focusing.

My problem is one that which has been vexing me for a while now. what is the best way to focus on the stars? I have relatively dark skies, but for some reason, I cannot get the focus super sharp, whether using my 18-55 or my 55 -200. I really prefer the wide views of the milky way, so my usual attempts are with the 18mm end. I just cant seem to get the stars to get super sharp.

Any ideas?

Justin

Use the moon if it's up.
If you're shooting wide, you can use a torch/flashlight or a streetlight to focus on. Have a look into hyperfocal distances if you're not familiar with the idea. An 18mm lens at f/4 focused on something 15ft away has everything from 8ft to infinity in focus. You just need to get it into one of the focus boxes.
If your camera has live-view, that can be helpful for manual focusing, although the kit lenses are really hard to manually focus.

+1 Steve. Plus make sure it isn't a trailing/motion blur problem, rather than mis-focus. Wider angle lenses should commonly focus on infinity when stopped down one stop from wide open and manually set to infinity.

If your camera has live view the you can also use that to get sharp focus. Make sure you zoom in on the LCD too for the fine adjustments.

I had the exact problem you are having and finally discovered that using Liveview or a software called Backyard EOS would solve my problems. However when using either of these with the lens you are using, the stars will be very faint in Liveview and you will have to be close to in focus to start with. I usually start with the lens focused past infinity and then slowly work my way back.

Also, you will have to focus on a very bright star. Anything that is under 1st magnitude will not show up. I spent a couple of evenings sorting all this out.

As someone else pointed out, using the moon works very well too in AF mode. Just remember to switch back to MF mode before shooting!

Good luck!

i dunno, i may wrong here- but the moon is a good starting point as mentioned- however, i think you really need to focus on a star, its seems to me, i have to refocus the moon an unusual amount of times

I used to use the focus/shoot/view on screen/zoom/refocus/sh​oot/view on screen ... then I bought a manual focus lens (Zeiss 21 Distagon) and infinity focus is at infinity. It is fantastic, just turn the focus ring to infinity and the stars are tack sharp. Auto focus lenses focus rings are sloppy (I guess to save wear and tear on the focus motor) and miserable to manually focus.

Justinryan215 wrote in post #12906887
My problem is one that which has been vexing me for a while now. what is the best way to focus on the stars? I have relatively dark skies, but for some reason, I cannot get the focus super sharp, whether using my 18-55 or my 55 -200. I really prefer the wide views of the milky way, so my usual attempts are with the 18mm end. I just cant seem to get the stars to get super sharp.

Any ideas?

Justin

I hear ya, I started with same kit lens as you, and no infinity mark....

Tip on focus camera with live view:

I've had luck with live view, 10x, then manual focus until the brightest star you can find gets small/sharp as possible.
Sometimes that takes a back/forth on the focus ring until you find that center spot of focus.
Even if you have to crank up the ISO just to focus to show the star brightrest, then move it down for the actual shot.
Infinity marking on lens is a good start, but that varies on temp and zoom.

markweaver wrote in post #12952287
I used to use the focus/shoot/view on screen/zoom/refocus/sh​oot/view on screen ... then I bought a manual focus lens (Zeiss 21 Distagon) and infinity focus is at infinity. It is fantastic, just turn the focus ring to infinity and the stars are tack sharp. Auto focus lenses focus rings are sloppy (I guess to save wear and tear on the focus motor) and miserable to manually focus.

You have just discovered the joy of MF lenses (of which the distagon is an AWESOME example). Make sure you do NOT get affected by the MF bug!!