Utah starscape..

Astronomically-related chat

Moderators: joe, Brian, Guy Fennimore

brian livesey
Posts: 5712
Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire
Contact:

Utah starscape..

Post by brian livesey »

This is not a composite picture: http://antwrp.gsfc.nasa.gov/apod/ap080929.html .
brian
Lady Isabella
Posts: 82
Joined: Tue Sep 23, 2008 2:16 pm
Contact:

Post by Lady Isabella »

Hi

I would think that it would be interesting if the exposure time had been given. I only say this because I have tried a similar thing in the past,
using a wide angle lens, and know how difficult it is to get detail in the image.
davep
Posts: 2814
Joined: Fri May 06, 2005 11:07 am
Location: South Lincolnshire
Contact:

Post by davep »

Lady Isabella wrote:I would think that it would be interesting if the exposure time had been given.
I've been wondering this since I saw it yesterday. There's a few things confuse me about the image. I'd imagine that a pretty long exposure would be required to catch the Milky Way like that. And a long exposure would suggest the camera was tracking the sky. And a camera tracking the sky would be moving in relation to the ground. So, I'd expect the horizon to be a blur.

Also, it appears to be pretty sharp front to back, while would suggest a very narrow aperture, which would further increase the exposure time.

Either I'm missing something obvious, or it doesn't quite add up.
spodzone
Posts: 56
Joined: Tue Jun 28, 2005 1:42 pm
Location: Perth, Scotland
Contact:

Post by spodzone »

davep wrote: Also, it appears to be pretty sharp front to back, while would suggest a very narrow aperture, which would further increase the exposure time.
Or it's a really tiny sensor-size (APS, compact digital) coupled with very wide-angle lens and high ISO speed.

However, let's consider a real-world datum: to get any milky way at all, you need something like (24mm, f/2.8, 20s, ISO1600) as viable parameters on a dSLR (DX sensor size). Any longer, and you start to get noticeable rotation-motion-blur.

Now that ISO1600 has ramifications for image-noise. There's a tonne of chroma-noise in the distant sky (either side of the main blob of the galaxy), but none in equally dark parts of the foreground (bottom-right). This I cannot explain.
~Tim
martinss
Posts: 744
Joined: Thu Mar 29, 2007 12:04 pm
Location: Alton, Hampshire
Contact:

Post by martinss »

Hello. I've just examined this image, and i think it is a fake.

There is more noise at the back of the image (the Milky Way) than in the foreground and there appears to be evidence of a 'feather' where the image editor has used an eraser tool in their software to remove the blackness of the sky in the mouth of the cave from that shot.

And as lack of trailing in the milky way because of the exposure time has already been stated, I'll not go into it, but I concur with that.

Also, there is no EXIF data in the image which you would expect from a 'single' exposure image as this information is stored in the image by the camera.

The list is a bit longer, but I think it is a fake.

However, it is still visually stunning and if we turn and look at our own images of the sky in our forum gallery- they've been stacked, cropped, mixed up, pushed, pulled, over processed (sometimes!) etc and yet we regularly pat each other on the back for producing these shots...these shots are all fakes too...they are not how we see the night sky at all. In that essence, neither is this shot.

Well done to whoever created it - it is atmospheric, moody and very, very beautiful, however you did it.

Martin
'I can calculate the motion of heavenly bodies, but not the madness of people...'[/b] Sir Isaac Newton
Scope:LXD75 10" SNT, Laptop, UnModded Phillips SPC900NC, Canon EOS5D and associated bits and bobs; Also using a stolen 2.5" Skywatcher Refractor (my son's).
Websites: http://www.hantsastro.org - http://www.m109.co.uk - http://www.saban.co.uk - http://www.workingimage.co.uk . Wishlist - Moonlight Crayford[/size]
Zeke
Posts: 371
Joined: Thu Jan 04, 2007 2:29 pm
Location: Wigan
Contact:

Post by Zeke »

It's the sort of picture that would or should compel someone to write a story.
Mmm!
Never worry!
Konus 500.
8x30 binos.
Canon EOS 1000F.
Tamron 80-210mm telephoto.
Fujifinepix S1000fd.
http://coriantumr.wordpress.com/
Meade ETX 80
martinss
Posts: 744
Joined: Thu Mar 29, 2007 12:04 pm
Location: Alton, Hampshire
Contact:

Post by martinss »

'It was dark. Somwhere, an owl hooted. The cattled herd dozed peacefully under the extremely bright Milky Way whilst the cowboys slept under their horses.

