Sekonic Exposure Profile Target II Card verses others.

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,673
Sekonic apparently no longer sells their "Exposure Profile Target II" card that is used to calibrate their better meters with their (free) Data Transfer Software that loads the camera's exposure profile into their meter once you shoot the targets and load them in the software. Card (then) was expensive given retail was around $180.

Mine has gotten beaten up over time blowing around the place and onto things that scratch its surface. When I inquired to Sekonic Japan (USA distributor is mum on the card's unavailability subject.) about it no longer being sold, they responded with "Use an x-rite Colorchecker Passport in the meantime while they come out with a new profile card."

Okay. Done that. However, the Colorchecker curves generated show a decrease in the Dynamic Range verses their Profile II card by about 1/2 EV. Likely due to the Colorchecker's having less gray patches than the Profile II card which has 25 of them spaced from +/-2 EV in 1/6 EV steps. Camera was E-M1 Mark II with 12-100mm lens.

Below is the Colorchecker Passport, the full-sized Colorchecker (i.e. Macbeth) Classic card, and the Exposure Profile Target II card in that order. I placed a light green and orange overlay on the Sekonic screen for better discrimination of the data.

Colorchecker Passport:
Colorchecker-Passport.jpg
Subscribe to see EXIF info for this image (if available)


Colorchecker Classic (i.e. Large MacBeth card):
Colorchecker-Classic---MacBeth-Card.jpg
Subscribe to see EXIF info for this image (if available)


Sekonic Exposure Profile Target II:
Sekonic-Exposure-II-Cards-Curve.jpg
Subscribe to see EXIF info for this image (if available)


Aside:
On the last Sekonic Exposure Profile Target II card, the odd dips at 140 and 80 were likely due to the room the card was shot in. The overhead lights metered about 1/10 less going down each of the three rows on the last Exposure Profile Target II. Think of flash 'Guide Numbers' and light fall-off with distance. Top top-to-bottom maybe 1/5 EV and might be issues given how sensitive the card and software are with its 1/6 EV patches. The Colorchecker Passport and Colorchecker Classic (MacBeth) seem to straight-line much of the data given less patches to read with their software.
 
Last edited:

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,673
Since Sekonic has ceased selling their Exposure Profile II card until a new one comes out, I thought I'd make my own. After all, "How hard could it be to print a bunch of gray patches with a calibrated system?"

Turns out it was a major PITA and I now know why Sekoonic laminates all those patches in their cards. If one patch is off a couple of RGB points, the entire card is worthless when it hits the Data Transfer Software that reads that card and sets up their meter for proper exposure with a given camera. So print accuracy is a definite!

I took the data from Luminous Landscape and printed a card using Epson Ultra Premium Presentation Matte paper from local
a office supply store. About $18 for 50 sheets which I thought would be enough. Without a lot of explanation as to what happened, it took 5 boxes.

Final calibration print's curve was close if not better than the OEM Sekonic card. One issue I had with the Sekonic OEM card is, being laminated, it warps at about 80 degrees F and then you can get odd reflections off some gray patches that make for a jagged curve. I cut the Epson 8.5x11 inch paper to slip into an old 8x10 inch Speed Easel used in darkroom to keep it flat to avoid the odd flare from warpage of the OEM Sekonic card.

I used an x-rite Colormunki Photo (Now replaced with a new version called iStudio for ~$490.) to calibrate and generate a B&W profile. Also used it to read the printed patches with their ColorPicker app that is included in their older version of the software (and still available) for that spectrometer. I added some white alignment dots to the lower portion of the card that helped me to align the Colormunki Photo's white LED so the thing was directly over the patch I was reading.

The RGB values of the gray patches were as follows from the Luminous Landscape's forum Link: https://forum.luminous-landscape.com/index.php?topic=64362.0 ):

Top row on card:
221 +2 EV White
210
199
189
179
170
162
153
146

Middle row:
138
131
124
118 The large center 18% gray.
111
106
100

Bottom row:
95
89
85
80
76
71
67
64
60 -2 EV Dark black.

I also used a variable ND filter to fine-tune the exposure so the center gray read RGB=118 in the Olympus Workspace or Viewer software. Can't get that degree of accuracy by the 1/3 stops of shutter or lens. Important since you are photographing the card and reading the JPEG tha camera makes (Sekonic's software does not read RAW image data.) so WB and exposure have to be spot on to read later with the Colormunki Photo and subsequent adjustments made for printing.

Once you accomplish getting a nice smooth curve out of the Sekonic Data Transfer software using whatever editing software you use to make the patches the right density, you'll understand why the bloody card costs so much. Explains the five boxes that were used here too (ahem!).

My DIY card with above RGB values:
DIY-Profile-Chart.jpg
Subscribe to see EXIF info for this image (if available)



Generated curve using E-M1 Mark II and 12-100 f/4 Pro lens+Variable ND filter.):
Sekpnic-Profile-Chart-Curve-Final.jpg
Subscribe to see EXIF info for this image (if available)
 
Last edited:
Links on this page may be to our affiliates. Sales through affiliate links may benefit this site.
Mu-43 is a fan site and not associated with Olympus, Panasonic, or other manufacturers mentioned on this site.
Forum post reactions by Twemoji: https://github.com/twitter/twemoji
Forum GIFs powered by GIPHY: https://giphy.com/
Copyright © Amin Forums, LLC
Top Bottom