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Old 12-01-2013, 03:15 PM
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peeb61 (Paul)
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Strange M42 artifacts.

HI All,
I was wondering if somebody has come across this strange artifact in an image I took last night of M42.

It is a stack of 5x 10 minutes, 20x 30 seconds and 20x 15 seconds. I am using the QHY8L, the gain and offset are 5 for gain and 30 for offset.

The camera was sitting on -15deg the whole night.

As you can see from the image there are a couple of strange lines running across the image toward the bottom.

Any ideas what may have caused them??

Paul
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Old 12-01-2013, 06:42 PM
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This is a known problem with QHY cameras. As you can see there is a dark "comet" of light coming from the very brightest of stars in the Orion Nebula as well as two in the running man nebula. The only fix Im aware of is to send it back to Theo., who will most probably have to send it back to China. This is what happened to my camera.
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Old 18-01-2013, 03:14 PM
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Hi Allan,
An update on my issue.

I have taken some test images in between the clouds as they came and went but this time I changed PCs, I used my laptop, loaded all of the updates etc as directed and fired away bearing in mind this Clamp setting and attached are the results.

The lines appearing in my original image have gone, attached are 30 second exposures using MaxImDL using the EQMod drivers with the Clamp off and then on. (Hover over the thumbnails)

The framing of M42 is not the best but I was dodging clouds and the processing is overdone to show any irregularities in the image.

One thing I have found is the spikes in the stars?? These appear on all images.

I have also taken 2 x 200sec of the same field and have used Ezycap as well. (I can post these if required)

So I'm starting to think there was a problem with my original PC?? I have also spoken to Theo who thinks along these lines as well but has told me to image a brighter star field to be sure and to let him know of the outcome.

Paul
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Old 18-01-2013, 03:30 PM
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Image Canopus or Acrux with clamp on and off as well as Normal and fast download. Also try EZCAP as an alternative capture program with these bright stars. With these bright stars do at least a 2-5 min exposure
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Old 18-01-2013, 03:55 PM
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Hi Allan,
Thanks....this sounds like a plan.

Paul
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Old 22-01-2013, 03:10 PM
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Hi Allan,
Attached is a 5 minute image of Canopus. The streaks are gone but I get this Halo or reflection of the Corrector plate on the brighter stars.

Any ideas on this??

Many thanks
Paul
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Old 22-01-2013, 03:55 PM
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Same as mine.

I have a QHY8 and have this same problem on bright stars. I am using an LX200 F10 with a focal reducer in the image train. I am going to remove the IR filter at the front of the QHY camera. The CCD will still be in a closed cell between the CCD and the focal reducer. I will connect them up on a dry day or add a little warm air when doing so. this will I hope remove moisture that may ice up when the CCD cools down. I am really looking for a solution to this problem also. I think it's reflection on the IR glass of the QHY8 that is out of focus casing the donut.



Mardy
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Old 22-01-2013, 04:22 PM
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AAAhhh Ha! Thanks Mardy..food for thought.
So its not just me?

Paul
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Old 22-01-2013, 05:49 PM
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This is also a problem that others have seen and only comes up with reflections off very bright stars. Fortunately most images don't contain such stars, however the exception is Alnitak when imaging the horse head nebula. I used to have this problem with my Qhy8 ( original model ) and the way I got rid of it was to shift the ir filter on the front of the camera out another 40 mm and this dramatically reduced the reflection off the ccd which was bouncing off the ir filter and back to the chip. Quite easy to do with a T spacer from Myastroshop I believe.
Glad to see that your dark comets have disappeared. Well done.
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Old 22-01-2013, 05:55 PM
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by George I think you have it!

Quote:
Originally Posted by allan gould View Post
This is also a problem that others have seen and only comes up with reflections off very bright stars. Fortunately most images don't contain such stars, however the exception is Alnitak when imaging the horse head nebula. I used to have this problem with my Qhy8 ( original model ) and the way I got rid of it was to shift the ir filter on the front of the camera out another 40 mm and this dramatically reduced the reflection off the ccd which was bouncing off the ir filter and back to the chip. Quite easy to do with a T spacer from Myastroshop I believe.
Glad to see that your dark comets have disappeared. Well done.
Thanks Allan.. You are thinking outside the square on this one.. I have been stuck inside a bubble! I just thought of removing the filter and not moving it forward.. That is real simple to do as I have plenty of T-spacers.. That's what is so good about this site, millions of hours of experience from our members... I will do my best to contribute with some brain power in the future (promise!)
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Old 23-01-2013, 05:43 PM
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Quote:
Originally Posted by peeb61 View Post
Hi Allan,
An update on my issue.

.......

One thing I have found is the spikes in the stars?? These appear on all images.

........

Paul
Paul
I missed this query re the star spikes. you dont say which scope you were using for these images . Was it the ED80 or the Mak_Newt or the SW102?
To me it looks as if the doublet spacers ar getting into the light path and thus giving diffraction spikes. Seen with some refractors.
Mak-Newt? dont know. But its something in your light path as its even in your original images.
Allan
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Old 23-01-2013, 05:44 PM
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Thanks Allan for your welcomed feedback.
Time to work out how to move the filter on my QHY8L.

Also the scope being used is the Mak-Newt, I will investigate further with this one, the good thing is I'm back to doing what I enjoying doing most...imaging!

Paul
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Old 23-01-2013, 05:54 PM
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Good one Paul, just relax and enjoy it as it seems you have most things under control and its a few minor things to tune up.
Allan
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