ZWO/Player One IMX 585 Sensor Image Showcase

[MichaelBibby]

Took another shot at the Orion Nebula as the moon was rising under not so great seeing conditions. 30 second exposures at a gain of 250 (think I'll try 45 seconds at 180 next time, so I can get even more dynamic range). Live stack, no post, 150p, guided. Such a beautiful thing...


 


And for something different, this is a look at the Magnificent Seven in the Small Magellanic Cloud (probably a little out of focus, I was testing my guiding setup and was trying to beat the clouds, so I was in a bit of a hurry).





The clouds held off long enough for me to refocus and get a quick stack of NGC1232.

Edited December 11, 2022 by MichaelBibby

[Lamplighter05]

On 28/11/2022 at 13:50, vlaiv said:

Stacking process.

I believe that if data were to be stacked using Siril with say Lanczos interpolation for sub alignment - pattern would go away, but I'd be happier if someone actually confirmed that by doing it.

It looks like it could be a 'rounding error' aka quantisation error in the stacking algo, with slight local variations causing a moiré effect with the data.  It could be rotational calculations on partial pixel coverage as the data values are clipped or 'binned' across pixel boundaries. One way to try 'fixing' it would be to pre-scale the stacking images (prior to stacking)  with a simple 2x  linear interpolation - basically creating a artificial bin2 of the data. Then stack the result and finally scale the result back down by 0.5x. 

[vlaiv]

4 hours ago, Lamplighter05 said:

It looks like it could be a 'rounding error' aka quantisation error in the stacking algo, with slight local variations causing a moiré effect with the data.

I identified such effect with bilinear interpolation and small angle rotation - here is brief explanation of what happens in that particular case:

Look at two columns of pixels and very small angle rotation:

Red line represents pixel centers after rotation (after rotation it will be vertical, but since we haven't rotated yet - it is tilted and pixels are at their regular positions).

In order to rotate - we need to calculate pixel values along that red line. Now for each pair of pixels, if we do linear interpolation between its values - at the bottom we will almost exclusively use left pixel value - it will be like 99%:1% ratio and on the top - it will be other way around 99% of right pixel and only 1% of left.

These two extreme cases introduce minimal pixel to pixel correlation, or softening / blur in the image, but as we move along vertical - we progressively move towards 50%:50% case - which perfectly mixes two pixel values or averages them - and that reduces noise the most / adds most blur / cuts off high frequencies the most.

Same thing happens in horizontal - except above diagram is rotated 90 degrees.

This creates rectangular pattern across the image of different levels of pixel to pixel correlation and thus different levels of blur that will pop up after certain types of processing.

Simplest way to see this is to generate random noise, then rotate it by small angle and then clip low values. Standard deviation variation (due to this blur) will produce this rectangular pattern:

rectangular pattern wavelength will depend on rotation angle. Above is produced with 2 degrees rotation.

If polar alignment is not as good - there will be field rotation over the course of imaging session, and subs from the end of session will be slightly rotated compared to those from beginning. In order to align them for stacking - the will need to be rotated back by small angle - which causes above effet

 

[Lamplighter05]

17 hours ago, vlaiv said:

I identified such effect with bilinear interpolation and small angle rotation - here is brief explanation of what happens in that particular case:

Look at two columns of pixels and very small angle rotation:

Red line represents pixel centers after rotation (after rotation it will be vertical, but since we haven't rotated yet - it is tilted and pixels are at their regular positions).

In order to rotate - we need to calculate pixel values along that red line. Now for each pair of pixels, if we do linear interpolation between its values - at the bottom we will almost exclusively use left pixel value - it will be like 99%:1% ratio and on the top - it will be other way around 99% of right pixel and only 1% of left.

These two extreme cases introduce minimal pixel to pixel correlation, or softening / blur in the image, but as we move along vertical - we progressively move towards 50%:50% case - which perfectly mixes two pixel values or averages them - and that reduces noise the most / adds most blur / cuts off high frequencies the most.

Same thing happens in horizontal - except above diagram is rotated 90 degrees.

