All this talk about "equivalence" is silly

Started Jun 10, 2011 | Discussions thread
ffmitch Contributing Member • Posts: 514
Re: It's all silly and don't matter anymore

Ehhh, poopeye. The f/1.4 refers to how much light the lens lets in. It has nothing to do with focal length, distance or the area in focus. An f/1.4 lens lets the same amount of light onto an aps-c sensor, FF sensor or a 35mm negative.

happypoppeye wrote:

ffmitch wrote:

I've read through this thread and can't believe how complicated some of you think this is. You realize that a "Full Frame" sensor is the same size as a 35mm negative(36mm x 24mm) and an aps-c size sensor is the same size as an aps-c film negative (25.1mm x 16.7mm). The c stands for "classic". Put it in "the google". The full frame sensor is 1.6 times larger than an aps-c sensor.

That's why people say a given focal length is equivalent to what would be on a 35mm camera. 10mm on a 60d (aps-c) is equivalent to 16mm on a 5d (FF) or a 35mm film camera.

The 1.6 "crop factor" doesn't change the aperture. When I use my 35 1.4 on my 60d it is still an f/1.4 but the focal length is equivalent to a 56mm lens on a full frame sensor or a 35mm film camera.

Ehhhh. Wrong. The 1.4 relative to the distance or area in focus does change...so much for that comment.

The aperture is changed only if you use a tele-convertor. Such as, a 1.4x (this has nothing to do with sensor "crop factor") tele-convertor would change a 200mm f/2.8 lens to a 280mm f/4 lens on a FF sensor or a 35mm film camera.

35mm is a reference point. The same as water is zero in a specific gravity scale and air is zero in a vapor density scale.

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