IC 5146 + 294MC Pro - Advice Needed

[AstroKane]

Hi All - Just looking for some advice/guidance.

I swapped out my DSLR for a ZWO camera and I am finding the switch tough. I am getting used to APT as an imaging package and now really rate it's features. My main issue is the camera. I opted for the one shot colour as it suits my time and circumstances - however lots of my test shots were coming out in Monochrome, at that time I also added a guiding system which was just not working at all. A little disheartened, I downed tools for a few months. I am now back at it. I have taken the guiding system off for the moment as I find the camera is so sensitive that anything longer than say 120 blows out the image with my locations light pollution.

Removing the guiding has enabled me to focus more on the camera, I realise now that perhaps the gain settings were too high (set to 200) I then changed this to 'Unity Gain 127' and finally success 😊my image has produced some colour (for a long time I thought it was DSS even though I knew I had the correct Bayer Filter).

So my questions, the image below (as well as full spec) is 4 hours on the Cocoon Nebula with very little processing and calibration frames...Am I on to something here and now it is just a case of getting the time in and adding calibration frames before I end up with a good data set? Is this a hard target to image from the northern hemisphere in light polluted suburbia? Any other users of this camera have any tips or tricks picked up during testing, gain settings for example?

Scope: Sky-Watcher ED80 with 0.85x Focal Reducer

Camera: ZWO ASI 294MC Pro

Mount: AVX

Moon 71.7%

Lights: 240x60

Darks 10x60

Processing: Stacked in DSS, processed in PixInsight: Background Neutralisation, Geometry crop, Screen Transfer Function on the Histogram.

 

[Adreneline]

Hi.

I can't help with the specifics of this camera - I have just started to use an ASI1600 - similar I guess.

An observation I would offer is not to use the STF transfer to Histogram. I have found it better to do multiple incremental stretches in HTwith careful incremental adjustment of the black point. Did you take flats?

HTH

[AstroKane]

Cheers! I'll be sure to play around in processing when I collect some good usable data! This was just a process on the fly to see if I finally managed to pull out any colour.

No calibration frames bar the 5 darks. My primary goal was to collect some data that showed colour. I am hoping the switch in gain from 200 to 127 is the answer and then I will build in the calibration frames along with more data.

Edited May 27, 2019 by AstroKane

[Adreneline]

3 minutes ago, AstroKane said:

pull out any colour

Sorry - misunderstood. If you're looking to pull out colour specificaly I've found ArcSinhStretch works really well - again used incrementally.

Good luck.

[AstroKane]

1 minute ago, Adreneline said:

Sorry - misunderstood. If you're looking to pull out colour specificaly I've found ArcSinhStretch works really well - again used incrementally.

Good luck.

No worries, I was confused because I knew I had selected the correct Bayer in DSS so couldn't fathom why I was getting Mono images from a one-shot colour. Hopefully the gain adjustment solves this - IC5146 seems to be quite a bright object so hopefully it is now just a matter of getting the data, 4 hours is perhaps not enough. And then of course proper calibration frames and processing.

 

Clear Skies!

[Adam J]

19 hours ago, AstroKane said:

Hi All - Just looking for some advice/guidance.

I swapped out my DSLR for a ZWO camera and I am finding the switch tough. I am getting used to APT as an imaging package and now really rate it's features. My main issue is the camera. I opted for the one shot colour as it suits my time and circumstances - however lots of my test shots were coming out in Monochrome, at that time I also added a guiding system which was just not working at all. A little disheartened, I downed tools for a few months. I am now back at it. I have taken the guiding system off for the moment as I find the camera is so sensitive that anything longer than say 120 blows out the image with my locations light pollution.

Removing the guiding has enabled me to focus more on the camera, I realise now that perhaps the gain settings were too high (set to 200) I then changed this to 'Unity Gain 127' and finally success 😊my image has produced some colour (for a long time I thought it was DSS even though I knew I had the correct Bayer Filter).

So my questions, the image below (as well as full spec) is 4 hours on the Cocoon Nebula with very little processing and calibration frames...Am I on to something here and now it is just a case of getting the time in and adding calibration frames before I end up with a good data set? Is this a hard target to image from the northern hemisphere in light polluted suburbia? Any other users of this camera have any tips or tricks picked up during testing, gain settings for example?

