90D and Infrared Photography

[BobSapey]

The 90D has an RGB+IR sensor and I have read on e-con systems that this means a camera can do away with the IR filter and instead this,

• Provides a dedicated IR channel to separate the visible and IR image data cleanly. This improves the quality of the RGB output by helping to measure the amount of IR light in the RGB component of the image accurately and do proper color correction.

So I'm wondering how this affects IR photography (without conversion) with the 90D. Does the lack of an IR filter and presence of IR pixels on the sensor make it better, or will the reliance on software to improve the RGB make it harder to get an IR photo?

I have tried it with a 720nm filter and I'm getting some pleasing results, though with more green retained than tends to be the case in IR tutorials.

[El Sid]

Do you have an example of what you get with the 720nm? My 80D also has an RGB+IR exposure sensor, albeit with far fewer pixels, and I wonder if that would be similar.

The main problem with using an IR filter on unconverted cameras is the huge increase in exposure time that results from the IR cut filter on the sensor and I don't see how this is going to be any less of an issue on the 90D. Think I'll stick with my converted bodies...

[BobSapey]

I've posted a few on Flickr - www.flickr.com/photos/Bob_Sapey

I appreciate a converted body would be much better, but I am puzzled by how an RGB+IR sensor affects IR photography. One thing I notice in comparison to tutorials I've viewed is that my images contain more green. As it is the green masks that have been replaced with IR, I wonder if IR light is normally treated as green by the camera's processor?

[El Sid]

Interesting examples. I'm actually quite surprised that you can get exposure times of 20-25 seconds at ISO100 - IIRC my 20D & 40D bodies needed to be set to at least ISO400 to get that sort of an exposure time. I wonder if the IR capability of the metering sensor has allowed Canon to use a less intense IR cut filter over the main sensor?

On my 20 & 40D bodies the picture normally comes out with a reddish cast - the same is also true of my converted bodies if I set the picture style to a colour setting. In the 90D it's possible the IR value measured by the metering sensor are interpreted as red and the processing is then offset towards green in an attempt to compensate... In a normal colour image this would be enough to offset the effect of any IR that gets through the cut filter thus ensuring that the colours especially greys and blacks, is reasonably neutral. I have an old Nikon D50 which has a fairly weak IR cut filter and in any kind of bright light blacks and greys have a reddish undertone caused by the IR boosting the readings from the red pixels.

I'll have to dig out my IR filter and try it on the 80D to see if I get the same effect.