This is the ninth in a series of posts on the effect of camera resolution on the quality of downsampled images. The series starts here.
When I started this series of tests, I didn’t expect it to take so long. But I’m glad I did it; I’ve learned a lot in the testing, and now I’d like to tell you what I think I’ve learned. But first, I’d like to explain my motivations. I love to print, and I still consider the print the highest expression of my photographs. But the proportion of photographers who feel that way seems to have diminished dramatically in the last decade. There seem to be many people who purchase their cameras with no intention of ever making large prints, and some of those say they don’t intend to make prints at all.
A lot of those non-printers are buying high-resolution cameras, which I’ll define for the purposes of this series as 42 megapixels (MP) and up. Why? Do these folks have 8K displays at home? Are they future-proofing? Many of them say that a 50 or 60 MP camera produces a better image than s lower-res camera, even when the captures are viewed on a 4K (3840×2160 pixel) display. I have noticed such improvement in the past, but it seemed to stop when the downsampling for the display resulted in a magnification of less than 50%. Since a 24 MP FF camera produces an image 4000 pixels high, that thus requires a bit less downsizing than that to get to an uncropped 4K screen-filing image, it would seem that 24 MP would be plenty for those whose primary way of displaying images is a 4K monitor.
A lot of people don’t see it that way, and are snapping up 50 MP and 61 MP cameras to make 4K images. As an aside, there is a smaller, but sometimes vociferous group of people who say that you never need more than 12 MP no matter how big you print. I guess it takes all kinds.
Here is what I’ve gleaned out of all my testing.
- Before downsizing to 4K, in the range tested (12-61 MP), increasing the resolution of the sensor results in greater detail, more sharpness, less false color, and less aliasing. We are in no danger of having the sensor be the limiting factor on sharpness, even with modest lenses and apertures narrower than optimum. It wasn’t part of this test, but the testing I’ve done with the GFX 100 indicates that all of the above benefits to increased resolution continue to at least 100 MP, and the simulations that I’ve done show those trends continuing until about 800 MP.
- With some test targets, increasing the resolution of the capture increases the quality of the 4K downsampled image in some respects across all the resolutions tested.
- With more realistic subjects, increases in image quality in the images is minor across all the resolutions tested, and especially so at 24 MP and higher resolution.
- The most common defects with low-resolution captures is false color due to the Bayer color filter array (CFA) and aliasing.
- Below 24 MP, there is also some small loss in sharpness of the 4K images.
- With test targets, the algorithms used for downsampling can make a difference in the aliasing and sharpness in the 4K images.
- With real-world images, there are many algorithms that yield nearly equivalent results.
- The above similarities between 4K images from captures of varying resolution apply with the best lenses, at optimum apertures, in the center of the frame. If you relax any of those constraints, the images will become even more similar.
- Photoshop’s export downsizing algorithm is excellent at reducing aliasing, and not bad at preserving sharpness, though there are sharper algorithms.
Netting it out:
I think that almost all photographers who intend to view their images at no higher resolution than 4K would be well-served with a 24-MP camera. There is little return in that application of a 42, 45, 50, or 61 MP camera.
A few caveats:
- There are many downsampling algorithms that I didn’t test, and several that I did test, but did not report on here.
- All my tests were performed at low ISO settings. There are advantages to higher resolution cameras with respect to trading off noise and detail using nonlinear noise reduction algorithms. I didn’t test those.
- There are some people who regularly crop a lot. I don’t, at least in both directions at the same time. If I need to crop much in both directions, it’s because I’ve erred in camera selection, lens selection, or my conception of the image. If you’re one of those people who routinely crop a great deal, than you will be better off with more resolution to start out with.
There are people who enjoy not only the whole picture on a screen, but to be able to zoom to a specific part of the frame @ 100%… so no, I don’t want 12mp camera for a 1920×1200 monitor… I like to zoom in into my 42mp and more and see more details from the specific part of the image … I am not sure why’d you miss this simple point ?
Are you saying that your viewers want to do the zooming in? Or is it just you doing the zooming in?
