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Finally - a Possible use for "High" ISO *** with the Foveon!

Started Oct 22, 2020 | Discussions thread
xpatUSA
OP xpatUSA Forum Pro • Posts: 23,016
Re: Finally - a Possible use for "High" ISO *** with the Foveon!

Johan Borg wrote:

What you want to avoid isn't just overexposing the sensor, but [clamping] the data in the resulting RAW file. Since the SD15 has a variable Analog Front End, the camera is likely to compensate for the change of ISO and the end result may not be very different.

I agree, Johan.

The Programmable Gain Amplifier within the SD15's Analog Front End chips does indeed compensate for the change of ISO by causing constant ADC outputs for a given scene (assuming zero EC), unlike earlier SD cameras.

Thus, particularly when shooting IR, it is important to have an adequate downward adjustment of EC available.

EDIT: Hypothetically speaking, have sold my SD15 and can't test...

Cloudy and wet forecast today ... maybe tomorrow ...

I also feel another test coming on ... I have a radiometric meter (W/m2, not lux) and a heat-lamp. It would be a simple matter to interpose my Marumi 700nm and see the difference. Of course, the spectral radiance of a heat-lamp bears little resemblance to that of a green leaf in full sunlight - maybe I should measure that instead ...

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