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The "No EQ" DSO Challenge!


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Just now, Nigel G said:

Ken. I'm really looking forward to seeing an image from your new CCD :) probably almost as much as you. This might make me start saving some ready's.

I found a stack from a couple of weeks ago I had forgotten about, I took this while waiting for another DSO to rise above my roof top.

A nice easy one to process,

M2. 30 minutes of 30s lights no dark or flats but 50 bias. 150p DSS & StarTools.

Nige.

Weather is looking promising tonight. I need to measure my spacing on the camera from the reducer. i don't have the spacers I need to get it perfect but I'm hoping I can get it close enough to test it tonight. I know I can reach focus (tested on the refractor already). If the wind dies down, then I think I'll try for the Soul again - maybe 60 mins of L and 20 mins each for RGB (bin2). Given the extra sensitivity, that should be more data than I've previously captured using the DSLR though it would mean having to learn how to upscale binned data. I'm more scared about the processing than the capture!

There's something I love about globular clusters. I also love that you can just start to see some diffraction spikes on some of your brighter stars - something I love to see on star fields (not so much on when the focus of the image is a nebula or galaxy).

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I'm still fairly new to imaging, but have had a good start with Planetary and Wide Field images. Obviously, like most of us, it's the Deep Sky stuff I'd like to glimpse, but time, location and more im

Assorted shots with a Nexstar 102SLT and a Canon 1000D. 30sec subs at ISO1600. Total exposures range from 5 mins (M20)  to ~1hr (M31). NigelM

this was taken a couple years ago on my AZGOTO mount with 130p...... about 50 x 5 sec subs, no calibration frames

Posted Images

3 minutes ago, Filroden said:

Your Soul is definitely more Elvis than Baby! I still find it amazing what you can capture in such short exposures. I definitely want to try more wider frame imaging.

There's something weird going on in the Heart. It's almost like DSS isn't aligning the frames right on the left hand side and it's introducing a noticeable blur. I don't think it's our normal "friend' of field rotation. I wonder if that's lens distortion? Did you have the aperture wide open? If so, it might be better to drop it down a couple of stops. If not, do you have either Lightroom or Photoshop? Both can "undistorted" lenses. In Lightroom you tell it which lens you are using (it can often auto detect it from the RAW metadata) and it warps the image based on known distortion models for that lens. Unfortunately, you have to do this on each sub individually then re-save/export each file. I'm not sure if other photo packages can do the same (it's a feature of Adobe Camera RAW module which is included in both Lightroom and Photoshop). You would probably have to do this with lights, darks and flats, as they would all have the same distortion. (I'm out of my depth on this part having not used wide angle camera lenses yet)

I took these frames over 2 nights, I think the camera might have been of line a fraction one of the sessions. XXXXXX

The aperture was set at 3.6 and I have an old version of photoshop.

I modified my focuser to achieve prime focus, it doesn't screw on its a tolerance push fit. I need to attach the camera then wind the focuser right down till the camera squares its self against the stopper. If this is not done correct this is the result. I had this with the Veil neb but spotted it straight away, the trouble with wide field you can set up your capture software and walk away for half an hour leaving the pc to it.

Silly me, this could not be the problem because I didn't use the scope, what a fool. hmm, perhaps I need to close the aperture a bit but I haven't had this before with the 210mm lens.....

It must be rotation or bad tracking.

Nige.

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47 minutes ago, Nigel G said:

Heart and Soul attempt.

I added 50 flats and 65 dark- 15 @ 90s and 50 @ 60s I asked DSS to stack 66% of lights due to lots of disturbance on the left and especially top left, so 106 lights total time about 1h 45 mins.

DSS sorts all the frames into order so I just added all the darks in one mixed batch, same as lights.

There is a big difference to no flats and less darks, the new stack is workable although still noisy, I managed to find some detail in there, the lights are not that good, think I went to long on exp times. ( I checked through the darks and was surprised to see quite a difference in some of them )

I didn't spend too much time processing this as I really don't think the data warrants it. I have learnt however, flats and lots more darks are worth it. So here it is :) 

210mm lens, around 40% cropped out. Its 100% better than my first try.

