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Very low light focusing techniques

Discussion in 'Open Discussion' started by MingTyhMaa, Apr 17, 2013.

  1. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    I recently was out shooting landscapes 1 hour before sunrise with my G5, and like previously with my dSLR, I had focusing issues. I tried to light the subject which was several hundred feet away with a LED flashlight, but it did not reach far enough. I had trouble manually focusing b/c of the high ISO grain on the EVF. Finally, I increased the exposure compensation between +3 to +5, and after that, I noticed that it would focus fairly easily. Then I would put the focus to manual, and reduce the exposure compensation back to 0 for the shot.

    How many of you utilize this for focusing in very low light? I wonder about the focus accuracy using this. My photos seem to be sharp, but the first 20 or so are not in focus. The latter set (when the sun was coming up) are all in focus.
     
  2. kwalsh

    kwalsh Mu-43 Top Veteran

    775
    Mar 3, 2012
    Baltimore, MD
    I use one of three techniques usually:

    - Focus on the horizon. Most landscapes are focused at infinity anyway and have plenty of DoF so this works most of the time. Typically there is some part of the horizon that is bright enough to focus on. Unless you were using a very long focal length this should have worked in your situation (subject more than 100ft away).

    - Focus on a flashlight. For a subject that is walking distance away just set your flashlight on it pointed at the camera. Focus and then remove your light. Works much better than trying to light up the subject.

    - Laser pointer. For more distant subjects or inaccessible subjects that are not within hyperfocal distance you can use a laser pointer to create a point to focus on. This can be very tricky though since you are most likely going to only need to do this with telephoto. Hard to hold the pointer steady where you are focusing. I made a hot-shoe adapter to hold a laser pointer for exactly this purpose but I've only ever actually used it once. The two easier techniques above have worked in almost every other situation.
     
  3. RobWatson

    RobWatson Mu-43 Hall of Famer

    I have a million candlepower lamp that runs on 12VDC (car cig light jack) with a tight beam that lights up for 200-300 yards very nicely. Not exactly portable ...

    I like kwalsh laser pointer trick! Don't know about a hot shoe but I'd stick it on a tripod.
     
  4. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    Thanks for the tips. What about the exposure compensation thing, though? If that works reliably, that would be a panacea almost.
     
  5. RobWatson

    RobWatson Mu-43 Hall of Famer

    Have you got live mode boost enabled? If the compensation works for you then go for it!
     
  6. arch stanton

    arch stanton Mu-43 Veteran

    411
    Feb 25, 2012
    London
    Malc
    What lens and aperture? Hyperfocal distance is often relatively close with a wide lens and a small aperture.

    A 14mm lens at f8 is hyperfocal focused 6 feet away - everything from 3ft to infinity is in focus:
    Online Depth of Field Calculator

    Mind you, if it's a tele lens for a subject a few hundred metres away hyperfocal's further away, 60 feet at f8 for the 45mm...
     
  7. mattia

    mattia Mu-43 Hall of Famer

    May 3, 2012
    The Netherlands
    +1 on the hyperfocal distance thing. If necessary in combination with manual focus, as focussing on something 6 feet away is easy enough to do in manual..
     
  8. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    I'm sorry, what is live mode boost? I searched the advanced manual and it didn't pop up.
     
  9. entropicremnants

    entropicremnants Mu-43 All-Pro

    Jul 16, 2012
    John Griggs
    Okay, I have noticed that same behavior where exposure compensation changes focusing behavior and I believe that to be a bug in the G5 firmware actually.

    My thought is this: if there's enough light to focus, it should focus. It shouldn't be relying on what it's doing to provide me with a "view" of the subject to focus.

    I was doing time exposed HDR in an old coal breaker that's been idle for 50 years or so and had similar experiences in the darkest areas. It was one of the few things I do dislike about the G5 but I can get around it okay with what I'm doing.

    The E-M5 has never done this to me that I've observed so Olympus got this right or I just haven't had it happen yet, lol.
     
  10. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    I was using a G5 with Panasonic 14-140mm at about 70mm. Is there a way to do hyperfocal distance with my lenses (none of which have a distance scale) other than calculating the hyperfocal distance, and focusing on something that is the hyperfocal distance away from where I am standing, and then re-framing?
     
  11. RobWatson

    RobWatson Mu-43 Hall of Famer

    Sorry, I don't know G5 but E-P1 and E-M5 and others have such a feature. Basically does auto-contrast and auto EV bump in the live view. Comes in very handy in low light.
     
  12. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    Thanks for your comment, John. I guess like all things, if it sounds too good to be true, it probably isn't.