A7iii vs A7Riii

Started 3 months ago | Discussions
tqlla Veteran Member • Posts: 5,115
Re: A7iii vs A7Riii

I would go with the A7Riii, simply because 8K(7680x4320) displays are a thing.

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SafariBob
SafariBob Contributing Member • Posts: 843
Re: A7iii vs A7Riii

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

This is incorrect. And why you are out by a clear factor of 4.
You need ONE pixel per screen "pixel". That pixel is then displayed as subpixels based on the image single pixel's RGB data.
You CAN NOT address each subpixel as you suggest with "more than 4K".
Andrew

Now I understand why you are so confused.

in a display each “pixel” contains 3 sub pixels (or more) such that each pixel contains full color information.

in a camera, each “pixel” contains just one color. Hence the pixel in a camera is comparable to a sub pixel in a display. For each full color site, there are 2 green, one red and one blue in a camera.

thus an 8k display contains 32 “camera” pixels, which are actually 24 rgb sub pixels.

in order to make the effect of pixels, interpolation, etc negligible, you need to oversample.

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SafariBob
SafariBob Contributing Member • Posts: 843
Re: Which is best? Comparison here at 4K.

andrewD2 wrote:

Since there are no monochrome pixels in a RGGB array the monochrome image has to be constructed from the colour data, it is just fine to compare two Bayer sensors.
At 4K the colour areas were the same, ISO100 maybe slight advantage A7RIII, pretty hard to tell, ISO800 slight advantage A7III.

Don't get angry with me, do the comparison yourself.
Andrew

I have no idea what I am looking at, even if 1 looks sharper than 2, that may be just because more sharpening has been applied, focus is more accurate or whatever. It’s far simpler to debayer a monochrome image.

if you read my other post and have some good faith questions, I am happy to answer, but if you continue with this stuff, I don’t really see the point.

Edit: if you still don’t believe me, I recommend looking at the detailed comparisons between the original a7 and the original a7r. Very easy to see there. Also for aa vs no aa, look at the rx1 vs the rx1r

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andrewD2 Veteran Member • Posts: 9,193
Re: A7iii vs A7Riii

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

This is incorrect. And why you are out by a clear factor of 4.
You need ONE pixel per screen "pixel". That pixel is then displayed as subpixels based on the image single pixel's RGB data.
You CAN NOT address each subpixel as you suggest with "more than 4K".
Andrew

Now I understand why you are so confused.

in a display each “pixel” contains 3 sub pixels (or more) such that each pixel contains full color information.

in a camera, each “pixel” contains just one color. Hence the pixel in a camera is comparable to a sub pixel in a display. For each full color site, there are 2 green, one red and one blue in a camera.

thus an 8k display contains 32 “camera” pixels, which are actually 24 rgb sub pixels.

in order to make the effect of pixels, interpolation, etc negligible, you need to oversample.

No, I'm not the one confused here. 
Yes, the Bayer array is there on the camera sensor meaning you get RGGB per 4 pixels. 
So ok, if you want to bin each 4 RGGB pixels to a superpixel you get ONE factor of 4 in your calculation. Bayer interpolation is better than that but OK, lets run with the x4 factor for the SENSOR array. 
Your OTHER subpixel screen factor is bogus. However many subpixels the screen uses to be able to show ONE image pixel we group those subpixels together in the same way
and call each, well, we just call it "a pixel".

By your calculations you'd need a 683MP camera for an 8K screen. Your calculation is off by a factor that doesn't exist. 
Andrew

andrewD2 Veteran Member • Posts: 9,193
Re: Which is best? Comparison here at 4K.

SafariBob wrote:

andrewD2 wrote:

Since there are no monochrome pixels in a RGGB array the monochrome image has to be constructed from the colour data, it is just fine to compare two Bayer sensors.
At 4K the colour areas were the same, ISO100 maybe slight advantage A7RIII, pretty hard to tell, ISO800 slight advantage A7III.

Don't get angry with me, do the comparison yourself.
Andrew

I have no idea what I am looking at, even if 1 looks sharper than 2, that may be just because more sharpening has been applied, focus is more accurate or whatever. It’s far simpler to debayer a monochrome image.

They are the dpreview test samples, you can see them too.

if you read my other post and have some good faith questions, I am happy to answer, but if you continue with this stuff, I don’t really see the point.

From someone that thinks 4K needs 144MP?

