another layer, so I had to "mask" it manually.

[Fay]

Well it just looks a bit soft, Carole. cant see the lines you mention. have you got a sub with them on?

[Carole]

cant see the lines you mention. have you got a sub with them on?

I've done a crop and brightened it and marked them.  

Noel's actions seems to get rid of the ones in the sky background (since post above), but not on the nebula.  But I want to know why they are there in the first place. 

[Fay]

http://stargazerslounge.com/topic/170449-qhy8l-de-bayering/

a post on SGL

http://qhyccd.com/ccdbbs/index.php?PHPSESSID=ddd83cae2a909ba80d34923a39b7cf94&topic=3321.0

you may have seen this one

[Carole]

Thanks for the link Fay, I think I've read that thread before as I took a note of the debayering method of GBRG and that's what I used in DSS.

I previously tried to stack in Nebulosity but it didn't like the files at all and kept crashing.

It's interesting to see that some-one else also has the lines, but the thread goes on more to talk about colour and doesn't resolve the lines issue.  Might do some more googling and have also asked the guys on Astronomy Shed as several have QHY8L cameras on there but not yet had a response.

Also joined the QHYCCD Forum but am still waiting to be activated.

Carole

[MarkS]

That's definitely a problem Carole, though not necessarily the camera itself.  The lines are every 85 pixels and I'm guessing you've scaled by a factor of 3 which means they are probably every 256 pixels in the original frame - a very suspicious power of 2.

You should definitely post a question on their user forum.  Here are similar issues:
http://qhyccd.com/ccdbbs/index.php?topic=3376.0
http://qhyccd.com/ccdbbs/index.php?topic=3194.0

Hope that helps

Mark

[Fay]

 

[Carole]

Interesting links Mark. 

Looks like it is possibly a USB extension cable problem, or a driver problem.  I have a shorter USB on order, and I'll test it out direct to laptop without an extension.  Let's face it they never supply a cable long enough to image so you always have to put an extension cable. 

I hope it's not anything more technical or I won't be able to sort it.

Seems like lots of people are getting these issues.

Don't know what this means Mark:

you've scaled by a factor of 3

Carole

[MarkS]

Don't know what this means Mark:

you've scaled by a factor of 3

Did you post the full size image (if so the camera doesn't have many pixels) or did you shrink the image before you posted it, or did you crop it?
I am guessing you may have shrunk it to 1/3 of its original size.

Mark

[MarkS]

It all sounds rather curious to me, if the USB can really interrupt and interfere with the data values being read off the CCD in that manner.

Is this a common shortcoming of dedicated astrocams?  It certainly doesn't happen with Canon DSLRs.  I wouldn't want to buy an expensive astro-cam and then find I get lines of noise across the image.

[Fay]

I remember when i got my SX, you had to set capture to either progressive or interlaced because of stripes. cant remember which one i had to use

[Carole]

Hi Mark, I posted a Crop as I orientated up the wrong way so M42 was lying on it's back and I really don't like it at that angle, so I rotated it 90 degrees and just cropped the top and bottom off it.

There is something in the users manual about how the camera downloads data which went right over my head Mark, and I wonder if herein lies the clue if you can understand what he is saying.
I would be grateful if you could put this in simple terms for me Mark, provided you can understand the Chinglish.
It's possible I should NOT use high speed download, but haven't quite yet fathomed out how to turn the download speed on and off in APT as it's not clear which is on and which is off (still trying to elicit the info on this).  

[MarkS]

Carole,

If I understand it correctly, it seems to be saying that a yellow amp (amplifier?) light comes on during the frame read and that the yellow light from this will leak onto your images.  This sounds odd to me, that an amp light would be positioned within view of the CCD.  But in any case, it goes on to explain that the frame read is actually done as 2 successive half frame reads (one interlaced with the other) and so the 2nd half frame will be worse affected by the yellow light than the 1st half frame.  But, it says, shooting darks should allow you to calibrate this problem out of your final images.

Does this relate to the problem you're seeing?  I've no idea.  You need to raise the question on their forum.

Mark

[Carole]

Thanks Mark.

I am thinking back to when I did the capture and I am wondering now whether I ticked the fast download option -as it was unclear a) what I needed and which way was was on/off.  Certainly some-one on another forum has asked me if I used high speed download.  I have asked Ivo (author of APT) and he says he can't help with my question as he doesn't have a QHY8L camera to try it out on and apparently this high speed box only appears with the QHY cameras, I thought I hadn't seen it before when I tried out the Atik.

So I think in the first instance I should have a try imaging again and try to work out which is on and off with the speed download thing.  Then if that doesn't work I'll post on the QHYCCD forum.

Yes the amp thing seems very odd, unless he is referring to the various LED lights on the power box, I did not watch that so don't know if the colour changed but they are red and mostly on all the time as far as I know.

Might try some indoor experiments.

Thanks for your help.

Carole

[Carole]

Hi Mark,

I posted the query on QHYCCD forum along with the blow up image above, and this is Mr Qui's reply.

Looks like some other device is taking USB bandwidth during QHY8L readout.  Do you use hub for two cameras?   Or there is some internet application(IE, etc) runnning? And do you use the slow readout or fast readout?

Obviously still to be resolved, but making some diagnostic progress.

Carole