This creates rectangular pattern across the image of different levels of pixel to pixel correlation and thus different levels of blur that will pop up after certain types of processing.

Simplest way to see this is to generate random noise, then rotate it by small angle and then clip low values. Standard deviation variation (due to this blur) will produce this rectangular pattern:

rectangular pattern wavelength will depend on rotation angle. Above is produced with 2 degrees rotation.

If polar alignment is not as good - there will be field rotation over the course of imaging session, and subs from the end of session will be slightly rotated compared to those from beginning. In order to align them for stacking - the will need to be rotated back by small angle - which causes above effet

 

Great analysis. Sampling science is fascinating. I'm now wondering what algorithms are used for 'dithering' - simple alt/az offsets will need  a minimum delta to help avoid introducing these pixel boundary conditions. Presumably 'on sensor' pixel binning will mitigate, or having an oversampling sensor to glass setup?

[MichaelBibby]

Everything is wrong with this image (bad polar alignment, bad guiding, terrible atmospheric conditions, moonlight, bad focus, over-exposed, etc.,) but the Carina nebula-- the location of Webb's famous 'Cosmic Cliffs' image-- is such a beautiful and forgiving target that it looks amazing anyway. Off the back of a livestacking EAA session, no post-processing (60" exposures at gain of 350, about 20 minutes of data).

Edited December 12, 2022 by MichaelBibby

[MichaelBibby]

Here's the Orion Nebula from livestacking session last night, 45" at a gain of 181, let it run for an hour. The only real limiting factor was the seeing conditions which haven't been very good here for about a month.




And here is the region of the Carina nebula which contains the 'Cosmic Cliffs' also from last night (you can see a bit of camera tilt across the horizontal plane). 90" at a gain of 181, which I let run for about 30 minutes.

Edited December 13, 2022 by MichaelBibby

[Ratlet]

That's a really nice Orion.  Very nice core region.

 

[MichaelBibby]

Seeing conditions were better tonight, this is about 35 minutes of 45 second exposures at gain of 181. Ridiculous....

 

[PeterC65]

Not really my thing, but I've done some post processing of the Moon, Jupiter and Mars that I think have come out well. These were all taken last week (it's taken me since then to figure out the post processing) with the Uranus-C / Explorer 150PDS / x0.6 Reducer.

 

 

[PeterC65]

And here's some from last night, live stacked on the night with the Uranus-C / Photoline 72 / x0.6 Reducer.

The Flame and Horsehead Nebulae. The Horsehead is faint but I could see it after only a few 4s frames. I saw photos of the Horsehead as a kid and have always wanted to see it. I've not managed to see it visually but EEVA has permitted me that pleasure finally.

M81 and M82 together is a favourite target of mine visually, but it turns out there are two more galaxies also visible in the same field of view, NGC3077 and NGC2976!

And finally a nice one of the Double Cluster, inconveniently orientated for the camera (it was way too cold outside to turn it) but beautiful as usual.

 

[MichaelBibby]

NGC300 also known as the Southern Pinwheel galaxy. I used poorly calibrated, barely adequate flats and darks, so its a pretty noisy image with a big stretch on it. Probably about 1 hours worth of data. Minimal post in Siril. Some very distant galaxies in the bottom left.

 

[Patty]

Just a quick few shots I got last night with my ZWO ASI585MC camera doing live stacking  EAA. Very rough polar alignment no guiding.  The ASI585 is fitted to a Hyperstar 6V4 with l`Enhance filter on a Celestron 6se with EAF autofocuser on a Skywatcher EQ3-2 goto mount. Live stacking done on an ASIAIR Plus. 35 x 30 sec exposures at 254 gain on the Rosette nebula, 60 x 30 sec exposures at 254 gain on the Horsehead and Flame nebulas and 30 x 30 sec exposures at 254 gain  on the California nebula.  No processing other than fliping the images and a stretch during the stacking.

[PeterC65]

AP isn't my thing but I've been playing with image processing software recently (I've settled on Affinity Photo and Topaz DeNoise AI) so here are a few post processed live stacks that have come out well I think.

The Flame and Horsehead Nebulae ...

