1 hour on NGC7000

[Phillyo]

I let the dogs out earlier this evening and noticed that it was actually clear here in Lincoln for the first time in weeks! Decided to try and snatch an hour on NGC7000 and give it a gentle process. It's a bit grainy, a bit noisy and it's not my finest processing ever. However, it's nice to actually catch some photons for a change! I'd like to add a LOT more data on this area, like another 19 hours or so.

Kit as per sig with the IDAS NBX filter.

Thanks, Phil.

[tooth_dr]

Very tasty for just one hour!  Unfortunately I can’t see you sig on the phone.  Was this with a lens?

[Phillyo]

14 minutes ago, tooth_dr said:

Very tasty for just one hour!  Unfortunately I can’t see you sig on the phone.  Was this with a lens?

Thank you, yes taken with the Samyang 135 @ f2.8. 4 min subs.

[michael.h.f.wilkinson]

Very nice result!

[tooth_dr]

23 minutes ago, Phillyo said:

Thank you, yes taken with the Samyang 135 @ f2.8. 4 min subs.

Nice. I saw this extra wide view on FB one day and had to try myself. For me the bit below the NAN and Pelican really enhances the image. 

[MartinB]

That's a beauty, I love the colour.  I think the best processing tool for managing noise and lack of exposure time is to present the image at a smaller scale.  This image demonstrates this perfectly.  And how often do we ever look at images at full scale unless we are pixel peeping.

[Stuf1978]

That's lovely for 1 hour, well done. If you persevere, another 19hours may take you to 2022 with the current weather 😂

[Phillyo]

48 minutes ago, Stuf1978 said:

That's lovely for 1 hour, well done. If you persevere, another 19hours may take you to 2022 with the current weather 😂

Aint that the truth 🙄

[Phillyo]

2 hours ago, MartinB said:

That's a beauty, I love the colour.  I think the best processing tool for managing noise and lack of exposure time is to present the image at a smaller scale.  This image demonstrates this perfectly.  And how often do we ever look at images at full scale unless we are pixel peeping.

Thanks Martin, and yes you're right. I uploaded this at full res if you click on it and it definitely shows the noise. I'm not too concerned about it as it is definitely a work in progress! It looks fine on insta/facebook too :P

[vlaiv]

2 hours ago, MartinB said:

And how often do we ever look at images at full scale unless we are pixel peeping.

I do it every single time

It's not about pixel peeping, it's about appreciating the scale of things. I also like to sometimes spot very faint background galaxy or see something else that I would miss by looking at "larger picture".

 

[kirkster501]

Super stuff.  I am thinking of connecting my QHY268C to the Samyang 135.

I am also very tempted, bonus permitting of getting a Sigma Art 105mm F1.4. 

[Phillyo]

2 hours ago, vlaiv said:

I do it every single time

It's not about pixel peeping, it's about appreciating the scale of things. I also like to sometimes spot very faint background galaxy or see something else that I would miss by looking at "larger picture".

 

Don't do it this time! Give me some more integration time first please 

[vlaiv]

15 minutes ago, Phillyo said:

Don't do it this time! Give me some more integration time first please 

I'm afraid it's already done

And don't worry - I have no issue with poor SNR - like you already said yourself - that is probably easiest thing to fix - you throw more time (I know, sometimes skies won't allow for more time, but in principle - time will come) at it.

On the other hand - I must notice that your focus might be a bit off? Or is it processing?

Did you do mosaic (highly doubt it since there is a bit of tilt that would repeat itself) or did you for some inexplicable reason opt to drizzle? As far as I can tell from your signature you have ASI533 which is 3008px and image is 6016px - I'm smelling x2 drizzle

Indeed there is some slight tilt - this is likely due to way lens is supported. If you choose proper resolution for your image, then even this issue won't be as noticeable.

That is the thing with drizzle, when applied on over sampled image - it makes everything so much more obvious with no particular reason. Take for example this:

Stars don't look nice and pin point, they have this sort of halo that you can get by either having your focus slightly off or using optics that is not diffraction limited (in this case, maybe even mixture of the both).

