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With regard to cooling temperature, I think -5C or even 0C is more than enough with this camera. I won’t be using any less than that with mine when it arrives. Dark current is completely negligible at these temperatures and will not contribute meaningfully to noise in the final image so there is no benefit to cooling below this, particularly with typical sub exposure times being < 1000s (including narrowband). Read noise and photon shot noise (light pollution) will be the dominant sources of noise here. The only reason I can think of to cool below -5C is if you experience extremely cold winter nights, which I appreciate some might.

Edited by cfinn
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Finally managed 3 hours with the new camera, 300s x 36 with SkyWatcher 250px. Quick process in APP and PS, cropped below.  Slight spacing issues but overall very happy, as conditions weren’t the best

A small gap in the clouds last night, 30mins on M81 M82, seeing was pretty bad last night.  Quick calibration and stack in APP: Edited to add: havent sorted the spacing yet, and this is pretty mu

Hi Guys the much waited for QHY268M has arrived along with CFW3M (7x36mm) and OAGM. The camera looks great and comes with the largest set of adapters I ever received with any camera.  It felt str

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Due to persistent clouds I have not had much actual exposure time with this new camera, di get a few Ha under the near full moon last couple of nights but viewing not great as over most of my 10 min exposures I think some cloud passed by.

But I did take some darks when it arrived and comparing to my ASI1600 it;s like chalk and cheese not that amp glow has gone.
Left is an auto stretched master dark (360S) from my 1600 and using exactly the same stretch on the QHY 268M on the right of a 360S master dark.

image.png.1f52cb5ab522232fbcbc7078f6867b85.png

So, forgive my ignorance, but are darks now basically only taking out hot pixels ?
I am assuming the white dots seen in the dark are hot pixels as they are present in all dark frames.

So if dithering are the dark frames doing much for us in the processing ?

Steve

 

Edited by teoria_del_big_bang
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Procyon and sounding stars.
 
My First Light image with my updated SpaceCat telescope setup, with the QHY268M + QHYCFW3-M-US combo.
 
240 frames of 25 seconds each (6000s total), luminance filter only - stars discernable down to magnitude 16 in the original. Note Bortle8+ zone, no Light Pollution Filter, lots of atmospheric shimmer, and a full Moon but fortunately about 45degrees out of frame.

This was a point at a bright star and find the focus point, check camera operates (first time powered up), is filter wheel recognized and operating, is balance okay for tracking, &c.

Low gain, Sharpcap said 30 and 30 offset. No idea how this translated into real numbers, probably not at all optimal, but hey I go some stars :)
 
SharpCap for image acquisition, stacked in Astro Pixel Processor, further processing in Photoshop including Astro Flat Pro tools.
 
This version image is 25% scale from the original 4104x6231 pixel image; which was slightly cropped to remove stacking edge artefacts, but is effectively the full frame.

210226-Procyon-L-stack240frames-Luminance-1a1-DeNoiseAI-low-light-scale25pc-1.jpg

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I think dither and Sigma Stacking will clean up any hot pixels. The Horse and Flame I put in the Deep sky Imaging forum has no Dark frames. Or Flats either for that matter.

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Any one have any icing issues?  I connected the camera to SHPro, and inadvertently cooled it to -20 dec C (the profile settings were for my QHY9 which I used to use at -20).  Anyway after it had cooled to -20 deg C over a period of 10 minutes, I tried to focus with a mask and saw nothing but a massive weird star in the middle of the screen.  Quick look down the tube, and sure enough the middle portion of the sensor (or glass) was iced over.  I warmed it up again and reset it to -10 this time, but doesnt look to be 100% clear.  I have the desiccant tube attached and it's in a dehumidified dome.  No issues with the other cameras.

Edited by tooth_dr
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21 hours ago, tooth_dr said:

Any one have any icing issues?  I connected the camera to SHPro, and inadvertently cooled it to -20 dec C (the profile settings were for my QHY9 which I used to use at -20).  Anyway after it had cooled to -20 deg C over a period of 10 minutes, I tried to focus with a mask and saw nothing but a massive weird star in the middle of the screen.  Quick look down the tube, and sure enough the middle portion of the sensor (or glass) was iced over.  I warmed it up again and reset it to -10 this time, but doesnt look to be 100% clear.  I have the desiccant tube attached and it's in a dehumidified dome.  No issues with the other cameras.

Condensation.. my QSI is bad for it if I cool straight away after powering up when there's moisture about. Power it on and leave it warm for a bit, it's just the shock of rapid cooling.

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21 hours ago, tooth_dr said:

Any one have any icing issues?  I connected the camera to SHPro, and inadvertently cooled it to -20 dec C (the profile settings were for my QHY9 which I used to use at -20).  Anyway after it had cooled to -20 deg C over a period of 10 minutes, I tried to focus with a mask and saw nothing but a massive weird star in the middle of the screen.  Quick look down the tube, and sure enough the middle portion of the sensor (or glass) was iced over.  I warmed it up again and reset it to -10 this time, but doesnt look to be 100% clear.  I have the desiccant tube attached and it's in a dehumidified dome.  No issues with the other cameras.

