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Old 05-01-2021, 09:47 PM
Zuts
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IC2118, Witchhead with new camera

IC2118, The Witch Head Nebula

19 by 600 sec, darks + flats + bias
TV85 + ASI 2600 MC, Guiding with ASI 120 MM Mini
0.8 Flattener/reducer, no filters

Processed in PixInsight

Taken from Ivanhoe NSW, Quite low in the sky and a 50% moon, but the only place in NSW not raining , so the 800 km trip, with 400 km detour due to flooding was worth it to try out my new camera.

I am happy with my new camera in terms of sensitivity but there are some issues. My previous camera had round stars to the corners with my TV reducer/flattener. With the new camera the scope and/or the reducer flattener does not cover the chip. Also the stars in one corner have strange cross like artifacts.

Does anyone know what would be causing this, do you think it is

1. Me
2. Camera
3. Scope
4. Reducer
5 . All of the above

Cheers
Paul
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  #2  
Old 06-01-2021, 05:42 AM
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PKay (Peter)
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10 out of 10 for effort Paul!

The image is interesting since it captures the illuminating light coming from Rigel.

With regards to cause of artefacts I choose 6: 'No idea'.
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Old 06-01-2021, 07:09 AM
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xelasnave
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7 tilt?
You did well.
Alex
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Old 06-01-2021, 07:59 AM
Startrek (Martin)
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Paul
Great image of the witch head
Well done !!
Even better as you traveled so far to get some clear skies
Only a guess but I reckon your eggy stars may be caused by tracking / guiding problems as its ok on the far left of the frame and progressively gets worse as you move across to the right side
Why 10 minute subs on a nebula ?? the 2600MC has a super high dynamic range with a QE of over 80%
Are you running the Ascom driver on HDR ( gain 0 )
I find the sweet spot for cooling on mine is -10 to -15C , what do you cool yours down to ?
Try shorter subs say 3 to 5 minute with more subs , it may resolve your eggy stars ??? Worth a try ??
Martin
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Old 06-01-2021, 08:21 AM
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Sunfish (Ray)
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Great image and a lot of dedication. A lot of detail and colour. Those cross shapes are very odd. Perhaps there was a fleck of fibre on the lense. Perhaps also you are exposing more of the full size of the lense with a larger sensor so seeing more problems than you would with a smaller sensor.
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Old 06-01-2021, 04:57 PM
carlstronomy (Carl)
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Really nice image, if we ever get clear skies again in QLD this is one I am interested in trying myself.

As for the issues with the stars I would say this is not related to tracking as every star would move the same in your field of view not only the ones on the edges, this looks very much like coma of some type.

I am no expert but could there is something with the image train you are using, maybe you already mentioned it with the chip being so large. This could be causing both issues. From your list number 2 seems more likely or the compatibility of 2 with 4. Like you said you have had no issues before the new camera. One thing I did notice is the elongated stars are on the right hand side of the image and the cross stars are on the left. Could there be some pinching or is the camera too heavy and leaning one way on the focuser?

Carl

Last edited by carlstronomy; 06-01-2021 at 10:04 PM.
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Old 07-01-2021, 12:30 PM
neurosis3000 (Reggie)
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Very nice! It’s a faint one. I tried this myself a few days back and saw nothing!

Well done!
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  #8  
Old 11-01-2021, 05:10 PM
Zuts
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Quote:
Originally Posted by PKay View Post
10 out of 10 for effort Paul!

The image is interesting since it captures the illuminating light coming from Rigel.

With regards to cause of artefacts I choose 6: 'No idea'.
Thanks Peter, yes Rigel does add a ghostly cast.

Quote:
Originally Posted by xelasnave View Post
7 tilt?
You did well.
Alex
Thanks Alex, I posted this question in advanced imaging, probably the sensor is to large for my imaging circle.

Quote:
Originally Posted by Startrek View Post
Paul
Great image of the witch head
Well done !!
Even better as you traveled so far to get some clear skies
Only a guess but I reckon your eggy stars may be caused by tracking / guiding problems as its ok on the far left of the frame and progressively gets worse as you move across to the right side
Why 10 minute subs on a nebula ?? the 2600MC has a super high dynamic range with a QE of over 80%
Are you running the Ascom driver on HDR ( gain 0 )
I find the sweet spot for cooling on mine is -10 to -15C , what do you cool yours down to ?
Try shorter subs say 3 to 5 minute with more subs , it may resolve your eggy stars ??? Worth a try ??
Martin
Thanks Martin.

After talking with people at Bintel I agree with them that while stacking can bring out details, if they are not there in the first place then stacking won't help. So for faint objects I have decided to try for 10 minute minimum subs, dependent on guiding conditions.

I am controlling things using the ASIAir pro, and set the gain at 100, which is the default.

I cool to -10 as I can reach this all year round. This was fine on my 1600 but with this new camera the power is running at nearly 85% to reach this temp.

I think to solve this problem I will purchase either an Esprit 100 or 120, after I sell some more equipment.

Quote:
Originally Posted by Sunfish View Post
Great image and a lot of dedication. A lot of detail and colour. Those cross shapes are very odd. Perhaps there was a fleck of fibre on the lense. Perhaps also you are exposing more of the full size of the lense with a larger sensor so seeing more problems than you would with a smaller sensor.
[QUOTE=carlstronomy;1505609]Really nice image, if we ever get clear skies again in QLD this is one I am interested in trying myself.

As for the issues with the stars I would say this is not related to tracking as every star would move the same in your field of view not only the ones on the edges, this looks very much like coma of some type.

I am no expert but could there is something with the image train you are using, maybe you already mentioned it with the chip being so large. This could be causing both issues. From your list number 2 seems more likely or the compatibility of 2 with 4. Like you said you have had no issues before the new camera. One thing I did notice is the elongated stars are on the right hand side of the image and the cross stars are on the left. Could there be some pinching or is the camera too heavy and leaning one way on the focuser?

Thanks Ray and Carl, I agree, I don't think my current scope and reducer can handle the chip size of the new camera.

Quote:
Originally Posted by neurosis3000 View Post
Very nice! It’s a faint one. I tried this myself a few days back and saw nothing!

Well done!
Thanks Reggie. Yes this is a very faint object. You need to expose for a long time to pick up any significant detail.
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