Jump to content

NLC-Banner.thumb.jpg.acb5ba835b9e8bf0718b90539633017d.jpg

QHY9 mono camera horizontal black lines


alpal
 Share

Recommended Posts

How to remove horizontal bleed or blooming lines from a QHY9 mono camera.

I've got the information for anyone who also needs it.

My camera was giving faint horizontal black lines on over exposed stars.

See the attached pic where I used HDR toning to exaggerate the effect.

The KAF 8300 sensor is supposed to take up to 1000 x  the well depth before blooming.

I'm an electronics technician & it looks fairly simple.

Disclaimer:

A camera is a very delicate piece of electronic equipment & it needs

to be opened on an anti-static bench by a qualified electronics technician

who uses an anti-static wrist strap

.

After downloading -

The document only shows arrow positions properly when I enable editing in Word.

200% zoom is best for viewing.

The 2.2 Volts needs to be measured with an oscilloscope as per the photo.

I have not tried this adjustment yet but I will report back when I do.

It may be prudent to wait until I do the adjustment before anyone else

uses the information provided.

Anyone using this information does so at their own risk.

The old version of the document is here:

https://drive.google.com/file/d/0B2VJKGAcwQ0ZQnNQNlZ1RTl0Wms/view

The latest version is here:

https://drive.google.com/file/d/0B2VJKGAcwQ0ZNGFQRE0xZ3FsVEE/view

I think what I need to do is to create an external potentiometer

that screws into the housing so I can adjust it while under the stars.

It would be too much mucking around to undo & keep adjusting all the time in order to test it.

Any comments welcome.

cheers

Allan

See here the Running Man Nebula - a stack of Luminance frames showing bleed lines.

post-10943-0-55801000-1421130380.jpg

Link to comment
Share on other sites

No replies?

I wonder if it's possible to create an artificial star indoors to test the camera?
It's a pity that I could do an adjustment -
reassemble the entire camera - & then have to wait until I set up
the whole system to test for the results.

Perhaps shining a very dim light from a LED into an optic fiber & then illuminating
a small part of the sensor?
I have an optic fiber cable in my cupboard somewhere.

Any ideas?

cheers
Allan

Link to comment
Share on other sites

Hi

I don't think I've seen it on my qhy8l but have seen vertical dark lines on my full-spectrum 1100d. I don't think many people have the qhy9 mono anyway? I have contemplated getting one but £1500 seems a lot of money especially with the limitations of the Glasgow weather and lp...

Louise

Link to comment
Share on other sites

I have noticed this same effect on my qhy8l osc camera were bright stars have a line leading in one direction from the bright star.

I have a feeling that there is something not quite right with the Quality Assurance at  QHY.

I'm not sure yet.

Link to comment
Share on other sites

Hi

I don't think I've seen it on my qhy8l but have seen vertical dark lines on my full-spectrum 1100d. I don't think many people have the qhy9 mono anyway? I have contemplated getting one but £1500 seems a lot of money especially with the limitations of the Glasgow weather and lp...

Louise

It;'s a lot of money but it's worth it.

The pics are so much better with a mono.

I will try to re-create the black lines indoors with a pinhole camera  -

some foil over the input with a pin hole at the center.

Link to comment
Share on other sites

Hi

Well, you have some lovely images on your Flickr page :) I'm so tempted... But the weather here... Getting any imaging time at all is rare! :(

I imagine the cause of the horizontal lines is the same as I get with the 1100d - there are several threads on here. But it's probably also a hardware/sensor problem i.e. blooming but not really defined as a fault. Maybe try reducing exposure times as much as possible. I'd say post on the qhy forum but that's been inaccessible recently - at least via my service provider. I tried to go on qhyccd's web page earlier and got a virus warning - puts me off going there... Hopefully they'll sort it eventually.

