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#1
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AA filter vs. OLPF filter
I'm confused by something. Many new cameras today advertise no
anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? |
#2
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AA filter vs. OLPF filter
Brianm wrote:
I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? Every AA filter is necessarily an OLPF. Not every OLPF works in the range needed to be effective as an AA. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#3
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AA filter vs. OLPF filter
In article , Brianm
wrote: I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? two names for the same thing. note that the d800 had an anti-alias filter for one direction and what nikon called an un-alias filter so that the optical path was the same, letting nikon produce the d800 and d800e without major differences. |
#4
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AA filter vs. OLPF filter
In article , nospam
wrote: I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? two names for the same thing. note that the d800 had an anti-alias filter for one direction and what nikon called an un-alias filter so that the optical path was the same, letting nikon produce the d800 and d800e without major differences. make that the d800e with the un-alias filter. the d800 had an anti-alias filter for both directions. |
#5
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AA filter vs. OLPF filter
nospam wrote:
In article , nospam wrote: I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? two names for the same thing. note that the d800 had an anti-alias filter for one direction and what nikon called an un-alias filter so that the optical path was the same, letting nikon produce the d800 and d800e without major differences. make that the d800e with the un-alias filter. the d800 had an anti-alias filter for both directions. "Un-alias" filter? -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#6
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AA filter vs. OLPF filter
In article , Floyd L. Davidson
wrote: I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? two names for the same thing. note that the d800 had an anti-alias filter for one direction and what nikon called an un-alias filter so that the optical path was the same, letting nikon produce the d800 and d800e without major differences. make that the d800e with the un-alias filter. the d800 had an anti-alias filter for both directions. "Un-alias" filter? yes. in the d800e, the second filter reverses the effect of the anti-alias filter, thus its name. http://imaging.nikon.com/lineup/dslr/d800/features01.htm https://www.nikonusa.com/en_INC/IMG/...Camera-Technol ogy/D-SLR/2012/Moire-D800-D800E/Media/OLPF_schematic.pdf With the D800E, the effects of the low-pass filter is removed, and the light is received by the image sensor at a single point, achieving higher-resolution images with minimal blur. http://www.dpreview.com/reviews/nikon-d800-d800e/3 Nikon uses slightly curious wording about the D800E - that the anti-aliasing effect of the optical filter stack in front of the sensor is 'cancelled' - and the diagram below shows what this means (courtesy of Nikon). Anti-aliasing filters work by using a birefringent material to split light rays into two based upon the polarization of the light; a first layer splits it horizontally, the second vertically. The practical result is a slight blurring of the image, to avoid moiré and aliasing artefacts. In the case of the D800E, the first filter is instead directly counteracted by the second, resulting in no overall blurring. |
#7
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AA filter vs. OLPF filter
nospam wrote:
In article , Floyd L. Davidson wrote: I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? two names for the same thing. note that the d800 had an anti-alias filter for one direction and what nikon called an un-alias filter so that the optical path was the same, letting nikon produce the d800 and d800e without major differences. make that the d800e with the un-alias filter. the d800 had an anti-alias filter for both directions. "Un-alias" filter? yes. in the d800e, the second filter reverses the effect of the anti-alias filter, thus its name. It's name is not, and never has been, "un-alias" anything. Nothing in any of your cites suggests that is correct terminology, and it isn't. It does suggest a total lack of understanding about what the filter does. It is an *anti* aliasing filter because it helps to stop aliasing. There is no filter that *un*-aliases anything. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#8
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AA filter vs. OLPF filter
In article , Floyd L. Davidson
wrote: I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? two names for the same thing. note that the d800 had an anti-alias filter for one direction and what nikon called an un-alias filter so that the optical path was the same, letting nikon produce the d800 and d800e without major differences. make that the d800e with the un-alias filter. the d800 had an anti-alias filter for both directions. "Un-alias" filter? yes. in the d800e, the second filter reverses the effect of the anti-alias filter, thus its name. It's name is not, and never has been, "un-alias" anything. it has, and is. Nothing in any of your cites suggests that is correct terminology, and it isn't. It does suggest a total lack of understanding about what the filter does. It is an *anti* aliasing filter because it helps to stop aliasing. There is no filter that *un*-aliases anything. in the d800e, the second filter reverses the anti-aliasing of the first filter, thus the 'un-' prefix. in the d800, the second filter is another anti-alias filter in the d800 for the second dimension. this is *clearly* spelled out in nikon's documentation and elsewhere. if anyone lacks an understanding about how it works, it's you. https://www.nikonusa.com/en_INC/IMG/...Camera-Technol ogy/D-SLR/2012/Moire-D800-D800E/Media/OLPF_schematic.pdf go tell nikon they're wrong. let us know how well that works out. |
#9
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AA filter vs. OLPF filter
nospam wrote:
In article , Floyd L. Davidson wrote: I'm confused by something. Many new cameras today advertise no anti-aliasing filter (AA) or optical low-pass filter (OLPF). But are they the same thing?? I came across one article that seems to say no, saying (IIRC) the Nikon D810 has neither. However, I wonder if some articles that say a certain camera doesn't have one or the other are maybe using the terms interchangeably. Is it possible if a camera does not have an AA filter it still has the OLPF, or vice versa? What's the scoop? two names for the same thing. note that the d800 had an anti-alias filter for one direction and what nikon called an un-alias filter so that the optical path was the same, letting nikon produce the d800 and d800e without major differences. make that the d800e with the un-alias filter. the d800 had an anti-alias filter for both directions. "Un-alias" filter? yes. in the d800e, the second filter reverses the effect of the anti-alias filter, thus its name. It's name is not, and never has been, "un-alias" anything. it has, and is. Making up your own set of facts doesn't make your argument correct. Not one of your cited references uses that term! Nothing in any of your cites suggests that is correct terminology, and it isn't. It does suggest a total lack of understanding about what the filter does. It is an *anti* aliasing filter because it helps to stop aliasing. There is no filter that *un*-aliases anything. in the d800e, the second filter reverses the anti-aliasing of the first filter, thus the 'un-' prefix. That suggests you haven't got a clue how an OLPF works. There is no "anti-aliasing" in the filter. The filter is a pair of layers of birefringent material aligned such that together they slightly blur the image. That reduces aliasing when the image is sampled by the sensor. All that happens in the D800E is that those two layers are not aligned to blur the image. in the d800, the second filter is another anti-alias filter in the d800 for the second dimension. The "second filter" is second layer of birefringent material oriented at 90 degrees to the first. In the D800E it is oriented at 180 degrees. this is *clearly* spelled out in nikon's documentation and elsewhere. if anyone lacks an understanding about how it works, it's you. https://www.nikonusa.com/en_INC/IMG/...Camera-Technol ogy/D-SLR/2012/Moire-D800-D800E/Media/OLPF_schematic.pdf go tell nikon they're wrong. let us know how well that works out. The Nikon document does not use the term "un-alias". In fact it does not even mention aliasing in any way. It talks about how an Optical Low Pass Filter works, and that does not directly involve aliasing, anti-aliasing, or your ridiculous term "un-aliasing". -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
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