Calling upon the help of the Astrophotographers

[Jonny_H]

Hi all,

I hope everyone is well.

I am relatively new to the astrophotography side of things albeit I have been dabbing into it on and off for about a year my DSLR (400d - so not the best).  In recent times however I treated myself to a dedicated AS camera in the form of the 533MC Pro.  Post processing however is new to me albeit I do/can use Photoshop.

Last night I had a go at capturing The Orion Nebula and the Horsehead Nebula as they happened to be in a good line of sight.  I started off with a fairly modest 10 x 60 second lights, 20 darks, 20 flats and 60 bias at 0.01 sec.  Camera gain was set at 200.

I initially used Deep Sky Stacker but the final stacked image came through very washed-out (more so than expected) which was challenging to do anything in PS.  I then tried the same in APP and the outcome was much better although I had a lot of vignetting (which i didnt seem to get in the DSS output).  I was however able to work the APP image in Photoshop and came up with the attached.

This is where i need the seasoned AP's to chime-in.  The images seem very noisy to me and I cannot seem to pull the details out of the HH.  Is this just a case of needing more exposure time on the lights / perhaps less gain on the camera etc....?  Re: the vignetting - not really sure on this.  My calibration frames seem to be ok but perhaps i need more?

Appreciate that a lot of factors come into play but what camera settings does everyone use.....gain / exposure etc...?

My set-up consists of:

Main scope: 150PDS. 

Guide scope:  Evoguide 50ED. 

Mount: HEQ5 Pro. 

Guide cam: ZWO120MM Mini. 

Imaging cam:  ZWO533MC Pro.

Using ASIAir Pro to control everything.

P.S. I know the focus is a little-out so be gentle!  I think I will treat myself to an EAF next 😉

 

Clear skies,

Jonny

[smashing]

Great effort! 

More lights are needed...you have around 10 minutes of data, I'm trying not to process much unless I have at least 2 hours worth of data (Granted I'm using a DSLR so need that extra time), 300 second subs are my sweet spot at the moment.

Although you may need an assortment of different sub lengths for some targets such as M42 to not blow the core out (which I did lol) and then blend them together...but that's a whole other topic that I haven't managed to do yet.

Edited February 28, 2021 by smashing

[Jonny_H]

1 minute ago, smashing said:

Great effort! 

More lights are needed...you have around 10 minutes of data, I'm trying not to process much unless I have at least 2 hours worth of data (Granted I'm using a DSLR so need that extra time), 300 second subs are my sweet spot at the moment.

Thanks Smashing.

Yes I'm reassonably happy with them considering it is a first go using all new gear.  I just would have liked more detail but as you said I need more lights!

I did try a 120 sec exposure last night but it seemed to be hugely over-expsosed hence dropping back down to 60 seconds. I probably should have experimented more if I'm honest but.... baby steps as they say! 

[smashing]

2 minutes ago, Jonny_H said:

Thanks Smashing.

Yes I'm reassonably happy with them considering it is a first go using all new gear.  I just would have liked more detail but as you said I need more lights!

I did try a 120 sec exposure last night but it seemed to be hugely over-expsosed hence dropping back down to 60 seconds. I probably should have experimented more if I'm honest but.... baby steps as they say! 

I think a lot depends on also where you live and local light pollution etc. etc. and I have 0 idea how that camera works so there maybe something that can be adjusted to help with that.

If that's your first go using all the gear then that is very very very well done...I couldn't even get the stupid thing to focus properly on my first real attempt never mind actually finding a target and getting something to look at!

[Jonny_H]

13 minutes ago, smashing said:

I think a lot depends on also where you live and local light pollution etc. etc. and I have 0 idea how that camera works so there maybe something that can be adjusted to help with that.

If that's your first go using all the gear then that is very very very well done...I couldn't even get the stupid thing to focus properly on my first real attempt never mind actually finding a target and getting something to look at!

Yes indeed - many factors will play a part in settings etc... I'm in the SE of England, bortle 6 skies. 

It was a bit of a nuisance last night as my neighbours security light kept going off so had to keep pausing the autorun and restarting 😩

[smashing]

Just now, Jonny_H said:

Yes indeed - many factors will play a part in settings etc... I'm in the SE of England, bortle 6 skies. 

It was a bit of a nuisance last night as my neighbours security light kept going off so had to keep pausing the autorun and restarting 😩

Oh I feel your pain, next door here are the same with a light shining directly onto the rig, my new filter has helped immensely!

I wouldn't worry too much about restarting all the time just let it run, some subs you'll need to ditch (I had 5 from my run the other night because clouds ruined them) but hopefully you get enough...I'm quite comfortable now letting the rig run for hours at a time and popping out every so often to check cables etc...even better if you can remote into the rig.

[Chefgage]

22 minutes ago, smashing said:

Oh I feel your pain, next door here are the same with a light shining directly onto the rig, my new filter has helped immensely!

I wouldn't worry too much about restarting all the time just let it run, some subs you'll need to ditch (I had 5 from my run the other night because clouds ruined them) but hopefully you get enough...I'm quite comfortable now letting the rig run for hours at a time and popping out every so often to check cables etc...even better if you can remote into the rig.