M33 ...

M35 and its neighbour NGC2158 ...

M42 of course ...

M52 and the Bubble Nebula, NGC7635, which now looks like a bubble ...

M81 and M82, one of my favourites ...

Caroline's Rose Cluster, NGC7789, which has recently become a new favourite ...

 

[MichaelBibby]

Livestack of the Rosette nebula which I let run for an hour (90" subs at gain of 300, 6" F5 Newt) and which got photobombed by a recent Starlink launch. I think I got rid of most of the tilt in my optics train, so it should give people a bit of an idea of how the coma looks with this chip on an F5 Newt without a coma corrector (this image hasn't been cropped).

Edited December 22, 2022 by MichaelBibby

[MichaelBibby]

I'm assuming the the diffraction spike that seems to be coming from the right hand side is an internal reflection in my optical train (probably the drawtube of my 6" F5 Newt) of the massive diffraction spike from Alnitak? This is about 100 minutes of 90's subs at a gain of 200 with darks and flats applied.

EDIT: I've just flocked the draw tube, the inside of the OTA opposite the focuser, and the edge of the secondary mirror (which were all a source of reflection). Hopefully I'll get a chance to image the Horsehead again tonight, and let it run for at least a couple of hours.


 

Edited December 26, 2022 by MichaelBibby

[bottletopburly]

Using the zwo585mc for imaging is there a recommended offset ? or does it not matter currently I have it set at 3 offset .

[MichaelBibby]

On 03/01/2023 at 07:38, bottletopburly said:

Using the zwo585mc for imaging is there a recommended offset ? or does it not matter currently I have it set at 3 offset .

I usually use 25. Its something that I am confused by as well. All I really know is that you should ensure your histogram is off the left edge, and that its not so far right of the left margin that its clipping on the right hand side. I would be curious to hear others with much more expeirence than myself have to say.

While I am here I may as well share a little mosaic I did with the Uranus-C with my 150p of the Carina nebula:

[bottletopburly]

2 hours ago, MichaelBibby said:

I usually use 25. Its something that I am confused by as well. All I really know is that you should ensure your histogram is off the left edge, and that its not so far right of the left margin that its clipping on the right hand side. I would be curious to hear others with much more expeirence than myself have to say.

While I am here I may as well share a little mosaic I did with the Uranus-C with my 150p of the Carina nebula:

Nice image I’ve currently got mine zwo585 coupled to a 50mm nifty fifty lens  though need to try at F4 as f2.8 no good but a friend recommended try f4 

 

[PeterC65]

4 hours ago, MichaelBibby said:

I usually use 25. Its something that I am confused by as well. All I really know is that you should ensure your histogram is off the left edge, and that its not so far right of the left margin that its clipping on the right hand side. I would be curious to hear others with much more expeirence than myself have to say.
 

I also use an offset of 25. It is what is recommended by SharpCap after carrying out a sensor analysis.

 

[MichaelBibby]

While I'm here I'll share an image I just took of the Orion Nebula using a gain of 0 with 120s subs. Its only about 10 minutes of data and straight off the Sharpcap live stack (so you can see satellite trails). Really its just a quick test of the full well depth and dynamic range on this target. (Obviously my stretch is a balance of core brightness and faint nebulosity, but its a bit too much of a stretch for my liking).
This is at F5, Bortle 3 skies, with the moon just past full.

Edited January 9, 2023 by MichaelBibby

[PeterC65]

50 minutes ago, MichaelBibby said:

While I'm here I'll share an image I just took of the Orion Nebula using a gain of 0 with 120s subs. Its only about 10 minutes of data and straight off the Sharpcap live stack (so you can see satellite trails). Really its just a quick test of the full well depth and dynamic range on this target. (Obviously my stretch is a balance of core brightness and faint nebulosity, but its a bit too much of a stretch for my liking).
This is at F5, Bortle 3 skies, with the moon just past full.

I've not gone below a gain of 180 for DSOs and usually stick with 400 gain, but I'm using much shorter exposures than you, usually no more than 8s. This is partly because I like to see images quickly with EEVA and partly because with my AZ mount anything more than 30s ends up looking blurred, due to mount movement I assume.

