Issues measuring near-blacks

[grahamh]

Hi Florian, thanks for a great product! Can you help me here though.

My Spyder5 takes ages to measure near-blacks and often gives up.  Typical log

2020-10-26 10:53:33,471 Patch 31 of 32 DE 1.865059, W.DE 20.517397, Repeat
2020-10-26 10:54:57,309 Patch 31 of 32 DE 1.879701, W.DE 18.477936, Repeat
2020-10-26 10:55:16,882 Patch 31 of 32 DE 3.799114, W.DE 547.995316, Repeat (got worse)
2020-10-26 10:55:36,372 Patch 31 of 32 DE 0.434353, W.DE 255.118894, Repeat (got worse)
2020-10-26 10:55:55,868 Patch 31 of 32 DE 0.389905, W.DE 244.749647, Repeat (got worse)
2020-10-26 10:56:21,107 Patch 31 of 32 DE 0.770783, W.DE 346.452526, Repeat (got worse)
2020-10-26 10:56:40,529 Patch 31 of 32 DE 0.796763, W.DE 347.663960, Repeat (got worse)
2020-10-26 10:56:59,910 Patch 31 of 32 DE 0.788681, W.DE 346.785574, Repeat (got worse)
2020-10-26 10:57:19,293 Patch 31 of 32 DE 0.786840, W.DE 347.320377, Repeat (got worse)
2020-10-26 10:57:38,674 Patch 31 of 32 DE 0.774074, W.DE 345.472176, Repeat (got worse)
2020-10-26 10:57:58,124 Patch 31 of 32 DE 0.772247, W.DE 343.554907, Repeat (got worse)
2020-10-26 10:58:17,516 Patch 31 of 32 DE 1.879701, W.DE 18.477936, Fail ( > 0.848528)

What exactly is W.DE? The values seem over the moon. The resulting calibration curves vary but mostly don’t look very convincing (see attached).

Is there any workaround (averaging the last 10 readings, perhaps) or do I have to buy a SpyderX?

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SpyderX Pro on Amazon  
Disclosure: As an Amazon Associate I earn from qualifying purchases.

[grahamh]

Update: I found that some settings I made in the service menu of my TV yesterday had mysteriously changed, which may explain the calibration curves.  Re-running it now.

But I would still like to know if I can trust these curves given the Spyder’s issues with near-blacks.

[grahamh]

OK, the new calibration looks better, now.

Supplementary question: What makes DisplayCal report the Luminance as 95 cd/m2 when before calibration (in the adjust WP dialog) it is 147 cd/m2?  I’m using white-point ‘as measured’.

The profiler seems to have decided to make a tone response curve that is BT 709 only up to that reduced luminance.  Why would it do that?

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