Why don't we need an anti-alising/low-pass filter in front of the sensor anymore?

donaldejose

First the D800e eliminated this filter. Then the D7100 did also. Now the Coolpiz A eliminates this filter. I assume the D400 will not have it either. What's up with this? I see eliminating the filter allows for sharper images but Nikon sold the D800e as a speciality item with the D800 containing an anti-alising filter as the normal choice for more than 80% of users. Now Nikon expects 100% of D7100 and Coolpiz A users to not need that filter. Why? How is Nikon handling Moire production in the new cameras?

PB_PM

That's the strange thing, Nikon is still using sensors that are vulnerable to moire. I cannot see any reason to remove the AA filter, the difference in sharpness is far less of an issue than trouble of removing moire from an image.

donaldejose

It makes me think perhaps Nikon has some anti-moire software at work or the size of the pixels are such that moire is unlikely to develop? Or perhaps it will prove to be an error.

SquamishPhoto

If it was a bad idea why would Leica continue to produce cameras with no AA filter? And ask someone who has both a D800 and a D800e which one they tend to use and what they think of the sharpness difference. I believe someone on this forum mentioned regretting not getting two D800e bodies instead of one each of the D800 and the "e" body.

donaldejose

I have noticed a few comments by D800e users that they did not find moire to be a problem. Do you suppose Nikon learned from the D800e user's experiences that the AA filter was not necessary? If so, was the AA filter always not needed or do the higher number of pixels on current sensors reduce the chance of Moire enough that an AA filter isn't needed now whereas it was needed back in the day of 6mp sensors? Or is it because of improved image processing software? Anyone know?

Ade

Higher sensor pixel density == less prone to moire.

So for a given sensor size, as pixel counts go up we can use progressively weaker AA filters.

As a byproduct of the "pixel wars", we're now reaching a point that in ordinary situations, the AA filter can be left out altogether without much harm -- and most remaining moire can be smoothed out via image processing.

PB_PM

I've read that there wont be enough pixel density to overcome moire until we reach 80-100MP. So even the D800 at 36MP is a long way off.

Having to smooth out images in post defeats the whole purpose of removing the AA filter in the first place, unless my logic is totally out to lunch.

SquamishPhoto

Having to "smooth out" the incredibly minute number of ones photos suffering detrimental effects from the lack of the filter is hardly a huge sacrifice for what is gained. The patch for PS is very effective from what I've seen.

Ade

The pixel density required to overcome all moire is infinite.

The pixel density required to overcome moire in most daily situations is already here.

TaoTeJared

Moire can not be fixed in software as well as the low pass filter does - period. Actually software stinks badly on it on many situations because the chroma is so strong and off color. Sorry Ade, but I too have read many convincing articles (with the math) and they say what PB_PM said - 80+mp will mostly get past it. We are not beyond it yet - not by a long shot. Digi cams have a huge density, and they show it all the time. That should be proof enough.

Squamish - give you an example, last weekend I shot a new born (not usually my thing, but 6 friends all had kids in the last 4 months! ugh) Anyway, the clothing, blankets, accessories, all produced bad moire. I was just pulling my hair out. It was on location, and I was stuck with what the parents had. At least I caught it not to far in, as the LCD doesn't show it well. In post I tried to fix it, but you loose all the details from software fixes - it just turns to mush. A blanket shouldn't look like a marshmallow land slide.
At least the Low pass filter retains most of the detail. That was with a D800, if I had a D800e I really would have been up a _____ creek with no paddle. Sometimes software can fix some types, but many times it just smudges it.

Sometimes just by changing your vantage point you can move out of the Moire pattern but unfortunately you may not know it is there until in post.

donald I don't know why Nikon is doing this or what they have "figured out" if anything to combat it. I am very curious to have Nikon make a clear statement on this. I know they make external low pass AA filters, mostly for film but they are rare and really expensive right now.

PB_PM

Nikon's marketing department is listening to a vocal minority who say that removing the AA filter is a "must have" feature. As if removing a feature is a net gain.

There are some subjects where removing the AA filter is helpful, for others it is a downright terrible decision. I wonder how many fashion photographers picked the D800E? My guess, very, very few.

KnockKnock

Maybe they do something in JPEG processing? I noticed one of the D7100 previews mentioning Capture NX2 can remove moire, but the didn't mention that it's not included with the D7100... to say nothing of the CP A. I guess time will tell.

Ade

Most high-end fashion and commercial photography for the past 5+ years have been shot on relatively low-density MF digital backs with no AA filters. Maybe the only exceptions are people who are still shooting film.

The D800E is being used by working pros like John Wright who makes a living shooting fashion for Versace, Louis Vuitton, Yves Saint Laurent, etc. Yet somehow it's not good enough for internet forum shooters with an abnormal fear of moire.

spraynpray

Hey Ade - don't poke the geeks! They're happy being geeky )

PB_PM

You speak as if being "geeky", or better said, intelligent was a crime.

MF is a different beast altogether, and has a much larger pixel pitch. If the editors of those fashion photographers work want to spend all day removing moire from the images that is their business. Doesn't mean I do.

spraynpray

No PB, I was having fun with you all. Heck, I may even be one! @-)

Geek in English is being an anorak - which means obsessed with detail to a disproportionate extent so not really a measure of intelligence, maybe 'obsessiveness'!.

PB_PM

You are here after all. Being on a forum is kind of geeky in and of itself.