An interesting philosophical/artistic/technology-dependent point. So, “N/A” is treating the viewing experience (on a monitor) as an interactive experience. And he thinks the viewer wants that too. Whereas I, as an old-timer used to prints, think of the print (with whatever framing, and/or crop in post) as a fixed, definitive choice by me, as the photographer, about what I want to “say” photographically, and that the photograph is to be viewed as a whole. I suspect that you, Jim, think similarly to my approach.
First, it’s not clear to me whether N/A is talking about his experience with his own photographs, or including his viewers’ experience. If the latter, it’s not clear how he provides his audience that experience. If he responds to my question above, we can continue the conversation.
Second, I’ve noticed when people view my work at exhibitions, they view it from a distance, then move in to look at details, then back away again. I have no problem with this behavior. I would have a problem if they just viewed the work from so close that they couldn’t take in the whole image, since when I design an image, I mean for it to work as a whole.
> since when I design an image, I mean for it to work as a whole.
Fortunately unlike a “(c)” you can’t legally prohibit people to look closer 🙂
I am my own viewer myself first of all ! … I respect people who only want to view a picture as a whole – but they need to understand that there are sufficient amount of people who like to ZOOM IN
Thanks for clearing that up. I view photography as a communications medium, and I don’t understand people who don’t, so what I say probably doesn’t apply to you at all.
https://blog.kasson.com/the-last-word/gourmet-cooking-for-one/
Jim
Personally I like zooming in. Imagine if cameras were so good, most people don’t even need macro lenses anymore, because they can just zoom, zoom, zoom. That might not even be possible, but that’s what I’d like. Half of the time, I am shooting to replicate reality in as high detail as possible. To me, all cameras today are nowhere near as good as I’d like them to be.
What gear people need really depends on what people want, and different people want and approach image viewing very differently.
I recall reading some research, decades ago, that monitored eye movement and gaze location of radiologists viewing x-rays, and of automobile drivers in a driving simulator. If I remember correctly, the results even for those highly-important tasks did NOT inspire confidence that the viewing was being performed as well as it should have been. I wonder if there exist any scientific studies (as opposed to just anecdotal observations) about how people view photographs. I’d expect considerable variation depending on both the photographic subject matter, as well as the person.
Quite a lot, actually, if you extend to art in general. For example:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170918/#!po=27.7778
@Graham Byrnes:
Thanks very much for that reference as an entry point into the research literature. If I follow up on some of its citations and the PubMed “cited by” and “similar articles” reference chain (as I intend to do), I think I’ll find it all very interesting and instructive. (The only downside is how much time I’m likely to spend at it, dammit!)
I’d suggest that they are far better than reality. You don’t normally get to zoom at all: you can go stand closer, but the scene will change while you are walking. Typically, if the scene involves people doing things, they will not hold still while you approach so that you can count their eyelashes, yet you can do that already with a 24MP APC and adequate AF.
What you are describing sounds more like a magic box able to freeze the world, leaving you the magic possibility to wander about inside the scene. These don’t exist… the best a photograph can do is to freeze your view of the scene, assuming you were paying attention. The camera is a device for freezing what you could *see*, not what *is*.
Personally, I feel that it makes good sense to compose the image in the camera. But I usually leave a little margin for cropping. It may be that I want a little bit more of that tree and so on. I am not a cropper, but I am not religious about it either.
Many times, it is much possible to take more pictures and stitch. I would do it if aspect ratio is not a good match. That of course depends on the subject. I wouldn’t do that shooting show jumping.
I am mostly shooting kind of landscape. Getting a good vantage point is not always easy. Zooming with your feet sounds like a good idea, but it is not always practical. Just to say, I cannot walk on water. I have heard about someone who could, but the book is less than clear if he could also use a tripod on water.
Also, moving around changes perspective. So, zooming with your feet means a different perspective.
Zooms allow to chose crop, but they give up on some image quality.
Using fixed focals, you are limited by what you carry. For my Hasselblad I had 40, 50, 60, 80, 100,120, 150, 180 mm lenses and a 2X extender. But, I cannot carry all that. So I ended up with 40, 60, 100, 120, 180 and that extender.
