Anti-Aliasing filter removal.

[Guest DaveW]

I just received Nikon's announcement of their new D7100 and noted like a few other camera makes they are now dropping the anti-aliasing filter, long an integral part of DSLR's, on their new cameras and wondered why?  Anyway I did a web search and came up with these links on the subject which are still relevant if slightly out of date regarding which models are now available:-

 

http://www.luminous-landscape.com/essays/the_naked_sensor.shtml

 

http://www.lifepixel.com/blog/anti-aliasing-low-pass-filter-removal

http://www.maxmax.com/nikon_d200hr.htm

 

 

 

Edited February 21, 2013 by DaveW

[Guest]

They have done this in another model that is now made available in versions with and without. The versions without this filter can give moiré effect that is difficult to deal with.

Edited February 21, 2013 by Bill

[Guest DaveW]

Also see:-

http://lavidaleica.com/content/anti-aliasing-filter-primer

http://photographylife.com/nikon-d800-vs-d800e#more-26630

http://www.btobey.com/nikon/nikon-d800e.php

[Black Pearl]

The D800e which doesn't have an AA filter is a very niche model and should only be bought be photographers who understand why it is/isn't there and need the images that can be produced without it.

If you use the supplied Nikon Capture NX software the moire is very easy to deal with so it is not an issue. 

 

I've used a number of high MP Blad's that don't have AA filters but their supplied software is fantastic at dealing with it - you don't hear of people moaning about it because they are only used by photographers who know what they are doing.

[Guest Lee]

Fujifilm's X-Pro 1 and XE-1 don't have the filter either; wouldn't mind either one to add to my X100.

[Black Pearl]

They don't have a conventional bayer pattern filter on their sensor though so get over the problem of moire by having an almost random colour filter:

 

Bayer:

 

 

X-Trans:

 

[Guest DaveW]

Evidently Nikon's idea of modifying the filter but leaving it in place may be patented. If you remove the filter or make it slimmer by removing the anti-aliasing part you need to alter the lens distance to the focal plane (sensor). Therefore Nikon can just modify it's current models without a lot of retooling. If this is so, for Canon to bring out a camera without an anti-aliasing filter it will have to be a totally new design with the sensor distance repositioned to the lens if they cannot come up with an idea to just modify current production cameras and retain the same lens to sensor distance.

 

A quote from one of my earlier links:-

 

"Now with the Nikon D800E model, Nikon took an interesting approach. We know that the full low-pass filter cannot be completely removed, because it would cause the focal plane to move; plus, the camera still needs to be able to reflect infrared light rays. Instead of making a single filter with one layer, Nikon decided to still use three layers, but with two layers cancelling each other out. As light rays get split into two with a vertical low-pass filter, then through the IR absorption filter, those same light rays get converged back when passing through a reversed vertical low-pass filter. Hence, instead of getting blurred details as in the first illustration, we get the full resolution.

 

I am not sure if the above method is the best way to deal with the issue, but I suspect that Nikon decided to take this route for cost reasons. It would probably be more expensive to produce a single IR absorption filter layer coated on both sides, than continue to use the same layers, but in a different configuration."

 

However expect to see all makers introducing cameras without anti-aliasing filters in the near future. It's a pity though the Foveon sensor that does not have moiré troubles, behaving more like colour film, has not had the same development as present sensors.

 

http://en.wikipedia.org/wiki/Foveon_X3_sensor