How to Calibrate Sekonic L-358 Light Meter
In a perfect world, all digital sensors, lenses, shutters and light meters would be precisely on the”same page”, and light metering would be an exact science. Unfortunately, the performance of any of these devices cannot be assumed, plus light meters are set to slightly different calibration constants from their respective manufacturers.
There is also the human factor; everyone will have their own opinion on “correct” exposure based on their eyesight. Since the perception of light and colour varies from person to person, exposure judgment will also vary.
I’m Going To Explain How to Calibrate Sekonic L-358 Light Meter
Sekonic provides the following steps, so you may need to check with the manufacturer of your specific device.
- Choose a subject that contains highlights, shadows and mid-tones.
- Position the meter so it faces the camera from the subject’s position. Mount it on a light stand or tripod, so it remains in a fixed location.
- Set the camera to its highest possible synch speed so any ambient light will not affect the meter’s reading. (Sekonic meters will” “see” any ambient light that is present and able to affect exposure-even in flash mode).
- Test-fire and adjust your lights, so the meter displays an even-numbered aperture (no tenths)
- Take your first test image by setting the camera to agree with what the meter shows.
- Take additional test images by adjusting your camera’s aperture over and under using the smallest aperture possible (usually 1/3 or ? stops). Do not move or adjust the lights.
- With a digital camera, you can evaluate the exposures immediately. If you are lucky, th” “perfect” exposure will be the one that exactly matches the meter. You will need no adjustment. If you feel that an over or under adjustment is required, use the meter’s calibration* or compensation function (see below for the L358) to make your changes. Shoot another test with the adjusted meter.
- With a film camera, shoot transparencies, and make sure that when the roll is processed, it is not cut and mounted. (It is easier to view a strip of film than it is a box of slides) Evaluate the images on a lightbox, and adjust the meter if necessary. A second roll will confirm your adjustments.
It is advisable to perform this test every six months. Repeat this test if you are going to use a different camera. You may also check the ambient mode the same way with a constant light source. (Modeling lights work well).
If you wish to match the incident readings to a particular grey card, mount the meter in a fixed location and take your readings, taking care not to permit any stray light through the back of the meter.
Shoot some test images and evaluate them as before.
*To enter the calibration setting, first turn off your Sekonic L 358.
Press the power button on while holding down the ISO 1 and IS0 2 buttons simultaneously; the screen will display CAL 0.0 (for calibration).
You can change the calibration setting by rotating the jog wheel while pressing and holding down the ISO 1 and IS0 2 buttons simultaneously.
A range of +/- 1.0 EV in 1/10 stop increments is possible for calibration. The calibration setting is not displayed on the main screen once.