Show us your subs!

[Guest Tuomo]

Hi!

This might sound stupid idea, but could you guys please share your single sub exposure image with some info. Reason for this is to show what kind of subs you get so starters can check if they are on the right track. I have always wondered if my subs are supposed to look the way they look.

Here goes my first.

M32, 80s. with ISO of 800, no filters.

SW 102/500 + EOS 500D on EQ5(AstroEQ)

[4th]

Quick Q. What is the meaning of the term "sub"?

[laser_jock99]

IC2118 Witch Head Nebula, 200mm F2.9 Newtonian telescope (unguided), Fuji S5 Pro DSLR camera at ISO2500 single 240s subframe......

 

 

.....and the result of stacking and processing 12 x 240s subframes.

 

 

[4th]

Q.Answered.Thanks.

[Guest Tuomo]

Awesome, please share your subs!

[Moonshed]

9 hours ago, laser_jock99 said:

IC2118 Witch Head Nebula, 200mm F2.9 Newtonian telescope (unguided), Fuji S5 Pro DSLR camera at ISO2500 single 240s subframe......

 

 

 

.....and the result of stacking and processing 12 x 240s subframes.

 

 

 

That's a great image but what has caused all those parallel diagonal lines and what is that bright horizontal line?

[Knight of Clear Skies]

3 minutes ago, Moonshed said:

That's a great image but what has caused all those parallel diagonal lines and what is that bright horizontal line?

I'd guess they are geostationary satellites. I'd have thought a Kappa-Sigma clip when stacking would remove the trails.

[Knight of Clear Skies]

Here's an example 2 minute sub on the Sadr region with a 135mm lens at f3.5, but this has had a quick process (colour balance, GradEx to remove vignetting, de-noise and a bit of selective colour).

I could post up some straight-out-of the camera shots if anyone is interested.

I've been finding it useful to process single subs as it gives me something to aim for after I've stacked and helps me make meaningful comparisons between images.

[Bagnaj97]

Here's my recent attempt at the Jellyfish. Both a single sub simply converted to jpg, and the end result.

15x600s light frames, 20x flats, 20x bias
Telescope: Celestron c6n
Mount: Celestron Advanced VX
Camera: Modded 450d
Guiding: 50mm guidescope, Altair GPCAM, PHD2
Other: Revelation/GSO coma corrector, Skywatcher 2" LP filter
 

[Guest Tuomo]

This is what I mean! So nice to see the foundation of those nice astroimages. Please keep it up! I think I need to insert final image of m32 too when I get home.

 

[laser_jock99]

7 hours ago, Moonshed said:

That's a great image but what has caused all those parallel diagonal lines and what is that bright horizontal line?

Thanks- Knight Of Clear Skies was correct about the geostationary satelite trails- there are so many in this part of the sky. They could be processed out but I kind of wanted to show what I was up against. The other line is a diffraction spike from bright star Rigel, just out of frame.

[laser_jock99]

7 hours ago, Knight of Clear Skies said:

Here's an example 2 minute sub on the Sadr region with a 135mm lens at f3.5, but this has had a quick process (colour balance, GradEx to remove vignetting, de-noise and a bit of selective colour).

I could post up some straight-out-of the camera shots if anyone is interested.

I've been finding it useful to process single subs as it gives me something to aim for after I've stacked and helps me make meaningful comparisons between images.

I often find it useful to do some basic processing to the RAW files prior to stacking. I usually colour correct, basic levels and slight noise reduction, stack the saved 32 bit TIF files then do the main processing on the stacked TIF.

[Guest Tuomo]

44 minutes ago, laser_jock99 said:

I often find it useful to do some basic processing to the RAW files prior to stacking. I usually colour correct, basic levels and slight noise reduction, stack the saved 32 bit TIF files then do the main processing on the stacked TIF.

Dont you lose some data by doing this?

[Starwiz]

Here's my last effort, a single sub and the end result after stacking 18 subs and processing.

John

 

 

[JOC]

I find it amazing that the camera can see more than my eye does and that all the detail is revealed by layering the images one on top of the other.  I am amazed that what isn't shown in a single exposure is revealed as the colours are layered up.  I can't wait to try it myself to see if I can make it work, but the wretched clouds haven't cleared since I sorted out my camera attachment.

[Starwiz]

3 minutes ago, JOC said:

I find it amazing that the camera can see more than my eye does and that all the detail is revealed by layering the images one on top of the other.  I am amazed that what isn't shown in a single exposure is revealed as the colours are layered up.  I can't wait to try it myself to see if I can make it work, but the wretched clouds haven't cleared since I sorted out my camera attachment.

And the moon's in the way until later next week.  I must get a narrow-band filter sometime.

