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I have an Olympus OMD EM5 and a Leica 25mm which takes wonderful pictures in daylight.

I was trying to take night pictures with this setup and I had the following results (after several tries and double-checking)

f/1.4, 1.3s extremely blurry f/1.4, 1.3s

f/2, 3.2s sharp f/2, 3.2s

f/3.2, 8s sharper f/3.2, 8s

I don't understand why this would happen. Is there any phenomenon responsible for that?

Thanks!

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  • \$\begingroup\$ Can you post an example? The stopped-down aperture will have slightly greater depth of field (more sharpness) and the lens may in fact exhibit greater sharpness oeverall as you stop down, but it seems unlikely that one stop will make an extreme difference. So examples would really help. \$\endgroup\$
    – mattdm
    Apr 20, 2014 at 4:23
  • \$\begingroup\$ @mattdm I added examples, zoomed on a detail. \$\endgroup\$
    – Kamchatka
    Apr 20, 2014 at 5:04
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    \$\begingroup\$ The first clearly is not in focus. How much of a crop is this? \$\endgroup\$
    – mattdm
    Apr 20, 2014 at 5:06
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    \$\begingroup\$ 1/9th of the photo. The thing is, it looked like I couldn't get anything in focus at f1.4. Could it be because I was focusing beyond infinity? (related to my other question: photo.stackexchange.com/questions/49667/…) \$\endgroup\$
    – Kamchatka
    Apr 20, 2014 at 5:17
  • \$\begingroup\$ So I went for a walk and took more pictures. I think you are right and it was because it's out of focus. For some reason I was successful in making the focus for the two other photos. \$\endgroup\$
    – Kamchatka
    Apr 20, 2014 at 6:15

1 Answer 1

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Olympus OMD EM5 is a mirrorless camera, hence no PDAF. So you would have very small chances (read: almost impossible) to use CDAF to a correct (spot-on) automatic focus at night.

Most probably you are at some distance from your subject, thing which makes the depth of field to grow a lot at closer apertures.

Hence, most probably, you got the photos at closed apertures "sharp" just because it happened to have your subject in the much greater depth of field given by the closed aperture.

The solution is, if you really want to use a small aperture (eg. to isolate your subject), to use Live View, zoom in (if your camera has a "Zoom in" feature in Live View), and do Manual Focus on your subject.

Manual focus is the by far the most precise focusing method, even in daylight, but you need to have your camera and your subject to stand still during focusing.

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  • \$\begingroup\$ What about pitch dark night? In that case, the Magnify feature doesn't help because the Live View is black. \$\endgroup\$
    – Kamchatka
    Apr 20, 2014 at 16:02
  • \$\begingroup\$ In low light, you should have your camera on a tripod. I am not familiar with this particular lens but to focus in pitch dark you normally focus to the infinity mark (to shoot stars for example) which should be on or near the focus ring or you bring a flashlight and and focus onto an illuminated area then turn the light off and take the shot. In the dark a solid tripod is a must. There are different techniques for different situations but night photography is challenging but fun and results can be rewarding. \$\endgroup\$
    – Jakub Sisak GeoGraphics
    Apr 21, 2014 at 3:15
  • \$\begingroup\$ @Kamchatka: Usually (at least on Canon, but I think that on other cameras as well) you can move the zoomed part from your Live View, in order to find that part (or an edge of it) brighter/darker than the background which you want to have it in focus. Because you must have something which is different from background (dark or not) which is (usually) the subject of your photos. Otherwise you can just shoot with the lens cap on. :) \$\endgroup\$
    – John Thomas
    Apr 21, 2014 at 9:53
  • \$\begingroup\$ @JohnThomas the problem is that the LiveView will be dark because the actual photo requires a long exposure. You could be in a pitch dark night and see nothing with your own eyes but if you let the camera shutter open for 2 minutes you will see the landscape. \$\endgroup\$
    – Kamchatka
    Apr 21, 2014 at 15:27

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