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Show us your subs!

Guest Tuomo

By Guest Tuomo
in Getting Started With Imaging

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Guest Tuomo

Guest Tuomo

Posted
Posted
23 minutes ago, martin_h said:

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

sub.jpg

stack.png

THIS! How the he** you managed to conjure image like this from simple black image with some stars :D.

 

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laser_jock99

laser_jock99

Posted
Posted

The reverse case to total blackness may also happen- an apparently overexposed, un-rescuable sub (The 'Wall' in NGC7000, 500s at ISO 3200)

DSIR6840_1024_zps3e41f52e.jpg

 

A process of the above (single sub).

DSIR6840_levels_noels_1024_zpso0q2ivbb.j

 

Don't underestimate the dynamic range of modern cameras (and the power of image processing software)!

 

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Bagnaj97

Bagnaj97

Posted
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55 minutes ago, laser_jock99 said:

The reverse case to total blackness may also happen- an apparently overexposed, un-rescuable sub

 

As I understand it the key is getting it somewhere in between. If you overexpose like that you blow the stars (like in your example and my Jellyfish) but get deeper/fainter details. If you underexpose you don't get so much faint nebulosity, but you get more star colour.

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Davey-T

Davey-T

Posted
Posted

The point of the exercise is to gather as much signal with as little noise as possible so the more subs the more the data can be manipulated without it disintegrating into a noisy mess.

Dave

Single 30minO111 sub California Nebula no processing.

1800sec-O111-00203ps.png

 

 

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JOC

JOC

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So I can't contribute at the moment.  A.  I got dew everywhere and those blobs I got were more fuzzy than the grey stuff you get from a filter in a tumble drier, and B. How do you know when the stars are in focus?  When I took a photo of the moon I could open the shutter, zoom in and do a bit of TTL focussing with the focus knob on the eyepiece holder.   You can't do this with a nebula as they aren't bright enough to see through the camera lens so how do you know when you are in focus on them?    

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Guest Tuomo

Guest Tuomo

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1 hour ago, JOC said:

So I can't contribute at the moment.  A.  I got dew everywhere and those blobs I got were more fuzzy than the grey stuff you get from a filter in a tumble drier, and B. How do you know when the stars are in focus?  When I took a photo of the moon I could open the shutter, zoom in and do a bit of TTL focussing with the focus knob on the eyepiece holder.   You can't do this with a nebula as they aren't bright enough to see through the camera lens so how do you know when you are in focus on them?    

When you manage to focus on stars using live view in DSLR or laptop screen you are done. 

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JOC

JOC

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So if I line up on a really bright star in the sky the live view in the DSLR it should bring up that star bright enough to see in the display and therefore focus on - I can then assume that any nebula will be in focus as all stars/nebulas are a long way out there and if one is in focus then they all are - yes?  Duh!  duffer moment here - I didn't think to try that logic as I didn't expect a bight star to be bright enough to see.:hiding:

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Guest Tuomo

Guest Tuomo

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48 minutes ago, JOC said:

So if I line up on a really bright star in the sky the live view in the DSLR it should bring up that star bright enough to see in the display and therefore focus on - I can then assume that any nebula will be in focus as all stars/nebulas are a long way out there and if one is in focus then they all are - yes?  Duh!  duffer moment here - I didn't think to try that logic as I didn't expect a bight star to be bright enough to see.:hiding:

Bright star like capella is good target. They say its easier to focus using laptop, because of larger screen and I can agree on that. You could use Bahtinov mask too. It gives you difraction spikes to help with the focusing.

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JOC

JOC

Posted
Posted
1 hour ago, Tuomo said:

Bright star like capella is good target. They say its easier to focus using laptop, because of larger screen and I can agree on that. You could use Bahtinov mask too. It gives you difraction spikes to help with the focusing.