Nige.

I think you captured that well Nige, and it's good to note that all the extra work doing flats and darks has paid off. As Ken says, though, there is something odd going on in the top left, as though the scaling of the image has changed slightly during the session so that the stars can't be made to line up throughout the whole image. I presume it is taken with a zoom lens, so is it possible that you might have nudged the zoom ring a tad part way through your session? Another thought, does your lens have image stabilisation, and if so, was it turned off? Not sure how that would affect the stacking process mind. It needs to be off anyway because it can 'jitter' when the camera is rock solid. Also, as it is cropped, is it symmetrical? In other words, do you have the same issue on the other side of the frame that has now been lost?

I like your globular. They are relatively easy to process as one doesn't need to tease out the minutest detail, which can come as a welcome relief! I too am drawn to them.

Ian

PS Just to add, I can't see that lens distortion would cause this, as all the frames would be distorted equally.

Edited by The Admiral
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1 minute ago, The Admiral said:

I think you captured that well Nige, and it's good to note that all the extra work doing flats and darks has paid off. As Ken says, though, there is something odd going on in the top left, as though the scaling of the image has changed slightly during the session so that the stars can't be made to line up throughout the whole image. I presume it is taken with a zoom lens, so is it possible that you might have nudged the zoom ring a tad part way through your session? Another thought, does your lens have image stabilisation, and if so, was it turned off? Not sure how that would affect the stacking process mind. It needs to be off anyway because it can 'jitter' when the camera is rock solid. Also, as it is cropped, is it symmetrical? In other words, do you have the same issue on the other side of the frame that has now been lost?

I like your globular. They are relatively easy to process as one doesn't need to tease out the minutest detail, which can come as a welcome relief! I too am drawn to them.

Ian

Ian that a very good point, yes its a zoom lens, it would only need the slightest touch to be noticeable, I use it at max zoom but its very possible and most likely the answer.

The image is worse on the left to top left .

Nige.

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8 minutes ago, Stub Mandrel said:

Call me an idiot, but I have read the explanations for the various opening options in Startools and I really don't understand how they relate to output from DSS.

You and me too, your certainly not an idiot. I have asked that question quite a few times and never got a straight answer to it, I'm still non the wiser :) 

I understand the choice is to do with colour only, it will not affect anything else. I have always used the first choice because I thought my data was white balanced but now I'm not sure !

Edited by Nigel G
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10 minutes ago, The Admiral said:

PS Just to add, I can't see that lens distortion would cause this, as all the frames would be distorted equally.

Normally that would be try but because our mounts introduce field rotation, won't the distortion rotate too? But I think you hit the nail on the head, it's possibly the zoom causing image scale. I'm not sure whether DSS can align and rescale subs? I've never had to merge images from two different image trains (effectively what a slight change of zoom creates) but I know it's possible.

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50 minutes ago, Filroden said:

Normally that would be try but because our mounts introduce field rotation, won't the distortion rotate too? But I think you hit the nail on the head, it's possibly the zoom causing image scale. I'm not sure whether DSS can align and rescale subs? I've never had to merge images from two different image trains (effectively what a slight change of zoom creates) but I know it's possible.

Well I took the view that any lens distortion would be axially symmetric, so it wouldn't depend on rotation. That said, I suppose everything is possible and without testing I suppose one couldn't rule out non-symmetric distortion. At the back of my mind I think I've read of a stacker that can account for different scaling (or zoom settings). PI doesn't cope with that does it?

As to which button in ST to use, I just take it literally. I choose the "Linear, was not Bayered or is whitebalanced", simply because my Fuji doesn't have a Bayer array. If it did, I would choose "Linear, is Bayered, is not whitebalanced", on the basis that it is a Bayer sensor, I'm using RAW, and I'm assuming that provided you switch off all the colour correction options in DSS and use the autosave FITS, then it would be the best match. Could easily be wrong of course :icon_biggrin:. In fact, I think this demonstrates one of the deficiencies in the ST documentation, in that all of the modules have sub-settings with parameter names that don't really mean much to me, and their individual functions are not explained. True, you can try each to see what it does (often nothing that I can see!), but it often feels like wading through treacle.