Edit: if you still don’t believe me, I recommend looking at the detailed comparisons between the original a7 and the original a7r. Very easy to see there. Also for aa vs no aa, look at the rx1 vs the rx1r

We are not comparing A7 and A7R here, might be interesting though at 4K. I'll have a look. 
The AA filter effect on the A7III is extremely weak, and as you can see from the comparison I presented has no effect on a 4K image. 
Andrew

SafariBob
SafariBob Contributing Member • Posts: 843
Re: A7iii vs A7Riii
1

andrewD2 wrote:

in a camera, each “pixel” contains just one color. Hence the pixel in a camera is comparable to a sub pixel in a display. For each full color site, there are 2 green, one red and one blue in a camera.

thus an 8k display contains 32 “camera” pixels, which are actually 24 rgb sub pixels.

in order to make the effect of pixels, interpolation, etc negligible, you need to oversample.

No, I'm not the one confused here.
Yes, the Bayer array is there on the camera sensor meaning you get RGGB per 4 pixels.
So ok, if you want to bin each 4 RGGB pixels to a superpixel you get ONE factor of 4 in your calculation. Bayer interpolation is better than that but OK, lets run with the x4 factor for the SENSOR array.
Your OTHER subpixel screen factor is bogus. However many subpixels the screen uses to be able to show ONE image pixel we group those subpixels together in the same way
and call each, well, we just call it "a pixel".

By your calculations you'd need a 683MP camera for an 8K screen. Your calculation is off by a factor that doesn't exist.
Andrew

You need to oversample. The cameras correct for optical aberrations etc.

4x (which effectively is 1x) is probably fine, but what i am saying is that 16x (which is effectively 4x) probably is sufficient to outresolve any pixel issues in all by the most extreme cases.

Why do you think film was mastered in 4K before being transferred to 1080p blueray? Why does 70mm exist? Why do film studios shoot in 6k or beyond when cinemas are 4K? This is moving image, where resolution is much less discernible.

those are rhetorical questions. No need to answer. And forgive me if I don’t. Read my original post. Nothing there is wrong or controversial.

Edit: when I bought my first dslr, it was 6mp, people were making the same arguments back then. My second was 12mp. It’s blatantly obvious with today’s equipment which is which. And that’s part of it too, you keep your images for life presumably, and it’s a bit sad when the resolution just isn’t there. Not always. Sometimes a less resolved picture has more ambiance. Photographers frequently add grain in post. But storage is so cheap these days, do your efforts justice and capture what you can.

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tqlla Veteran Member • Posts: 5,115
Re: Which is best? Comparison here at 4K.

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

Since there are no monochrome pixels in a RGGB array the monochrome image has to be constructed from the colour data, it is just fine to compare two Bayer sensors.
At 4K the colour areas were the same, ISO100 maybe slight advantage A7RIII, pretty hard to tell, ISO800 slight advantage A7III.

Don't get angry with me, do the comparison yourself.
Andrew

I have no idea what I am looking at, even if 1 looks sharper than 2, that may be just because more sharpening has been applied, focus is more accurate or whatever. It’s far simpler to debayer a monochrome image.

They are the dpreview test samples, you can see them too.

if you read my other post and have some good faith questions, I am happy to answer, but if you continue with this stuff, I don’t really see the point.

From someone that thinks 4K needs 144MP?

Edit: if you still don’t believe me, I recommend looking at the detailed comparisons between the original a7 and the original a7r. Very easy to see there. Also for aa vs no aa, look at the rx1 vs the rx1r

We are not comparing A7 and A7R here, might be interesting though at 4K. I'll have a look.
The AA filter effect on the A7III is extremely weak, and as you can see from the comparison I presented has no effect on a 4K image.
Andrew

Did anyone point out this video to you two?
https://www.youtube.com/watch?v=fzJsb56jrnc

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SafariBob
SafariBob Contributing Member • Posts: 843
Re: Which is best? Comparison here at 4K.

tqlla wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

Since there are no monochrome pixels in a RGGB array the monochrome image has to be constructed from the colour data, it is just fine to compare two Bayer sensors.
At 4K the colour areas were the same, ISO100 maybe slight advantage A7RIII, pretty hard to tell, ISO800 slight advantage A7III.

Don't get angry with me, do the comparison yourself.
Andrew

I have no idea what I am looking at, even if 1 looks sharper than 2, that may be just because more sharpening has been applied, focus is more accurate or whatever. It’s far simpler to debayer a monochrome image.

They are the dpreview test samples, you can see them too.

if you read my other post and have some good faith questions, I am happy to answer, but if you continue with this stuff, I don’t really see the point.

From someone that thinks 4K needs 144MP?

