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Iris nebula with Skywatcher 72ED

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Hello all!

The weekend that just passed we went to my girlfriend's parents. The skies in that rural area are pretty much as good as you can get. I don't have an SQM reader, but Clear Outside estimates 21.91.

I didn't take the EQ6R with me, I still consider it a big lump of iron, and the AZ-EQ5 should be on its way back this week as a Stellar mount. So I used the EQ5 which was left in the car for a while. While the tracking/guiding on the RA axis is quite good, the DEC control jumps a lot after multiple consecutive guiding commands, I blame the "enhanced" handset.

So with all the drawbacks, I tried to do align the mount as good as I could and I put the 72ED with the ASI1600 on it and a finder-guider.

Perhaps also focus could have been done a bit better, FWHM in the subs was 3.x.

Below is a quick process from last night, no deconvolution yet and a purple area at the bottom that I have to fix. 58x120s lum, 30x120s each RGB.



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Edited by moise212
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Hello all! The weekend that just passed we went to my girlfriend's parents. The skies in that rural area are pretty much as good as you can get. I don't have an SQM reader, but Clear Outside esti

Thank you and clear skies!   I reprocessed the Iris, I hope I can call this one the last version. On astrobin: https://www.astrobin.com/382251/

Thanks! I only skipped the ones when the moon was near full. Imaging, sleep, pack some gear, sleep, work and again.

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Yeah I have to say, that looks pretty darn good to me. Without being able to pixel peep on my current device, your processing looks really good. Good color without looking overprocessed, very natural.


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Very nice image there, nice to see those stars in the corner looking round.

Looks like Skywatcher might have another winner on their hands regardless of some fiddling with spacing.

Edited by Skyline
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  • 2 weeks later...

Thank you too!

I thought/wanted to reprocess this, but I have tons of other data waiting in the queue. It's been clear here almost every night for the last 2 months maybe. Processing time now it is as the clouds rolled in.

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5 minutes ago, tooth_dr said:

Fantastic, you really can see the dust just sitting in front of the stars.  Lucky you having too many clear nights :D :D :D

Thanks! I only skipped the ones when the moon was near full. Imaging, sleep, pack some gear, sleep, work and again.

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3 minutes ago, swag72 said:

That's a super Iris...... the dust is really good, you've processed it really well ????

Thank you, Sara! Actually this was so easy to process, but I "blame" the good skies for this. It makes such a big difference to have good data to start with. That weekend we arrived home at 1-2 AM after a wedding. I had the stacks already, I registered the channels, I applied some DBE on the L and the RGB images, I extracted a synthetic luminance from RGB, I combined it with the real luminance, I took the highlights from the synthetic luminance (I think the stars were just a tad tighter), made an LRGB, TGV, MMT, stretch, slight star reduction, background enhance, increased the saturation on the highlights and at 3 AM I was sleeping already.

I should have applied some deconvolution and some sharpening, plus a better gradient handling as there's an annoying blue area at the bottom.

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  • 1 month later...



Lovely image - Did you use the 0.8X Reducer with this?  I’m toying with either this or the WO ZS61.  This is faster with the reducer but obviously not FPL53 glass.  From your image though the stars colour looks bang on.

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Hi and thanks!

I haven't had yet the time and drive to process this properly. It's still on the process queue, but with a lower priority.

I used the dedicated reducer which is actually a reducer for the 80ED with an adapter. You need to increase the distance between the reducer and the sensor to about 60-62mm in order to get round stars towards the corners. More distance and you end up not reaching focus anymore.

I measured the focal distance with the 0.85x reducer/flattener and a backfocus distance of ~60mm and it turned out to be ~375mm. With a non reducing flattener I got ~430mm.

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13 hours ago, blinky said:

Hmmm.... thanks for the info, sounds a bit of a pest to get the spacing correct

Around 60mm is not perfect, but quite fine.

13 hours ago, Pompey Monkey said:

Wow! That's brilliant.

Where I live, I can't get close to that with even 10+ hours of lrgb.

I'm going to concentrate on NB from now on....


Thank you! I can't get such results where I live either, but at a dark site... quite impressed too.

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  • 4 weeks later...

Really very nice. I remember imaging this with an ED120 years ago, it takes me back looking at yours. 

You've got that wonderful deep 3D effect going on with all that dust. Lovely!

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Thank you all very much!

18 hours ago, Lockie said:

I remember imaging this with an ED120 years ago, it takes me back looking at yours. 

One day... I will have an 120ED too, perhaps with a full frame DSLR on it when traveling light.

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