[laser_jock99]

6 minutes ago, Tuomo said:

Dont you lose some data by doing this?

Possibly- when shooting at very high ISO speeds I'm trying to smooth out spurious camera noise prior to stacking. Deep Sky Stacker sometimes mistakes noise for stars with 'interesting' results. But then again I'm starting with a 4000x3000 pixel image which eventually gets reduced to 1064x652 for the Web- even more loss of data there!

[Knight of Clear Skies]

Here's a couple more examples straight out of the camera (except resized to 2560 width), taken with an ED120 + reducer and modded Canon 100D at ISO 800.

And here's an 11.5 second sub, I used a set of these to fix the over-exposed core.

And here's the final result, 1h8m of data in total.

[wimvb]

My latest

Single sub 7 minutes unguided 135 mm @ iso 400, downsampled, converted to 8 bit jpeg

And the processed image (but not the final version), cropped

More info, and the unprocessed stacked image here:

https://stargazerslounge.com/topic/284568-m45-the-punked-version/

Cheers,

[Moonshed]

3 hours ago, laser_jock99 said:

Thanks- Knight Of Clear Skies was correct about the geostationary satelite trails- there are so many in this part of the sky. They could be processed out but I kind of wanted to show what I was up against. The other line is a diffraction spike from bright star Rigel, just out of frame.

Okay, thanks for that. That must be very frustrating for you. I recently took 30 subs of M42 and on examination had to ditch 6 of them due to a combination of satellites and planes. I didn't actually notice  them before stacking unfortunately, it was only looking at the lines and dots tracking across the stacked image that force me to go back and check. Lessen learned, I now check each sub carefully before stacking. Patience is a virtue! 

[Guest Tuomo]

3 hours ago, Knight of Clear Skies said:

Here's a couple more examples straight out of the camera (except resized to 2560 width), taken with an ED120 + reducer and modded Canon 100D at ISO 800.

 

And here's an 11.5 second sub, I used a set of these to fix the over-exposed core.

Very useful image! Now I understand more how to take proper image out of Orion.

 

[M106]

great idea for a thread! hving taken just a single shot of the moon through a supermarket refractor i always wondered what people were seeingin their raw shots

[Knight of Clear Skies]

10 hours ago, Tuomo said:

Very useful image! Now I understand more how to take proper image out of Orion.

Glad you found it useful. Looking again, my subs aren't quite right as the Canon DPP software has decided to apply some noise reduction. Here's a 4 minute sub again with a quick colour balance (just dragged the red channel down a bit to help compensate for the screwy balance from the modded camera) and all NR turned off.

As you can imagine, I was smiling when I saw these coming in.

On 10/01/2017 at 20:30, SilverAstro said:

 

 

14 hours ago, laser_jock99 said:

Possibly- when shooting at very high ISO speeds I'm trying to smooth out spurious camera noise prior to stacking. Deep Sky Stacker sometimes mistakes noise for stars with 'interesting' results. But then again I'm starting with a 4000x3000 pixel image which eventually gets reduced to 1064x652 for the Web- even more loss of data there!

To be honest, I suspect that is counter-productive. I'd expect any noise reduction algorithms to work better with the cleaner, stacked data. Stacking is very good at reducing noise, especially when using dithering.

12 hours ago, Moonshed said:

I recently took 30 subs of M42 and on examination had to ditch 6 of them due to a combination of satellites and planes. I didn't actually notice  them before stacking unfortunately, it was only looking at the lines and dots tracking across the stacked image that force me to go back and check. Lessen learned, I now check each sub carefully before stacking. Patience is a virtue! 

If you select the Kappa-Sigma clip option when stacking you'll probably find those subs will add to the stack without any problems. It's a statistical method that rejects outlier pixel values. In my sub above there is a satellite trail at lower right but it isn't visible in the final image.

[Moonshed]

59 minutes ago, Knight of Clear Skies said:

13 hours ago, Moonshed said:

I recently took 30 subs of M42 and on examination had to ditch 6 of them due to a combination of satellites and planes. I didn't actually notice  them before stacking unfortunately, it was only looking at the lines and dots tracking across the stacked image that force me to go back and check. Lessen learned, I now check each sub carefully before stacking. Patience is a virtue! 

If you select the Kappa-Sigma clip option when stacking you'll probably find those subs will add to the stack without any problems. It's a statistical method that rejects outlier pixel values. In my sub above there is a satellite trail at lower right but it isn't visible in the final image.

Thanks for that. Yes, I have only in the last couple of weeks learned what Kappa-Sigma does, I was not using it when I stacked those M42 subs. I will go back to them and stack using it.  

 

[martin_h]

Single 5 minuet luminance sub and the result from a 12 sub stack