Msmoto

AA filter to Geek....this is interesting....

I am definitely 90+% Geek on post processing....

About the AA filter...I guess we will see how this works. And for those of us who end up with a moire disaster...I guess I am still wondering why Leica does not have one. Does anyone here shoot a Leica M9 or M8?

On a Leica forum the issue was identified, yet all said it was easily removed or eliminated with poet processing. As I recall, they were stating something like a little sharpening removed a lot of it. But, the consensus was it presented little problem overall.

heartyfisher

I think a large part of it is software( though maybe the resolution now is so high that the micro lenses acts to some extent as an AA filter) .

Some years ago I came across some paper presented by some uni student relating to Demosaicing. The interesting thing about it was he used matrices with more than 4 pixels (red, green, blue, green) to determine the colour of a demosaiced pixel. He showed that using larger matrices of 6, 9, 11 etc pixels you can increase colour accuracy and reduce noise and improve high iso sensitivity. Makes sense if you think about it. It seems logical to me that by improving colour accuracy and using larger matrices you should be able to reduce moire. It would seem to me that the use of larger matrices also makes them behave as larger pixels so more light gathering ability and higher ISO capability and less noise.

The maths boggled my brain but maybe not the nikon engineers :-) Yea I am dreamer geek but maths is not my strong point :-).

DenverShooter

I must have missed it. I have 10K clicks on my D800E and can't recall a single moire problem.

Denver Shooter

dissent

On a Leica forum the issue was identified, yet all said it was easily removed or eliminated with poet processing.

Awesome typo.

So when will the "Carl Sandberg - e e cummings" slider be coming to Lightroom?
[Sorry Tommie; I just couldn't resist. In retrospect, I find that oftentimes a lot of my photos could really benefit from some "poet" processing]

donaldejose

Great idea: a slider which adds emotion!

It actually could be done to some extent. Use the software in Portrait Professional which changes facial features to produce features which express anger on the one end of the slider and happiness on the other end of the slider. Then adjust the subject's facial expression to taste.

Fred_B

Some of what we see as moire from the camera is actually related to the resolution of the displays we use to view the image. Your monitor down-samples the image resolution unless you zoom to 1 to 1 (pixel for pixel). The same can happen with a print image. Your monitor and printer are both arranged in horizontal and vertical lines. Mismatching the resolution of the image and the resolution of these lines will cause moire in the display/photo.

Remember that resolution (and more importantly changes in resolution) can create moire that is not really the fault of the camera. Shoot a window screen at a slight angle with a D800 (E or not) and zoom on the picture of the window screen in camera. It will have moire due to the resolution of the display and the mismatch of the strictly horizontal/vertical lines in the display. The moire changes with zoom levels (resolution). The same happens with your computer monitor. If you can't display the image at the same resolution as the camera moire (in this case it's aliasing) can be created.

Resolution should be matched with the medium you are planning on displaying. There is a sweet spot where moire (and aliasing) will occur. Shoot at that resolution and you'll have aliasing in your picture as displayed. Change the resolution of either the picture or the display and the moire will change and at some point be eliminated.

Wondering if your camera has moire? Only displaying a repetitive pattern at 1 to 1 (pixel for pixel on the horizontal and vertical planes) will show a camera problem. Anything else and you may be introducing aliasing that is simply not there at the camera level. This level of zoom may be unrealistic with a 36mp image.

spraynpray

Let us know when you have finished the Lightroom Emotion Plug-in then Donald :P

SquamishPhoto

Squamish - give you an example, last weekend I shot a new born (not usually my thing, but 6 friends all had kids in the last 4 months! ugh) Anyway, the clothing, blankets, accessories, all produced bad moire. I was just pulling my hair out. It was on location, and I was stuck with what the parents had. At least I caught it not to far in, as the LCD doesn't show it well. In post I tried to fix it, but you loose all the details from software fixes - it just turns to mush. A blanket shouldn't look like a marshmallow land slide.
At least the Low pass filter retains most of the detail. That was with a D800, if I had a D800e I really would have been up a _____ creek with no paddle. Sometimes software can fix some types, but many times it just smudges it.

As someone who shoots portraits every week of the year I can tell you that I haven't once run into a situation where the problem presented itself.

TaoTeJared

Squamish If this came up a week ago, I would have said the same thing-for the most part. I don't run into it much at all, but when I do, I just toss the images if I can. Unfortunately when it happens there is not much you can do with it.

The true key with moire is if it is the primary focus, of if it is so distracting it yanks your eye to it. Usually it is just a iridescent tie or scarf or a window screen on a house which is rarely the primary subject matter so it is not that big of a deal - at least until it is.

The D800E is being used by working pros like John Wright who makes a living shooting fashion for Versace, Louis Vuitton, Yves Saint Laurent, etc. Yet somehow it's not good enough for internet forum shooters with an abnormal fear of moire.

It's all about subject matter and the ability to control light. In a studio where you can move the light (increase or decrease the angle of reflection) you can eliminate the issue. Oh and by the way - I have never seen leather create moire. I hadn't seen John Wright's work before (thanks for the new name) - there is moire in quite a few of his images and you can pick out some of the editing. Also remember many of the "big" photo shoots get sent to professional editors that edit photos for a living - 8+hrs a day, 220+ days a year, for many years and get paid to hand remove stuff if needed. That is a whole different world, and one that very few photographers reside in.