First light ASI294MC-Pro

[fwm891]

Great night for first light with my new ASI294MC Pro: Full moon, high cloud, bright sky... Oh yeah Dust bunnies!

Started with M27, sky quite bright and shoot 15 x 30s subs. Gain set to 122 and off-set to 15 (no idea about the offset setting. Took the gain from the plots on ZWO's 294 details page and set fractionally higher.

Then moved to M16. Subs: 5x 120s 2x 300s. Gain / offset as before

Finally NGC6888. Subs: 3x 180s other settings the same.

M27 and NGC6888 were captured via SG Pro with M16 captured with Sharpcap. All as fit files.

Processing via PI typically: Debayer, Star align, Integrate, DBE, Saturation, Curves transformation, SCNR and Histogram Transformation - Save Tif and jpg.

No calibration frames used.

Filter: I added a Baader UV/IR cut filter immediately before the sensor

Scope: Altair Astro Wave Series 115 EDT-APO

Mount CEM60

Guided with PHD2 and ASI120mm on TS 80mm guidescope.

Waiting now for darker skies but really quite pleased with last nights trial.

 

Edited August 16, 2019 by fwm891
text added

[tooth_dr]

Nice Francis, lots of potential here.

[fwm891]

25 minutes ago, tooth_dr said:

Nice Francis, lots of potential here.

Thanks - What I've found with this is that shorter exposures really seem to work. M27 image with only 15x 30s subs shows a lot more detail than I ever expected. The M16 image is mainly 2 min subs...

Definitely need to pursue this further. Couple with dither between frames and that seems an easy way of reducing background noise.

[smr]

I'm thinking about buying the ASI294MC Pro.

These are good results considering the lack of calibration files, full moon etc.

Shows the colour it can achieve and how sensitive the camera is with such a short integration time on these targets, go for 5 or so hours on each at new moon, with properly calibrated files and they should look very good indeed. I'd be interested to see what the results look like.

[sloz1664]

Great images for such short exposures, Francis. I got a feeling you are going to like this camera

Like to see them again, after calibration.

Steve

Edited August 16, 2019 by sloz1664

[fwm891]

Thanks - I'm not going to try to calibrate these images (I have now cleaned the filter!) but I will revisit the objects and try putting together longer runs of 2 - 3 min . I'm currently gathering dark and bias frames with the camera at -20°C below ambient in preparation.

[smr]

6 minutes ago, fwm891 said:

Thanks - I'm not going to try to calibrate these images (I have now cleaned the filter!) but I will revisit the objects and try putting together longer runs of 2 - 3 min . I'm currently gathering dark and bias frames with the camera at -20°C below ambient in preparation.

was it a light pollution filter?

[MarsG76]

Imagine the results with more data and calibration frames.. 

 

[vlaiv]

Please do include both dark and flat calibration.

CMOS sensors have pixel to pixel variation in QE as each pixel has its own amp so you will benefit from flat calibration even if you don't have any dust shadows on your optics.

Don't need bias with CMOS sensors (it can even mess up your calibration). Use darks, flats and flat darks only.

[fwm891]

1 hour ago, smr said:

was it a light pollution filter?

NO. Standard UV / IR cut filter to reduce star bloat.

[andrew s]

1 hour ago, vlaiv said:

Please do include both dark and flat calibration.

CMOS sensors have pixel to pixel variation in QE as each pixel has its own amp so you will benefit from flat calibration even if you don't have any dust shadows on your optics.

Don't need bias with CMOS sensors (it can even mess up your calibration). Use darks, flats and flat darks only.

...and lots of them to beat down the non Gaussian telegraph noise which reduces slower  than the sqrt(N).

Regards Andrew 

[fwm891]

OK. I've been letting the camera run this afternoon (not gathering photons) but generating master darks. I've processed the darks in PI via the usual route for darks and bias integration but the results rather floored me - I was not expecting the outcome. A quick G**le showed me that this is 'normal' 🙏

Posted below are 2 min, 3 min and 5 min dark masters. Plus a bias master. All captured using SG Pro. Gain 122 Offset 15. Camera temp -15°C.

 

Edited August 16, 2019 by fwm891
text deleted

[vlaiv]

3 hours ago, andrew s said:

...and lots of them to beat down the non Gaussian telegraph noise which reduces slower  than the sqrt(N).

Regards Andrew 

I found that dithering helps with this. Telegraph type noise is confined to pairs of pixels - at least that is the case with ASI1600. With dithering you spread them around in the same way as hot pixel - sigma clip deals with the rest.

