Our Beautiful Universe - Photos and Videos

[davenn]

comet 46P/Wirtanen: here's a 1:1 crop of a single frame

nice shot, Andy

 

[pinball1970]

tis a little difficult ... the forum software plays havoc with images, it lowers the quality quite a bit

View attachment 236037

Got it!

 

[Andy Resnick]

Here's the best I could coax out of DSS- 200 frames covering about 2.5 hours of observing time, keeping the comet still and letting the stars drift. Also, either a plane or a satellite moved through the image field, so you can easily see the effect of non-zero wait times between frames.

The image has been downsized a bit, but if you think you can discern a short stubby tail on the comet, it's actually the result of non-perfect centering. This is also a tiny fragment of the entire image plane- suffice to say I'm still having problems with flat field correction.

Trying to 'double stack', so that both the stars and comet are 'frozen', resulted in a mess. Unclear what that problem is.

All in all, not bad for urban astronomy.

 

[davenn]

Images of the LMC ( Large Magellanic Cloud) showing the effect of increasing ISO and opening the aperture, with the same exposure time.
Canon 6D, Lens 70-200 f2.8 @200mm, 30 sec exp ---
1000 ISO, f4.0
2500 ISO, f3.5
3200 ISO, f2.8

Dave

 

[davenn]

Following from the previous 3 image with experimenting with ISO and aperture settings.
This LMC ( Large Magellanic Cloud) image is a stacked version
Canon 6D, 70-200 f2.8 @200mm, 30 sec exp ...
3200 ISO, f2.8, a stack of 8 frames = 4 minutes total exposure time, no darks or bias frames.
For the non astronomy people ... stacking images helps to reduce the noise level

Dave

 

[davenn]

M42, The Great Orion Nebula

 

[Stavros Kiri]

Just "wow!" from me here, for all latest images in this thread ...
The result is still clear and great even after maximum magnification on my screen. Hey! we got an "electronic telescope" that way! ... (thanks to Dave etc. ...)

 

[davenn]

Single exposure of the SMC ( Small Magellanic Cloud) including 47 Tuc globular cluster
Canon 6D, 70-200 f2.8 @200mm, ISO 3200, 30 sec exp.

Dave

 

[DennisN]

M42, The Great Orion Nebula

Wow, those colors!

 

[Andy Resnick]

Andromeda galaxy (M31) @ 105/2, 30s ISO 64, 2h total integration time- full frame:

1:1

 

[pinball1970]

M42, The Great Orion Nebula

View attachment 236615

View attachment 236614

wow!

 

[pinball1970]

Andromeda galaxy (M31) @ 105/2, 30s ISO 64, 2h total integration time- full frame:

View attachment 236796

1:1

View attachment 236797

Started the year off with some corkers!

 

[Andy Resnick]

Some images from last weekend (Pleiades and Orion): all taken at 400mm, each about 2.5 hours integration time, f/4 for the Pleiades and f/2.8 for the nebulae. I also took a series of images with at 105/2.8, but background subtraction has proven oddly difficult... I have a few more tricks to try out before it's ready to post.

 

[davenn]

Some images from last weekend (Pleiades and Orion): all taken at 400mm,

great shots Andy

in the last one, the Flame Nebula is easily visible and the Horsehead Nebula is just there with a close inspection

just some thoughts ...

I will note that particularly with the Pleiades and the Flame/HH images, I am surprised you haven't captured much more light for 2.5 hours of total exposure ??
You didn't comment on camera or ISO settings ? ...
I wonder if you are using a very low ISO and or the camera is an older one with a less sensitive sensor chip ?

For 2.5 hrs exposure time, the nebulosity around the Pleiades should be so bright
Dave

 

[davenn]

Hi Andy

Just as an example ... here's M45 that I took 34 x 30sec frames of last Friday nite (4th Jan)
That's 990 Sec (16.5 minutes) total time and stacked.

Incidentally, the first time I have captured the nebulosity

Note the similar amount of nebulosity compared to your image.

Canon 6D camera 400mm lens, 34 x 30 sec exposures, ISO 4000 and F5.6 apertureDave

 

[Andy Resnick]

just some thoughts ...

I will note that particularly with the Pleiades and the Flame/HH images, I am surprised you haven't captured much more light for 2.5 hours of total exposure ??
You didn't comment on camera or ISO settings ? ...
I wonder if you are using a very low ISO and or the camera is an older one with a less sensitive sensor chip ?