Edit: if you still don’t believe me, I recommend looking at the detailed comparisons between the original a7 and the original a7r. Very easy to see there. Also for aa vs no aa, look at the rx1 vs the rx1r

We are not comparing A7 and A7R here, might be interesting though at 4K. I'll have a look.
The AA filter effect on the A7III is extremely weak, and as you can see from the comparison I presented has no effect on a 4K image.
Andrew

Did anyone point out this video to you two?
https://www.youtube.com/watch?v=fzJsb56jrnc

Thanks. I prefer ken Rockwell over the Northrups.

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ActionPhotoPassion Senior Member • Posts: 1,533
Re: A7iii vs A7Riii

jae_buckley wrote:

I'm in the same boat with this. Considering the switch over from Canon. I mainly do wedding and event photography but also a fair bit of travel and landscape stuff as well. Don't know whether to go for the A7iii for the AF or ARiii for the resolution. Will probably wait and see what the specs on the Canon RS.

It doesn't sounds like you need super duper quick and snappy AF for those... Landscape well MF. Weddings well the R3 is doing well in churches and you get more details than with A7m3...

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tqlla Veteran Member • Posts: 5,115
Re: A7iii vs A7Riii

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

16:9, 4K wide = 4096 * 4096 * 9/16 = 9.4mpx full colour= 37.6 mpx camera

Used British spelling if that helps cognition for ya

Your math is just way off here.

4K at 3x2 = 3840x2560   = 9.8304MP
4K at 16x9 = 3840x2160 = 8.2944MP
8K on a 3x2 sensor would require 7680x5120 = 39.3216MP

I dont know that much about color detail on a per pixel level.  But my assumption is that each pixel on a camera sensor is more than just a Red or Green or Blue.

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SafariBob
SafariBob Contributing Member • Posts: 843
Re: A7iii vs A7Riii

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

This is incorrect. And why you are out by a clear factor of 4.
You need ONE pixel per screen "pixel". That pixel is then displayed as subpixels based on the image single pixel's RGB data.
You CAN NOT address each subpixel as you suggest with "more than 4K".
Andrew

Now I understand why you are so confused.

in a display each “pixel” contains 3 sub pixels (or more) such that each pixel contains full color information.

in a camera, each “pixel” contains just one color. Hence the pixel in a camera is comparable to a sub pixel in a display. For each full color site, there are 2 green, one red and one blue in a camera.

thus an 8k display contains 32 “camera” pixels, which are actually 24 rgb sub pixels.

in order to make the effect of pixels, interpolation, etc negligible, you need to oversample.

i made a typo. It should be 4K not 8k display. My sincerest apologies

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Jacques Cornell
Jacques Cornell Forum Pro • Posts: 11,691
Re: A7iii vs A7Riii

MattPointZero wrote:

I love sony cameras, and although earlier this year I bought a gfx50s, I wanted a sony for my carry around and back up camera, so went with the full intention of getting the balanced a7iiii as the fuji would be my high resolution body - however even at normal viewing size, the R body just gave punched, more detailed shots for me, and the a7iii, whilst good, just didn't compare.

Yes, but this begs the question I raised earlier: HOW ARE ASSESSING THIS? As I said before, in a properly sharpened print up to about poster-size, you're unlikely to notice any difference at all. I don't care how my images look at 100% onscreen. I care what my audience sees, and my audience views my images on screen at 4K rez at most, or in a print up to 16"x24".

I think though, this is because a lot of my comparisons were studio headshots, and I think the eye and face detail really shows the differences in the sensor.

I think it's because you pixel peep.

I think if you are shooting full body shots, people in environments or architecture etc (and ignoring crop capability) then the differences are much less obvious or worth the money.

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SafariBob
SafariBob Contributing Member • Posts: 843
Re: A7iii vs A7Riii

tqlla wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

16:9, 4K wide = 4096 * 4096 * 9/16 = 9.4mpx full colour= 37.6 mpx camera

Used British spelling if that helps cognition for ya

Your math is just way off here.

4K at 3x2 = 3840x2560 = 9.8304MP
4K at 16x9 = 3840x2160 = 8.2944MP
8K on a 3x2 sensor would require 7680x5120 = 39.3216MP

I dont know that much about color detail on a per pixel level.

read the other post. That is why this is not the correct interpretation. Different kinds of 4K. What you are talking about is ultra hd. 4K is 4096. But it’s the same for practical purposes.

But my assumption is that each pixel on a camera sensor is more than just a Red or Green or Blue.

it ain’t.