I have the colour version and have run this at -20 degrees C on a number of sessions to date, no icing issues so far. No desiccant tube attached, camera is in a dome.

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1 hour ago, Sp@ce_d said:

Condensation.. my QSI is bad for it if I cool straight away after powering up when there's moisture about. Power it on and leave it warm for a bit, it's just the shock of rapid cooling.

 

1 hour ago, tomato said:

I have the colour version and have run this at -20 degrees C on a number of sessions to date, no icing issues so far. No desiccant tube attached, camera is in a dome.

Cheers guys.  The desiccant tube is attached and the beads are still yellow.  10 minutes too fast then to get to that temp?

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I think it's fine, but, wait till the scope is cooled a bit maybe?, I turn my rig on, which runs a fan on the back of the primary mirror, which means some air flows through the rig, moving any moisture from the night before, give it 10 to 20 minutes (by the time I'm PA, got the camera rotated, target framed etc), then I cool. I'm only going to -10. The camera will have already got to just above 0 by then too as it starts cooling as soon as it's turned up (but remains above freezing)

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My dome is not heated so the camera is at ambient temperature when I switch on the cooler. I set the cool down time to 10 minutes, which so far has not caused any icing problems.

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Seems to be working fine last night, apart from mist/cloud issues.  I’m only cooling to -10 deg C though.

I just wanted to add an update on attaching the camera to an Atik EFW3. Currently the only way was to use the M48 adapter, which added 5mm. This meant the total back spacing of the camera is 19.5mm

The Atik EFW3 is designed to mount directly to an Atik 16200 camera. Both seem to have a similar spacing of bolts.

Indeed it’s very close and in fact I only had to widen the holes by 0.15mm using 3.5mm drill bit) to let me screw the EFW3 plate directly onto the QHY268.

5mm doesn’t seem like much, but it means I can use my ZWO OAG (16.5mm) and Atik EFW3 (22mm) with my Baader MPCC mk1, and still maintain the correct back spacing (56mm).

Plus it is a secure flat fit 👍🏻

 

 

29E37A87-FCA0-4BF4-954D-BE6378B52803.jpeg

0FC36E75-7E82-4C33-9771-ECA5A420D7E4.jpeg

FF5A3709-0216-4899-942B-DF2796D830D5.jpeg

06F4EAC2-4D9F-4951-9E95-33DEAC19C3FF.jpeg

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Yes, bolt together on flat faces is the way to go. I'm always concerned by the meagre couple of threads on the nosepiece that holds my EFW2 in place.

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Thought I would try a lunar mineral composition. I have to say that being able to do this is a massive bonus. I know it won't be as good as e.g. a 290MM/MC, but considering that this is primarily a DSO camera, it's pretty good!

Taken at a resolution of approx. 1600x1200. 3,000 frames for each RGB channel, 50% selected in PIPP, then best 25% stacked. RGB channels aligned using PI's FFTRegistration script, RGB image created in PS followed by Curves and Saturation adjustments and blending in of an L layer with Luminosity blend at 50% opacity.

RGB_registax.thumb.png.cc24ae74075b0368a03e4ee470ee4c37.png

 

Edited by SyedT
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Finally managed 3 hours with the new camera, 300s x 36 with SkyWatcher 250px. Quick process in APP and PS, cropped below.  Slight spacing issues but overall very happy, as conditions weren’t the best with high cloud.

 

BA0A29D0-4D0F-42B4-8DE4-247A6032FE1D.jpeg

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This is 4 hours H-alpha on the Horse and Flame. 130 apo, Astronomik 6nm. I *think* the first 2 hours were with Gain 56 Offset 176, the second with Gain 1, Offset 10 as I had been experimenting and neglected to reset the parameters.

1299463754_4HourHSADDPUM.thumb.jpg.a42feb74a716ba54aab0ffbf1d2bbd44.jpg

I've left the alignment edges in for technical reasons, but what really concerns me are some huge artifacts around Alnitak. This is just the light frames, still got to get all the calibration frames.

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On 08/03/2021 at 12:45, tooth_dr said:

Finally managed 3 hours with the new camera, 300s x 36 with SkyWatcher 250px. Quick process in APP and PS, cropped below.  Slight spacing issues but overall very happy, as conditions weren’t the best with high cloud.

 

BA0A29D0-4D0F-42B4-8DE4-247A6032FE1D.jpeg

That looks amazing Adam! Especially for just 3 hrs. It looks like you have a killer Galaxy setup there. 

Can i ask, judging by the image dimensions, it looks like you have downscaled or binned, which i think is smart, otherwise the image scale would be too high at ~0.62". Which did you do - capture at Bin x2 or capture at full res and just downscale it afterwards? I suspect just downscaling will be no different. 

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1 hour ago, Xiga said:

That looks amazing Adam! Especially for just 3 hrs. It looks like you have a killer Galaxy setup there. 

