How many pixels is overkill?

[Mr. Lips]

For many of us, our photos never go farther than a computer screen.

A typical good computer screen might be 2160 X 3840 pixels.

Multiplying the short side by 1.5 you get 3240, so the maximum photo image size would be 2160 X 3240.

That's a little under seven megapixels, if I'm doing the calculation correctly.

So, why do I need a 24 megapixel camera, let alone 33 megapixels?

When I went to buy an upgrade from my a7 II, I paid extra to get the IV instead of the III, mostly because it has more megapixels.

Did I waste my money?  Are most of us wasting money?

 

[Pieter]

13 minutes ago, Mr. Lips said:

So, why do I need a 24 megapixel camera, let alone 33 megapixels?

You don't, unless you're planning to print large or want to have some leeway to crop in post for better composition. I've had 24MP cameras for the past decade and never have I felt that the amount of pixels was holding me back in any way.

As for the A7iv vs the A7iii: there's a list of features that the A7iv improved upon over the already excellent A7iii, the least interesting of which is the megapixel count (to me at least).

[Cameratose]

This is highly dependent on the expected output medium. I have 22" x 28" prints in my office from a 20MP M-4/3 camera that look great, but I upscaled them before printing. I also have 33MP images printed the same size that have been cropped, no upscaling needed.

I bought an A1 for two reasons: MP and speed. The speed is self-explanatory as I shoot action. The MP takes a bit more discussion. 

The vast majority of people look at images on a tiny little cellphone screen. For that, almost anything will work. 1MP will fill the bill.

A typical 'good' computer screen is actually 4K, which translates to 4096 x 2160 pixels display resolution, or 8.8MP. You need 8.3-ish MP to meet 4K minimum. Given that, an 8-10MP camera will give you a solid image on a 4K monitor.

So, why do I need 50MP? There are times when I'm shooting that distance is a problem. Things happen fast and sometimes I can't be as close as I'd like. Many times, the subject is moving away from me, quickly. In those cases, I have to crop to get the desired composition. I try not to crop too much because I sell my shots, and sometimes the buyer wants the subject to be 'closer', which means even more cropping. 

As long as I'm selling a print it's not a big deal because I can control what goes out. The problem comes when the buyer wants the digital file that the customer buys the full rights to. Flyers, hero cards, advertising, etc. Most of these people have no idea how cropping can affect the final product. They could take a 24MP file, 'cut out' the part that they want which could end up 3 or 4MP, print it at 24" x 30", and then wonder why it looks all blurry.  

From my standpoint, I want there to be as many MP in the digital file I send out as possible. I just feel safer having the extra resolution in case it gets butchered.      

[Pieter]

6 hours ago, Cameratose said:

The vast majority of people look at images on a tiny little cellphone screen. For that, almost anything will work. 1MP will fill the bill.

Which is why I really don't understand the megapixel-war in smartphones. Cheap phones are being advertised with having 108 MP or more cameras. But this is really marketing for the ignorant. To me it's a downside really: it means excessively large files with low quality (noisy/blurry) pixel detail.

6 hours ago, Cameratose said:

I have 22" x 28" prints in my office from a 20MP M-4/3 camera that look great, but I upscaled them before printing. I also have 33MP images printed the same size that have been cropped, no upscaling needed.

Do bear in mind that even if you print large, high resolution is only needed if the print can be viewed (and should be appreciated) up close. 24 MP is perfectly fine for a huge billboard print which is viewed from 10's of meters away.

6 hours ago, Cameratose said:

 

From my standpoint, I want there to be as many MP in the digital file I send out as possible. I just feel safer having the extra resolution in case it gets butchered.      

Those are all good points you make, which might all be relevant to professional photographers. For amateurs/enthusiasts, high MP is mostly about some cropping headroom and the perceived sharpness of the images when edited in their favourite post-processing program. Oh and the desire to buy something 'better' than the previous generation. No viewer - other than the photographer - will ever appreciate the high MP used to take the shot. I dare to say that for all amateurs/enthusiasts, 12 MP covers 99% of their needs.

[Mr. Lips]

I'd be interested in knowing what upscaling is, even if I never use it.

When I worked (I'm retired) I would, occasionally, print a photo, from one of my trips, and post it where I could look at it while I worked.  A way to escape the drudgery.  But I never went past standard home printer size and quality.  Now, what I hope for my photos is they will make it into a trip report for my canoe club or get shown on a website like 500px.

Although I don't do it very often, I can see the need for enlarging a small, cropped portion of a photo.  For instance, I want to get a photo of an odd bird, that is coming to my feeder, but I don't have a long telephoto.  I may end up taking a photo with my 75mm and enlarging a small part of it.

