Christoph Polcin

Choosing A Camera Lense

Sometimes it's so hard to make a decision, even on a simple thing. Therefore I considered the metadata from old images to get an overview of my settings. The rate of focal length, exposure time and aperture values might help me to select a new lens which may fit my needs.

My Old Lens

The Candidates

Extract The Metadata

grep 'Focal length' | \
awk -F: '{print $2}' | \
sed -e 's/^\s//g' -e 's/\.0\smm.*//g' \
> focal_length.txt

exiv2 pr */*.JPG 2> /dev/null | \
grep 'Aperture' | \
grep -v 'Aperture priority' | \
awk -F: '{print $2}' | \
sed -e 's/^\sF//g' -e 's/\./,/g' \
> aperture.txt

exiv2 pr */*.JPG 2> /dev/null | \
grep 'Exposure time' | \
awk -F: '{print $2}' | \
sed -e 's/^\s//g' -e 's/\ss.*//g' \
> exposuretime.txt

Generating The Charts

  1. Import each file in Open / Li­bre­Of­fice (specify the input data type).
  2. Sort the imported column A.
  3. Apply a distinct filter on column A and write it to B.
  4. Sort B.
  5. Compute the rate to column C based on A as data and B as categories (use a function).
  6. Compute a column D with relative rates based on C (use a function).
  7. Create a chart with column D as Y-values and column B as X-values.

Grab the source ods file to compare the values

The Metadata Charts

The Results

The focal length graph shows that

The exposure graph shows that the most of the pictures was taken in low light levels

The aperture graph shows that 75% of my pictures was taken with an aperture less or equal 5.6mm. Thats closely related to the exposure graph and the low light shots.

Well, the static evaluation would leftover the 24-70mm and the 24-105mm lens. It seems to me that I need to check more reviews. Your rec­om­men­da­tions are welcome.