The "No EQ" DSO Challenge!

[SteveNickolls]

I'm well pleased you enjoyed that bottle ;-) Either a good accompaniment to an imaging session or as an alternative. We did a tour of some of the Western Isles and Oban earlier this year but didn't quite get as far south as Jura unfortunately. 

Cheers,
Steve

[SteveNickolls]

With the current poor weather affecting Alt-Az imaging sessions I recently decided to take out a trial of BYEOS. I was interested to find that BYEOS actually obtains details of the temperature of the camera (no one knows where the sensor is located so it may not be on the chip of course but a guide to the internal temperature of the camera nonetheless). For a short while now I've not been using dark frames with my images and this ability to record internal camera temperatures will be useful to see how temperature varies over an imaging session. It has implications of course for imaging in Alt-Az with our extensive numbers of light frames. I've checked the exif temperature data for two imaging sessions, the first on the 17th March this year. The session was split into two main sessions allowing me to adjust the position of the object in the finder scope as it was a long session. There was a second interval between images and the big division to recenter M51 lasted 1 min 37 seconds.

M51-

Frame number   Sensor Temperature (degrees C)

1382                                23

1391                                20

1400                                18

1409                                17

1418                                17

1427                                16

1436                                16

1445                                16

1454                                16

1461                                15

Break of 97 seconds

1462                                13

1471                                15

1480                                15

1489                                15

1501                                15

The results are very interesting. I'd guess the camera was cooling down and slowly reached 15 degrees. An interpretation could be-the outside temperature may have been lower that 15 degrees and the camera cooled more while it was not in use then tried to rebalance itself at 15 degrees when images were once again taken. I'm going to check other image sessions where there were different imaging lengths and intervals between images. Pity I didn't take the ambient temperatures at the time, never mind that. What purpose are temperature dependent dark frames? :-)

NGC 1499-

A more recent imaging session on 2.10.2016 involved taking x91 sixty second images of NGC 1499 at ISO 800. The camera had been placed outside in the afternoon so had time to cool down before use in the evening. The were three divisions of images taken as I was using my intervalometer to take x30 frames in a session-

Frame number   Sensor Temperature (degrees C)

4878                                  16

4887                                  18

4896                                  18

4905                                  18

4907                                  18 

Break of 2 minutes

4908                                  17

4917                                  19

4926                                  19

4935                                  19

4937                                  19

Break of 5 minutes

4938                                  20

4947                                  21

4956                                  21

4965                                  21

4967                                  21

Interesting goings on there.

The next time I run an imaging session I will record the external temperature to compare the camera sensor value with posthumously.

Hope this proves interesting to others :-)

Cheers,
Steve

Edited October 15, 2016 by SteveNickolls

[Nigel G]

That is interesting Steve, it would be handy to know the outside temp at the time. That's something I have never taken in to account. 

I had noticed that the first few image's taken do change in colour as the camera settles in, I guessed it was temp but didn't know whether it was cooling or rising. 

It could be either by the look of your findings depending on outside temperature. 

Cheers Steve.

Nige.

[Stub Mandrel]

You might find the graph in this thread interesting, made by looking at dozens of Exifs...

 

[SteveNickolls]

10 minutes ago, Stub Mandrel said:

You might find the graph in this thread interesting, made by looking at dozens of Exifs...

Thanks Neil for this, will take a good look at the thread, it's a most interesting subject.

Cheers,
Steve

 

[SteveNickolls]

24 minutes ago, Stub Mandrel said:

You might find the graph in this thread interesting, made by looking at dozens of Exifs...

A very interesting read indeed Neil. I guess each equipment set up will slightly affect the temperature variation experienced (e.g. if the camera sensor is behind a filter etc) so there's value in checking your own situation and seeing how temperatures vary over a session. I will be recording external temperature over my sessions from now on and even if it is not 'scientific' using calibrated thermometers it is still an insight into how temperature varies over a period and maybe I can make a better informed decision over whether to use dark frames in the future or not. I will also look at the software EXIFLOG. Thanks once again.

Best Regards,
Steve
 

 

[Herzy]

Does anyone have any ideas of what I could image tonight? I want to image away from the horizons and I don't know of any bright nebula that I haven't already done. I've done the Eastern and Western veil, the Bubble nebula (although this could use 10x the integration that I have right now), the crescent nebula (this could use a lot more integration as well) and the Wizard nebula. Any ideas? Andromeda galaxy might be an option, although I'm not sure if 4 hours would do it justice. It might need far longer integrations.

[Stub Mandrel]

Four hours of Andromeda is great. Or you cold try the Heart and Soul or Flaming Star.

 

[alacant]

Hi. Good suggestions but I think you're gonna have to wait until next week for the nebulae. HTH.