Ian

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On 27/09/2016 at 14:04, Nigel G said:

Theres a link to the fts at the bottom if anyone is bored and wants something to process :) 

https://1drv.ms/u/s!Av3mI1-jgAvwcIvZwbzjRcPwXIU

Thanks Nige, not bored, a good excuse to continue my practicing in Gimp :) !

That is a very nice image of the veil that you have managed, very impressive wispy detail.

I am late on parade with my version because originally I could not get Gimp to eliminate the vignetting, but a bit more practice with a gaussian blur subtraction and I've come up with these two for your inspection/amusement, the first is a bit 'warmed up' and the second is more true to the original blue. A curious thing is that Gimp is opening the .fts vertically flipped compared to others here :(

Autosaveveil2S.jpg

AutosaveveilS.jpg

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31 minutes ago, The Admiral said:

At the back of my mind I think I've read of a stacker that can account for different scaling (or zoom settings). PI doesn't cope with that does it?

I think it might but I've never needed to find out yet. It can cope with mosaics (but so does DSS). I think it's down to alignment (both PI and DSS do this) and whether it has a function to rescale if the images can be aligned but are of different scales. I can't think of a case where I could test it given my equipment until I can set up some wide area imagery with my stock Canon zoom lens (but that's another project once I've learnt how to use the camera on the scope!).

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Hi All,

I've reprocessed the Heart and Soul Nebula image this time taking more time with mask before using the COLOR module and the LIFE module. I used the option to draw the outline of the nebulosity then grow the mask. I used the same mask for the COLOR module (inverted) and returned the mask to normal for use in the LIFE module. I also used 'less=more' option rather than 'isolate'. I'm now going to lie down...

Cheers,
Steve

Heart and Soul 003 2.jpg

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You just know it's going to be one of those nights. It's clear, the wind has settled. The scope is set up. The camera is working. I even managed to get it focused using SGPro - not easy when you're fine tuning and waiting a second for the image to update. Nonetheless, I have to say this is the best focus I've ever achieved. Stars looks *sharp* on the screen.

And then it all went wrong...

It's almost impossible to do a three star alignment using SGPro and 1 second image capture. I need to find a better "live view". I persevered though. Until the fourth failed attempt and I decided to get the DSLR and use that and BackyardEOS to do the alignment. Success first time!

And then it all went wrong again...

The wifi on the mount decided to bug out and I couldn't control the mount from the iPad. I tried everything, even powering the mount down (knowing I would have to realign it). I tried connecting via SkySafari, Celestron's own app, through the iPhone and the iPad. None of them would connect. I finally gave up and got the old hand remote and tried to remember how to use that.

Anyway, a quick two star alignment later and I was centred on IC1848 and taking my first 30 second L sub.

I'm now running a sequence of 10x LRGB at 30 seconds and I'll keep repeating that for as long as I have the stamina (probably recentering after each sequence).

I have to day, I don't know if I've captured any nebulosity but the star field looks much nicer that anything I've taken before. Fingers crossed!

 

P.S. Remember to plug the power into the camera's cooling. That's 30 mins of subs taken at 11C rather than -20C.

Edited by Filroden
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Nige, I've just had an Archimedes moment regarding your fuzzy stars! Have you heard of something called "zoom creep"? It's when a zoom lens slowly extends under its own weight whilst it's being carried around on the camera. I was wondering if that could have happened in reverse, so that whilst it was pointed up at the sky it was slowly collapsing and the focal length changing? The zoom barrel would need to be fixed in position some how.

Ian

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8 hours ago, The Admiral said:

Nige, I've just had an Archimedes moment regarding your fuzzy stars! Have you heard of something called "zoom creep"? It's when a zoom lens slowly extends under its own weight whilst it's being carried around on the camera. I was wondering if that could have happened in reverse, so that whilst it was pointed up at the sky it was slowly collapsing and the focal length changing? The zoom barrel would need to be fixed in position some how.

Ian

Ian, a good thing about my 210mm lens, the zoom is at max when closest to the camera, so if pointing up it can't slip or move, also the focus is easy,  turn the focus until it stops ( infinity ) actually is prime focus, not like my 135mm which requires a nudge back for focus.

