[argyllcms] Re: Using an i1 to measure FWA content?
- From: Martin Weberg <martin.weberg@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 9 Feb 2010 13:02:50 +0100
2010/2/9 Graeme Gill <graeme@xxxxxxxxxxxxx>:
> Martin Weberg wrote:
>
>> That's what I've been thinking. If the UV filter goes in both
>> directions, which I assume, why do we get reflectance below 400nm? No
>> UV wavelength's are emitted to the paper and no UV wavelength's
>> reaches the measurement device.
>
> Actually if you look closely at the filter, it only filters
> the light source. This make sense if you want to still measure
> reflectance below 420nm, as filtering the sensor will simply
> reduce sensitivity at those wavelengths.
Looking at the filter, what a strange idea....;-)
Thanks, all true. The UV filter is the greenish one and then something
darker in the middle for the sensor. Then, off course, we'll expect
reflectance below 400/420nm* if any.
* Graeme, you say 420nm. The standard says 10-400nm, cited on
wikipedia ;-) I guess, what we really are interested in is what
wavelength's interacts with OBA's regardless of what the UV standard
says. Maybe they begin at 420nm?
Martin Weberg
Other related posts:
