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As I said: look at the diagram! It has two devices doing exactly the opposite things, and
labels both the same. The two things cannot be the same if they don't do the same thing.
A Low Pass filter simply by definition cannot correct for a previous Low Pass filter. (It would have to be a "High Pass Filter".)
Look up the definitions for such filters! Two low pass filters in sequence form a filter that is necessarily a stronger low pass filter than either of the two components alone, simply because the effects are cumulative.
Here's an interesting view of Nikon's D800E filter, how it relates to their recent patent of an "on/off AA filter", and what we will see in the future.
First, as I've mentioned before, a slice of birefringent material in itself is not a "low pass filter", and understanding that has to be clear. The actual effect it provides is to cause a phase shift in one direction (and that includes rotating the polarity too) and not in another. When a phase shifted beam is added to an unshifted beam and sampled, the frequency response of the resulting sample is determine by the amount of phase shift. That is what makes a "Low Pass Filter".
Other important characteristics are that the two beams output from a birefringent material can be separated with a polarizing filter, and thus could potentially be individually focused, perhaps with microlenses, and that the amount of phase shift is controlled by the thickness of the slab of birefringent material.
That would suggest a few things that might be done (and I don't know exactly what Nikon has actually managed to do). One is that rotation of two sequential slabs can vary the angle of what is called the "extraordinary" rays, which are the ones that have a shifted phase. If the second slab is rotated 180 degrees (as Nikon is indicating they have done in the D800E) it would be possible, perhaps using polarizing filters and/or microlenses, to focus only the previously shifted rays into a second birefringent lens and thus cancel the phase shift without losing half the light. Just keep in mind that is not two sequential low pass filters. It is just one singe low pass filter, which happens to be adjustable.
But consider another potential "adjustable" variation. If a rotating polarizing filter was placed between the two birefringent slabs, it might be possible to vary the relative amplitudes of the two differing phased rays, and thus vary the phase cancellation when sampled. That would perhaps result in a continuously adjustable low pass filter.
Now imagine a camera with perhaps 2 times the pixel density of the D800... about 150 MP. This camera is going to be diffraction limited at perhaps f/5.6 (that's a guess, as I haven't calculated what it would actually be). With a variable AA filter the camera could determine that with an aperture of f/8 there is no need for any low pass filter. At f/5.6, the camera may be diffraction limited, but that isn't with a sharp enough cutoff, so a very weak AA filter is dialed in. And of course right down to f/1.4 each wider aperture is cause for a slightly stronger AA filter.
That's going to be a few years. But a few years after that sensors with more than 500 MP will be developed, and at that pixel density there is no benefit from an AA filter.
As I said: look at the diagram! It has two devices doing exactly the opposite things, and
labels both the same. The two things cannot be the same if they don't do the same thing.
A Low Pass filter simply by definition cannot correct for a previous Low Pass filter. (It would have to be a "High Pass Filter".)
Look up the definitions for such filters! Two low pass filters in sequence form a filter that is necessarily a stronger low pass filter than either of the two components alone, simply because the effects are cumulative.
Apparently you don't read well: Link.........us..........to.........your.........s ource.
Apparently you don't read well: Link.........us..........to.........your.........s ource.
I was trying to avoid embarrassing you. The sources aren't going to do you a bit of good, because they provide facts and details, but perspective on how those facts relate to each other is the hard part. Perspective often cannot be arrived at quickly, and may take years of working with the technology to allow each advancing step to become apparent. Often of course that can be shortened by simplified explanations, such as what I've tried to provide.
Perhaps these will provide more background as well as specifics:
I was trying to avoid embarrassing you. The sources aren't going to do you a bit of good, because they provide facts and details, but perspective on how those facts relate to each other is the hard part. Perspective often cannot be arrived at quickly, and may take years of working with the technology to allow each advancing step to become apparent. Often of course that can be shortened by simplified explanations, such as what I've tried to provide.
Perhaps these will provide more background as well as specifics:
Pretty presumptous for someone who can't follow a simple request.
There is no reason to "follow" every presumptuous dumb request made here that will waste time.
Have you been able to grasp yet that two sequential low pass filters do not cancel, but instead are additive and create a "stronger" low pass filter? By definition if a second device cancels the effects of a low pass filter, the second device is a high pass filter. (The other alternative is to realize that whatever is being defined as a "low pass filter" in both instances cannot be in either instance a low pass filter. That is simple logic applied to the basic definitions.)
There is no reason to "follow" every presumptuous dumb request made here that will waste time.
Have you been able to grasp yet that two sequential low pass filters do not cancel, but instead are additive and create a "stronger" low pass filter? By definition if a second device cancels the effects of a low pass filter, the second device is a high pass filter. (The other alternative is to realize that whatever is being defined as a "low pass filter" in both instances cannot be in either instance a low pass filter. That is simple logic applied to the basic definitions.)
Again, you must have trouble with reading comprehension. I've made only one simple request, it is you who has been wasting time.
Again, you must have trouble with reading comprehension. I've made only one simple request, it is you who has been wasting time.
You've made a simple request that has no logical value, and you continue to make ridiculous insults in response.
How about if I ask for a copy of your birth certificate? Will you post it? Or a copy a transcript to prove you have advanced past the 6th grade? Will you post that?
Logical discussion does not require anyone respond to any of that kind of "simple request".
Regardless of all that, you now have a significant list of source material, and you still want to argue silly points that have no logical bearing...
ill leave ya'all to argue the technical points while i go out and jump right to the bottom line.. using our cameras for taking good shots and perfecting our skills.
that far eclipses talking about pixels and moire'.
ill leave ya'all to argue the technical points while i go out and jump right to the bottom line.. using our cameras for taking good shots and perfecting our skills.
that far eclipses talking about pixels and moire'.
Until you absolutely need to get a shot of something that produces horrible moire'.
At that point you'll have to admit to not being capable of "using our cameras for taking good shots and perfecting our skills" unless you've spent some time discussing and learning all these technical topics that are prerequisites for making good photographs at will, rather than by accident.
Just having fun and making a hobby of photography is wonderful, and certainly to be encouraged. But the purpose of this forum includes serious photography too, whether for amateur or professional work.
Disparaging discussion because it is above your current level lacks class.
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