Questions about Infrared.

<p>Hello Im interested in buying this camera with the 590nm filter. I just have a couple questions.<br /><br />I have the impression that 590 lets the most infrared light in so I could add a filter that would limit it to lets say only the 720 spectrum. Do I have this the wrong way around? If not what filters could I use to make this camera see the normal visible spectrum? I read and saw videos of people using an IR-UV cut filter to bring it back to normal. This in my head seems to make sense because your basically adding the filter that was removed in front of the sensor back in front of it.<br /><br />I can only go from a 590 look to a 720 look using filters but not the other way around correct?<br /><br /><br />Setting the white balance in the camera doesn't matter unless I shoot jpeg and / or I want to get a better idea of what the image will look like correct?<br /><br />Thanks! I have so many questions but there aren't any clear resources online. Id love any input and hardware I should buy. Im planning on getting a Sony A3000 modified.</p>

<p>From my limited understanding filters for IR photography are low pass means anything lower than the stated wavelength passes them and yes indeed a 720 filter on a 590 camera creates the desired 720 look.<br>

To make a camera see visible light you could use the IR & UV blocking filters from the Leica M8 realm with an IR filter in place they will lead to rather eternal & tripod demanding exposure times.+ maybe some color shiftings. - You could also get your camera modified to <em>no</em> internal filter and always use something in front of the lens. <- Cost factor, image tweaking challenge and potential AF issues. In case of a DSLR also need for external OVFs. <br>

I haven't understood which kind of AF needs recalibration for an IR mod. - Obviously phase detection in SLRs & SLTs - but how about contrast AF?</p>

<p>Filters are generally classified as high/low pass in terms of frequency, which is inverse to wavelength. The result is that a low pass 720nm filter passes IR (wavelengths greater than 720nm). </p>

<p>Silicon gap is about 1.1eV, or about 1100nm in wavelength, so a silicon sensor naturally works down to about 1100nm. As many materials have high IR reflectance, and both sunlight and incandescent lamps have a lot of IR, it is necessary to block it to get the right coloring.</p>

<p>Visible block, IR pass filters are readily available, as those are used for IR film photography. </p>

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<p> If not what filters could I use to make this camera see the normal visible spectrum?</p>

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<p>None, if you have a camera which was converted for 590nm and above, then this means that the Original "Hot Mirror( the filter that stops IR and UV) was removed from the camera. Aftewr that a new filter ws builth in front of the sensor which stops all UV and visible light up to 590 nm ( so where the red spectrum starts) this allows most of the red spectrum and near infrared ( 720nm - 1100nm) to pass through. Above 1100nm a normal camera sensor will not register.<br>

If the camera would have been converted for "full spectrum" (so no uv-IR filter what so ever ( clear glass filter) then it would be possible to ad an external "Hot Mirror"to stop everything outside of the visible spectrum and it would act as a "normal camera" but this is not the case with a camera converted to see 590nm and above.</p>