A7iii vs A7Riii

Started 2 months ago | Discussions thread
andrewD2 Veteran Member • Posts: 9,190
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.


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. 

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