High in the hills of Utah, a lone phorographer stood with his camera on a trusty tripod, waiting patiently for his galaxy to arrive in the centre of the cave mouth. It was cold and his breath steamed from his nostrils as he reached for another Lucky Strike. 'Any minute now', he thought quietly to himself, 'that darn galaxy is gonna be right where I wan'it.'

Slowly but surely, the band of the Milky Way crept across camera viewfinder, until, suddenly; BAM, there is was, just where the snapper wanted it! As quick as a flash, he triggered the cable release and left the camera alone for at least 30 seconds at ISO 'something silly'......

And then, as the image passed from CDD to SD card, the loner knew he'd caught a good'un.'

The End.

It's still a cracking shot!!

Martin
'I can calculate the motion of heavenly bodies, but not the madness of people...'[/b] Sir Isaac Newton
Scope:LXD75 10" SNT, Laptop, UnModded Phillips SPC900NC, Canon EOS5D and associated bits and bobs; Also using a stolen 2.5" Skywatcher Refractor (my son's).
Websites: http://www.hantsastro.org - http://www.m109.co.uk - http://www.saban.co.uk - http://www.workingimage.co.uk . Wishlist - Moonlight Crayford[/size]
Zeke
Posts: 371
Joined: Thu Jan 04, 2007 2:29 pm
Location: Wigan
Contact:

Post by Zeke »

I thank you!
Never worry!
Konus 500.
8x30 binos.
Canon EOS 1000F.
Tamron 80-210mm telephoto.
Fujifinepix S1000fd.
http://coriantumr.wordpress.com/
Meade ETX 80
davep
Posts: 2814
Joined: Fri May 06, 2005 11:07 am
Location: South Lincolnshire
Contact:

Post by davep »

martinss wrote:Also, there is no EXIF data in the image which you would expect from a 'single' exposure image as this information is stored in the image by the camera.
Lack of Exif data doesn't have to mean it's not a single image. It can just mean that the data was stripped from the image during some sort of conversion/export process (or even on simply on purpose).
martinss wrote:The list is a bit longer, but I think it is a fake.
Yeah, everything about it says "composite" to me (and a rather enjoyable one at that).
martinss
Posts: 744
Joined: Thu Mar 29, 2007 12:04 pm
Location: Alton, Hampshire
Contact:

Post by martinss »

Morning Dave,

Have never known all EXIF data to be stripped from an image in 10 years pro digital experience, no matter how much processing has been undertaken in Photoshop, there's generally something...of course, our lonesome cowboy may not have been using the fabled PS!

I agree, very enjoyable!

It's one of those, 'if only it were possible' shots...
'I can calculate the motion of heavenly bodies, but not the madness of people...'[/b] Sir Isaac Newton
Scope:LXD75 10" SNT, Laptop, UnModded Phillips SPC900NC, Canon EOS5D and associated bits and bobs; Also using a stolen 2.5" Skywatcher Refractor (my son's).
Websites: http://www.hantsastro.org - http://www.m109.co.uk - http://www.saban.co.uk - http://www.workingimage.co.uk . Wishlist - Moonlight Crayford[/size]
brian livesey
Posts: 5712
Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire
Contact:

Post by brian livesey »

I don't do imaging, so I took the text to the picture on trust.
brian
Robin Scagell
Posts: 1059
Joined: Sat Jul 24, 2004 12:12 pm
Location: Flackwell Heath, Bucks, UK
Contact:

Post by Robin Scagell »

That picture simply screams composite, for all the reasons mentioned, and I think it's a shame that APOD swallowed it. Nothing wrong with composites, mind, as long as either the result is natural-looking or they are created for technical reasons (such as improving the brightness ratio). But to claim that it's a single exposure is just plain silly. Presumably the photographer's flash managed to illuminate the distant horizon as well as the foreground. The Milky Way just doesn't illuminate landscapes like that, as the same photographer's other images show.

I'd put good money on this being a composite.

Robin
brian livesey
Posts: 5712
Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire
Contact:

Post by brian livesey »

Regarding what you said, Robin, about the horizon being illuminated. It says in the text that there was a crescent moon on the night of the exposure/s.
brian
Paul Sutherland
Site Admin
Posts: 921
Joined: Sat Jul 24, 2004 6:06 pm
Location: Walmer, Kent
Contact:

Post by Paul Sutherland »

Robin Scagell wrote:I'd put good money on this being a composite.
Good money? Is there such a thing in these troubled times?
brian livesey
Posts: 5712
Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire
Contact:

Post by brian livesey »

Good money? Don't worry about that, Paul, just let me know how much you'd like and I'll run it off for you to-night. :wink:
brian
Post Reply