So straight for the very beginning, I won’t be hiding anything from you. Maybe that is bad for storytelling, but I like people with opinions. I believe there are too many gooey, jelly people out there.
In general, you need it all. If you want to make awesomely-looking films and videos, you just need it all. Plain and simple. That is also why filmmaking is so hard, and so many people are needed. So yeah, ideally, you need an amazing lens, and fantastic camera body, and tons of other stuff too. But if you are like me, a normal human being, without a fortune that you inherited after a recently deceased, mysterious family member, then you need to make strategic decisions based on your budget.
In my opinion, the camera body is the most essential tool. And if at the start you can have only one lens and one body, I would spend much more on the camera body. Here is why.
Camera Body
Consider the camera sensor. This is the part that catches the light and registers analog images. So directly. Better the sensor -> better the end image. If you have a very good lens, and a crappy sensor, the image still will be weak. It will lack information for you to work with.
Like with many things in life. Size is not all that matters. Sometimes it’s skills. 😝 Same with a sensor and a camera. They do not have to be big to be good. They usually are though. I think… (awkward moment)
Camera body means also electronics. So how the image/video is recorded, what format, color depth (how many colors – plainly speaking), how many different audio tracks, encoding, chroma subsampling, raw format, etc.. All that directly affects what you can do with your video later. Because shooting the video is one thing, but editing it, so it looks good is another.
Dynamic Range. In simplest words, dynamic range is a spectrum of brightness values possible to register, from dark to light. So how big a difference in light is, that your camera can register. And this directly affects the image quality, and what you can do in postproduction. Especially if you are after a “film look”, you need a nice, wide dynamic range. It makes shots like “man standing in front of the window” so much easier.
A good, modern camera body will have a Dual Native ISO. Since Panasonic Varicam invented it for the first time, that is a must. Dual Native ISO will help you to control this ugly digital noise you can see sometimes, when recording videos with your phone in a dark room. This will affect how much light equipment you will need for your shots. Basically, in this era, I see no option me buying a camera without this feature.
A good camera body can help you greatly in achieving the desired look. For instance, additional tools like Zebra, or Waveform, or LUTs, handling multiple audio tracks, how you can customize your buttons, and more. All that adds to the mixture.
One big reason to start with a body is operational complexity. The lens is usually very simple to operate. Even the most complex ones, you can figure out how they work in minutes. Camera on the other hand is a great complexity of hardware and software. It takes time to learn it, and even more time to master it and configure it in a way, that works best for you. So naturally it is much easier to change the lens than to change the camera. Of course, as you will turn pro, you will learn your way to work with pretty much everything. But still, you will have your preferences, and with well-known systems, you will be able to be more efficient.
Lens
One of the biggest reasons to buy a great lens (consumer level) is usually autofocus. I almost don’t use the autofocus feature. Maybe except pictures and some YouTube shots. But even then, I tend to get away from it more and more. And when I shoot for film I don’t use it at all. It may feel scary at first, but after a while, you learn to let this go, and it is a big change in how you approach filming. In a professional situation, you may have a Focus Puller with you, who will take care of focus for you much smarter than any automatic system. On the other hand, if you are alone, learning how to shoot manually IMHO is a necessity in a pro situation, so the quicker you learn it, the better for you. All the professional-grade lenses are manual.
Also, the focus is an artistic decision. I feel (or maybe I just don’t know how to set up autofocus properly!), that when you have a situation, where you could profit from a good autofocus system, then it fails. For instance at 1.4 aperture, or some dark scene with a mist filter on. It’s really hard to see then. But it is also when autofocus is lost.
I rarely use apertures below 2.0. I usually shoot at 3.5 +. If you consider that, lenses that can go only 3.5 wide are very affordable. I use apertures like 1.4 or 1.8 when shooting product shots, or capturing some more personal moments when close-ups are a must.
Modern, very sharp lenses provide amazing image quality, that filmmakers were hoping for for years. But, when we achieve this level of quality, more often we search for vintage lenses and reserve cynically clean images for special occasions. As a matter of fact for most cases, if I shoot with a modern lens, I will need some additional effects to make it look more organic. So I would add a vignette, or some filter, or other effects. So in my mind for most situations it looks absurd: buying clinically clean and sharp lenses for massive sums of money, then putting a mist filter over it, and using complex software and effects, to make it look more imperfect.
So eventually, I started to shoot with old lenses. Lenses that are imperfect from definition. They are relatively affordable and come in different properties. In a way, learning to use imperfect lenses taught me more about images, and pushed me to explore looks that I like. Before I was considering the lens, as specific aperture and focal length, period. Now I consider so many different properties of the lens, and that is only because I started to explore more and more. Using vintage glass, you can afford those experiments quicker, so you learn at speed.
Final Words
Considering all of the above, If I would start now, I would consider a body to be more important. That is an investment that in a way allows more exploration and experimentation, which are essential parts of artistic growth.
I think in general, it is important to treat filmmaking tools as tools, part of your craft. And leave emotions totally out of it. Buy exactly what you need, and don’t pay for stuff you don’t need (in my case autofocus). Go and try many different things. Only that way you learn, and start to make artistic decisions not based on smart advertising of selected brands. What we talk about here applies to camera bodies, lenses, but also lights and other film stuff. You just can’t have it all. It’s impossible.