For 2.5 hrs exposure time, the nebulosity around the Pleiades should be so brightDave

Yeah, the images aren't as amazing as I expected, given the parameters (FWIW, most of the images were taken @ 8s, ISO 1000). Surely, some of the problem is the fact that I am imaging in an urban environment with all of those problems. Another is the clear difference in display characteristics between my laptop (Mac) and desktop (Windblows)- it's an issue with 'gamma' and so what you see is likely different than what I post.

Even so, for a couple of years I have tried to get a better understanding of 1) the (stacked) image statistics and dynamic range and 2) the downsampling process that results in posterized images, and haven't made much progress on either one. To be perfectly honest, the various online forums aren't helpful and often fixate on a 'magic button' in Nebulosity or some other program.

If there is interest, I could open a new thread and walk through the entire process, maybe you (or anyone!) have a useful suggestion.

 

[berkeman]

(Windblows)

LOL

 

[davenn]

If there is interest, I could open a new thread and walk through the entire process, maybe you (or anyone!) have a useful suggestion.

awesome idea ... label the thread " astro image stacking" or words to that effect

 

[Andy Resnick]

Ok, here's a quick-n-dirty result obtained by using a different DSS RAW interpolation- no post-processing (background subtraction, noise reduction, etc): on the same stacked set of images that I showed previously on this thread.

I think there's a significant improvement. More to come!

 

[Andy Resnick]

A few quick results after post-processing: First is a full-frame, the second a more pleasing crop, and the third is good ol' Mr. Ed:

It's not really clear how much of an improvement there has been, but there really is a significant improvement at the pixel level. Background subtraction is also a lot easier- the previous stairstep background made background subtraction exceedingly tricky.

 

[DennisN]

First is a full-frame

Awesome photo!
...and even I know what that is, even though I am pretty bad at star navigation.

Spoiler

It is six shiny stars in a night sky.

the second a more pleasing crop

I actually prefer the first one to the second one. I think it's nice to see the vast surroundings of the constellation .

Edit: And you even managed to capture a black hole :

 

[Andy Resnick]

Edit: And you even managed to capture a black hole :
View attachment 237620

Glad you like them! The 'black hole' is what happens when there's a small piece of dust on the lens when acquiring flat frames. There's a few others present around the periphery...

 

[Andy Resnick]

Here's a re-stack of the Orion nebula (M42): 400mm, DX format: About 1hour of acquisition time.

Here's an image comparison showing that choosing a different RAW converter fixed my problem. The first image is the 'old' converter, the second the 'new' converter using the same set of files (bright and flat)

Clear improvement. In addition to fixing the posterization, it's a lot easier to control the color in the new image. This image also demonstrates what I mean by 'improved dynamic range'. The whole image contains both (more or less) clear renderings of the Trapezium (above, the tight open cluster of 4 stars), of which the brightest star (Theta¹ Orionis C), has an apparent magnitude of 5.13 and simultaneously clear renderings of magnitude 13 stars (as checked using Aladin).

That span of magnitudes corresponds to a total brightness variation within the image of 1600. An alternative specification is that the image intensity encodes 11 bits of dynamic range. "Ideally", I should be able to generate images with about 20 bits of dynamic range. Practically speaking, I seem to hit a limit at magnitude 15, which would correspond to a practical limit of 14 bits (that the original RAW files have 14 bits is a coincidence).

Just recall that in the end- the final displayed or printed image- is an 8-bit/channel format. So here, I had to compress the 11 bits into 8, losing some of the 'photometric precision'.

 

[DennisN]

Here's a re-stack of the Orion nebula (M42): 400mm, DX format: About 1hour of acquisition time.

Simply glorious!
It looks like it could be a good desktop wallpaper too (if it's turned + or -90°).
You don't have a flickr account? For uploading images in large resolutions?
See e.g. this thread: https://www.physicsforums.com/threads/best-online-free-photo-storage-option.947054/
and e.g. my post #5.

 

[Andy Resnick]

Simply glorious!
It looks like it could be a good desktop wallpaper too (if it's turned + or -90°).
You don't have a flickr account? For uploading images in large resolutions?
See e.g. this thread: https://www.physicsforums.com/threads/best-online-free-photo-storage-option.947054/
and e.g. my post #5.

Thanks!