  

[MichaelBibby]

9 hours ago, PeterC65 said:

I've not gone below a gain of 180 for DSOs and usually stick with 400 gain, but I'm using much shorter exposures than you, usually no more than 8s. This is partly because I like to see images quickly with EEVA and partly because with my AZ mount anything more than 30s ends up looking blurred, due to mount movement I assume.

  

I'm often impressed with the results that people like yourself are achieving with AZ mounts. I suppose if you pair a really fast optical system (imagine for example a F4 newt with a Starizona Nexus 0.75 reducer to turn it into an F3 system, or a RASA, or a SCT with Hyperstar) with a sensitive camera like the 585 you could achieve really great results with AZ mounts.
 

[Icearcher]

18 hours ago, bottletopburly said:

Nice image I’ve currently got mine zwo585 coupled to a 50mm nifty fifty lens  though need to try at F4 as f2.8 no good but a friend recommended try f4 

 

 

Hi, May I ask how you connected the cam to the nifty fifty and how you have it mounted to the base plate (dovetail bar)?

Is it just connected with the ZWO EOS-T2? Any weirdness with setting up or spacing?

Im about to pull the trigger on the Player One version and I would like to use the 50mm lens and also connect to my SW 72ED w/ reducer.

Regards

Chris

[bottletopburly]

16 hours ago, Icearcher said:

Hi, May I ask how you connected the cam to the nifty fifty and how you have it mounted to the base plate (dovetail bar)?

Is it just connected with the ZWO EOS-T2? Any weirdness with setting up or spacing?

Im about to pull the trigger on the Player One version and I would like to use the 50mm lens and also connect to my SW 72ED w/ reducer.

Regards

Chris

Hi I bought a follow focus adapter from Shapeways to fit my nifty fifty  EF mk2 1.8 lens https://www.shapeways.com/product/9ZMKHDM3G/nifty-fifty-canon-50mm-f1-8-follow-focus-adapter

connected to a stepper motor via a 151 6mm belt https://www.ebay.co.uk/itm/173640532294?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=4KixEfdrSPu&sssrc=2349624&ssuid=xQsxeo45SGa&var=&widget_ver=artemis&media=COPY

camera connection is via a zwo lens adapter 

https://www.firstlightoptics.com/zwo-accessories/zwo-adjustable-eos-lens-to-t2-adapter-for-all-asi-cameras.html

camera sits in an adapter a friend kindly made me , which then fits in a zwo 78mm camera holder , I will take a closer picture to show how it fits together .

dovetail is a losmondy style diy job made from 20mm black plastic sheet .

 

 

 

Edited January 10, 2023 by bottletopburly

[Icearcher]

On 10/01/2023 at 23:56, bottletopburly said:

Hi I bought a follow focus adapter from Shapeways to fit my nifty fifty  EF mk2 1.8 lens https://www.shapeways.com/product/9ZMKHDM3G/nifty-fifty-canon-50mm-f1-8-follow-focus-adapter

connected to a stepper motor via a 151 6mm belt https://www.ebay.co.uk/itm/173640532294?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=4KixEfdrSPu&sssrc=2349624&ssuid=xQsxeo45SGa&var=&widget_ver=artemis&media=COPY

camera connection is via a zwo lens adapter 

https://www.firstlightoptics.com/zwo-accessories/zwo-adjustable-eos-lens-to-t2-adapter-for-all-asi-cameras.html

camera sits in an adapter a friend kindly made me , which then fits in a zwo 78mm camera holder , I will take a closer picture to show how it fits together .

dovetail is a losmondy style diy job made from 20mm black plastic sheet .

 

Thanks A Million, thats amazing.

I think you just answered a bunch of questions I didnt even have.

Out of interest,  any idea how much the cam and lens with the ZWO connector weighs?

If I go the Player one version, Im thinking Ill just connect it via the 1/4" hole on the back but worried it might be too heavy all up.

Thanks again

Chris

Edited January 15, 2023 by Icearcher