Shooting Stars... Focusing

philxthomas

philxthomas

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So I got a D40 the other day and have just been out trying to take some shots in't garden. Everything was working fine, got some decent shots, but its a really clear night and the stars are out. Tried to take some shots of just the stars and I could not focus.

I used to have a Canon G9, with that, I could just set manual focus to infinity and point and shoot etc.. But with the D40, it will not auto focus, and with manual focus its too dark and far away to see anything.

How do I do it?
 
LOL. You have no chance of getting AF lock on a star. Use manual focus.

Soz, I'm not sure why it's so dark with your D40? What's the max aperture of your lens.
 
Max aperture is 36 I think. I know AF wont work but how can you get it to manual focus if you cant see when the stars are in focus?

As for why it's too dark.... Erm, its night time?
 
put it on manual, and move it to the infinite logo when you try and focus (the logo should be on the lens somewhere on the focusing 'ring' - again i dont know the technical word for this)

This essentially opens up the camera so it focus's on pretty much everything that is far away. I would get my camera out to check that this is till normal on a DSLR (ive only had mine a month, and used an old film camera from 1986 before this), but im in bed and feeling lazy :).

You'll probably need a substantially slow shutter speed to get anything to come up, and something stable to leave the camera on (a tripod ideally, but I've propped mine up on books before), and you will probably have to knock the ISO up, personally i'd whack my settings up with a high ISO, open the Av up (the lowest number it will go to - means that the shutter is opening further and letting more light in) and a long shutter speed and see what happens, adjusting my settings from there. It might over expose with whatever foreground you have, but atleast its a starting point with your settings.

hope it helps, might be a bit vague.
 
Hi philxthomas,
either focus on a far away street light then swich lens to manual focus (or tape down) or take a picture in manual of stars and zoom in on lcd screen for focus, adjust focus if necessary and repeat until star is as small as you can get it.
HTH
 
LOL. I'd have thought you'd be able to see the stars through the viewfinder.

I meant the other end of the aperture scale - wide open not stopped down to the smallest aperture.

Actually, you got me at it - I've just been and had a go with the 50mm 1.4 and manually focused to infinity I can just about see the stars and it's far from an ideal night - not very clear at all. I can see how you might struggle with a smaller max aperture.

I'm struggling to see why you could do it with your G9 and not with your D40 though. Set to MF and infinity you should be able to get a general view of an area of the sky I'd have thought. I can see how lining up on a particular star might be a problem.
 
Thanks for the tips, just had another go out the window and got a decent ish shot, in focus at least.

Smallest aperture is around F4 or something with the zoom im using. However, when I use this aperture of F4 (so is that low or high?) its blurry again.

My settings for the in-focus shot were something like 30 second exposure, F36, ISO 1600
 
F4 is your widest, (biggest) aperture. If you set a smaller aperture which you really should - say f8 or f11 you should get a sharper shot I'd think. My experience is limited to shooting the moon, but aren't the stars moving,( or we are) so you're likely to get star trails with very long exposures. You need to use a tripod or a firm base of some sort and relaase the shutter with a remote release or with the delayed timer to avoid touching the camera.

Once you've focused, mirror lock up is a good idea to avoid vibration too.

We've got a few people into astral photography who'll probably be able to give you better advice.
 
The only way you'll get sharp shots aof the stars is to take muliple images and stack them or using a dedicated tracking mount. The problem is you need a long shutter speed to get enough light onto the sensor but by doing that, the stars have moved (or rather we have) and therefore you get the trail effect.
Where's Jgs001 when you need him, he'd explain it better :)
 
philxthomas said:
cool, will try that tomorrow night.

btw, mirror lockup?
Click to expand...
Mirror lock up should be available on your camera, but I'm not into Nikons. It might be a button on the outside of the camera or it might be buried in your camera menus and need to be enabled.

Once it's enabled, the first press of the shutter flips the mirror up. Pause to let the vibration die away, and the second press of the shutter button fires the shutter.
 
GarynLea said:
The only way you'll get sharp shots aof the stars is to take muliple images and stack them or using a dedicated tracking mount. The problem is you need a long shutter speed to get enough light onto the sensor but by doing that, the stars have moved (or rather we have) and therefore you get the trail effect.
Where's Jgs001 when you need him, he'd explain it better :)
Click to expand...

thanks, but its not really the rotation of the earth im bothered about, i was just running off some test shots and couldnt focus at all.
 
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