Depth of Field at f/1.8 and 35mm

On my walk the other day in the bright sun I was trying something different.  I wanted to see how my 35mm Sony lens did on the NEX-6 at an aperture of f/1.8 in bright sun.  I wanted to deliberately move as much of the image (other than what I focused on) out of focus.  The NEX-6 handled it very well since it had a 1/4000 max. shutter speed.  I only had exposure problems (without using a neutral density filter) in a couple of pictures but I was able to shift the exposure in LR4.  The above pictures aren’t especially notable but they represent examples of my focusing at different ranges so I could observe the degree of non-focus both in front and behind the focus point.  Some people like this effect, others don’t.  I only plan to use it under certain situations.

My only real problem was that I couldn’t see the LCD well enough in the bright sun to determine the effect while I was taking the pictures.  I now need to go back and try some more specific types of images.  It is all part of my desire to get better in selecting the appropriate aperture for different subjects in different lighting situations.  It is also part of my desire to use faster prime lenses more often since they give me more latitude along these lines.

For those of you who would like to calculate the depth of field (DoF) … the in-focus range … for your camera, lens, aperture, and subject distance, you can use this on-line calculator.  Click here.  You will learn that it is a very narrow range when the subject is close.  That is one reason that you really need to use a tripod if the subject is close and the aperture is large in order to get the focus correct.  Since I don’t use a tripod when out shooting, I have to be very careful to hold the camera still.  I really have a problem when I’m trying to use a narrow depth of field when taking pictures of flowers if they are blowing in the wind.  Since we have a lot of wind here, I often miss.

I have three events coming up starting tonight where I will be taking pictures and DoF is just one of my many problems that I will have since the subjects will be in motion and I will be using wide open apertures due to poor lighting.  Since I will be traveling and working with lots of pictures it is also why you might not see too many posts for a while.

2 comments

  1. John from Boston

    I was looking at that DOF calculator just last night. I’m trying to sort out some issues using my Pentax FA 50mm 1.7 on my K-30. When I get it right, it produces wonderfully sharp images. Unfortunately, I’m also getting some unexpectedly soft shots. Mostly, I think my problem was that I was drifting closer than the minimum focus distance (even though the K-30 gave me focus confirmation). One odd thing I noticed in my testing is that AF was dead-on at f2 but it started to back-focus when I got to f4. In any case, the calculator tells me I’ve got less than a 1cm of DOF at f2 at 45cm; I may have been locking focus and then drifting out of the 1cm. (I’ve linked one of my shots that worked.)

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  2. Dee

    I do agree with you about the sun interference, often I take the pic and have to wait to see what I took exactly, sometimes is interesting, sometimes brings a chuckle.

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