[vlaiv]

1 minute ago, fwm891 said:

OK. I've been letting the camera run this afternoon (not gathering photons) but generating master darks. I've processed the darks in PI via the usual route for darks and bias integration but the results rather floored me - I was not expecting the outcome. A quick G**le showed me that this is 'normal' 🙏

Posted below are 1 min, 2 min, 3 min and 5 min dark masters. Plus a bias master. All captured using SG Pro. Gain 122 Offset 15. Camera temp -15°C.

That is quite normal. May people dread amp glow in cmos sensors but I think you have nothing to worry about, as long as it is repeatable (no huge variations between subsequent subs - and so far I think it is always the case). Even dark current in amp glow section is order of magnitude of read noise in most cases - again not something to worry too much about.

Offset 15 is probably too low. Since you already did your bias subs, you can put them to good use - estimate if offset is too low. Do minimum stack on bias subs and then do stats on that resulting stack - if you get value of 4 that is not good. You want your bias values to all be above minimum value for camera. I think that minimum value that you can read off in single sub from your sensor is 4ADU (14 bit ADC, min value of 1 multiplied by 4 to fit 16bit format should be 4).

IF you find that offset is too low - raise it but be aware that you will need to reshoot all your calibration subs for next session (this session you need to calibrate with subs that you have - with same offset of 15).

[Anthonyexmouth]

On 16/08/2019 at 11:00, fwm891 said:

Thanks - What I've found with this is that shorter exposures really seem to work. M27 image with only 15x 30s subs shows a lot more detail than I ever expected. The M16 image is mainly 2 min subs...

Definitely need to pursue this further. Couple with dither between frames and that seems an easy way of reducing background noise.

yeah, the shorter subs work well with this super sensitive chip. i think this is where a lot of the early compaints for this camera came from, people pushing the sub length too far.

what driver are you using? i thought the offset was locked in the latest driver. 

[fwm891]

11 minutes ago, Anthonyexmouth said:

yeah, the shorter subs work well with this super sensitive chip. i think this is where a lot of the early compaints for this camera came from, people pushing the sub length too far.

what driver are you using? i thought the offset was locked in the latest driver. 

Anthony - I have two drivers loaded:

ZWO_ASI_Camera_ASCOM

ZWO_ASI_Camera_Driver

I'm capturing through SGPro and SGP allows me to enter both gain and offset values either from camera settings (red arrows) or (blue arrow) via event settings.

Screen shot from the ZWO ASI294MC Pro web page - support/software... Red arrows indicate which software/drivers I have loaded.

[Anthonyexmouth]

7 minutes ago, fwm891 said:

Anthony - I have two drivers loaded:

ZWO_ASI_Camera_ASCOM

ZWO_ASI_Camera_Driver

Ah, I'm using APT and in the ascom setting the offset is locked at 30. Was told this is what it's locked at in the latest drivers. 

[fwm891]

Two more captures tonight:

M8 + M20 25 x 120s  Gain 122 Offset 15 Processed in PI aligned, stacked, saturation and levels

NGC7000 8 x 120s (as above settings/process)

I tried applying bias and darks but the images just washed out of colour and left with magenta stars.

 

 

 

 

Edited August 19, 2019 by fwm891
Changed images

[sloz1664]

Great images Francis, I can't believe the amount of detail you have collected from such short exposures. Time to have a look in the piggy bank, me thinks

Steve

[fwm891]

A little reprocessing of the above at a more reasonable time in the morning. Images replaced

[fwm891]

1 minute ago, sloz1664 said:

Great images Francis, I can't believe the amount of detail you have collected from such short exposures. Time to have a look in the piggy bank, me thinks

Steve

Thanks Steve - I've reprocessed these. 02:30 was not the hour to do it in the first place.

[fwm891]

Change of scopes last night as low cloud to the south robbed me of any chance to add further sub data to the M20/M8 image. So put the ASI294MC Pro on the AA 115EDT-APO and took a look at M27. 25x 120s subs. Processing in PI. Added a cosmetic correction step this time after the debayer step.

 

 

Edited August 20, 2019 by fwm891
wrong file uploaded

[teoria_del_big_bang]

Another nice Image. Lucky to get anything decent recently, certainly up north anyway maybe a bit better further south. I hope so anyway heading to Suffolk for a weeks holiday with missus and my sons dog and of course my imaging setup so hoping for some clearer skies 🙂 

 

Steve