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Focal length movies vs stills (1 reply and 9 comments)

Dolenc
8 months ago
Dolenc 8 months ago

Hello everyone and especially James and Roger.

I've listened to a lot of fantastic topics on Team Deakins podcast, but otherwise I'm new to this fantastic place on the web.

I don't know if this has been debated already but this topic really intrigues me right now. I'd like to talk about focal lengths in stills photography and in movies. Why do stills photographers use narrower lenses for than most movies do? It's totally common for a photographer to use 80 mm or even 100 mm lens for pa portrait when in movies you wouldn't go further than up to 50 mm?

I can think of a few reasons but want to hear your opinion first.

Cheers!

dmullenasc
8 months ago
dmullenasc 8 months ago

Field of view is determined by the focal length plus the sensor size (crop factor). Smaller sensors crop more so use shorter focal lengths to achieve the same field of view. “Full-frame” is usually around 36mm wide and Super 35 and APS-C is close to 24mm wide, so that’s a 1.5X crop factor, so those smaller formats need to use a focal length that is 1.5X shorter to match field of view. Hence a 50mm instead of a 75mm, etc.

Dolenc
8 months ago

@dmullenasc Thank you for your answer.
I get all of this about crop factors when talking about different sizes and field of view and stuff ... I get that.
But the crop factor speaks only about the field of view but not about how longer focal length compresses your face and it's characteristics and how it changes viewers perspective of a subject on the screen.
Also considering only field of view then lenses' focal length should change considering what size of sensor the camera in use has. But Roger shot his 1917 movie (Arri LF sensor is full frame) with just as wide of a lens - 35 mm and 40 mm.

dmullenasc
8 months ago

That’s a common misunderstanding - the perspective on a face (size of ears relative to the nose, etc.) is determined by camera/lens distance, not focal length. The “compression” of the face is the same on a 50mm in Super 35 as it is on a 75mm in Full-frame if the distance is the same. Relative sizes of foreground to background objects isn’t even a lens issue, the same principle works on your eyes, it is a perspective issue determined by your spacial relationship to the world.

dmullenasc
8 months ago
dmullenasc
8 months ago
Dolenc
8 months ago

That does make sense yeah, when I think about it. Thank you for pointing that out.

dmullenasc
8 months ago
Dolenc
8 months ago

I will definitely take a closer look at these links. Thanks a lot!

dmullenasc
8 months ago

A zoom lens would show you that facial perspective/compression is determined by the distance and not the focal length. The proportions of the face do not change as you zoom in or out. But back up the camera and the face gets “flatter” because the distance of the camera now makes the distance from the ears to the tip of the nose relatively smaller to each other.

Dolenc
8 months ago

Yeah. When you put it that way it makes sense.

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