Louise

Link to comment
Share on other sites

Hi

Well, you have some lovely images on your Flickr page :) I'm so tempted... But the weather here... Getting any imaging time at all is rare! :(

I imagine the cause of the horizontal lines is the same as I get with the 1100d - there are several threads on here. But it's probably also a hardware/sensor problem i.e. blooming but not really defined as a fault. Maybe try reducing exposure times as much as possible. I'd say post on the qhy forum but that's been inaccessible recently - at least via my service provider. I tried to go on qhyccd's web page earlier and got a virus warning - puts me off going there... Hopefully they'll sort it eventually.

Louise

Hi Louise,

Thanks - I hardly get any imaging time either but it doesn't matter - I's nice to have a mono CCD when it is clear.

QHYs site was hacked but it should be OK now.

cheers

Allan

Link to comment
Share on other sites

Well the forum seems accessible now but I can't even find their main web page... Maybe my service provider has blocked it!

HI Louise,

It seems to be working now:

http://qhyccd.com/ccdbbs/index.php?PHPSESSID=c1b5021bcb4d1c2db206378f106f7aa2&

I haven't had a chance to look at my camera yet.

I'll report back when I do.

I know there are many others out there with the annoying black line problem.

cheers

Allan

Link to comment
Share on other sites

I get the black line problem as well with my unmodded DSLR but can be easily over come with Noels actions , Horizontal /Vertical Banding Noice reduction. If you have Photoshop.

Also Startools does the same thing very well 

Nick

Link to comment
Share on other sites

I get the black line problem as well with my unmodded DSLR but can be easily over come with Noels actions , Horizontal /Vertical Banding Noice reduction. If you have Photoshop.

Also Startools does the same thing very well 

Nick

Hi Nick,

Yes I have been processing the black lines out with Photoshop - it's easy.

Just select a long rectangle around the black line, blur it in a mask & increase the brightness with curves.

They only appear on very bright stars.

The Running Man above was a troublesome example.

I will attempt to make the black lines appear indoors this weekend

& then adjust the pot  called  R27.

My goal is to be able to fix it all indoors & be ready to image with no problems on the next clear night.

I have an oscilloscope & all the right tools including an anti-static mat & wrist strap.

cheers

Allan

Link to comment
Share on other sites

  • 4 weeks later...

I opened up the camera & made the adjustment.
The value of the Pot R27 is 100 ohms.

The info provided by QHY is misleading.
They say 2.2 Volts but their Oscilloscope documents show 2 + .2 of a division
( because they are on 2 Volts per centimeter ) which is actually 2.4 Volts.
When I checked my QHY9 it was 2.4 Volts but the waveform does not look
identical to their picture.
I used 1 volt per centimeter to get more accuracy.
I can't see any ringing on top of the waveform but maybe my CRO doesn't have the bandwidth..

I adjusted it to 2.2 Volts & will test it at the first opportunity
to see if the black horizontal lines on bright stars have gone.

I bought 2 different types of 100 ohm preset pot so that I could install
one of them at an external location but I will see if the above works first.

see pic:

post-10943-0-77635300-1424488268_thumb.j

post-10943-0-17971300-1424488295_thumb.j

Link to comment
Share on other sites

Just in case it is of use, a friend of mine had one of these and he was getting lines (though if I recall they were vertical). We discovered that the threads on the t connection were protruding into the camera (only select QHY attachments had a shorter thread). The longer threads were interfering with the shutter.

Quite possibly nothing to do with your problem but good to know just in case.

Link to comment
Share on other sites

Just in case it is of use, a friend of mine had one of these and he was getting lines (though if I recall they were vertical). We discovered that the threads on the t connection were protruding into the camera (only select QHY attachments had a shorter thread). The longer threads were interfering with the shutter.

Quite possibly nothing to do with your problem but good to know just in case.

Yes - that's a mechanical problem.

This is an electrical problem that I hope I've solved.

If not I will install an external 100 ohm trimpot.

It will be easy to do as there is a gap around the gold threaded connector where 

wire wrap wires can go through the case onto an external trimpot.

I can stick the trimpot on with double sided sponge tape.