Why having both 100 and 120 mm? Because the 120/4 is intended for close up work while the 100/3.5 is intended for long distance.
With fixed focals, I still look for a vantage point. But, once it is found, I try to find the best composition to match my lens options.
So, with zooms: Find vantage point, find composition, shoot.
With primes: Find vantage point, find best lens and find best composition for it. This may be an iterative process. Once all pieces are in place… shoot.
Sitting at the computer at home or in my RV I may find that I messed up DoF.
A year ago, I tried to stitch two shots of a fern and the root of a three:
https://photos.smugmug.com/Tankworthy/i-WNvgBWg/2/32aedd6a/X2/20180926-CF047721-X2.jpg
https://photos.smugmug.com/Tankworthy/i-Dm4px8J/2/088e3755/5K/20180926-CF047723-5K.jpg
It didn’t work out so well…
But, fortunately, I was able to reshoot it a month later:
https://photos.smugmug.com/Tankworthy/i-pfL9HMd/1/ea34e510/5K/20181010-_DSC1234-5K.jpg
Here I used tilt with 35-135 Sonnar made for the Contax RTS system:
https://photos.smugmug.com/Tankworthy/i-pfL9HMd/1/ea34e510/5K/20181010-_DSC1234-5K.jpg
In this case I was very lucky. Usually, you have just one time to nail a shot…
World changes.
Where as in the past, one was “forced” to enjoy the photograph in the size the photographer printed it out, today that no longer applies, thanks to modern technology.
In one end, we do have highly popular services like Instagram, which will force you to work on rather post stamp size images that frankly do not benefit at all from modern sensor development outside of maybe making ISO12800 and so on usable. Here, we are force to enjoy the image in the size the delivery medium forces us. It is like a image in a newspaper.
But then there is services like Prodibi, which allows photographer to determine the resolution, and viewer to determine how deep they zoom into. This is more relevant in the times of mobile phones, where the display is ridiculously small (yet high resolution). Yes, the IG restrictions are partly due to the small screens. But zoom in into a high res work approach will also allow mobile phone users to take a closer look, just like in an art gallery.
Does the closer look mean anything, shouldn’t image be only absorbed as a whole? Sometimes yes and sometimes no. If we look at photographers who make big bucks today, many of them tend to print ridiculously large, with one key aspect being studying the image and details by going closer to the image. It is impressive and also immersive experience to study those small things you first didn’t even notice. It is (in many ways) a new experience in photography, although 8×10″ have produced enough resolution for huge prints for decades. Now, with services like Prodibi, one can achieve this at anywhere and anytime even through their mobile phones.
On a very modest aspect, switching to a 4K Retina display was a revelation : many of my images came out much sharper and more beautiful than I thought they were…. Now I’m almost “addicted” to that kind of display, also considering the color quality. Is it explainable by your findings ?
My findings don’t address that question, since, presumably, your captures have higher resolution than 3840×2160 pixels.
Now that I have a Sony A7r3, I have sold my 35mm 2.8 Sony lens and use my Batis 25 mm and crop as needed. I am considering selling my Sony 24-105 too, and use my Batis 85 mm for the long end and crop as needed.
And yes, I print. Mostly A4 but sometimes A3 and A3+.
Interesting investigation, so thanks. To answer the specific question, I generally prefer to frame my pictures accurately when i take them, but there are plenty of special cases:
– If I take primes with me, I use digital zoom/crop to frame
– I often crop one side for different formats
– I usually keep the lens axis horizontal on UW so need to crop the bottom
– With big sky I often need to chose the best crop in PP, so either a take a lot of shots and pick one, or I take a wider angle and crop a lot.
In addition, some of us who rarely get around to printing, or have little room to put prints up on the wall, have changed to viewing on screen INSTEAD of printing. Zooming in to details on-screen is the modern equivalent of standing closer to the photo and using a magnifying glass!
This is especially nice in landscapes and city views where you can see the whole picture to get a feel for ‘where you are’ and zooming in to see details.