Timescapes - Digital Timelapse Discussion
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manual focusing on star?
http://forum.timescapes.org/phpBB3/viewtopic.php?f=17&t=9367
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Author:  fstop570 [ Wed Nov 21, 2012 9:42 am ]
Post subject:  manual focusing on star?

Hello! This wealth of knowledge is most helpful. I did notice you said
manual focusing. Any tips on manually focusing on the stars? Also,
do you have a recommended shutter speed for a Milky Way shots?
I have a prime that opens to 1.8. I’ll be using a higher iso, 800 or above.
My goal is to produce something like this….

http://www.flickr.com/photos/57078694@N04/6965889718/

but as a time lapse.
Hope you can help !! :-)

Mod Edit: I moved this to it's own topic so it could get the attention it deserved

Author:  pixelbot [ Wed Nov 21, 2012 11:13 am ]
Post subject:  Re: manual focusing on star?

the settings on that shot are listed at 30 secs at ƒ2.8 and 3200 iso - so I would start there in terms of setting. I know that some lenses wide open aren't super sharp - what lens are you using?

timt

Author:  sparkydave [ Sat Jan 18, 2014 6:42 am ]
Post subject:  Re: manual focusing on star?

Ok I know this is dragging up an old thread, however I do a lot of star shots and thought I'd share my focusing tips, I hope I'm not repeating stuff that everyone knows, I'm thinking this could be somewhat helpful for beginners like me :-)

I Use cheap Canon cameras (1000D DIY Modded and 500D), these like most of the newer Canons have Live view function, its really useful if you don't have a laptop to view the image while focusing, I'm sure Nikon have something similar IDK.

With telephoto lenses its a little easier but with wide angle lenses it can be quite tricky to get the very best focus at night and I never totally rely on the infinity mark

So when setup on a tripod outside in the dark, set your shutter, aperture, ISO to approximate values and switch on Live view.
Now point your camera at a bright object in the sky, for me in the UK right now I use Jupiter, Capella, Sirius or the Moon if its up but try to find something bright a street light at great distance would do if its cloudy etc.
On the Canon you can digitally zoom in while in live view up to 10X (get the little "zoom square" over the bright object then press the zoom button until you reach 10X Zoom)
Now focus your lens back and forth slowly, you will see the object start get bigger and smaller as you pass the focus point it will be at its best focus or its smallest. I do this a few times until I'm sure its right in the point the object appears the smallest.
Once you're happy with the focus leave it alone! same if you have a zoom lens lock down that zoom before you set your focus or make sure you don't touch it.
If you have a laptop hooked up you can normally get perfect focus.

When using telescopes I use DIY Bahtinov masks http://en.wikipedia.org/wiki/ and that makes focusing a breeze I'm sure it would be possible to make something similar for prime lenses.

I hope this is useful to someone :-)

SD.

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