We've all heard it. "If only (fill in the blank) camera had a full frame sensor, I'd be able to use it." Or, "The image from the GH4 sure is great, but I just couldn't get used to a Micro 4/3 sensor." If you've spent any time reading editorial comments about digital cameras in the past 5 years, then you're almost certainly familiar with these types of statements. While different sized sensors can provide substantial differences in both aesthetic qualities and low-light performance, the argument that's most often thrown around in these discussions is about "crop factor," or the relative field of view from one sensor size to the next. Personally, I think it's about time we put the issue of sensor size into perspective so that we can stop making goofy, arbitrary statements like these. Zack Arias over at DedPxl agrees, and his new video does a fantastic job at providing that perspective.
For photographic applications (not filmmaking applications, mind you), there has been a belief for some time that 35mm is the minimum sensor size necessary for "professional" work. Here's Zack Arias' video, which promptly tears down that dogmatic belief:
At this point, you're probably saying to yourself, "That's all well and good, internet guy, but we're filmmakers, and those larger formats don't apply to us, so we're going to keep arguing about crop factors." Not so fast, internet people! In order to understand why crop factors are largely an arbitrary and irrelevant discussion to be having, we need to take a look at the historical context provided by the frame sizes of traditional filmmaking formats. A vast majority of the films that have been shot over the past 100 years originated on 35mm film. Many people mistakenly believe that the imaging planes of motion picture 35mm film and photographic 35mm film (which we refer to as "full frame") are, in fact, the same size. This is not the case, however. Here's a nifty graphic from Noam Kroll that shows a relative comparison of motion picture and photographic 35mm frame sizes.
As you can see in the above comparison, 35mm motion picture film has a significantly smaller frame size than its photographic brother. Based on that alone, we can put to rest the idea that full frame 35mm is the standard frame size for cinema applications. With that out of the way, let's take a look at how the frame size of traditional 35mm motion picture film compares to the size of some of our more modern digital sensors, such as the sadly maligned APS-C. This comparison chart from Prolost sums it up nicely.
This chart really nails what I'm trying to get at with this post. In the Zack Arias video above, he says that the relative difference between full frame and APS-C is negligible. In fact, he repeats that sentiment quite a few times to really drive the point home. For filmmakers however, where the historically-standard frame size is actually smaller than "full frame" 35mm, the difference is even more negligible.
Of course, despite the fact that APS-C is the closest size to what cinema is traditionally shot with, the Canon 5D's massive popularity in the late 2000s had some interesting effects. For one, it sewed into the collective consciousness of a new wave of DSLR filmmakers the idea that full frame is the standard frame size for all cinema applications. Instead of viewing APS-C cameras as the modern equivalent to motion picture 35mm film (at least in terms of frame size), DSLR filmmakers starting comparing everything to full frame. All of the sudden, APS-C cameras had a 1.6x crop factor, and that was inherently a bad thing.
So let's get this straight. Comparing a sensor's field of view to full frame 35mm film makes no sense, and we should all stop doing it immediately. There, I said it.
Larger sensors do have some advantages, like more easily-achieved shallow depth of field, and they can be far superior in low light situations. With that said, large sensors aren't inherently superior than their smaller counterparts in other areas of image quality, especially areas like dynamic range.
Ultimately, what I'm getting at is that we need to stop arguing about crop factors as if they are some kind of all-important and defining characteristic of image creation. We have the ability to choose from any number of formats - full frame, APS-C, Micro 4/3, s16 - and those formats have differences in field of view and aesthetics. That's just how it is. Some formats better meet the needs of certain shooters and certain stories, and determining those needs is a crucial step in figuring out which camera system to use. But if we keep arguing about crop factors, then chances are we're not spending that time doing something productive, like shooting.