Amateur Shots: First attempt at shooting the stars!

I've been driving across the country and made a stop in Colorado and pulled on my 50D, 28-135 and tripod. Snapped the following at 30 seconds, F3.5, and ISO3200:

Good effort. you must have some clear skys where you live

If you want nice round stars you're going to have to shorten your exposures a little.
You're using a 50D, a 1.6 crop body camera with a 28-135mm lens. Use the shortest focal length. And then here is a little formula you might want to keep handy.
1.6 x 28 = 44.8.
IOW that's like using a 44.8mm lens on a FF Body to get the same FOV.

Now divide 500 by 44.8 = 11.16seconds

Or just 500 / 28 = 17.85seconds / 1.6 = 11.16 seconds
or 500 / (28*1.6) = 11.16
That's how long you can shoot with your camera on a stationary tripod without trailing stars. However, You can probably get away with 20 seconds clearly as long as you are only reducing its size for display on the web.

Edited: Made a terrible mistake with the formula and corrected it.:o

nebulight wrote in post #12649396
I've been driving across the country and made a stop in Colorado and pulled on my 50D, 28-135 and tripod. Snapped the following at 30 seconds, F3.5, and ISO3200:

...

And I took this in Arizona a few nights ago, not sure why it's so blurry:

I'm looking into the possibilities of taking similar photos in PA. If it's possible, I'll be making a few purchases to take better photos.

It's blurry because your subject moved!!

archer1960 wrote in post #12651168
It's blurry because your subject moved!!

Technically the camera moved, now you just need a lens with IS.

e.pie wrote in post #12651199
Technically the camera moved, now you just need a lens with IS.

Technically, everything is moving

TheLostVertex wrote in post #12651249
Technically, everything is moving

Touche

e.pie wrote in post #12651199
Technically the camera moved, now you just need a lens with IS.

Not when the camera is mounted on a tripod! Which it was, and that lens does have IS. If the IS was turned on while mounted on a tripod, that can cause blur.
However, I suspect that he didn't have a remote switch and was pushing the shutter button which will cause blur also.


Technically it is the Earth that is moving at approximately 1000 mph, at the equator. Additional it is moving around the Sun at about 67,000 mph
See, we're not so slow after-all!
The stars are so distant that any movement among them wouldn't be detected with the naked eye.

tkerr wrote in post #12651476
Not when the camera is mounted on a tripod! Which it was, and that lens does have IS. If the IS was turned on while mounted on a tripod, that can cause blur.
However, I suspect that he didn't have a remote switch and was pushing the shutter button which will cause blur also.


Technically it is the Earth that is moving at approximately 1000 mph, at the equator. Additional it is moving around the Sun at about 67,000 mph
See, we're not so slow after-all!
The stars are so distant that any movement among them wouldn't be detected with the naked eye.

I think the point was that the camera was moving WITH the earth, not that it was moving RELATIVE to the earth.

You may not be able to detect the *apparent* star motion with the naked eye, but put a long zoom on, and it's easy.

archer1960 wrote in post #12651663
You may not be able to detect the *apparent* star motion with the naked eye, but put a long zoom on, and it's easy.

You think so!
Is a 1200mm Focal length 10 inch Aperture f/4.7 Telescope long enough? or how about doubling that to 2400mm focal length?
The motion you detect is not the stars moving but rather the motion of the Earth relative to the position of the stars against the night sky. A longer focal length only increases the magnification (narrower FOV) therefore making the motion of the Earth more obvious.

By The Way, I knew what the point was. Thus the in my comment.

This is going to be one of "those" threads.

tkerr wrote in post #12651862
the motion of the Earth relative to the position of the stars

I'm sure you meant the rotation of the Earth rather than its motion through space.

Not that it matters anyway, because the OP asked why they were blurry and that isn't due to the motion. It's blurry because it's out of focus.

Nebulite - Good effort and welcome to the world of astrophotography. That looks like a nice dark spot. Use manual focus and live view on max zoom to focus on a bright star or planet and then recompose if you need to.

Steve.

Yes, I understand the motion of the earth so I knew I was going to get some star trail, however the one last shot was much more blurry than the other three. I did use a tripod with IS disabled and a time release shutter. Could it have position (one in south Arizona, the other in north Colorado?) Could angle be a factor?

And thanks for the info and comments.

Also, could anyone answer my question about PA? Is it possible to get something similar at the lower elevation? Sorry if these are newbie questions, this is my first shot at it so it's ALL new to me.

nebulight wrote in post #12659690
Yes, I understand the motion of the earth so I knew I was going to get some star trail, however the one last shot was much more blurry than the other three. I did use a tripod with IS disabled and a time release shutter. Could it have position (one in south Arizona, the other in north Colorado?) Could angle be a factor?

And thanks for the info and comments.

Also, could anyone answer my question about PA? Is it possible to get something similar at the lower elevation? Sorry if these are newbie questions, this is my first shot at it so it's ALL new to me.

Elevation and or latitude have nothing to do with clarity. Other than camera shake or focus, the other things that effect focus are the atmosphere. Either Astronomical Seeing, Transparency or a combination of Both.

Seeing is the stability of the atmosphere, Air and thermal currents throughout different altitudes. And transparency is the amount of moisture throughout the atmosphere. Either or both can make your pictures look blurry.
Refer to this web site to learn more about Seeing and Transparency.
http://cleardarksky.co​m/c/Starfestkey.html?1

When I PA, if you find a clear area you should be able to get the shot you are after.

On Edit:
If it is windy and your tripod is not very stable you will also get blurred pictures.
If it is humid, watch for condensation on the lens.

tkerr wrote in post #12659762
Elevation and or latitude have nothing to do with clarity. Other than camera shake or focus, the other things that effect focus are the atmosphere. Either Astronomical Seeing, Transparency or a combination of Both.

...

Latitude will affect trailing, though. Targets near the poles don't move by as many pixels during a given exposure time as targets near the celestial equator, so if you're shooting straight up (or nearly so), being further south will give you trails sooner than points north.

archer1960 wrote in post #12660844
Latitude will affect trailing, though. Targets near the poles don't move by as many pixels during a given exposure time as targets near the celestial equator, so if you're shooting straight up (or nearly so), being further south will give you trails sooner than points north.

Yes, but that is not why one is blurry and the others not. Latitude will not effect focus / clarity.
Location however will, Especially near the mountains of Arizona and Colorado. Where you are in relationship to the mountains can have serious effects on the Astronomical Seeing. That is if that is the problem and not an unstable tripod or poor focus.