Hi Tuomo - I was about to post that I couldn't see how I could bring the laptop into play.  However, I've just taken a closer look at the camera (which I've owned for years).  It's got an mini HDMI Out connection!  I've just discovered that for a few pounds I can buy a cable that has mini HDMI to big HDMI output - my portable has an HDMI connection.  HDMI is a video link!  Things are now falling into place - is this how I can control the focus through the PC - I link the camera to the PC via the HDMI video link - do I need specific software to get the portable to take in the camera input?  Then I find Capella (I can find that now :-D ) and add the Bahtinov mask (Santa got me one - I hadn't found out how to use it yet, but that Wiki link certainly helps).  Focus on Capella and then move to M42 and try some exposures (and hope I can do it all before the dew comes down!!).  If I can manage all this I'll post on this thread!

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Guest Tuomo

Guest Tuomo

Posted
Posted
12 hours ago, JOC said:

Hi Tuomo - I was about to post that I couldn't see how I could bring the laptop into play.  However, I've just taken a closer look at the camera (which I've owned for years).  It's got an mini HDMI Out connection!  I've just discovered that for a few pounds I can buy a cable that has mini HDMI to big HDMI output - my portable has an HDMI connection.  HDMI is a video link!  Things are now falling into place - is this how I can control the focus through the PC - I link the camera to the PC via the HDMI video link - do I need specific software to get the portable to take in the camera input?  Then I find Capella (I can find that now :-D ) and add the Bahtinov mask (Santa got me one - I hadn't found out how to use it yet, but that Wiki link certainly helps).  Focus on Capella and then move to M42 and try some exposures (and hope I can do it all before the dew comes down!!).  If I can manage all this I'll post on this thread!

I do things like this:

First my setup: Sky watcher star travel 102/500+Canon 500D on AstroEQ modded EQ5 mount.

Insert DSLR into focuser with adapter and tighten everything. Now slew scope to Capella and manually adjust focusing knobs in scope to achieve tight focus. Heres large laptop screen comes into play. DSLR and laptop talks to each other via Canon own EOS utility. I think theres is no way to achieve focus via HDMI link, because you would need to control your scope focuser. You could buy Skywatcher auto focuser and then add  USB extension to controll your scope with laptop. This is my next plan. With some DIY skills you can insert auto focuser to other focusers too....Heres how auto focuser with USB extension works.

 

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JOC

JOC

Posted
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1 minute ago, Tuomo said:

I do things like this:

First my setup: Sky watcher star travel 102/500+Canon 500D on AstroEQ modded EQ5 mount.

Insert DSLR into focuser with adapter and tighten everything. Now slew scope to Capella and manually adjust focusing knobs in scope to achieve tight focus. Heres large laptop screen comes into play. I think theres is no way to achieve focus via HDMI link, because you would need to control your scope focuser. You could buy Skywatcher auto focuser and then add  USB extension to controll your scope with laptop. This is my next plan. With some DIY skills you can insert auto focuser to other focusers too....Heres how auto focuser with USB extension works.

 

I don't think I'm looking to use the laptop to control the focus - I can easily twiddle the focussing knobs - if I can see the stars on the large laptop screen this would probably help though and this is what I assume I can achieve with the HDMI cable, i.e. get the laptop to show me what the camera can see - does this need special software?  I've got the adapter and can get the camera body onto the 2" manual focusser so that bit is already solved.

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Guest Tuomo

Guest Tuomo

Posted
Posted
5 minutes ago, JOC said:

I don't think I'm looking to use the laptop to control the focus - I can easily twiddle the focussing knobs - if I can see the stars on the large laptop screen this would probably help though and this is what I assume I can achieve with the HDMI cable, i.e. get the laptop to show me what the camera can see - does this need special software?  I've got the adapter and can get the camera body onto the 2" manual focusser so that bit is already solved.

I focus using my fingers too, but it causes shakes and unwanted actions with polar aligned mount/scope. Canon EOS utility does have live view function. Do you happen to have Canon DSLR?

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Guest Tuomo

Guest Tuomo

Posted
Posted
17 minutes ago, JOC said:

Yes, I've got a Canon T3 Rebel (which is an 1100D) and still have the Canon Utilities CD's that came with it.

So I think you are good to go then!

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