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andrewD2 Veteran Member • Posts: 9,193
Re: A7iii vs A7Riii

SafariBob wrote:

andrewD2 wrote:

in a camera, each “pixel” contains just one color. Hence the pixel in a camera is comparable to a sub pixel in a display. For each full color site, there are 2 green, one red and one blue in a camera.

thus an 8k display contains 32 “camera” pixels, which are actually 24 rgb sub pixels.

in order to make the effect of pixels, interpolation, etc negligible, you need to oversample.

No, I'm not the one confused here.
Yes, the Bayer array is there on the camera sensor meaning you get RGGB per 4 pixels.
So ok, if you want to bin each 4 RGGB pixels to a superpixel you get ONE factor of 4 in your calculation. Bayer interpolation is better than that but OK, lets run with the x4 factor for the SENSOR array.
Your OTHER subpixel screen factor is bogus. However many subpixels the screen uses to be able to show ONE image pixel we group those subpixels together in the same way
and call each, well, we just call it "a pixel".

By your calculations you'd need a 683MP camera for an 8K screen. Your calculation is off by a factor that doesn't exist.
Andrew

You need to oversample. The cameras correct for optical aberrations etc.

4x (which effectively is 1x) is probably fine, but what i am saying is that 16x (which is effectively 4x) probably is sufficient to outresolve any pixel issues in all by the most extreme cases.

Why do you think film was mastered in 4K before being transferred to 1080p blueray? Why does 70mm exist? Why do film studios shoot in 6k or beyond when cinemas are 4K? This is moving image, where resolution is much less discernible.

those are rhetorical questions. No need to answer. And forgive me if I don’t. Read my original post. Nothing there is wrong or controversial.

Edit: when I bought my first dslr, it was 6mp, people were making the same arguments back then. My second was 12mp. It’s blatantly obvious with today’s equipment which is which. And that’s part of it too, you keep your images for life presumably, and it’s a bit sad when the resolution just isn’t there. Not always. Sometimes a less resolved picture has more ambiance. Photographers frequently add grain in post. But storage is so cheap these days, do your efforts justice and capture what you can.

Wait, now its oversampling 16x not bayer x4 and display subpixel x4?
Having sufficient pixels to resolve textures without moire would be great.
But when you look at the A7III vs A7RIII at 4K the moire effects are worse on the A7RIII.
Download the raws from dpreview, resize to 4K anyway you like and see for yourself.

My partner used to be an iMax projectionist btw.

And I know where you are coming from, while most were shooting 6MP-12MP I was using a 1DsIII. 
I'd still not put anyone off a A7III based on viewing 4K images because above ISO800 I prefer the A7III images and at all ISOs I find the A7III has the better colour. Operation shot to shot is so fast.

The A7RIII might be better for some but the hyperbole in this thread could push someone into spending more money on something that will not get better photographs of his toddler running around.

My friend has a 100MP H6D, I had a go with a nice Rodenstock 40mm lens. At 4K you can't see the difference from the 42MP camera even with the weaker 28mm f2. Same detailed scene, the view from my window.

Andrew

tqlla Veteran Member • Posts: 5,115
Re: A7iii vs A7Riii

SafariBob wrote:

tqlla wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

16:9, 4K wide = 4096 * 4096 * 9/16 = 9.4mpx full colour= 37.6 mpx camera

Used British spelling if that helps cognition for ya

Your math is just way off here.

4K at 3x2 = 3840x2560 = 9.8304MP
4K at 16x9 = 3840x2160 = 8.2944MP
8K on a 3x2 sensor would require 7680x5120 = 39.3216MP

I dont know that much about color detail on a per pixel level.

read the other post. That is why this is not the correct interpretation. Different kinds of 4K. What you are talking about is ultra hd. 4K is 4096. But it’s the same for practical purposes.

But my assumption is that each pixel on a camera sensor is more than just a Red or Green or Blue.

it ain’t.

Is that something you learned from Ken Rockwell?   Open a picture with your photo editor.   Using the editors magnify, zoom into a single pixel in a white portion of the image.

If what you believe is true, that pixel would be red green or blue.

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SafariBob
SafariBob Contributing Member • Posts: 843
Re: A7iii vs A7Riii

tqlla wrote:

SafariBob wrote:

tqlla wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

16:9, 4K wide = 4096 * 4096 * 9/16 = 9.4mpx full colour= 37.6 mpx camera

Used British spelling if that helps cognition for ya

Your math is just way off here.

4K at 3x2 = 3840x2560 = 9.8304MP
4K at 16x9 = 3840x2160 = 8.2944MP
8K on a 3x2 sensor would require 7680x5120 = 39.3216MP

I dont know that much about color detail on a per pixel level.

read the other post. That is why this is not the correct interpretation. Different kinds of 4K. What you are talking about is ultra hd. 4K is 4096. But it’s the same for practical purposes.

