Focal Length Calculator

I’ve talked about lenses so much. But I’ve never actually done a post about Focal Length Calculator!

Focal Length Calculator is those main numbers you see on your lens. Like: 50mm or 24-105mm or in some other more advanced lens 70-200mm.

You may already know the basics of these Focal Length Calculator numbers and that 50mm is ‘wider’ than 200mm. And 24mm is even wider than 50mm. And 200mm is ‘zoomy.’

But do you know what it means Focal Length Calculator? Well, then, I’ll tell you!

How to calculate the focal distance to the lens range?

Focal Length Calculator

Focal Length Calculator

Focal Length Calculator is the amount of space (in millimeters) from the optical center of your lens to the camera’s sensor. Much like a magnifying glass, the further away the glass is stretched from your sensor, the more magnified the subject will be in your viewfinder. Also, on the sensor when you capture the image.

As an example, if you have a 50mm prime lens, you have a focal length of 50mm. Moreover, if you have a zoom lens varying from 24mm to 70mm, then you have a varying focal length. Your lens range will be between 24mm to 70mm.

Focal Distance for Focal Length Calculator

The focal distance is the distance between sensor to the object you have in focus. This does not correlate with lens range.

So when you look through a 24mm lens, you may be seeing the same field of view that you see with your naked eye. But a 200mm zoom lens magnifies just one portion of that scene. Wherever you point at the moment.

So you can see now why what you see through the same lens on a crop sensor camera and a full frame camera are very different. It’s not the lens making the difference. Since the measurement from the center of the lens to the sensor is the same. But, preferably, the sensor making all the difference.

Because one sensor, the cropped sensor, is still magnifying the subject the same. It’s just cropping the edges like cutting the crust off the bread.

Prime Lenses

Prime Lenses are a collection of lenses that cannot zoom. Consequently, those lenses have a fixed focal length. If you use a prime lens you cannot zoom so you have to move away from the subject to frame your shot.

The is a better way then zooming when capturing an image. If you consider you zoom as a collection of prime lenses.

James Heidel
 

Scroll Up