On 2012-05-31 20:43, Alberto Tirado wrote:
Send your XT to LifePixel (www.lifepixel.com). They'll swap out your
senser filter with an R87, or other specialty IR filter they sell.
You'll then be able to shoot 1/400 @f8 AND look through your viewfinder.
This has me thinking !
If an r87 filter has a compensation of, say, 8 or 16 steps, how come you can convert your camera, in which they place an r87 filter on the sensor, and then go about happy-shooting?
My "reasoning" is that an r87 has a certain density, no matter if it is in front of the lens or behind it.
So how can you shoot at higher speeds with a camera conversion, but not with a filter?
Normally, the camera body has an infrared-blocking filter in it, because
the sensor is sensitive to infrared and the color filters (Bayer filter)
don't block it; so infrared would mess up the colors if allowed through.
When you use an R87 in *front* of the lens, it's fighting with the
"hot mirror" inside the camera body.
Then, when you try to do infrared with a visible-blocking
(infrared-passing) filter in front of the lens, it has to block enough
of the visible light so the infrared that gets through the
infrared-blocker in the camera will provide most of the data to the
sensor.
When a camera is converted for IR, they remove that internal IR blocker.
For physical and I think optical reasons, they have to replace it with
*something*. In fact, most of them (Lifepixel certainly) give you a
choice of what they replace it with -- anything from UV-transmitting
glass to a visible-blocking IR-passing filter.
--
David Dyer-Bennet, dd-b@xxxxxxxx; http://dd-b.net/
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Dragaera: http://dragaera.info