Can i ask, judging by the image dimensions, it looks like you have downscaled or binned, which i think is smart, otherwise the image scale would be too high at ~0.62". Which did you do - capture at Bin x2 or capture at full res and just downscale it afterwards? I suspect just downscaling will be no different. 

Thanks Ciaran.

Actually that is a crop of the centre, binned 1x1, and not downscaled.  I did consider binning during capture or afterwards though, but wanted to try it out full size.  Guiding was sitting around 0.5"/px, using an OAG.  The full image has some nice detail in the small background galaxies.

Trying to work out the spacing - does it need some more or less spacing?

 

 

 

 

M51-Lum-Test-.jpg

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On 02/03/2021 at 11:50, tooth_dr said:

Seems to be working fine last night, apart from mist/cloud issues.  I’m only cooling to -10 deg C though.

I just wanted to add an update on attaching the camera to an Atik EFW3. Currently the only way was to use the M48 adapter, which added 5mm. This meant the total back spacing of the camera is 19.5mm

The Atik EFW3 is designed to mount directly to an Atik 16200 camera. Both seem to have a similar spacing of bolts.

Indeed it’s very close and in fact I only had to widen the holes by 0.15mm using 3.5mm drill bit) to let me screw the EFW3 plate directly onto the QHY268.

5mm doesn’t seem like much, but it means I can use my ZWO OAG (16.5mm) and Atik EFW3 (22mm) with my Baader MPCC mk1, and still maintain the correct back spacing (56mm).

Plus it is a secure flat fit 👍🏻

 

 

29E37A87-FCA0-4BF4-954D-BE6378B52803.jpeg

0FC36E75-7E82-4C33-9771-ECA5A420D7E4.jpeg

FF5A3709-0216-4899-942B-DF2796D830D5.jpeg

06F4EAC2-4D9F-4951-9E95-33DEAC19C3FF.jpeg

I'm impressed the SW focuser copes with all that weight... very nice M51! 

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18 minutes ago, tooth_dr said:

Thanks Ciaran.

Actually that is a crop of the centre, binned 1x1, and not downscaled.  I did consider binning during capture or afterwards though, but wanted to try it out full size.  Guiding was sitting around 0.5"/px, using an OAG.  The full image has some nice detail in the small background galaxies.

Trying to work out the spacing - does it need some more or less spacing?

M51-Lum-Test-.jpg

Fantastic image!

Based on this diagram it looks like you could do with adding a tiny amount. Your eccentricity looks pretty good across the frame, and only drops off in the extreme corners. What coma corrector are you using?

915241512_flattenerspacing.jpg.a6833a95acca503166f08bb88911e625.jpg.59fa772a5dc7946306e9f62e8e1a43e0.jpgimage.thumb.png.ba609bc23e3108033d37e082a91a348d.png

 

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6 minutes ago, Spongey said:

Fantastic image!

Based on this diagram it looks like you could do with adding a tiny amount. Your eccentricity looks pretty good across the frame, and only drops off in the extreme corners. What coma corrector are you using?

915241512_flattenerspacing.jpg.a6833a95acca503166f08bb88911e625.jpg.59fa772a5dc7946306e9f62e8e1a43e0.jpgimage.thumb.png.ba609bc23e3108033d37e082a91a348d.png

 

Thanks for that analysis. It's already at about +1.5mm over the recommended 58mm, I have a few shims, will try another bit.

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1 hour ago, tooth_dr said:

Trying to work out the spacing - does it need some more or less spacing?

I too would say it needs more spacing but not much. Probably messing with less than 1mm spacers.
Is it me or are the stars a little worse on the bottom corners, which maybe tilt ?

Steve

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1 minute ago, teoria_del_big_bang said:

I too would say it needs more spacing but not much. Probably messing with less than 1mm spacers.
Is it me or are the stars a little worse on the bottom corners, which maybe tilt ?

Steve

I've a 0.3 and 0.5mm spacer, can try those.

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1 hour ago, teoria_del_big_bang said:

I too would say it needs more spacing but not much. Probably messing with less than 1mm spacers.
Is it me or are the stars a little worse on the bottom corners, which maybe tilt ?

Steve

The FWHM is quite consistent over the frame, deteriorating by 0.5-1px in the corners, but this looks concentric around the optical axis so doesn't imply tilt to me.

Eccentricity, however, drops significantly as you get out towards the corners though, and by looking at the offending stars it seems like a little more space is needed.

Interesting that you're beyond the recommended distance already, what corrector is this? Also I assume you've accounted for filter thickness in your backfocus calculations?

Edited by Spongey
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15 minutes ago, Spongey said:

The FWHM is quite consistent over the frame, deteriorating by 0.5-1px in the corners, but this looks concentric around the optical axis so doesn't imply tilt to me.

Eccentricity, however, drops significantly as you get out towards the corners though, and by looking at the offending stars it seems like a little more space is needed.

Interesting that you're beyond the recommended distance already, what corrector is this? Also I assume you've accounted for filter thickness in your backfocus calculations?

I will go with that my eyes are not to 1 px anymore.

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