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Iris Nebula second attempt


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Posted (edited)

I think I've managed to improve the back-spacing of the field flattener for the Zenithstar 73 and also tightened up the rotator to avoid any sag/tilt. 

72 x 3 min lights plus flats, dark flats and bias

Do I need more data on this to pull out the dust?

Is the horizontal banding due to my non-cooled camera?

Many thanks

Iris Nebula 01 Jun 22.png

 

20220601_220446.jpg

Edited by Peter Reader
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A very nice setup, and a very nice image.

On 02/06/2022 at 10:18, Peter Reader said:

Is the horizontal banding due to my non-cooled camera?

It's hard to see on my tablet, but I guess it's "ordinary" canon banding, ie the read pattern of the sensor. PixInsight has a acript to remove it. With a relatively slow scope and a light pollution filter, you don't have that much light reaching the sensor, and you may need to increase the exposure time in order to drown the read pattern of your camera.

On 02/06/2022 at 10:18, Peter Reader said:

72 x 3 min lights plus flats, dark flats and bias

Do I need more data on this to pull out the dust?

3.5 hours isn't much and you definitely need more data to pull out the dust. Afterall, it's dark dust on a dark background. As long as the contrast in the dust is competing with the contrast in the banding, you're fighting an uphill battle.

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7 hours ago, wimvb said:

A very nice setup, and a very nice image.

It's hard to see on my tablet, but I guess it's "ordinary" canon banding, ie the read pattern of the sensor. PixInsight has a acript to remove it. With a relatively slow scope and a light pollution filter, you don't have that much light reaching the sensor, and you may need to increase the exposure time in order to drown the read pattern of your camera.

3.5 hours isn't much and you definitely need more data to pull out the dust. Afterall, it's dark dust on a dark background. As long as the contrast in the dust is competing with the contrast in the banding, you're fighting an uphill battle.

Thanks for the info. I'm considering removing the light pollution filter, although I am Bortle 5 here with many street lamps...

I have never tried going beyond 3 minute exposures but I suppose this makes sense - how long would you suggest? can I stack different exposure lengths together in DSS?

Cheers

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I'm currently at around 10 hours at f6 and still little detail in the image. A lot of it comes from post processing and really really stretching levels and contrast to get the detail out. I experimented in siril and got somewhere after around ten level adjustments though the noise starts to get bad. So as a result I'm going to try at least another 5-10 hours.

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3 hours ago, Peter Reader said:

I have never tried going beyond 3 minute exposures but I suppose this makes sense - how long would you suggest? can I stack different exposure lengths together in DSS

I'm not sure I would go beyond 3 minutes for the individual subs - in light polluted skies there would be little to gain. Just up the total time. At this time of year and the long exposures the noise from the Canon sensor will just get worse. Your sensor certainly looks cleaner than mine, but it still will still struggle with dark nebula during the summer months and minimal astro darkness.

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15 hours ago, Peter Reader said:

Thanks for the info. I'm considering removing the light pollution filter, although I am Bortle 5 here with many street lamps...

I have never tried going beyond 3 minute exposures but I suppose this makes sense - how long would you suggest? can I stack different exposure lengths together in DSS?

Cheers

I too am at Bortle 5, but without any street lights. Even with a cooled mono cmos, I struggled to lift the dust from the background at 3,5 hrs integration time. Imo, you need to at least double or tripple that time to get anywhere. Try to shield your gear from any interfering light sources. (Set up in the shadow of any street lamps if that's possible.) As long as the banding is more pronounced than contrast in the dust, you won't be able to pull that out.

Optimise your exposure time. For uncooled DSLRs, the general recommendation is to put the peak of the histogram in the camera display at 1/4 of the horizontal scale. As @Clarkey noted, this time of year with warmer nights and less darkness, is not a good time to image such faint objects. Revisit the nebula when nights get longer and cooler.

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