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Old 8th of February 2012 (Wed)   #1
imranali
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Default Focusing in the dark...

So on the way back from work at around 2-3am i drive over an unlit road through a forest. Being the macho man i am i decide to stop and do a lil long exposure shooting especially as the moon was full.

so i've taken a range of pics and to all intents and purposes they've come out as i've wanted them - aside from the fact that the tree range i was including is out of focus.

Since it was actually very very dark (and very cold -9) i wasnt able to see the tree line through the viewfinder and it would only show once the image was captured.

How would you go about getting around this next time?

here's two pics showing what i mean

In the 2nd pic i think i was about to pass out from the cold but with the first the tree line though visable to the eye - through the viewfinder i wasnt able to focus it clear enough.

Last edited by imranali : 9th of February 2012 (Thu) at 19:28. Reason: removed large pics
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Old 8th of February 2012 (Wed)   #2
ohata0
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Default Re: Focusing in the dark...

first off, pics are WAY too huge...resize it to 1024 on the longest end (POTN image posting rules)

As to your focusing problem...you can check your focus in live view. If you have to, up your ISO until you have a "viewable" image. After you're done w/ focusing (probably manually, but you can try the live view contrast AF and see if it works), set the ISO back down to whatever you were going to shoot at.

It might not be necessary, but I'd use mirror lock up and the timer or a remote for long exposures. You can either shoot in live view or use mirror lock up. I personally use mirror lock up to keep from draining the battery using live view, as well as to prevent the sensor from heating up and creating more noise.
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Old 9th of February 2012 (Thu)   #3
imranali
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Default Re: Focusing in the dark...

sorry for the huge pics!

i think i'll need to take my laptop with me next time
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Old 9th of February 2012 (Thu)   #4
SteveInNZ
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Default Re: Focusing in the dark...

Here's the relevant Exif data from one of your HUGE images.

Camera Model: Canon EOS 600D
Focal Length: 18mm
Focus Distance: 0.59m
Aperture: f/7.1

You (the camera) focused at 0.6m (2ft). Oops. You need a better method.
Do a search for "Hyperfocal distance" and understand what it is and how it works.
For your camera, that lens and f/stop, the hyperfocal distance is about 2.6m (9ft). So if you focus on something, say twice that distance to be safe, then everything from there to (and including) infinity is in focus.
So next time, turn on your headlights and shine them on something 20ft away (or further), focus the camera and lock the focus, turn off the lights and point the camera to the sky. Click.
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Old 10th of February 2012 (Fri)   #5
archer1960
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Default Re: Focusing in the dark...

If I need to focus in the dark, I turn the manual focus ring to the stop on the infinity side, and then back it off a bit. How much a "bit" is, I've learned by trying it in the daytime.
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Old 10th of February 2012 (Fri)   #6
hollis_f
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Default Re: Focusing in the dark...

Quote:
Originally Posted by SteveInNZ View Post
Here's the relevant Exif data from one of your HUGE images.

Camera Model: Canon EOS 600D
Focal Length: 18mm
Focus Distance: 0.59m
Aperture: f/7.1

You (the camera) focused at 0.6m (2ft).
Unfortunately the 'subject distance' exif data is notoriously unreliable. This is supposed to be 0.4m

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