I too have a light shining from next door ( although not all the time). I have installed a retractable washing line that goes from one end of the garden to the other. On this I hang a blackout sheet, does the job of blocking out the light perfectly. At the end of the night I can then remove the sheet and retrack the line. 

[steppenwolf]

I think this is a great effort - congratulations on your progress so far.

Apart from the vignetting, the two images are very much what I would have expected with the exposures that you took. The Horsehead Nebula is a rather dim object and the 60 second exposures were really pushing your luck on this one! Things would get a lot more interesting if you pushed this to 5 or even better, 10 minute exposures and lots of them!

[Jonny_H]

11 minutes ago, steppenwolf said:

I think this is a great effort - congratulations on your progress so far.

Apart from the vignetting, the two images are very much what I would have expected with the exposures that you took. The Horsehead Nebula is a rather dim object and the 60 second exposures were really pushing your luck on this one! Things would get a lot more interesting if you pushed this to 5 or even better, 10 minute exposures and lots of them!

Thanks steppenwolf,

Yes it is going to be an learning curve for me. Next time I will increase the exposure time significantly especially on 2023.

I did try 120 seconds on M42 but the shot appeared to be very over exposed. I will have to have a play around with the settings until I find that sweet spot!

Any suggestions on the vignetting issue?

42 minutes ago, smashing said:

Oh I feel your pain, next door here are the same with a light shining directly onto the rig, my new filter has helped immensely!

I wouldn't worry too much about restarting all the time just let it run, some subs you'll need to ditch (I had 5 from my run the other night because clouds ruined them) but hopefully you get enough...I'm quite comfortable now letting the rig run for hours at a time and popping out every so often to check cables etc...even better if you can remote into the rig.

What filter did you end up going for to combat the issue?

18 minutes ago, Chefgage said:

I too have a light shining from next door ( although not all the time). I have installed a retractable washing line that goes from one end of the garden to the other. On this I hang a blackout sheet, does the job of blocking out the light perfectly. At the end of the night I can then remove the sheet and retrack the line. 

Now there's an idea!

[smashing]

9 minutes ago, Jonny_H said:

Thanks steppenwolf,

Yes it is going to be an learning curve for me. Next time I will increase the exposure time significantly especially on 2023.

I did try 120 seconds on M42 but the shot appeared to be very over exposed. I will have to have a play around with the settings until I find that sweet spot!

Any suggestions on the vignetting issue?

What filter did you end up going for to combat the issue?

Now there's an idea!

I have an IDAS D2 and more recently an L-extreme (there's a post on here where I've put up some images on M42)

[Jonny_H]

Just a thought re: the vignetting. I wonder if it was caused by the fact I was using the 1.25" T-mount to attach the camera to the scope?  Not sure if there is another recommended option? 

I just did what the manual said to do! 

[Clarkey]

As has already been mentioned, longer subs and much more integration time will really help. But a good start none-the-less.

WRT the vignetting, this should be removed by the flats. I assume the stacking has been set up correctlty? I'm not sure of the size of the 533 sensor, but I can use a 1.25 connection on my 1600mm without issue (although this is right at the end of the image train).

[rickwayne]

APP should work your flats to completely defeat vignetting. If it isn't, something weird is going on.  Have you tried comparing a sub in different modes in APP's viewer? Try looking at it calibrated and uncalibrated, with a good hard stretch set in the DDP panel on the right (more than you'd ever use to develop the image). Likewise, pull up one of your flats and stretch it till it screams, see if anything jumps out at you. Did you shoot flats for this session, or reuse a set? Are you sure the focus was in the same position?

[Jonny_H]

3 hours ago, Clarkey said:

As has already been mentioned, longer subs and much more integration time will really help. But a good start none-the-less.

WRT the vignetting, this should be removed by the flats. I assume the stacking has been set up correctlty? I'm not sure of the size of the 533 sensor, but I can use a 1.25 connection on my 1600mm without issue (although this is right at the end of the image train).

Thanks Clarkey.

The 533 sensor is square @ 3008 x 3008. I only have the camera in the image train at the moment, I.e. not using any filters etc...

2 minutes ago, rickwayne said:

APP should work your flats to completely defeat vignetting. If it isn't, something weird is going on.  Have you tried comparing a sub in different modes in APP's viewer? Try looking at it calibrated and uncalibrated, with a good hard stretch set in the DDP panel on the right (more than you'd ever use to develop the image). Likewise, pull up one of your flats and stretch it till it screams, see if anything jumps out at you. Did you shoot flats for this session, or reuse a set? Are you sure the focus was in the same position?

Thanks rickwayne.

To be honest I have only used APP for the first time today so it is a bit of a learning curve. I will have another look later.

Re: the calibration frames - these were all taken last night at the same time as the lights, e.g. same focus, temperature, exposure time etc.. (except for bias which had the quickest exposure time set).