Scope: Sky-Watcher ED80 with 0.85x Focal Reducer

Camera: ZWO ASI 294MC Pro

Mount: AVX

Moon 71.7%

Lights: 240x60

Darks 10x60

Processing: Stacked in DSS, processed in PixInsight: Background Neutralisation, Geometry crop, Screen Transfer Function on the Histogram.

 

I would say that even in a red zone with the moon at over 70% it will have the most effect on your imaging, much more than light polution.

[Thalestris24]

Hi

You need to take calibration frames, especially flats. Also, you need to adjust your reducer spacing so that it's 55mm between the reducer and sensor plane (won't affect the colour as such but, yeah). Pixinsight gives good options for colour processing which you may need to investigate further  . If you don't already have it, 'Inside Pixinsight' by Warren A Keller is a good reference book. Also, you might benefit from a good lp filter such as an IDAS one.

Louise

[Hughsie]

I have just started using the ASI294MC pro cool. I started at unity gain and recently went as high as a gain of 300 (my Iris Nebula picture posted earlier today shows this with an IDAS light pollution filter).

You will benefit from taking calibration frames as already pointed out. I generally take 100 light frames using the tool in APT then 100 dark flats ( same gain/exposure as flat but with the lense cap on).

The darks can take a while to capture but as you are using the cooled version of the 294 you can create a dark library on cloudy days. I have a library of darks at -15 degrees, unity gain over 1 to 5 minute exposures, say 50 frames at each time.

As for DSS, I find stacking in PI is better. Also I tend not to use the batch processing tool having had mixed results in the past. There are some great tutorials on the Light Vortex website. This is the workflow for calibrating your flats, darks and dark flats and then stacking together.

It’s a long process but really helps you to understand how the calibration frames help improve your image https://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html

Keep at it, it’s a great camera!

John

[AstroKane]

2 hours ago, Thalestris24 said:

Hi

You need to take calibration frames, especially flats. Also, you need to adjust your reducer spacing so that it's 55mm between the reducer and sensor plane (won't affect the colour as such but, yeah). Pixinsight gives good options for colour processing which you may need to investigate further  . If you don't already have it, 'Inside Pixinsight' by Warren A Keller is a good reference book. Also, you might benefit from a good lp filter such as an IDAS one.

Louise

Hi Louise - Thanks for your feedback much appreciated. Totally on board with calibration frames. The only reason none are included here is I was just testing to see I could get  the image to produce colour. It certainly looks like for my location setting the gain lower was the key. The outing prior to testing on Cocoon (selected purely on it's position) I imaged Vega and ended up with a lovely mono star.

Two questions if I may re the highlighted above - How can you tell the spacing is out? I will have to re-check this as I thought it was ok - is it something in the image that suggests this? I will definitely look into the IDAS filter - I have LED street lighting, assuming that helps block those.

Clear Skies

[AstroKane]

2 hours ago, Hughsie said:

I have just started using the ASI294MC pro cool. I started at unity gain and recently went as high as a gain of 300 (my Iris Nebula picture posted earlier today shows this with an IDAS light pollution filter).

You will benefit from taking calibration frames as already pointed out. I generally take 100 light frames using the tool in APT then 100 dark flats ( same gain/exposure as flat but with the lense cap on).

The darks can take a while to capture but as you are using the cooled version of the 294 you can create a dark library on cloudy days. I have a library of darks at -15 degrees, unity gain over 1 to 5 minute exposures, say 50 frames at each time.

As for DSS, I find stacking in PI is better. Also I tend not to use the batch processing tool having had mixed results in the past. There are some great tutorials on the Light Vortex website. This is the workflow for calibrating your flats, darks and dark flats and then stacking together.

It’s a long process but really helps you to understand how the calibration frames help improve your image https://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html

Keep at it, it’s a great camera!

John

Hi John - I am based in Essex too so encouraging news you are having success with the Camera. I have no doubts it is a capable piece of kit, once I get it up and running. My previous gain setting was 200 which was resulting in Mono images.

I haven't added any calibration frames as I only wanted to see if I could get some data that produced colour - Looks like lowering the unity gain solved that. Now to collect better data when the Moon isn't so obstructive. I had a dark library for the winter (-15 same as you) but now we are getting in to the warmer months I need to redo for the summer season (a job on the to do list).

