On Formats and Sensors

Why do photographers use different cameras? Why for example would they choose to photograph with a large format, cumbersome old camera versus a nice new modern 35mm DSLR? Why do some photographers prefer using a Pentax 645 or a Hasselblad 6 by 6 for their work? And why on earth would some photographers choose film over digital?

I want to say first of all, that even though photography is a visual art and the end product of what we do is something to study and look at, it is also an activity that is based on process. Therefore image quality aside, some photographers very much enjoy the process of shooting on large format compared to how easy it is to snap an image with say a cellphone or a 35mm point and shoot.

But in terms of image quality, let’s consider a few of the most important differences between formats.

1.) The larger the format or sensor size, the less depth of field and the better the separation between focus planes in the image. Typically when you go to a larger format you need a longer lens to get the same image coverage. And although you could shoot at a smaller aperture to compensate for the depth of field difference, the image is still rendered differently. Image planes are separated better and with a sharper transition than wider lenses can accommodate.

2.) The larger the format or sensor size, the greater the dynamic range and the more subtle the transitions between adjacent luminosities. This is perhaps the number one reason many landscape photographers tend to choose large format cameras. Not only are they typically shooting scenes with large dynamic ranges, but they also tend to print big. Some modern DSLR cameras handle dynamic range quite well while others do not. The capture curve on some cameras is very linear producing unnatural looking tonality. And there are some cameras that may have a smaller actual dynamic range, but they have a curve that renders the high-mids to high luminosities in a much more gradual and natural looking way.

3.) The larger the format or sensor size, the larger the image receptors and the more spread out over a greater area they are. This results in better signal to noise ratios which are perceived as better edge definition and clarity. And, when viewing large prints up close, certainly more pixels per inch is a huge part of what gives us the sensation of being immersed into a scene rather than just say looking at some flat rectangle from a distance.

An interesting aspect to this story that most people do not realize, particularly when it comes to tonal transition and resolution, is that most web images simply cannot show you these differences. In fact it’s not until you start to display images that are at least 3000 pixels in size that you will begin to appreciate this. Not many people are in the habit of outputting 100 percent crops of their web images or displaying them in that size. 4k monitors are becoming much more prevalent, but even still, the typical size of a web image and that kind of downsizing of a high resolution sensor cannot possibly yield any advantage to resolution or edge acuity, the very reasons why we think we should choose a large format camera.

So this brings us back to the question of why we need to shoot with a larger format camera or sensor size. I’d like to think that most who shoot these kinds of cameras are in the habit of outputting their images to large prints. But there are also those who simply choose to shoot different formats because it is the “process” that they enjoy regardless of the image quality. It is indeed a whole different thing to shoot a large format camera compared to a 35mm.

And lastly, why do some photographers choose film over digital? It’s been my experience that the response curve of film is very much like what we see with very gradual tonal transitions in the high end, whereas most digital cameras, particularly those with smaller sensor sizes have rather unnatural and abrupt response transitions to clipping. Trying to capture large dynamic range landscapes with an iPhone is going to produce images that not only suffer from poor resolution, but may have unfavourable highlight clipping or poor colour rendering. Cell phone cameras have really improved of late, and may be a huge advantage as far as stealthiness and convenience, however, they are not the camera of choice if you’re looking for high output resolution or image plane separation.

This all brings us back to what I’ve mentioned in many of my previous blogs about things to consider when choosing a camera. You need to look at and consider your end goal. If you’re only interested in printing the occasional 4 by 6 or outputting your images to Instagram, then why are you using a medium format sensor or a DSLR with a massively high resolution?  I hope your answer is because you enjoy using the camera and not because it gets you more likes. (But we all know that those of us who still shoot film cameras are cooler right?)

Something to think about…

Happy Shooting,

Doug