Astro Picts.

[tkerr]

Here are a couple of my astrophotos.


The Pleiades (Messier 45) In Taurus.
Camera: Canon EOS 50D.
Lens: Celestron C80ED f/7.5 Refractor telescope (600mm Focal Length).
ISO 800
Stack of 45 x 180 second exposures.








Messier 31 The Andromeda Galaxy
Camera: Canon EOS 50D
Lens: Canon EF 100-400mm L IS USM, at 300mm f/5.6
ISO 800
Stack of 25 x 180 second exposures.




Telescope mount used was the Celestron CG5-GT Computerized mount.
Autoguiding with Stark Labs PHD Autoguiding software.
Image stacking with Deep Sky Stacker
PP with Photoshop CS5

[PaulM]

Hi Tim,


In laymans ( read I

[tkerr]

Generally, it's usually a matter of the Aperture of the objective lens.
A majority of astroimages are done with a telescope, but not all. I guess it depends on what you are trying to accomplish. A camera lens is usually smaller and will give you a wider field of view. Using the 100-400mm gives me more flexibility than using a fixed focal length telescope. But the telescope has a larger aperture and longer focal length which will have greater light grasp and resolving power.(Greater Detail), and increased image scale.


BTW, you don't need a telescope mount to take pictures of the night sky. You will if you want to do something like these two pictures, but there are other things you can do also.


[View:http://www.youtube.com/watch?v=6JvzlMhZavc&hd=1]

[Baker]

What program/software do you use to make your time lapse?


Here is a shot I took a couple of weeks ago. I believe it is 70 thirty second exposures stacked together.








IMG_1634-IMG_1697 by Chris-Baker, on Flickr

[tkerr]

What program/software do you use to make your time lapse?
<div style="clear: both;"]</div>

Currently I use Pinnacle Studio HD Ultimate 14. when I first started creating time lapse I would just use Windows Movie Maker. But I didn't like the rendering and limitations so I had to look for something else.


How did you stack you star trails image, Photoshop Or Startrails?

[Jon Ruyle]

Here is one of the pictures I took last night from my yard in Wonder Valley, CA:


[img]/resized-image.ashx/__size/550x0/__key/CommunityServer-Discussions-Components-Files/15/6523.m81-wonder-valley.jpg[/img]


5DII (long exposure NR on) + 9.25" Edge HD (2350mm @ f/10) + Astrophysics Mach 1 GTO mount


10 exposures, 4 min each, stacked with Deep Sky Stacker.


I had some trouble with tracking: though autoguiding, I experienced a slow steady drift. Don't know if it was differential flexure, mirror flop, or what, but 4 min was about as much as I could do. I never had such problems with my refractor.


Seeing was lousy, but it was a nice dark night. I looked at galaxies through the big telescope while the small one was taking pictures. My idea of a nice evening!

[Baker]

How did you stack you star trails image, Photoshop Or Startrails?

Actually I used ImageStacker for that shot

[Jon Ruyle]

Nice shots of the andromeda galaxy and pleadies. I like the color in m31. I haven't been able to get nice color like that in my pics.

Generally, it's usually a matter of the Aperture of the objective lens.

Exactly. Many people get hung up on focal length, but with a large, high pixel density CCD, there is a lot of latitude for adjusting effective focal length. (Though admittedly, for a very wide angle picture, one needs a wide angle lens).


An interesting question, though, is which is preferable when there is overlap? Eg, would an 800mm f/5.6 L be preferable to say, a 140mm AP refractor? I don't know the answer . Most of us don't have both, so we make do with what we have


I took a couple of pics last night with my little scope. I'll post them when I get them processed.

[PaulM]

Hi Tim - thanks for the answer:

Generally, it's usually a matter of the Aperture of the objective lens.
A majority of astroimages are done with a telescope, but not all. I guess it depends on what you are trying to accomplish. A camera lens is usually smaller and will give you a wider field of view. Using the 100-400mm gives me more flexibility than using a fixed focal length telescope. But the telescope has a larger aperture and longer focal length which will have greater light grasp and resolving power.(Greater Detail), and increased image scale.


BTW, you don't need a telescope mount to take pictures of the night sky. You will if you want to do something like these two pictures, but there are other things you can do also.

I've been out all weekend and only now have the opportunity to reply. I was referring specifically about capturing magnified images of galaxies, nubulae etc. I remain a little confused about two things though.

Generally, it's usually a matter of the Aperture of the objective lens.



<div style="CLEAR: both"]</div>

However a Canon 600mm f/4 hasa bigger aperture than the telescope you used, which was 600mm f/7.5 if I read it right. I have no idea which is more expensive. The canon lens is not cheap.


Then you said:

BTW, you don't need a telescope mount to take pictures of the night sky. You will if you want to do something like these two pictures, but there are other things you can do also.

but that was my main point of surprise because the second shot was not from a telescope but instead a Canon 100-400mm f/5.6, yet it shows what I typically thought required a long focal length.


In my limited exposure to telescopes I've encountered the term "light bucket" which was explained to me as "not a particularly long focal length but very large aperture to capture the light". My expectation would be a focal length not dissimilar to a telephoto camera lens but a monster aperture. Conversely if it were simply this description then I don't know why people wouldn't use these "light bucket" style telescopes more often for land based photography, yet I don't believe they do...


I understand your reference to the telescopes being prime lenses when compared to a camera's zoom lens. I'd expect these long+stacked exposures are sensitive to distotions that are lesser in prime lenses.


Great video. Nice alternate use of your obvious skill at time-lapsefor stacking!


Paul

[Jon Ruyle]

However a Canon 600mm f/4 hasa bigger aperture than the telescope you used, which was 600mm f/7.5 if I read it right. I have no idea which is more expensive. The canon lens is not cheap.

I'll bet the 600 f/4 would do far better (due to its larger aperture) than the 80mm Celestron ED, but it is much more expensive and much heavier (thus requiring a far more expensive mount). A more balanced comparison would be between a fast 6" refractor and the 600 f/4, or between a 5.5" refractor and the 800 f/5.6.

In my limited exposure to telescopes I've encountered the term "light bucket"

The term "light bucket" originally referred to a large aperture telescope of not-so-great optical quality- usually a large dobsonian. Today people use the term for any big dob (I've never heard anyone refer to anything but a dob as a light bucket). The term, as far as I know, has nothing to do with focal length. But today's big dobs are getting *fast*. f/3.3 in apertures of 20" and up is no longer unusual.