Honestly, I'm very conflicted about 'sharing my gifts' (see Apple's ad: ). A colleague of mine, who teaches photography, has very definite ideas about how 'freely shared photos' has wrecked the profession : https://csuphoto.wordpress.com/2011/10/13/um-no-only-more-polite/ and https://photoprofessionals.wordpress.com/. To be clear, I'm not a professional, nor do I aspire to sell any of my images. Even so, I don't want to contribute to a bad situation.

 

[DennisN]

A colleague of mine, who teaches photography, has very definite ideas about how 'freely shared photos' has wrecked the profession

I understand.
Maybe it was my mention of wallpaper which made you think about "freely sharing", I'm not sure, but I want to say that on Flickr you can reserve your rights (and this is the default setting), see the text to the bottom right on this example which is one of my photos:

Edit: And If I remember correctly you can also mark certain photos as "private" or "semi-private", i.e. only viewable after invitation.

 

[bruha]

Hello,
I just attach my most well-done image of moon up to know- right down is Copernicus I think and right darker elipse is plato (dont know name).
"Bitten" shape in the middle down is some characteristic moon feature as well…
Next two Images is Pocyon and Gomeisa star-it looks quite some color although Gomeisa is cca 4000 K more hot (but is as well cca 15 times mor far..)
All made by Hyperion eyepiece 5 mm f.l. (telescope 600 x 100 mm ) Lot of success and as beginner I appreciate any advices and experiences.

 

[davenn]

I just attach my most well-done image of moon up to know- right down is Copernicus I think and right darker elipse is plato (dont know name).

Hi you and a happy new year

great moon pic ... always good to see the improvements as time goes by

looking forward to more imagesDave

 

[Andy Resnick]

Improved image of the Veil Nebula- this object nearly fills the entire field of view at 400mm:

A few close-up crops:

 

[bruha]

Hi, it is amazing images…
Can you tell me from which place you made it (probably absolutely without light noise..?) and which devices you use?

Lot of success and happy new year …..

 

[davenn]

Went out several Friday nite's ago as a guest of a local astronomy group. There were around 7 of us with scopes of all types
We were in a reasonably dark site about 40km SW of Sydney ( it still produced sky glow in the NE area so we just did imaging
in other parts of the sky. It had been a long time since I was last out with a group of experienced astrophotographers

It's a great way to be able to bounce ideas and issues off each other. Some really nice gear on display !

We set up around 7 - 7:30PM and then awaited the darkening sky

in this second image, my two scopes are on the centre right. A Celestron CPC925 Schmidt-Cassigrain and a Skywatcher 120 x 1000mm refractor

 

[Andy Resnick]

Hi, it is amazing images…
Can you tell me from which place you made it (probably absolutely without light noise..?) and which devices you use?

Lot of success and happy new year …..

Thanks!

My astrophotography is done in my backyard, located in an inner-ring suburb of Cleveland, Ohio (USA) (that is, I live in a heavily light-polluted location). Your assumption is one of the reasons I post my results- going to a dark area is preferred, but in my case unrealistic (or at least more effort than it's worth).

With the exception of the tracking mount, my 'gear' is also my photography equipment: I primarily use a telephoto lens (400/2.8), with or without a 2X adapter. I am beginning to use a 105/1.4 lens and have also done all-sky type imaging with a 15/2.8 lens. All lenses are used with a full-frame camera. The tracking mount is a Losmandy GM8 and I 'star hop' to find objects. I don't have an autotracker, but I do run an extension cord out of my house to power the mount.

 

[Andy Resnick]

Went out several Friday nite's ago as a guest of a local astronomy group. There were around 7 of us with scopes of all types

No fair! You all are clearly dressed for summer whilst we are suffering at -40... I guess being upside down has some advantages :)

 

[bruha]

Hi and thank you to all for post and images
I live in Prague so I can not get unpolluted sky as well. (it is little better on cottage in Bohmerwald mountains but not quite satisfying.) It is great if you could join to group of experienced people. I have just small compact camera (exp. time and clone is auto) so I can not get enough light for enough short exp. time.
(for example I did not manage to image Saturn rings satisfyingly).

 

[davenn]

whilst we are suffering at -40...

Whilst we are suffering at 40C + that nite it was still 30C + after the sun went down

but I do run an extension cord out of my house to power the mount.

You do know there are power packs to take your mount portable ?

I use one of these ...

https://optcorp.com/products/celestron-12v-7ah-power-tank

they are awesomeDave