Filming, Video Production Tips

Fixed Lenses & Determining The Best Focal Length

admin / July 12, 2012

Go to any electronics store and pick up a handy cam. Even with that tiny little lens on there, they boast about their 700x digital zoom. But, when you zoom in digitally like that, the quality of the image drastically degrades and you’re stuck looking at a blocky mess when you get past the 10x mark. So that 700x is worth zip. Hopefully you’ve moved on from those lower end cameras and have yourself a DSLR and a zoom lens. And now, if you really want top notch image quality and the ability to get that crisp Hollywood look, take the leap into the world of fixed focal length lenses.

With a fixed focal length lens, you don’t get any kind of zoom out of it. You pick a lens, hook it on, and that’s the millimeter you get. Kind of like the human eye… You can’t zoom with these suckers and when they’re working properly, they deliver a pretty nice image to your brain, so why not try to recreate that in camera?

The main advantage here is that fixed focal length lenses have less glass in them, so they let in more light to give you that ultra shallow depth of field we’ve talked about before, and the image sharpness gets bumped up to the next level.

Lenses range from fisheye lenses down in the single digit millimeter range all the way up into the thousand millimeter telephoto range. To give you some perspective, the human eye sees about what a 22mm lens would see, and that will be our starting point. Moving down from there will bring you into fisheye territory. The lower you go, the more of the scene you’ll see, and the more distorted your image will get. The low focal length makes it easy to keep your subject sharp, but you get a super deep depth of field. Everything is in focus and there’s not much you can do about it, except, ya know, put another lens on it.

Putting on a higher millimeter lens will really help ‘crush’ that depth of field, but doing so can be tricky. The shallow focus really gives you that Hollywood polish, but only if you can keep your subject sharp. If you can’t manage that, you’re going to be stuck with a bunch of blobs moving around your shot (and no one is going to want to look at that). Long lenses are more for low movement detail shots (NOT really for sports or interviews), but the quality of the images you can produce are incredible.

Moving up to fixed focal length lenses is a huge step for beginner cinematographers since it basically means you’re stepping out of the amateur realm and working like a pro.

Read our other Video Production Tip blogs, watch the videos, and give us feedback about what you would like to learn next!

Allow others to StumbleUpon this article, click below!