Canon Community Canon Community
 


Reply
Esteemed Contributor
Posts: 4,184
Registered: ‎08-13-2015

Re: Share your Astrophotography Photos

"The last I knew, there was no South Star. Has one been discovered while I wasn't paying attention?" 

 

They do use a reference star to align equitorial mounts in the southern hemisphere.

 

https://en.wikipedia.org/wiki/Polar_alignment#Southern_Hemisphere

 

The star used in the southern hemisphere is not as close to the center of axis of rotation as polaris.  It is sometimes referred to as the Southern Polar Star in some circles, because of how it is used.

----------------------------------------------------------------------------------------------------------------------------------------------------------

"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
New Contributor
Posts: 1
Registered: ‎04-20-2016

Re: Share your Astrophotography Photos

[ Edited ]

canon 6d and sigma 35 1.4

12973566_1116030695085947_6414515772366653680_o.jpg

Honored Contributor
Posts: 7,279
Registered: ‎12-07-2012

Re: Share your Astrophotography Photos

Bob from Boston,

"Yes, really. The Earth does a full rotation in 24 hours, regardless of how many exposures one takes to document the process."

 

Yes, it may take the Earth nearly 24 hours to make a full rotation but it doesn't take 24 hours to make that shot.  I will guess you have not done it before?  I will also guess the exposure is not as long as you think.  It is, however, many shots.

When I suggested the idea of a fill flash, I didn't mean it for that shot.  Only that it is used a lot in this type of photography.  The lack of color in the trees suggests there was no extra light.

A lot of Canon stuff. Along with, a lot of other stuff.
Honored Contributor
Posts: 7,279
Registered: ‎12-07-2012

Re: Share your Astrophotography Photos

Bob from Boston,

The williamphoto does have some extra fill light on the lower and mountain scene.

 

Very nice shot, BTW.  Smiley Happy

A lot of Canon stuff. Along with, a lot of other stuff.
Esteemed Contributor
Posts: 4,184
Registered: ‎08-13-2015

Re: Share your Astrophotography Photos

 

"You can see where the center of rotation is, and you know that a full rotation takes 24 hours."

 

Not really.  Several short exposures of, say 6 or 8, of approx. 5 to 10 minutes can do that.  It also eliminates a lot of error factors from long exposures.

------------------------------------------------------------------------------------------------------

I was confused.  Were you saying the total exposure time was 5-10 minutes, or each exposure was 5-10 minutes?  I think the total exposure time is 2-3  hours.

----------------------------------------------------------------------------------------------------------------------------------------------------------

"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Honored Contributor
Posts: 7,279
Registered: ‎12-07-2012

Re: Share your Astrophotography Photos

"I think the total exposure time is 2-3  hours."

 

Possibly. I wouldn't argue.  Who knows for sure?  It just doesn't require 24 hours.

A lot of Canon stuff. Along with, a lot of other stuff.
Occasional Contributor
Posts: 22
Registered: ‎04-13-2016

Re: Share your Astrophotography Photos

[ Edited ]

ebiggs1 wrote:

"I think the total exposure time is 2-3  hours."

 

Possibly. I wouldn't argue.  Who knows for sure?  It just doesn't require 24 hours.


So multiple 5-10 minute long exposure shots for a total of 2-3 hours or one big 2-3 hour exposed shot? You guys are confusing me lol.

Esteemed Contributor
Posts: 3,026
Registered: ‎06-25-2014

Re: Share your Astrophotography Photos


ebiggs1 wrote:

Bob from Boston,

"Yes, really. The Earth does a full rotation in 24 hours, regardless of how many exposures one takes to document the process."

 

Yes, it may take the Earth nearly 24 hours to make a full rotation but it doesn't take 24 hours to make that shot.  I will guess you have not done it before?  I will also guess the exposure is not as long as you think.  It is, however, many shots.

When I suggested the idea of a fill flash, I didn't mean it for that shot.  Only that it is used a lot in this type of photography.  The lack of color in the trees suggests there was no extra light.


Where did I ever begin to suggest that it took 24 hours to make the shot? If that's what you thought I said, I obviously didn't make myself clear. And I see no evidence to support your assertion that the picture was made with multiple shots. The only conclusive evidence I can think of would be gaps in the individual trails, and I see none.

Bob
Boston, Massachusetts USA
Esteemed Contributor
Posts: 4,184
Registered: ‎08-13-2015

Re: Share your Astrophotography Photos

"So multiple 5-10 minute long exposure shots for a total of 2-3 hours or one big 2-3 hour exposed shot? You guys are confusing me lol." 

 

You just hit the nail on the head.  There is no one answer, "Do it like so." Captuing an image of star trails like that is not a task for the beginner.  It requires a lot finesse, creativity, and experience at shooting in the dark and the night skies.  I would not take exposures as long as 5-10 minutes, for the exact reasons that Ernie has already cited.  Noise.

 

You will learn that using the same exposure time with widely different focal lengths can give widely different results, most especially when it comes to star trails.  The focal length and aperture that you use will directly impact the best exposure time to capture star trails.  There is a lot room for variance in the Exposure Triangle. 

 

I would also advise starting out small and working your way up: like taking shots of the Moon on full, half, and quarter phases, to learn about how to take pictures of the night skies.  Taking shots of the Moon will teach about stabilizing your camera on a tripod, releasing the shutter, and optionally shutter lockup. I would suggest taking pictures of the Moon just as the sun sets, or rises, too.

 

I would think the next step would be taking a wide field shot of night landscapes and the night sky, where you would learn about stacking photos, white balance, and exposures, or even layering if you use a commecial applicaiton like Photoshop Elements, or Photoshop CC.  Taking shots landscapes with full Moon at your back can produce some pretty dramatic looking shots.  I would use the same White Balance as I would for a bright sunny day., because the Moon is a perfectly neutral reflector of direct sunlight. 

 

Once you have gone through those trials and errors, you could attempt to create a final shot of star trails.  I would encourage taking shots of star trails all long the way, too. 

 

 

 

 

----------------------------------------------------------------------------------------------------------------------------------------------------------

"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Esteemed Contributor
Posts: 4,184
Registered: ‎08-13-2015

Re: Share your Astrophotography Photos

"Where did I ever begin to suggest that it took 24 hours to make the shot? If that's what you thought I said, I obviously didn't make myself clear. And I see no evidence to support your assertion that the picture was made with multiple shots. The only conclusive evidence I can think of would be gaps in the individual trails, and I see none." 

 

I knew what you meant by your 24 hour comment.  I also thought it was a bit technical, also.  Hence, my comparison to an hour hand on a clock face.

 

Depending upon the focal length used to capture the shot(s), a pause in between shots of up to 10-15 seconds will not produce gaps in the star trails.  I also see the silhouette appearance of the trees as being highly suggestive that short exposures were involved.  I think that a really lengthy exposure should have lit up the trees a bit more than what they are. 

----------------------------------------------------------------------------------------------------------------------------------------------------------

"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
powered by Lithium

LIKE US on Facebook FOLLOW US on Twitter WATCH US on YouTube CONNECT WITH US on Linkedin WATCH US on Vimeo FOLLOW US on Instagram SHOP CANON at the Canon Online Store
© Canon U.S.A., Inc.   |    Terms of Use   |    Privacy Statement