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DSLR without low-pass filter


manh_le

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Thank you all for your responses.

 

Quite a few years ago, I've read about the low-pass filter being on the light path and its contribution to the degradation

of the image quality. It's been a while until I come across the one line mentioning the lack of such filter in the Sigma

DP2.

 

I don't want to start yet another film versus digital debate here, but film is the only reference I know until last year.

With

film I can tell the image quality differences between various brand names as well as film types. With digital it looks

like most pictures are very much the same, according to my view anyway. So, I wonder if this low-pass filter has

anything to do with this image quality. For example, the sensors from D3/D700/D300/D90 produce pictures with

similar image quality; so as those from D2/D200/D80/D60/D40. By similar image quality I mean unmanipulated

pictures. Apart from the sensors and processors differences, I

wonder if lacking the low-pass filter would produce a better picture?

 

By means of better picture, refer to the following quote from the Sigma DP2 : "Since the moiré is not generated, use

of a low-pass filter is not needed because full information of light and color can be captured with three-dimensional

feeling."

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Just guessing on this, but an AA/blur/low pass filter would spread a point of light across three differently colored pixels of the R/G/B/G bayer pattern on the sensor and thus might help with color fidelity. The Sigma uses the Foveon three layer chip so this issue doesn't come into play.

 

The AA filter also minimizes the effect of dust, especially at larger f-stops.

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maybe the link in my last answer was a bit unobtrusive. It's hidden behind the word 'this'. Here are some examples of a modified D200 <a href="http://www.maxmax.com/nikon_d200hr.htm" >Link to AA modified D200</a>, but I think, there will be more moiré than whithout modification. The comparison of the pictures of car interior is really impressive. But I've no experiences with this modification. Just found it and it looks really interesting.
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When evaluating a M8 vs Nikon D200, the M8 images (same time, same place) were much sharper and developed halos at much lower sharpening levels. Putting a Leica lens on the Nikon improves contrast and shadow detail a little, but nowhere to the level of M8. At appropiate sharpening levels, I could see little difference in the images after post processing was complete. Consequently I have film Leicas and digital Nikons, D200 and D40. I am tired of carrying two systems.
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I thought you were asking about any future Nikon that would lack the AA filter. We don't know, only Nikon does. All current Nikons have an AA filter but other posters have linked to services that will remove it for increased sharpness.

 

Sigma explains the reason for the AA filter. Moire. Just google moire patterns and you can learn all about it. From what I know it only occurs in tightly repeating patterns like fabric and if you photograph a screen door. I do neither so maybe I should have the AA filter removed...

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I'm aware of the Moire pattern and the anti aliasing filter which is also called low pass filter. Without getting into the

actual physics, the low pass filter is used to remove the aliased (or jagged diagonal edge). This in effect makes the

image looked blurred and so the image needs the sharpened filter. Removing the low pass filter means the sharpened

filter is no longer required.

 

A side effect to having the sharpened filter is that the lens need not be of high quality. The image is sharpened

anyway !

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