Author Topic: Pixel-Shifting Vs. Larger Sensors  (Read 30419 times)

Michael Erlewine

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Pixel-Shifting Vs. Larger Sensors
« on: October 27, 2017, 14:55:57 »
There are a number of threads here on the new Sony A7r3 mirrorless camera, and I even started one myself. It would be nice if we could keep this thread here on topic, since that is why I am posting it and perhaps post other issues on more general threads.

What I would like to discuss is why the A7R3 may be particularly useful to me and the reasons I feel this way. And, of course, I am trolling here for more information on this topic and other photographers with a similar bent.

The first “major” DSLR that I had was the Nikon D1X, sometime in 2001. And I have had almost all of the DSLRs from Nikon since then, at least of the landscape variety. Since I shoot close-up nature photos, I never cared about sports-related cameras, high ISOs, and autofocus.

Anyway, for me, there have been a string of cameras all the way up to Nikon’s recent release of the D850. In my case, it’s always been onward and upward, onward to more and better features and upward toward sensors with ever greater megapixels. And the last couple of years have been kind of a climax of sorts, at least a branching out of options. And of course, I was swept up in it all, especially the seeming-endless waiting, etc. I marched through buying (and returning) three medium-format cameras, a long time ago the Mamiya RZ67 (with eleven lenses) and more recently the Hasselblad X1D and the Fujifilm GFX.

And along in there I also bought and tested out the Pentax K3 and K1, mostly because of their pixel-shift technology. And I had the Sony A7S and A7R. I bought the A7R2, sold it, bought it again and sold it yesterday. I also ordered a copy of the A7R3 yesterday, mainly because of the pixel-shift feature, which brings me to my point in writing this.

Of course, like many of us I am in the habit of getting cameras with more and better pixels, and without really thinking about it I imagined I would like a 100 Mpx camera or even greater. However, I have been recently having doubts about this after getting the Nikon D850 camera, with its 45.7 Mpx.

I have a very big and fast PC, one with two GPUs, eight cores, a fast processor, 128 GB of RAM, etc. However, I did notice with the new Nikon D850, which has only a modest increase in megapixels, a difference in the computing power required. Keep in mind, that I stack focus, so I often have to process 100 or more large TIF files in the same batch. This takes time, and with the D850 it takes a little MORE time. Not that much, actually.

However, I can see that when we get 100 Mpx sensors, it will increasingly take more time (and storage). I keep all my stacked layers, so I have many hundreds of thousands of images by now. And this set me to thinking. 

Of course, I have wanted larger sensors, but not just for more megapixels, but for larger-sized photosites that collect more light. That is why I originally purchased a Sony A7s, for more light and larger photosites or whatever we call them.

By using the Pentax K3 and K1, both of which have pixel-shifting technology in them, I could see that they provided superior color and its resulting resolution, but I was not happy the way Pentax handled non-native lenses (of which I have a lot), so eventually it was more trouble than it was worth and the Pentax lenses did not make me happy. I like APO lenses.

So, my point and perhaps question here to those techsperts out there is: can we have a discussion here about perhaps not yearning for ever greater-sized sensors and concentrate more on improving the color and resolution in smaller-sized sensors, the ones we already are using.

I am happy with about 50 Mpx in sensor size, not less please, but perhaps I don’t need more. Since I don’t make prints of my images (never have), I only need a size to display on the web or place in an e-book format. Typically, I used images that are 2048 pixels on the long side for what I post, depending on where I post of course.

So, I’m wondering if my Nikon D850, which is great by the way, much nicer than I had imagined, along with the new Sony A7R3 (if it works as advertised) might be all that I need?  At 42 Mpx, the A7R3 is not much different than the 45.7 Mpx of the D850, and that may be as much as I need.

I am wondering, since I ONLY do still photography on a tripod, whether the pixel-shift technology of the A7R3 may give me the color (most important to me) and the enhanced resolution (however that works), so that instead of having to ever project myself forward to larger and larger sensors, I might (at least for a time) be happy with what I have (or will soon have with the A7R3)?

I am sure some of you here will have more technical thoughts about this conundrum I am in, either agreeing with me or pointing out something I have not thought of. Thanks for feedback.

P.S. This is the style of photography I tend to do, this with the D810 if I remember right.
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armando_m

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #1 on: October 27, 2017, 17:41:03 »
Higher resolution sure

better color ? I do not know
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Michael Erlewine

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #2 on: October 27, 2017, 17:48:24 »
Higher resolution sure

better color ? I do not know

By that I mean what we get by having pure color from the pixel-sifting of the four images. What do you call it? We avoid the Bayer filter.
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Les Olson

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #3 on: October 27, 2017, 18:21:14 »
The aim is not to improve the colour or resolution or anything else of the sensor.  The aim is to improve something in the final output: the print, or the computer monitor, if you must.  That raises a whole other world of considerations, including psychophysics and all the Weber-Fechner stuff, the often large gulf between pleasingness and accuracy, and whether your aim is aesthetic or documentary, and if aesthetic, which aesthetic - David Attenborough or Robert Mapplethorpe or Carl Blossfeldt. 