Having said that it is very smooth and easy to move and is the most likely cause,  when I'm about to start shooting with the lens I check that it's turned all the way to the right and pulled right back to max zoom,  even after doing this I noticed it out of focus once, checked the lens and I'd managed to move the focus.

So it possible. 

Nige

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I have yet to take flats (scope/camera is sat in the lounge ready for me to run them) so my initial integration suffers from vignetting.

Here's a single, bias/dark calibrated, L sub of 30s with no processing other than to convert the fits file to a jpeg (first image). I also applied a very quick stretch with levels and curves (second image). I've applied no noise reduction, etc.

Now off to take the flats.

M45-single_L-sub_30s.jpg

M45-single_L-sub_30s_stretched.jpg

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25 minutes ago, Filroden said:

I have yet to take flats (scope/camera is sat in the lounge ready for me to run them) so my initial integration suffers from vignetting.

Here's a single, bias/dark calibrated, L sub of 30s with no processing other than to convert the fits file to a jpeg (first image). I also applied a very quick stretch with levels and curves (second image). I've applied no noise reduction, etc.

Now off to take the flats.

A good start Ken! Nebulosity coming through on a single sub, should be good when it's all put together. I'm presuming this is M45 rather than IC1848?

As to your alignment woes, is it possible to use a much shorter capture time in order to get more of a Live View experience? Or is this a case for a Star Sense :wink2:

Ian

Edited by The Admiral
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10 minutes ago, The Admiral said:

A good start Ken! Nebulosity coming through on a single sub, should be good when it's all put together. I'm presuming this is M45 rather than IC1848?

As to your alignment woes, is it possible to use a much shorter capture time in order to get more of a Live View experience? Or is this a case for a Star Sense :wink2:

Ian

Yes, I'd wasted so much time setting up then messing up the first 30 minutes of subs that I swapped to M45 given its a much brighter target and I was running out of time/stamins. I did capture some subs of IC1848 which I will also process but given the run was short I don't know what to expect.

SGPro seems to only allow a minimum of 1 second in its framing and focus module. I did finally manage to align using SGPro and the handset, it just takes a lot more patience. I need to figure what's wrong with the wifi though, as using the handset is a pain compared to controlling the scope from the iPad using SkySafari.

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Hi,

I have followed the ST's guide I posted above and used it to wavelet sharpen (SHARP module) the nebulosity in my Heart and Soul image. It does look different on my monitor but interested what anyone else can see regarding a better image.

Original-

Heart and Soul 003 2.jpg

New-

Heart and Soul 003 2EXPERIMENTDONE.jpg

It appears (here) brighter and more detail within the nebulosity plus the stars look brighter.

Cheers,
Steve

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It's definitely much clearer - you can see the full extent of the Heart Nebula now. Wavelets are great for pulling apart an image into different structures and giving you the control to sharpen/noise reduce only those structures you really want to (whether it be the lowest wavelets to reduce noise or the higher wavelets to improve sharpness or contrast). It took me a while to wrap my head around wavelets (having first come across it processing planetary images) but now I think it's a great tool along with various masks.

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4 minutes ago, Filroden said:

It's definitely much clearer - you can see the full extent of the Heart Nebula now. Wavelets are great for pulling apart an image into different structures and giving you the control to sharpen/noise reduce only those structures you really want to (whether it be the lowest wavelets to reduce noise or the higher wavelets to improve sharpness or contrast). It took me a while to wrap my head around wavelets (having first come across it processing planetary images) but now I think it's a great tool along with various masks.

Thanks for this Ken, there's a way to go with StarTools but this has lifted me at just the right moment through the glass ceiling I felt I was up against. Good luck by the way with your new camera, I'm sure we are all looking on at how improved your results are going to be.

Cheers,
Steve

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Ken, that's a good promising start, I'm impressed. 

Steve, that's a good improvement,  the heart and soul are both easily visible. 

Going to check out that StarTools link now. 

A great link, very interesting,  I had no idea you could use it like that, looking forward to trying that on some of my images,  first book work to catch up with ?

Cheers 

Nige.

Edited by Nigel G
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