Re: Digital IR Testing

["Lee Tarpley" <tarpley@xxxxxxxxxxxxxx>]

>--- Gavin O'connor <ogavin@xxxxxxxxxxx> wrote:
> I have looked around on the internet and in many magazines but have failed
> to find digital IR tests, so i've had to come up with my own.  The
responce
> of any camera, digital or Axg, will depend on many factors the main ones
of
> which are, the light source used, the medium used to capture the photons
and
> the materail that the light source passes through to get to the capturing
> device.  All of the cameras that i've test bar one, have all had
integrated
> lenses, so my results, when completed, will show the ir responce of the
> camera system as oppose to the capturing device or the lens.  As IR values
> change outside on a regular basis, i decided i needed to control the light
> source and am using two tungsten lamps.  I do know that the lamps emit ir
> but unsure as to what amount, so later this week i am going to measure the
> spectral output of the lamps.  I now know the light source and by putting
a
> filter over the camera i can tell, from transmittance tables, what
frequancy
> of light is being transmitted throught lenses.  I then used two test
targets
> a grey scale and a colour chart.
----------
These targets differ visibly but how about in the 700-1000 nm NIR range that
you are interested in? Are there other materials that will provide known
wide variation in this NIR range? There are several members of this list who
might know of such materials. Art restorationists, geologists? Would a thick
layer of quartz sand be nearly "white" in the NIR?
Lee Tarpley
---------
> I have just finished recording these
> results and am looking at them as i type.  I am going to put the results
> into photoshop and measure the pixel values.  The varying degree of pixel
> value will tell me how well the camera is a detecting IR.


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