( yes - the camera is not sealed.  There are gaps around the 3 connectors )

cheers

Allan

Link to comment
Share on other sites

Update:

I made in an indoor test of the results using an Antares guide scope attached to the QHY9.
Luckily my old Starshoot auto guider had exactly the right threads &
T piece - M42/0.75 - to screw on to the QHY9 so I used that.
It focused on to the target which was only 2 meters away
& I used my trusty tripod to center the target.
For an artificial star I tried many variants but the best ended up
some aluminum foil over a LED lamp.
There were already tiny holes in the old aluminum foil so I didn't need to make any.
I also tried many different exposure lengths.
The bright "stars" all exceed the well depth.
I was unable to see any black tails on my artificial stars
on any of the frames I took no matter what processing I used
& if the camera was warm or cold.
I know that's not very scientific because I didn't test the camera this way
before I adjusted it.

The only true way to test this is under real stars.
Actually the "black tails" are hard to see from RAW frames.
They come out mostly after heavy stretching & processing.

cheers
Allan

post-10943-0-48156100-1424604707.jpg

post-10943-0-19112700-1424604774.jpg

Link to comment
Share on other sites

New ideas:

I have thought of a way to improve the artificial star test.

I am lucky that I can focus at only 2 meters from the target with that Antares guide scope attached to the QHY9.

What I need is a simple cardboard tube 2 meters long painted black on the inside.

That would make it super dark inside & mimic as close as possible real dark conditions.

I could then paint some Aluminum foil black as well & make tiny holes in it.

I would also need a focus adjustment on the guide scope.

The LED light needs to have a variable power supply or variable resistor to alter the brightness.

I have proven the concept - & I might build the above setup.

cheers

Allan

Link to comment
Share on other sites

  • 4 weeks later...

Update after the black horizontal line problem:

Using my 8" f6 Newt -
I finally got to do a proper star test after I adjusted the pot in the QHY9 mono.
It's much better - I had to really stretch it with HDR toning to see any black line.
See the pic of Alpha Centauri.

I also did a Ha 20 minute bin 2x2 exposure of the statue of Liberty Nebula
which came out quite well.
I also took a fair bit of LRGB of the same target.
I have a lot of processing to do.

cheers
Allan

post-10943-0-02836800-1426957338.jpg

post-10943-0-87268100-1426957367.jpg

  • Like 2
Link to comment
Share on other sites

Great to see you have sorted out your QHY9. The final two images look good. Well done for your hard work, expertise and perseverance to fix the problem.

Steve 

Thanks Steve,

I also like to give something back to the astronomy community as

this is a problem that many people have with the QHY9 camera & now this thread will stand as a record

of how to fix it which any electronics technician can follow.

cheers

Allan

Link to comment
Share on other sites

  • 1 year later...

Update 29th January 2017.

The QHY9M horizontal bleed line problem is solved.


I took 2 pics & posted them here on the Australian Ice in Space forum forum:
http://www.iceinspace.com.au/forum/showthread.php?t=152997


The trick was to adjust the pot R27 here:
https://www.flickr.com/photos/24719437@N03/16597181705/in/photostream
to get the correct waveform &
then only use slow download - about 12 seconds.
Don't tick the box for fast download when in capture mode.
( Actually it says that in the book but it should be in giant letters - I missed it.)

Also - the slow download has far less noise than fast download.
The dark noise on fast download is about 4225 bit count of the maximum 65536 bit count
whereas the dark noise is only about 1029 bit count for slow download.
4000 is about the average sky noise so you get a considerable advantage in signal to noise ratio too.

see the attached pic showing the difference using NASA FITS liberator & centering
the slider in the middle of the noise hump of 2 dark frames
depending on the readout speed.
Left hand side is slow readout speed & Right hand side is fast readout speed.


cheers
Allan

Low & high speed readout comparison.jpg

Link to comment
Share on other sites

11 minutes ago, Thalestris24 said:

Yeah, it's a general thing with qhy, at least, to only use slow download for the best quality images

Louise

Hi Louise,

it's good once you know - as always it pays to read the book ! -

however I happen to know that too many cameras left the QHY factory with this problem.

I shouldn't have had to adjust anything.

cheers

Allan

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.