Shooting the night sky / shutter speed

[Gavjenks]

Uh all the stars should be equally in focus or not. If some are and some aren't, then something is wrong with your lens / it is tilted or very distorted?
I've never had any problems using LCD view with 5x or 10x zoom in

 

[Aloicious]

the key is to zoom in as far as possible in LCD/live view on one star (preferably close to center frame) and focus on it manually, AF will likely never work correctly on stars and if you don't zoom in on the LCD it'll be really hard to determine critical focus (not to mention atmospheric seeing conditions may be poor in your area that day). also, it could be the lens/settings you're using (some lenses are really poor performers wide open, others are fine).

if you have an example shot, post it up, it could help diagnose the problem.

 

[EIngerson]

You could also just set it to hyper focus. Very simple fix and should work well for you.

 

[cchoate]

I should clarify, some of the pictures were badly out of focus, others were slightly out of focus. Here are a couple examples.

 

[Gavjenks]

One possibility: since youre using a 70-300, some of those lenses like that tend to slide in and out of zoom under their own weight when pointed up or down. Perhaps your lens is zooming out slightly in between you focusing and shooting?

 

[epeddy1]

With my telescope I use a Bahtinov mask to get perfect focus. I imagine the same concept of using a focus mask should work on a DSLR lens but I never tried. Once you get focus, lock. Shouldn't need to change it unless you change up your focal length.

There are also programs to control the camera from a laptop. Laptop screen > camera LCD. I use Backyard EOS with my Canon. I imagine a quick Google search and you can find something. Also nice because image goes straight to the laptop, controls your shutter, you can setup time lapses, see results on the big screen, etc etc.

 

[epeddy1]

I should clarify, some of the pictures were badly out of focus, others were slightly out of focus. Here are a couple examples.

FYI, in the top image in the center, that "star" isn't out of focus. That looks to be the Orion Nebula. That could be processed to show more nebulosity and color (with the original RAW file).

Also, if you're serious about shooting the stars, I'd suggest visiting an astronomy forum. Most serious amateur astronomers are also experienced astrophotographers. There's only so much the eyes can see, so eventually even the casual astronomy hobbyists progress to astrophotography. No offense to this forum, but astrophotography is a very specialized subject. Takes more skills and technique, and knowledge of what you're shooting, than your typical low light shots... if you're serious about it.

 

[Aloicious]

those are both definitely out of focus a little bit, that's not seeing conditions or tracking error. its not terrible OOF, as pointed out orion can still be identified.

if you have trouble getting focus on your LCD, you can try tethering the camera and using a computer with some kind of live view control on it to give you a larger view, I know canon and Nikon both have programs that do that, not sure about sony though.

 

[bribrius]

..just following along.

 

[Seventen]

Not to sure if it was a focus issue maybe slightly but when you zoom in on a star on the first image you can see a small star trail and camera shake. Second image was clearly camera shake.

What tripod are you using? Are you using a shutter release cable? Was it very windy?