Random question re: cooling.  Can you have 'too much' cooling depending on the ambient temperature? E.g. if it is 9 degrees can you still set the cooling temp on the camera to -10, -15 and so on? Apologies in advance if that is a daft question!

[alacant]

6 hours ago, Jonny_H said:

120 sec exposure last night

Ah, ok. But last night was full moon. Try again in a week or so and you'll be fine.

[Adam J]

7 hours ago, Jonny_H said:

Hi all,

I hope everyone is well.

I am relatively new to the astrophotography side of things albeit I have been dabbing into it on and off for about a year my DSLR (400d - so not the best).  In recent times however I treated myself to a dedicated AS camera in the form of the 533MC Pro.  Post processing however is new to me albeit I do/can use Photoshop.

Last night I had a go at capturing The Orion Nebula and the Horsehead Nebula as they happened to be in a good line of sight.  I started off with a fairly modest 10 x 60 second lights, 20 darks, 20 flats and 60 bias at 0.01 sec.  Camera gain was set at 200.

I initially used Deep Sky Stacker but the final stacked image came through very washed-out (more so than expected) which was challenging to do anything in PS.  I then tried the same in APP and the outcome was much better although I had a lot of vignetting (which i didnt seem to get in the DSS output).  I was however able to work the APP image in Photoshop and came up with the attached.

This is where i need the seasoned AP's to chime-in.  The images seem very noisy to me and I cannot seem to pull the details out of the HH.  Is this just a case of needing more exposure time on the lights / perhaps less gain on the camera etc....?  Re: the vignetting - not really sure on this.  My calibration frames seem to be ok but perhaps i need more?

Appreciate that a lot of factors come into play but what camera settings does everyone use.....gain / exposure etc...?

My set-up consists of:

Main scope: 150PDS. 

Guide scope:  Evoguide 50ED. 

Mount: HEQ5 Pro. 

Guide cam: ZWO120MM Mini. 

Imaging cam:  ZWO533MC Pro.

Using ASIAir Pro to control everything.

P.S. I know the focus is a little-out so be gentle!  I think I will treat myself to an EAF next 😉

 

Clear skies,

Jonny

 

 

Hi Jonny, 

If you literally mean last night then the cause is the full moon. Even low in the sky as it was early evening you can still expect this effect when imaging in broad band OSC, later in the evening it will have gotten even worse as the moon climbed higher.

I think imaging in the full moon is valid when you are starting out as there is so much to learn that you need to take every opportunity you can get. With that in mind for the conditions you have produced a smashing result.

As most people gain experience they move away from imaging under the full moon. But it really does cut down on imaging time. A little either side of full moon you could try a duel channel narrow band filter down the line as this will greatly increase contrast. 

Adam 

Edited February 28, 2021 by Adam J

[Clarkey]

Regarding the cooling question - cool to the same temperature regardless of the external temperature. I normally cool to -20 but in theory it would be possible to go lower. I have my Darks library at -20 so it make sense to keep at this temperature. Below this temperature you will not see much improvement in the amount of noise from the sensor. Having said that, you could try it and see. The only possible benefit of not cooling so much is if you were running a mobile unit from a battery. If it was warm you might want to save power by reducing the cooling current. Not really a problem in Cumbria!

[The Lazy Astronomer]

7 hours ago, Jonny_H said:

Random question re: cooling.  Can you have 'too much' cooling depending on the ambient temperature? E.g. if it is 9 degrees can you still set the cooling temp on the camera to -10, -15 and so on? Apologies in advance if that is a daft question!

Check out the specs for your camera, ZWO usually state their cameras can be cooled to 30 - 40C below ambient temp, once you set the target, it should hold that temperature indefinitely (provided adequete power and as long as the set point isn't outside of its maximum cooling capacity in relation to the ambient temperature).

Also, don't worry too much about cooling massively - the noise reductions are quite insignificant. Check out this talk from Dr Robin Glover for some very helpful info on CMOS imaging:

 

Edited March 1, 2021 by The Lazy Astronomer

[Jonny_H]

16 hours ago, Adam J said:

Hi Jonny, 

If you literally mean last night then the cause is the full moon. Even low in the sky as it was early evening you can still expect this effect when imaging in broad band OSC, later in the evening it will have gotten even worse as the moon climbed higher.

I think imaging in the full moon is valid when you are starting out as there is so much to learn that you need to take every opportunity you can get. With that in mind for the conditions you have produced a smashing result.

As most people gain experience they move away from imaging under the full moon. But it really does cut down on imaging time. A little either side of full moon you could try a duel channel narrow band filter down the line as this will greatly increase contrast. 

Adam 

Thanks Adam /all re: the moon issue.

I actually had forgotten about the full moon as I was so engrossed in what I was doing imaging wise ☺️

 

I had another little play last night but then the haze/clouds came in and spoilt it! Grrrr! Anyhow - I noticed on some of my preview images little white thin circles of light (perhaps 4-5 ish in total). I assume this was caused by a light source entering the tube, whether through the aperture, focuser etc...? I will see if I can get the images off of the asiair/ipad but can't remember if I saved them or not!