Michael Erlewine

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #4 on: October 27, 2017, 19:04:02 »
The aim is not to improve the colour or resolution or anything else of the sensor.  The aim is to improve something in the final output: the print, or the computer monitor, if you must.  That raises a whole other world of considerations, including psychophysics and all the Weber-Fechner stuff, the often large gulf between pleasingness and accuracy, and whether your aim is aesthetic or documentary, and if aesthetic, which aesthetic - David Attenborough or Robert Mapplethorpe or Carl Blossfeldt.

I don't understand your post or miss the point. I am talking about getting more RGB pure colors via the pixel-shifting and nothing else. What we do in post, etc. is individual. Please stay with what I pointed out.
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simsurace

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #5 on: October 27, 2017, 20:32:24 »
This is already being done e.g. by Pentax. By shifting the pixels three times in a U shape (left-up-right, for example), you collect 2 green samples and one red and one blue for each pixel. This is more data so it cannot be worse than having only one of them and interpolated values for the other two. Are you asking whether the Sony will also do it, or just whether the principle works? I guess that the benefit is mainly seen at very high spacial frequencies close to the Nyquist limit, and the potential for color moiré may be reduced if the camera's AA filter is on the weak side.
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Michael Erlewine

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #6 on: October 27, 2017, 21:04:10 »
This is already being done e.g. by Pentax. By shifting the pixels three times in a U shape (left-up-right, for example), you collect 2 green samples and one red and one blue for each pixel. This is more data so it cannot be worse than having only one of them and interpolated values for the other two. Are you asking whether the Sony will also do it, or just whether the principle works? I guess that the benefit is mainly seen at very high spacial frequencies close to the Nyquist limit, and the potential for color moiré may be reduced if the camera's AA filter is on the weak side.

No, I expect the A7R3 pixel-shifting to be identical to the Pentax version, but perhaps smoother if there is any benefit from doing the collating in post rather than in-camera. My point (and perhaps not a question) is that the benfits are not necessarily seen in ever-larger sensors, but in getting better color and perhaps resolution in something like 50 Mpx. I don't need giant prints, but rather finer-looking images. Was looking for comments on that.
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Frank Fremerey

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #7 on: October 27, 2017, 21:23:56 »
With pixel shift you get more spatial resolution.

With larger pixels you get more color information (better statistics = higher differentiation)

Do I understand you question correctly, that you want a Multishot camera like it was done in earlier Digital Medium Format backs to go to quarter-pixel-resolution but you want less pixels to make them bigger and get more color differentiation?

Then my answer would be to use a Multishot Sensor:

https://www.youtube.com/watch?v=7N135xTbrZI

With a 16-shift-multishot you only need very small amount of very big pixel to achieve a 50MP result, namely 50/4...
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Michael Erlewine

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #8 on: October 27, 2017, 21:35:14 »
I guess it is hard to be understood. All I was saying is that after trying the pixel-shift technology on the Pentax K3 and then the K1, I got what I considered medium-format-like results. If the A7R3 is similar (which it promises to be) and I get MF results again, then I don't need the sensor to be larger than around 50 Mpx to be happy, ESPECIALLY since I have a lot of APO lenses that could probably work pretty well on the A&R3. I do notice more than a slight difference between Bayer interpolation and pixel-shift. I was looking for support in this view or reason why we must endless move on to larger sensors.
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Jack Dahlgren

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #9 on: October 28, 2017, 06:05:47 »
Michael,

I have a Nikon Df which has a 24x36 sensor with 16mpx and use of a Canon 5DSR which has same size sensor and 50mpx. For posting on the web the Nikon delivers better colors and a broader range. The Canon ultimately has more resolution but if you are shrinking to 2000px most of that is lost and color and tonality become more important.

For what I do it does not make sense to chase more pixels or larger sensors. Life is too short to spend it wishing for something I don’t have and being dissatisfied with what I do have. For you it seems like chasing that hardware is interesting and important to you. I wish you peace in your journey.

My point is that we all seek something different out of our photography so our desires for different cameras will vary. I think you will need to keep seeking, no matter what new thing comes out.

Ethan

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #10 on: October 28, 2017, 09:33:29 »
Please correct me if I misunderstood:

You want a super duper type of sensor Pixel Shift to give you a super duper rendition of colours.
Nevermind that whatever light source you are using will affect the final colour of the image, but you do not print your images and instead reduce the size to 2000ish pixels on the long end to publish on line and Ebook which means converting to Jepg.

So you are starting with RGB NEF and converting by downsizing to Jpeg sRGB and you wish to protect the color rendition? Correct?

I mean seriously, you start with a Wagyu to end up with a Bolognese!!!!!!! and you wonder why the taste is lost???!!!???

At least start with a Prophoto color space which is larger than RGB which in turn is larger than Jpeg but you do not wish to discuss or consider the processing side or the colour gamut and psychoshit of it.

