Sekonic L-858D underexposes by 1EV. Is that normal?

Discussion in 'Lighting Equipment' started by pavelkupcik, Jan 16, 2021.

  1. Hi,

    I have Sekonic L-858D-U that seems to be underexposing by 1EV and I'm trying to figure out if that's normal or if I should send it for repair. I've had it for a while, but never really used it much. Recently I decided to compare it to light meters in my cameras and to Hasselblad PME45 meter. All the various meters I tried are very consistent, within just 1/3 stop of difference at most. But the Sekonic is full stop underexposing both in incident and reflective metering.

    Here's the equipment I compared it with:

    Canon 5D IV - Spot Metering
    Canon EOS 1V - Spot Metering
    Hasselblad PME45 - Spot Metering and Incident metering
    iPhone 11 Light meter camera app for reflective metering

    Test 1:
    I took 18% gray card, placed it in various lighting conditions - indoor, outdoor, direct light, indirect light, low light, strong light, etc. I then used the various cameras/light meters and made sure sufficient amount of view is covered by the meter and measured. Sekonic was consistently 1EV underexposed. Both in incident and reflective spot metering.
    I tested at ISO 100, 400, 3200.

    Test 2:
    I repeated test 1 procedure, but instead of gray card metered of off solid surfaces: walls, sky, floor, etc. Same results as Test 1.
    I tested at ISO 400.

    Test 3:
    I setup flash lights, set camera on tripod at 1/200s shutter, ISO 100, manual flash, took incident flash reading with the Sekonic, adjusted camera aperture, took a shot of 18% gray card, measured brightness in photoshop, which showed under exposed as I was expecting RGB of 127 and it was below it. I then added +1EV compensation on my light meter, metered the flash again, adjusted light output until meter showed the same aperture as on the first meter reading. Then again took shot of gray card, loaded to photoshop, cropped in the gray card and reading was 128, which is what I expected. I then repeated the same procedure with ColorChecker Passport and measured the 18% patch (4th patch from bottom left) and got perfect result. This concluded my testing.
    I tested at ISO 100.

    I have then modified the HW calibration in the meter to add +1EV. Now the question is, is this normal or should I send the meter for repairs/factory calibration? On hand I'm thinking it's no big deal, I was able to dial in the correction. On the other hand the manual states that the maximum amount of HW adjustment is +-1EV in 0.1EV steps, which means if I ever needed to adjust it further than 1EV I won't be able to at a HW/system level. I would then have to use other means like manually dialing in exposure compensation when I meter.

    Oh, and I did check to make sure there wasn't any custom Sekonic profile or EV, filter adjustments loaded in the Sekonic meter that would modify exposure readings.


    Thank you.
    Last edited: Jan 16, 2021
  2. In the hardware settings there is a user calibration function as well as reset to factory default function. Check them out otherwise it would need to be sent to Sekonic for calibration.
  3. Yeah, that’s where I checked, and then entered my calibration adjustments. I even reset to factory settings before that just in case. Thank you for the advice.
  4. But the meter should be correct with the calibration set at 0. If I were you I would send it in for calibration. It's a new meter and should be correct without any user correction settings.
  5. Check there's not a lump of crud under the lumisphere, or something similarly simple before sending it off for calibration.

    Also, I believe there's a switch that detects when the lumisphere is replaced with a reflective baffle. Try removing and re-fitting the lumisphere to work that switch a few times. It might have got stuck or dirty.

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