Anti-Aliasing Filter-less DSLRs.

Markw

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There are rumors circulating about, you've all heard them, that the D800 will come in two models; one with the AA filter removed.

Now, I don't really fully understand the implications of this. I do know, however, that there are companies out there that will remove the filter for you (click). To my understanding, the filter intentionally takes some of the detail out of the photo in order to inhibit moiré. I hear that the high-resolution 36MP sensor of the D800 will be so much so that it will get rid of the moiré risk; thereby ridding the camera for the need of a filter in the first place.

To me, it looks like this can only be a good thing. It will render your lenses much sharper than their AA-filtered counterparts, and will bring out much more detail. But, if this were the case, why would they offer a D800 model with the filter at all? There has to be some drawback I'm missing.

As you can tell, I'm a bit unknowledgeable about this concept. So, if you could help me out in understanding the implications of having, and not having the filter, I'd greatly appreciate it, since the camera will likely be announced shortly.

Thanks!
Mark
 

Overread

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A part of me is wondering if this isn't just the general sharpness addicts crowed rumour milling about the idea of losing the AA filter and getting even purer sharper images. IF they were to do two releases it would strongly suggest to me that the lack of the AA filter was leading to a detrimental effect - thus meaning that the AAfilter-less edition would be targeted at a specific segment of the market for which moire might be a lesser issue in what they shoot.
 

Helen B

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The new Fuji Pro-X1 doesn't have an AA filter, I believe. It does have an unusual filter matrix instead - it isn't regular like the Bayer filter on most cameras. It's not a DSLR, however.
 

nickzou

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The new Fuji Pro-X1 doesn't have an AA filter, I believe. It does have an unusual filter matrix instead - it isn't regular like the Bayer filter on most cameras. It's not a DSLR, however.

Yeah.... that new rangefinder looks sexy... Speaking of rangefinders, I'm pretty sure the the Leica M9 also does not have an AA filter.
 
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unpopular

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There is a rumor that the A99 and the D800 will share the same sensor, there is also a rumor that the a99 will be a 3mos configuration. I sort of really doubt that will be the case, a full frame 3mos assembly would be huge. Perhaps though Sony is producing some kind of maskless sensor that would make an AA filter obsolete and perhaps explain - perhaps disappointingly - the somewhat outlandish 36mp figure.

I very much doubt there will be two versions. Two versions means two production paths. Manufacturing at this scale isn't as easy as "leaving some out".
 

KmH

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So far that has only happened in Nikon's Dx series cameras. It has never happened in the Dxxx series.

The D3s was just an interim update to the D3, while the D3x was developed specifically for the studio shooter.

But, everything online about the D800(?) is still just speculation at this point.
 

Patrice

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The new Fuji Pro-X1 .........

Yeah.... that new rangefinder looks sexy... Speaking of rangefinders, I'm pretty sure the the Leica M9 also does not have an AA filter.


The Fuji Pro-1, although it has a certain body shape that is similar to a rangefinder cameras, it is not a rangefinder. 'Rangefinder' refers to a type of manual focusing system.
 

unpopular

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The new Fuji Pro-X1 .........Yeah.... that new rangefinder looks sexy... Speaking of rangefinders, I'm pretty sure the the Leica M9 also does not have an AA filter.
The Fuji Pro-1, although it has a certain body shape that is similar to a rangefinder cameras, it is not a rangefinder. 'Rangefinder' refers to a type of manual focusing system.
How will it focus then? I always thought it would be an electronic rangefinder, like the Contax G2? Will it just be contrast detect or use phase detect similar to the F300 EXR?
 

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I will never understand how people seem to believe the megapixel count is a easy singular dictator for image resolution and sharpness... If the lens can't resolve the proper level of detail for a 80MP sensor then you're going to have a 2MP image. You cannot just upgrade the MP count and suddenly moire is gone.
 

unpopular

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I will never understand how people seem to believe the megapixel count is a easy singular dictator for image resolution and sharpness... If the lens can't resolve the proper level of detail for a 80MP sensor then you're going to have a 2MP image. You cannot just upgrade the MP count and suddenly moire is gone.
2mp? Are you using a potato? I'll have to think about the moire issue...
 

Garbz

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There's a couple of things anti-aliasing does for cameras, and believe me they are positive, not negative, or do you think Nikon / Canon intentionally cripple their cameras?

Firstly there's the Moire effect that comes from recording a repeating pattern with a grid of pixels. A minor reduction in sharpness is greatly preferred to a photo which ultimately looks like this which is one of the two things the AA filter tries to avoid:
moire-pattern-300x225.jpg


The effect of the AA filter not only solves the horrendous edges on patterns, but it also helps details which are too small to render as a pixel on an image contribute to the final image. Yes the result is not "sharp" but at least it doesn't look weird either. This is best illustrated with a computer game as per this GIF: http://h9.abload.de/img/antialiasing0qbuf.gif . Now take a look at the TV antenna on the left building. Would you rather a slightly less sharp TV antenna or an antenna that is so sharp that parts of it aren't actually visible and other bits appear out of nowhere?

Thirdly the AA filter addresses an issue of how we grade the megapixels of a camera. Most sensors have a beyer pattern which is interpolated to give us a final image. That means our 12 mpxl cameras doesn't have 12 million RGB pixels, they actually have 6million green, 3million red, and 3million blue pixels. The software interpolation then makes this a 12mpxl image. The AA filter is designed in a way to ensure that if any signal light point is small enough to hit a signal pixel it is diffracted across any group of 4. This is where the supposed problems with sharpness come in. The reality is that while removing the AA filter does increase the sharpness, any detail you gain runs the risk of not being recorded across 2 green, one red, and one blue pixel and thus results in incorrect colour. A good example of an AA filter that isn't well matched to the camera is the Canon 5DmkII which produces rainbow patterns on greyscale images when aliasing occurs:
alias.jpg



So rumours.... yes rumours is likely all they will be. Unless Nikon has some crazy sensor design that isn't laid out in a grid, or just wants to piss quality against the wall, sure. The problem is that aliasing is always a problem. As the sensor resolution increases it just means the new finer detail will start to suffer aliasing effects. I hope this isn't an acknowledgement from Nikon that they don't have a lens sharp enough to resolve their new sensor because while that would allow the camera to work without an AA filter it would also be incredibly funny. :D
 

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I believe that it is very likely though that the masked sensors are not the way of the future. They are so tremendously problematic and truly represent the majority of problems we're seeing in DSLRs today.

Eventually I think there will be a drive away from this antiquated technology. I don't know if it will be the with the d800 generation or not, but eventually it's just going to have to happen one way or another.
 
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Markw

Markw

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That was a wonderful description Garbz, thank you for that! But, is there no chance since there will be 36MP jammed into the sensor, that the light will diffract the light enough to hit the correct color pixels, and the aliasing won't be a problem? I'm not 100% certain how this would affect the moiré issue, but for aliasing, this seems like it would fix most of the problem, if I understand the problem correctly in the first place.

My only disgruntle is that I can't believe Nikon would produce a camera to the caliber of their Dxxx line, and hinder the ability of it to do what it is supposed to do, take proper photos. I think if we all know it would be a waste of R&D funds, and production funds, then charge an extra $900 for the camera without the filter, and it still had such serious problems as aliasing, they know it, and they wouldn't make it if that were the case...

Mark
 

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