Some have said that the M240 exhibits color shifts with in-camera ISO setting changes. Before I try to track down he details of the green shadow shift under pushing, I thought I should check the unpushed shifts out.
I made a series of ETTR exposures of the Classic X-Rite Color Checker at one-stop intervals to compensate for in-camera ISO changes from ISO 200 through ISO 6400. The lighting was window light on a foggy day. I picked a constant custom color balance for the whole series. I exported from Lightroom in 16-bit ProPhoto RGB. I measured the CIEL*a*b* values of the bottom row (the grey squares) in Photoshop cc 14.1.
Here’s what I got. A little shift across the squares, which could be lighting, but no shift with ISO setting:
| Patch 19 | L* | a* | b* |
| 200 | 93 | 0 | 1 |
| 400 | 94 | 0 | 1 |
| 800 | 95 | 0 | 1 |
| 1600 | 95 | 1 | 1 |
| 3200 | 95 | 1 | 1 |
| 6400 | 95 | 1 | 1 |
| Patch 20 | L* | a* | b* |
| 200 | 89 | 0 | 1 |
| 400 | 90 | 0 | 1 |
| 800 | 91 | 1 | 1 |
| 1600 | 91 | 1 | 0 |
| 3200 | 91 | 1 | 1 |
| 6400 | 92 | 1 | 0 |
| Patch 21 | L* | a* | b* |
| 200 | 80 | 0 | 0 |
| 400 | 82 | 1 | 0 |
| 800 | 84 | 1 | 0 |
| 1600 | 84 | 1 | 0 |
| 3200 | 85 | 1 | 0 |
| 6400 | 85 | 1 | 0 |
| Patch 22 | L* | a* | b* |
| 200 | 62 | 1 | 1 |
| 400 | 64 | 1 | 1 |
| 800 | 66 | 2 | 1 |
| 1600 | 67 | 2 | 0 |
| 3200 | 67 | 2 | 0 |
| 6400 | 69 | 2 | 0 |
| Patch 23 | L* | a* | b* |
| 200 | 39 | 1 | 0 |
| 400 | 41 | 2 | -1 |
| 800 | 44 | 2 | -1 |
| 1600 | 42 | 2 | -1 |
| 3200 | 45 | 2 | -1 |
| 6400 | 47 | 2 | -1 |
| Patch 24 | L* | a* | b* |
| 200 | 22 | 3 | -3 |
| 400 | 21 | 3 | -2 |
| 800 | 20 | 4 | -2 |
| 1600 | 19 | 3 | -2 |
| 3200 | 18 | 3 | -2 |
| 6400 | 16 | 3 | -1 |
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