Now, have a look at this:

It does not matter that I "zoomed" in to 100% in this second version (which is your original version reduced in size by x4 - or to 25% of drizzled version, or 50% of original version, or 100% of super pixel debayered version - which is proper sampling rate for OSC camera). It looks nice - stars are points (more or less - one would be hard pressed to tell that there is a bit of halo on them) - it just looks right even on 100% zoom.

And then all that is left to do is proclaim: "Pixel peeper's gonna peep" (and you could not care less).

And yes, remember that tilt issue (right bottom corner):

What tilt issue (same corner)?:

 

[Phillyo]

Haha no that's fair. I did indeed do 2xdrizzle, I will do it again without the drizzle. However, the reason for the halos is due to the very fast processing I did. I removed the stars with Starnet to work on just the nebula on it's own, then I added them back in with pixelmath at like 0.8x maybe? Like I say, it was quick and dirty and if/when I come to do a 'final' edit (whenever I get more data) I'll not remove the stars and edit the same way. 

There is some tilt, though I don't know why. I'm supporting the lens, with 2 rings and the camera with a ring too so neither should be tilting/sagging. I'm wondering if it might be a distance thing? Is it definitely tilt? I'll upload a picture later of how it's all set up (I'm at work now). 

I have a friend-made bahtinov mask which work's 'okish' but I'm looking at getting a better one as it isn't great. That being said, I spent a good long while getting focus so I think focus is fine and I think it's more the processing that caused the slightly out of focus look at 100%.

Cheers Vlaiv.

Phil

[vlaiv]

4 minutes ago, Phillyo said:

Haha no that's fair. I did indeed do 2xdrizzle, I will do it again without the drizzle. However, the reason for the halos is due to the very fast processing I did. I removed the stars with Starnet to work on just the nebula on it's own, then I added them back in with pixelmath at like 0.8x maybe? Like I say, it was quick and dirty and if/when I come to do a 'final' edit (whenever I get more data) I'll not remove the stars and edit the same way. 

There is some tilt, though I don't know why. I'm supporting the lens, with 2 rings and the camera with a ring too so neither should be tilting/sagging. I'm wondering if it might be a distance thing? Is it definitely tilt? I'll upload a picture later of how it's all set up (I'm at work now). 

I have a friend-made bahtinov mask which work's 'okish' but I'm looking at getting a better one as it isn't great. That being said, I spent a good long while getting focus so I think focus is fine and I think it's more the processing that caused the slightly out of focus look at 100%.

Cheers Vlaiv.

Phil

Indeed could be processing thing.

It is most likely tilt - as it affects only bottom part of the image - that is signature of the tilt - which is in reality - distance issue - one part of sensor having different distance then the rest of it. If it affects only one corner or two corners - it is likely tilt.

By the number of corners it affects - you can figure out direction of the tilt. If it's only one corner - it is "diagonal" to sensor, but if its two corners - it is parallel to sides of sensor.

[Phillyo]

2 minutes ago, vlaiv said:

Indeed could be processing thing.

It is most likely tilt - as it affects only bottom part of the image - that is signature of the tilt - which is in reality - distance issue - one part of sensor having different distance then the rest of it. If it affects only one corner or two corners - it is likely tilt.

By the number of corners it affects - you can figure out direction of the tilt. If it's only one corner - it is "diagonal" to sensor, but if its two corners - it is parallel to sides of sensor.

Interesting! I'll need to take a look at that then. Thanks again.

[kirkster501]

You posted a wonderful NAN and Pelican for us to view and enjoy.  My counsel is not to be obsessive about it Phil with this guidance.

[Phillyo]

18 minutes ago, kirkster501 said:

You posted a wonderful NAN and Pelican for us to view and enjoy.  My counsel is not to be obsessive about it Phil with this guidance.

Thank you. I don't obsess over it, but I like tinkering and making things 'better', it's one of the things I find most interesting in the hobby. Gotta strive to be better right? 