[Nigel G]

The weatherman was wrong, I had intermittent clear sky's this morning between 2.30 and 4.30 . I managed to get 30 mins on M42 despite the full moon.

10 minutes of 10 seconds and 20 minutes of 20 second exp. plus 70 dark and 45 flat @ 1600 iso, The core is over exposed so I'm trying stacking the 10s subs alone.

Its a nice neb to image as there's plenty to look at on screen, it's my first attempt at stacking M42 and I'm pleased apart from the messy core.

I tried short subs to get a sharper image, I think its worked, the 10s stack should tell.

150P Canon 1300D DSS & ST, touch up in PS express, Alt-Az goto.

Any ideas on core exposure welcome  

Cheers

Nige.

[SteveNickolls]

26 minutes ago, Nigel G said:

The weatherman was wrong, I had intermittent clear sky's this morning between 2.30 and 4.30 . I managed to get 30 mins on M42 despite the full moon.

10 minutes of 10 seconds and 20 minutes of 20 second exp. plus 70 dark and 45 flat @ 1600 iso, The core is over exposed so I'm trying stacking the 10s subs alone.

Its a nice neb to image as there's plenty to look at on screen, it's my first attempt at stacking M42 and I'm pleased apart from the messy core.

I tried short subs to get a sharper image, I think its worked, the 10s stack should tell.

150P Canon 1300D DSS & ST, touch up in PS express, Alt-Az goto.

Any ideas on core exposure welcome  

Cheers

Nige.

Well done with M42 Nige, both capturing a nice image and being able to get up at 'too early in the morning' to image at all :-) I can't help about combining different exposures but I bet it's in the StarTools guide.

Cheers,
Steve

[SilverAstro]

52 minutes ago, Nigel G said:

 I think its worked, the 10s stack should tell.

150P Canon 1300D DSS & ST, touch up in PS express, Alt-Az goto.

Any ideas on core exposure welcome  

Worked very well indeed ! A very nice image. Would be interesting too to see what a stack of 20s would show of the outer regions.

There is a technique for using the shorter exp inner image (#1) as a mask over the longer exp image (#2) such that the dark areas in #1 become transparent and show/reveal #2 but the bright ( inner) areas of #1 are used (opaque) to mask out the overexposed bits of #2. I have only just started experimenting with it in Gimp, so not an expert and I cant advise how in ST, but PS I believe also has layer masks. A google on "layer mask" and "astro" should turn up something, and I'm sure an expert will be along here soon

 

 

Edited October 16, 2016 by SilverAstro
grammer

[Nigel G]

20 minutes ago, SilverAstro said:

Worked very well indeed ! A very nice image. Would be interesting too to see what a stack of 20s would show of the outer regions.

There is a technique for using the shorter exp inner image (#1) as a mask over the longer exp image (#2) such that the dark areas in #1 become transparent and show/reveal #2 but the bright ( inner) areas of #1 are used (opaque) to mask out the overexposed bits of #2. I have only just started experimenting with it in Gimp, so not an expert and I cant advise how in ST, but PS I believe also has layer masks. A google on "layer mask" and "astro" should turn up something, and I'm sure an expert will be along here soon

 

 

Cheers

Stacking the 20's now. 10's done and in ST

I think shorts has given a sharper image but its such a bright nebula we can get away with very short exp's

I just finished the 10's and the outer nebula is not as clear but the core is better. waiting for the 20's now

Nige

Edited October 16, 2016 by Nigel G
add 10's bit

[Nigel G]

33 minutes ago, SteveNickolls said:

Well done with M42 Nige, both capturing a nice image and being able to get up at 'too early in the morning' to image at all :-) I can't help about combining different exposures but I bet it's in the StarTools guide.

Cheers,
Steve

Thanks Steve, I'll start looking, Ian mentioned it a few posts back i'm sure.

Nige.

[Stub Mandrel]

Core doesn't look bad to me - there are stars in it, unlike mine!

[Nigel G]

2 minutes ago, Stub Mandrel said:

Core doesn't look bad to me - there are stars in it, unlike mine!

Thanks Neil, its not that bad your right, the 10 second stack isn't that much different, not quite as sharp but I got a bigger crop due to less rotation. I'll post them after finished processing.

Nige.

[SilverAstro]

 

35 minutes ago, SilverAstro said:

be interesting too to see what a stack of   20s  10s !

 

10 minutes ago, Stub Mandrel said:

Core doesn't look bad to me - there are stars in it, unlike mine!

