# 5D Mark IV Diffraction Correction



## szinski (Sep 8, 2016)

I was watching Canon's detailed overview of the new 5D Mark IV and was intrigued by one feature mentioned.

That feature is "Diffraction Correction" which he said enhances the sharpness by cancelling the effects of the low-pass (anti-aliasing) filter.

The video can be found here:

https://www.youtube.com/watch?v=PYhBjb-01KQ

Skip to the 2:45 mark to hear him talk about it.


----------



## szinski (Sep 8, 2016)

I found this in the owner's manual (pg. 212):



> With "Diffraction Correction", degraded resolution due to the low-pass filter, etc., is corrected in addition to diffraction.



So a menu option to disable the effects of the AA filter?


----------



## neuroanatomist (Sep 8, 2016)

The AA filter adds blur. The 'cure' for blur is sharpening. Since the amount of blur is fixed (for a given AA filter design, based on the thickness of the lithium niobate crystal sheets), the amount of sharpening needed to 'cancel' it is also fixed. 

Likewise, the amount of diffraction can be determined by the aperture setting (and pixel size), and that can be corrected with appropriate sharpening for the selected aperture. 

In other words, 'diffraction correction' and 'AA filter cancellation', in this context, sound like marketingspeak for applying an appropriate amount of sharpening. Some RAW converters with camera-specific modules (LR, DxO) do this as well.


----------



## hji1945 (Sep 8, 2016)

szinski said:


> I found this in the owner's manual (pg. 212):
> 
> 
> 
> ...



Will this work with a RAW file or only with JPEG?


----------



## rs (Sep 8, 2016)

hji1945 said:


> szinski said:
> 
> 
> > I found this in the owner's manual (pg. 212):
> ...



Try DPP for converting CR2 files. With lesser cameras, Digital Lens Optimiser is there to claw back what's lost due to diffraction etc. It does a good job, but like any sharpening, it does it at the expense of noise.


----------

