Klaus Karcher wrote:
Do you really need to go below 740 nm ?Measurements in this region are a way to indirectly learn something about the IR sensitivity and -filtering of scanners or cameras.The example <http://digitalproof.info/argyll/eye-one_IR_calibration/sensor_example.pdf> (unfiltered scanner sensor) might point out that an ill-suited IR filter can have disastrous consequences.
Hmm. I see what you mean, but I'm not sure the i1pro is the right instrument. To really see what's happening, something that goes down to 1000nm would be better.
But as I have to measure a vast number of samples in the near future, I want to make sure to get the best possible results. I'm thinking about buying a Barbieri LFP for that purpose. It would save plenty of work and has a broader spectral range (380 ... 780nm) -- but unfortunately it's not exactly cheap.
None of the more flexible instrument are. To measure down to 1000m or into the UV needs something like an Ocean Optics module, which start around US$5000.
Just one (maybe silly) idea: Might USB power issues have an influence on the IR problem? I'm asking because I noticed that my eye-one works only on the right USB port of my MacBook Pro (even though both ports are specified to provide 500 mA). When I plug it to the left port, it is accessible, but calibration fails with both the Argyll and Xrite driver. Argyll reports "Calibration failed with 'Measurement misread' (White reference reading error)", MesureTool returns "Error 20310".
I'd like to think it wouldn't make any difference, but there are reports of problems like this, and I've even had it happen to me that one instrument repeatedly failed to calibrate on one port, but did so eventually after changing leads and several re-pluggings (probably a bad connector contact.) Whether this has a direct bearing on the IR response I have no idea. Graeme.