[Phillyo]

@vlaiv this is how it's all connected (Sorry for bad picture, cold and dark!) so I'm not sure where the tilt is coming from. I'll need to do some investigations me thinks! I don't suppose there's a way of checking for tilt using software is there? I hate to waste clear nights.

[vlaiv]

4 minutes ago, Phillyo said:

@vlaiv this is how it's all connected (Sorry for bad picture, cold and dark!) so I'm not sure where the tilt is coming from. I'll need to do some investigations me thinks! I don't suppose there's a way of checking for tilt using software is there? I hate to waste clear nights.

That looks rather nice. Maybe something is tightened too much and creates pressure on optical train (are these rings height adjustable?).

There actually is a way to check for tilt in software. There is piece of software that is called CCD inspector.

You take one calibrated linear sub of star field (relatively uniform star field) and you analyze it in this software and it will produce diagram of field curvature, collimation and possilbe tilt.

It looks like this:

Above image shows a bit of curvature and some tilt / possibly slight collimation issue if scope is newtonian.

It will show both height diagram and 3d representation of focal plain. Again - corner affected will be lighter in color.

Software needs to be purchased but I've seen some members here offer to analyze subs with their copies if you upload them in these kind of situations when troubleshooting.

 

[Phillyo]

On 16/11/2020 at 19:06, vlaiv said:

That looks rather nice. Maybe something is tightened too much and creates pressure on optical train (are these rings height adjustable?).

There actually is a way to check for tilt in software. There is piece of software that is called CCD inspector.

You take one calibrated linear sub of star field (relatively uniform star field) and you analyze it in this software and it will produce diagram of field curvature, collimation and possilbe tilt.

It looks like this:

Above image shows a bit of curvature and some tilt / possibly slight collimation issue if scope is newtonian.

It will show both height diagram and 3d representation of focal plain. Again - corner affected will be lighter in color.

Software needs to be purchased but I've seen some members here offer to analyze subs with their copies if you upload them in these kind of situations when troubleshooting.

 

So you can get a trial version so I'm giving that a go. I uploaded all the images I took to create the image of this post and both curvature and tilt vary on each image, the worst being 18.1% curvature and 15% tilt. The best being 14.6% curvature and 5% tilt. Why does it vary so much image to image? Is there anything I can do about that?

I ended up removing the spacers this evening and reattaching it without doing it up super tight. I only took 2 images before clouds blocked the stars out but they were better, with curvature being about 10-12% and tilt being either 5% or 1%. 

So now I'm confused. I did shoot the first image (with 1% tilt and 10.3% curvature) at a narrower aperture of like f4 maybe? Just to see if it made much difference. The second image was shot wide open at f2, but it's still only 5% and 12.3%.

I'm rather confused now! Maybe I'll just take as many photo's as a can then just crop in a slightly to remove the very nasty stars

Thanks,

Phil. 

[vlaiv]

We probably need someone with more CCDInspector experience to explain what is going on.

I do know that software is sensitive to what type of star field you select, and it can interpret issues what come from lens being wide open as curvature (at least I think so since I have some idea of how it works).

For tilt and other issues - best to use it stopped down to say F/4 - that should give you proper stars all over, so there will be less chance to confuse the software.

[Phillyo]

5 minutes ago, vlaiv said:

We probably need someone with more CCDInspector experience to explain what is going on.

I do know that software is sensitive to what type of star field you select, and it can interpret issues what come from lens being wide open as curvature (at least I think so since I have some idea of how it works).

For tilt and other issues - best to use it stopped down to say F/4 - that should give you proper stars all over, so there will be less chance to confuse the software.

Thanks Vlaiv. I'll give F4 a shot, although it'll mean more integration time it will also (hopefully) mean a bette final image. I have some step down rings I can use too so that should help also.

[AstroNtinos]

This image is superb. It has so much details. Very well done.

[Phillyo]

Added another 5 hours of data last night and reprocessed it (without drizzle this time Vlaiv ;)) so this is now 6 hours with a slightly different process. I've done stars and starless as I really like seeing both?