Let me rephrase, you want a camera that will give you the result that you want with minimal post processing  as you are too much investing time in the shooting set up and subsequent stacking.

Please, when you find the Valhalla camera and sensor and tech to go with it, do let me know.

Michael Erlewine

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #11 on: October 28, 2017, 09:48:02 »
Please correct me if I misunderstood:

You want a super duper type of sensor Pixel Shift to give you a super duper rendition of colours.
Nevermind that whatever light source you are using will affect the final colour of the image, but you do not print your images and instead reduce the size to 2000ish pixels on the long end to publish on line and Ebook which means converting to Jepg.

So you are starting with RGB NEF and converting by downsizing to Jpeg sRGB and you wish to protect the color rendition? Correct?

I mean seriously, you start with a Wagyu to end up with a Bolognese!!!!!!! and you wonder why the taste is lost???!!!???

At least start with a Prophoto color space which is larger than RGB which in turn is larger than Jpeg but you do not wish to discuss or consider the processing side or the colour gamut and psychoshit of it.

Let me rephrase, you want a camera that will give you the result that you want with minimal post processing  as you are too much investing time in the shooting set up and subsequent stacking.

Please, when you find the Valhalla camera and sensor and tech to go with it, do let me know.

That's not it at all. It must be that it is my fault and that I am not able to communicate on blogs like this one, and there is no point in endlessly repeating myself. It's tiresome.

I use ProPhoto RGB in Photoshoip, like many people. I enjoy looking at it in full-res, but most (or many) web sites don't support large files or have a limit, so I limit the size for online posting. I do all this for my own enjoyment and share very few images online via photo-related forums.

This kind of discussion, where my original point is not only NOT understood, but brings forth no response that is helpful. This is why I don't post at these forums as much as I used to. It is like "Whack a mole." There is no communication, much less discussion to speak of. No offense, but such a tone is not helpful or on point.

It's just easier to post a few images and let it go at that.

Here is an image I took today using the D850 with the Nikon "O" (CRT) lens, just for fun.
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Les Olson

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #12 on: October 28, 2017, 13:56:07 »
I don't understand your post or miss the point. I am talking about getting more RGB pure colors via the pixel-shifting and nothing else.

But what do you mean by "more RGB pure colours"? 

If you mean you want to avoid the channel-contamination that causes low-ISO noise in monochrome areas like blue sky, pixel shift won't do it.  Your best bet with current technology is a 3CCD sensor, with prisms separating the light into red, green and blue and separate sensors for each.

If you mean "more, pure" - ie, an expanded colour space, you can't get away from the question of how you want your human observers to perceive the image.  The electro-magnetic spectrum is continuous: there is no such thing as "colour" in the absence of a human observer.  The only possible understanding of phrases like "accurate colour" or "better colour" is "human observers perceive the colour of the photograph as being the same as when they looked at the real thing" or "people like it better".  Then, you can't get away from the fact that there is such as thing as the "least noticeable difference", that differences smaller than that are not perceived, and that the least noticeable difference, in many parameters, depends on the background level (a given increase in light intensity may be obvious when the light is low, but undetectable when the light is bright). You cannot ask whether a new and/or improved sensor will produce a perceptible change in the print without defining what aspects of the print  - brightness, colour saturation, etc - you are interested in and what the current levels of those parameters are. 

If you mean more saturated colours or purer hues, the situation is even more complicated, because as well as the least noticeable difference issue the tristimulus colour system assumes that the three stimuli - hue, luminance and chromaticity - do not interact, and they do.  Brighter colours are perceived as more saturated and of purer hue, and more saturated colours are perceived as brighter. 

The upshot is that there is no such thing as truth in colour.  That is why you also can't get away from the aesthetic choice: it is not a matter of lying or telling the truth, it is a matter of which lie.

Michael Erlewine

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #13 on: October 28, 2017, 15:15:51 »
But what do you mean by "more RGB pure colours"? 

I mean what I wrote, the four-shot technique of Red, Green, Blue (withtwo Greens) compared to the Bayer interpolated, nothing more and nothing less. What is hard to understand about that?
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Frank Fremerey

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Re: Pixel-Shifting Vs. Larger Sensors
« Reply #14 on: October 28, 2017, 16:13:46 »
I mean what I wrote, the four-shot technique of Red, Green, Blue (withtwo Greens) compared to the Bayer interpolated, nothing more and nothing less. What is hard to understand about that?
look at the video I linked to understand that you need a 12.5 MP sensor with huge 8 micron pixels and  16 shot with full native color information fo every pixel.

The point is to also work on the lighting setup to get a better color response and contrast. You are already in the highend, so better lighting will cost you.

Another question is, which company will deliver such a camera that is better than the superb D850? Look at my natural light shots from the botanical gardens with no stacking...
You are out there. You and your camera. You can shoot or not shoot as you please. Discover the world, Your world. Show it to us. Or we might never see it.

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