 

Most of the big advantages of the a7 IV over the III have to do with autofocus.  Currently, I'm not in need of it, but I'd like to go beyond landscape type photos for my club reports.  More toward photojournalism type photos.  I want to tell the story of the trip, not just show a bunch of pretty pictures.  Then, I'll have more of a need for what the IV will do.

[Pieter]

1 hour ago, Mr. Lips said:

I'd be interested in knowing what upscaling is, even if I never use it.

Upscaling is just increasing the resolution of an image by interpolating/resampling the missing pixels and perhaps apply a little sharpening. Though this doesn't increase the actual detail of an image, it does improve the perceived quality when viewing a large print up close as the pixels are much smaller. Nowadays AI techniques can be used to actually create (fake) detail in missing info, much improving the quality and potential of upscaled images.

Edited February 2 by Pieter

[FunWithCameras]

It seems you think that you only need as many pixels in your camera as you want to display or print.

There are good reasons to use more pixels.

First off, you need to consider the desire to take photograph a little more loosely, and crop to get the final composition.

Secondly, you can use a higher resolution and then scale it down to get your final image - you get cleaner and sharper images than you can shoot. It also reduces any random noise in the image by "averaging it out".

[Pieter]

1 hour ago, FunWithCameras said:

It also reduces any random noise in the image by "averaging it out".

To call this a benefit of high-res cameras is a bit nonsensical as cameras with larger pixels have lower noise to begin with. Best case scenario is that the noise 'penalty' of high res cameras is largely negated when downsampling to a lower resolution.

[Cameratose]

6 hours ago, Pieter said:

Which is why I really don't understand the megapixel-war in smartphones. Cheap phones are being advertised with having 108 MP or more cameras. But this is really marketing for the ignorant. To me it's a downside really: it means excessively large files with low quality (noisy/blurry) pixel detail. 

Do bear in mind that even if you print large, high resolution is only needed if the print can be viewed (and should be appreciated) up close. 24 MP is perfectly fine for a huge billboard print which is viewed from 10's of meters away.

Those are all good points you make, which might all be relevant to professional photographers. For amateurs/enthusiasts, high MP is mostly about some cropping headroom and the perceived sharpness of the images when edited in their favourite post-processing program. Oh and the desire to buy something 'better' than the previous generation. No viewer - other than the photographer - will ever appreciate the high MP used to take the shot. I dare to say that for all amateurs/enthusiasts, 12 MP covers 99% of their needs.

The OP didn't specify professional or amateur use. He just asked why someone would want more MP. 

The viewing distance argument gets kind of tired when discussing a framed print. Obviously, you can walk right up to these images and view them in detail. Viewing distance comes into play when talking about wall murals, billboards, etc. A billboard can be printed at less than 1MP and still appear clear from 1000' away. The link below might be of interest to the OP:

How Many Megapixels Do You Need to Print a Billboard? | Fstoppers

I believe the megapixel wars are over, at least with regard to cameras. Someone may still introduce cameras with higher MP counts, Sony is likely to do it just to prove they can, which is really the impetus behind the A9 III. However, the release of the A9 III and Canon's R1 both at 24MP should tell anyone what they need to know. When it comes to cellphones though, that may not be the case. Bigger is always better, and the typical cellphone purchaser isn't the most informed buyer when it comes to camera related specifications 

Your point to @FunWithCameras isn't a given anymore. Improvements in sensors and processors have rendered this down to more of a case-by-case basis rather than the generally accepted fact it used to be. 

[Pieter]

3 hours ago, Cameratose said:

The OP didn't specify professional or amateur use.

Indeed, which is why I provided all points elaborated on by you concisely:

19 hours ago, Pieter said:

you're planning to print large or want to have some leeway to crop in post for better composition.

As to OP's use case:

3 hours ago, Cameratose said:

The viewing distance argument gets kind of tired when discussing a framed print.

I already covered this in my post. Matter of fact, today I was standing in a bus-stop right next to an A0-size printed ad with a portrait and thought to myself: boy would this have been ugly if the print was all pixelated. So indeed, of you print really large and the viewer can stand close, megapixels do matter.

3 hours ago, Cameratose said:

Your point to @FunWithCameras isn't a given anymore. Improvements in sensors and processors have rendered this down to more of a case-by-case basis rather than the generally accepted fact it used to be. 

It was just a response to @FunWithCameras suggestion that high MP sensors have a factual benefit over low MP sensors when it comes to noise performance at same MP. There is no such advantage, period. There is only an advantage of generational improvement of technology and implementation in specific cameras, much like the point you're making.