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tooth_dr

4 hours on the Horsehead Nebula - evaluation of image ?

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Basically - looking a more experienced eye cast over this, so that I can tweak my set up.  How can I tell if there is a spacing issue / focus issue / collimation issue?  I've it as close to focus as I can get it but it still looks soft to be.  I'm imaging at 2.23"/px.

Equipment used: Takahashi Epsilon 180, QHY9 mono sensor, with 2" filters.  PA is good and guiding was on average < or = 1"/px

I have it spaced as close to 56mm (+.6mm for filter glass) as I can get it, but I could introduce delrin rings if required to tweak it slight.  The focuser should be ok as it is an upgraded 2.5" moonlight CR focuser. 

 

Maybe a high speed reflector was a step too far for my ability.  This is 4 hours data, luminance, in 300s subs.

 

Any advice - positive or negative - welcomed!

 

CS

Adam.

 

HH-jpeg.jpg

Edited by tooth_dr
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Nothing wrong with that Adam, anyone can look for faults in any image including the Mona Lisa.

The details is great and you have tamed Alnitak.

Now just get the colour combined.

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Looks spectacular.

My one comment, which is probably more about processing than acquisition, is that it would be great to see Alnitak as a double (and, IIRC, the other bright star whose name I forget.)

Tony

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Fantastic Adam. 

The image has a 3D quality to it.   The Head is distinctly in front of the background cloud.   

Don't beat yourself up over  'pixel-angst',  it is going to be a spectacular image.....  btw   don't enter  the final masterpiece  for  SGL Challenge 29...  ;) 

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57 minutes ago, Jkulin said:

Nothing wrong with that Adam, anyone can look for faults in any image including the Mona Lisa.

The details is great and you have tamed Alnitak.

Now just get the colour combined.

Thanks John.  You know how it is with new scope you want to make sure its performing to it's best.  Then I can undo it all with the processing.  I'm getting an Atik EFW3 7x 2" so no colour until then.

18 minutes ago, AKB said:

Looks spectacular.

My one comment, which is probably more about processing than acquisition, is that it would be great to see Alnitak as a double (and, IIRC, the other bright star whose name I forget.)

Tony

Cheers! I agree Tony about the doubles.  Even in a completely unstretched stacked image it's just about split.  I've take a few more exposures of shorter duration and layer mask it in!

6 minutes ago, Craney said:

Fantastic Adam. 

The image has a 3D quality to it.   The Head is distinctly in front of the background cloud.   

Don't beat yourself up over  'pixel-angst',  it is going to be a spectacular image.....  btw   don't enter  the final masterpiece  for  SGL Challenge 29...  ;) 

Thanks Sean, yes I think I'm being a bit over critical.  The head does have a particular 3d feel to it :D  

 

I'm imaging IC5070 now, and I've dialed in the focus a bit better but then I notice a slight distortion of the star shapes as I do so.  I'll check the collimation on Thursday when I'm off.

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Have you checked some of the individual subs, it looks like the star spikes are blurry, could there be a tiny rotation change throughout the set? Failing that, could it be collimation leading to the blurring.

Not sure if you have pixinsight, you could then measure fwhm through the set to assess your focus, collimation etc?

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@jimjam11 Thanks for the reply.  I'll have a look at the subs later.   I'm not sure if there is rotation, that could be some movement in the kit but I my guess is that that is unlikely.  I don't have pixinsight but may be I could use a trial?

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I think there is a PI trial. If you want to upload a few subs I can easily check them using subframe selector...

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I think the image is very good. Could it be a tad tighter? Hard to say. I think the guide RMS is rather high if it's around an arcsecond but it should be OK for the image scale. Focus? Again hard to say. It might be a question of seeing. Ours has been poor of late and others have found the same. I'm not a fan of the Moonlite focuser for imaging, I must say. It's quite prone to slip since it has the roller driving the polished anodised drawtube, which is a not a good idea. Most experienced users of imaging Newts suspend the camera beneath the tube (ie in the lowest possible position with the scope pointed at Polaris.) This requires a truly non-slip focuser.

Olly

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1 hour ago, ollypenrice said:

I think the image is very good. Could it be a tad tighter? Hard to say. I think the guide RMS is rather high if it's around an arcsecond but it should be OK for the image scale. Focus? Again hard to say. It might be a question of seeing. Ours has been poor of late and others have found the same. I'm not a fan of the Moonlite focuser for imaging, I must say. It's quite prone to slip since it has the roller driving the polished anodised drawtube, which is a not a good idea. Most experienced users of imaging Newts suspend the camera beneath the tube (ie in the lowest possible position with the scope pointed at Polaris.) This requires a truly non-slip focuser.

Olly

Thanks for looking at this Olly. I was planning on mounting the camera beneath the tube as you say, but the shortness of the scope limits how much I can slide the rings back and forth. Currently the dovetail fouls the focuser if I rotate it - I plan to remove the dovetail excess this weekend and reposition and see if that helps to reduce loading. Hopefully there won’t be much slippage. 

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I would hope to get tighter stars but it depends on so many things that it's hard to say.  I'm going for a wider field version of that target so will be interested to see what I can get.  I won't be using a reflector though.

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fwiw. i love that image. 

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I can see a small tilt of the sensor plane, probably due to focuser flex or misalignment (see my own effort of focuser alignment here), most obvious in the upper left corner. Maybe there is also a small collimation error since I think the stars are a little soft in general, but I realize it is not an easy task with such a fast scope (maybe collimation is temperature related ?)

What is your focusing procedure ?

A very nice picture anyway !

Ragnar

tilt.thumb.jpg.054172d39b2afcb70107c41a119bd559.jpg

 

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