What temp do you push your 294 during the summer? I imaged the above at 0 and didn't imagine I would go much lower.

Clear Skies

[Thalestris24]

1 hour ago, AstroKane said:

Hi Louise - Thanks for your feedback much appreciated. Totally on board with calibration frames. The only reason none are included here is I was just testing to see I could get  the image to produce colour. It certainly looks like for my location setting the gain lower was the key. The outing prior to testing on Cocoon (selected purely on it's position) I imaged Vega and ended up with a lovely mono star.

Two questions if I may re the highlighted above - How can you tell the spacing is out? I will have to re-check this as I thought it was ok - is it something in the image that suggests this? I will definitely look into the IDAS filter - I have LED street lighting, assuming that helps block those.

Clear Skies

From the elongated stars in the corners. - always a giveaway! Check out the graphs for optimum dynamic range vs gain, and dark current vs temperature: https://www.firstlightoptics.com/zwo-cameras/zwo-asi-294mc-pro-usb-30-cooled-colour-camera.html

Not sure if it's your processing but colour appears to have been lost from the stars - maybe you overstretched them or did something with the contrast? LED lights might be tricky to deal with using a filter - the D2 might help https://www.firstlightoptics.com/idas-filters/idas-d2-light-pollution-suppression-filter.html Adding a filter may affect the reducer spacing slightly - it's something you have to fiddle with sometimes. I think the idas is 2.5mm thick so increases the backfocus by 0.5mm (1/3 of thickness).

Louise

 

[Hughsie]

Hi Kane,

I only bought the camera earlier this year so have had no experience using it during warmer nights. So far I have had no issue getting the temperature down to -15c. Technically it can go -35 to -40c below ambient so even on a really warm night -10 to -15 should be possible. I will find out soon enough.

9 hours ago, Thalestris24 said:

From the elongated stars in the corners. - always a giveaway! Check out the graphs for optimum dynamic range vs gain, and dark current vs temperature: https://www.firstlightoptics.com/zwo-cameras/zwo-asi-294mc-pro-usb-30-cooled-colour-camera.html

Not sure if it's your processing but colour appears to have been lost from the stars - maybe you overstretched them or did something with the contrast? LED lights might be tricky to deal with using a filter - the D2 might help https://www.firstlightoptics.com/idas-filters/idas-d2-light-pollution-suppression-filter.html Adding a filter may affect the reducer spacing slightly - it's something you have to fiddle with sometimes. I think the idas is 2.5mm thick so increases the backfocus by 0.5mm (1/3 of thickness).

Louise

 

On the above points;

For best gain/exposure settings you may wish to check out the Sensor Analysis on SharpCap. It's part of the free setup so a Pro licence is not needed. The analysis will review the chip over various gains and exposures and present a bespoke analysis a bit like the charts you see in the ZWO manual. It can be done during the day with the lense cap on and off and a white t-shirt to cut down on the brightness; takes 5-10 minutes. Once done all you do is aim your scope and camera towards your target at night and select the histogram tool. Press the 'brain' icon and SharpCap will report back a recommended gain/exposure given your sky conditions and chip sensitivity.

On the second point, I have a 55mm back focus from the rear of the William Optics Flat 6A II flattener to the camera chip. I use a 2 inch Idas D2 LPS filter, however, it screws into the front of the flattener not the rear so does not impact on back focus. If your flattener allows the same then there should be no need to take into account the thickness of the filter.

Back focus is a pain, for me the manual states the flattener should be adjusted to 4.6mm. I have had digital callipers on it and still see some elongation towards the edges which I end up cropping out. So it's a bit hit and miss adjusting it inwards or outwards to get the best setting. I have some shims so may start using adjusting shy of 4.6mm and use those to make minor adjustments.

Cheers,

John

[AstroKane]

On 28/05/2019 at 17:11, Thalestris24 said:

Also, you need to adjust your reducer spacing so that it's 55mm between the reducer and sensor plane (won't affect the colour as such but, yeah).

 Thank you again Louise for making me revisit this - I hadn't factored in the 294 has 6.5mm of back focus already. So I was indeed out!

Corrected now 😊

Edited May 29, 2019 by AstroKane