 

Looks very good to me as well,  which may explain why I confused my 20's with my 10's !! anyway, yes it will be interesting to see the differences , ,  but anyway layer masks to make HDRs

[alacant]

1 hour ago, Nigel G said:

Any ideas on core exposure welcome

Hi. Process the 20s and 10s individually and then layer them in ST. It's just a couple of clicks. HTH.

[The Admiral]

1 hour ago, alacant said:

Hi. Process the 20s and 10s individually and then layer them in ST. It's just a couple of clicks. HTH.

 

1 hour ago, Nigel G said:

Cheers

Stacking the 20's now. 10's done and in ST

I think shorts has given a sharper image but its such a bright nebula we can get away with very short exp's

I just finished the 10's and the outer nebula is not as clear but the core is better. waiting for the 20's now

Nige

Well done Nige, but I have to agree with Steve, far too late in the night/early in the morning for me to be out. I think the core is naturally 'messy', there's a lot going on there (see http://www.messier-objects.com/messier-42-orion-nebula/), and you've at least captured the characteristic green. It'll have to wait, but I do plan on having another go as I was only just setting out on this journey when I first did it. Then, I used 100 x 15s lights, but I think (a) the core may be a little blown, and (b) there is more to the nebular that I didn't capture, so this time around I'll try what you are doing and take subs with different exposures, though I'm still debating with myself what they should be. It seems to me that they can be combined in DSS, as I assume you did for your picture, or combined in ST.

The only problem with our Alt-Az imaging is tracking and field rotation, so prior to stacking in ST they'll need to be aligned. If I understand correctly, as I've not tried this, you would take the output of, say, your 10 second stack and use it in the stack of the 20 second subs as a master frame (i.e. to which the 20s ones will be registered against), but presumably deselected so that it is not used as part of the stack of the 20s subs. Is that what you are doing? I'm not sure if DSS will allow you to use a non-selected image as a master though. More to learn .

Looking forward to seeing what you get out.

Ian

Edited October 16, 2016 by The Admiral

[The Admiral]

This morning I've been messing around with my M33 image again. This time I went back to manual develop in ST, and I didn't bin as I'd have to crop a decent amount for the final image. To be honest, binning 25% didn't seem to get me anywhere better. I think it's an improvement over the last attempt (https://stargazerslounge.com/topic/228101-the-no-eq-dso-challenge/?do=findComment&comment=3060403), and the colour balance seems better than my original (currently in my gallery), which was too blue. I think this is the best I'm likely to get to be honest. The reality is that it's not a bright object and there's a lot of noise, and it's not a large object in the frame. Finished off with a bit more noise reduction in Lightroom.

Ian

 

Edited October 16, 2016 by The Admiral

[Nigel G]

14 minutes ago, The Admiral said:

This morning I've been messing around with my M33 image again. This time I went back to manual develop in ST, and I didn't bin as I'd have to crop a decent amount for the final image. To be honest, binning 25% didn't seem to get me anywhere better. I think it's an improvement over the last attempt (https://stargazerslounge.com/topic/228101-the-no-eq-dso-challenge/?do=findComment&comment=3060403), and the colour balance seems better than my original (currently in my gallery), which was too blue. I think this is the best I'm likely to get to be honest. The reality is that it's not a bright object and there's a lot of noise, and it's not a large object in the frame. Finished off with a bit more noise reduction in Lightroom.

Ian

 

There's much better colours now, Looks great,

Nige.

[The Admiral]

19 minutes ago, Nigel G said:

There's much better colours now, Looks great,

Nige.

Thanks Nige.

Ian

[Nigel G]

Thanks Ian.

There's a noticeable difference in the ease of processing these 3 images. Easiest was the combined subs, hardest the 10s, but it seems the 10s is as good if not better than the 20s. The 20s had most noise I think. As usual there's quite a bit of difference in colours but that's down to me.

First approx. 10 minutes of 10s subs.

Second approx. 20 minutes of 20s subs.

Third combined subs.....My fav #3

 I'm going to look into layering images, but first I'm going to run the combined again  lazy Sunday afternoon.

This one I would love to see from Kens CCD.

Cheers

Nige.

[The Admiral]

That's a bit odd Nige, you'd expect the 10m of 10s to be noisier than 20m of 20s. Also, your second image doesn't seem to be as deep as the first, despite having longer time and longer subs! Is that just down to a difference in processing, or is there a chance that they could have got swapped? Nice result though.

I also found this statement in the DSS manual: " If you select a reference frame that is not checked, the offsets will be computed from this reference frame even if the reference frame will not be stacked."

So, all looks to be doable then.

Ian

 

Edited October 16, 2016 by The Admiral

[alacant]

14 minutes ago, Nigel G said:

going to look into layering images

Hi. Nice images anyway. I think the main advantage of Ivo's ST layers is that you can choose how much of each exposure you take.