But my assumption is that each pixel on a camera sensor is more than just a Red or Green or Blue.

it ain’t.

Is that something you learned from Ken Rockwell?

lol, touché

Open a picture with your photo editor. Using the editors magnify, zoom into a single pixel in a white portion of the image.

If what you believe is true, that pixel would be red green or blue.

It’s not, because it is interpolated. Just like clear image zoom.

edit: this is just marketing from the camera companies, just like hard drive makers use factors of ten bit while os’es use factors of 2. To make them sound bigger. Camera makers exaggerate 300% though not 2-8%

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andrewD2 Veteran Member • Posts: 9,193
Re: A7iii vs A7Riii

tqlla wrote:

SafariBob wrote:

tqlla wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

16:9, 4K wide = 4096 * 4096 * 9/16 = 9.4mpx full colour= 37.6 mpx camera

Used British spelling if that helps cognition for ya

Your math is just way off here.

4K at 3x2 = 3840x2560 = 9.8304MP
4K at 16x9 = 3840x2160 = 8.2944MP
8K on a 3x2 sensor would require 7680x5120 = 39.3216MP

I dont know that much about color detail on a per pixel level.

read the other post. That is why this is not the correct interpretation. Different kinds of 4K. What you are talking about is ultra hd. 4K is 4096. But it’s the same for practical purposes.

But my assumption is that each pixel on a camera sensor is more than just a Red or Green or Blue.

it ain’t.

Is that something you learned from Ken Rockwell? Open a picture with your photo editor. Using the editors magnify, zoom into a single pixel in a white portion of the image.

If what you believe is true, that pixel would be red green or blue.

https://en.wikipedia.org/wiki/Bayer_filter

A7III, A7RIII are both Bayer type sensors. What factor should be applied to compare a sensor that can record RGB per pixel vs a Bayer type has been discussed for years. "x3" has been used on some Foveon cameras in the past.
It has been shown that if there is a single strong primary colour like a red rose the resolution advantage can be significant but the advantage on most images is not so large. 
Andrew

MattPointZero
MattPointZero Senior Member • Posts: 1,055
Re: A7iii vs A7Riii
1

It's not about pixel peeping

Take two good quality, well exposed and focused close studio headshots with a 3 and R3 with a decent 85mm lens, and the difference will be obvious at any viewing size (within reason).

Take a shot of someone standing 10 feet away with a 35mm and I don't think the differences will be anything like as obvious, or significant - unless you are pixel peeping, which is a different thing all together.  That's my experience at least, YMMV

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Indiglo50 New Member • Posts: 20
Re: A7iii vs A7Riii

Can someone comment on the autofocus performance? I have heard conflicting opinions?

https://www.youtube.com/watch?v=X92uJ52Nk84&t=526s

How do folks feel about tests like these, with movement in the Z direction? This video and a few other show A73 outperforms A7riii by some margin? I think this was before the firmware update - did the update help A7riii bridge the gap?

tqlla Veteran Member • Posts: 5,115
Re: A7iii vs A7Riii

SafariBob wrote:

tqlla wrote:

SafariBob wrote:

tqlla wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

16:9, 4K wide = 4096 * 4096 * 9/16 = 9.4mpx full colour= 37.6 mpx camera

Used British spelling if that helps cognition for ya

Your math is just way off here.

4K at 3x2 = 3840x2560 = 9.8304MP
4K at 16x9 = 3840x2160 = 8.2944MP
8K on a 3x2 sensor would require 7680x5120 = 39.3216MP

I dont know that much about color detail on a per pixel level.

read the other post. That is why this is not the correct interpretation. Different kinds of 4K. What you are talking about is ultra hd. 4K is 4096. But it’s the same for practical purposes.

But my assumption is that each pixel on a camera sensor is more than just a Red or Green or Blue.

it ain’t.

Is that something you learned from Ken Rockwell?

lol, touché

Open a picture with your photo editor. Using the editors magnify, zoom into a single pixel in a white portion of the image.

If what you believe is true, that pixel would be red green or blue.

It’s not, because it is interpolated. Just like clear image zoom.

edit: this is just marketing from the camera companies, just like hard drive makers use factors of ten bit while os’es use factors of 2. To make them sound bigger. Camera makers exaggerate 300% though not 2-8%

Okay, I see what you are saying.  But still a 42MP sensor has 42MP of resolution regardless of how the color definition of each pixel is created.

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