Do CMOS DSLRs need hot mirror/Ir reduction filters?

I

Imamacuser

Veteran
Are hot mirror filters (IR reduction) necessary for CMOS DSLRs? I have a D7000 and I read that it has an IR reduction filter in front of the sensor, is that correct? If so, do I still need a hot mirror filter if I'm shooting with NDs to further cut down IR light?

Thanks
 
As long as you aren't pointing your camera at the sun for a substantial amount of time you should be fine. Pretty much all digital cameras include these filters, at such a strength that during normal use (which can be pretty substantial work) there should be no issue. I don't know about that camera in particular.
 
The situation is about the same as any digital cinema camera - if you are using heavy ND without IR blocking filtration, you may experience the IR/visible light balance become slanted toward IR such that you can see infrared contamination in the blacks. Now what constitutes "heavy ND" might be different depending on camera, however.

The problem was exacerbated on some early digital cinema cameras with especially weak on-sensor IR filters, most notably the Red One, which benefited from IR filtration when using ND 0.9 or above. The on-sensor IR filters on DSLRs are generally better, and IR contamination doesn't usually become a problem until ND levels reach 1.5 or so - although with the ability to dial ISO down to 100 on these camera, the need for ND that strong is lessened.

As always YMMV, so when in doubt shoot tests.
 
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