A Simple Explanation of F-Stop

This video explains the f-stop scale used in photography and video. It explains what f-stop actually is and why the f-stop numbers are what they are. I also give an easy trick for remember the entire f-stop scale.

• Category

  Education

[ilincanuc]

How did you get an area of 314 mm2 when having a 20 mm? I think you used 10 mm in the calculations.. 20^2 * 3.14 = 1256 mm2

[Dylan Bennett]

You are correct, I did use 10mm. Remember that the formula for the area of a circle uses the radius, not the diameter, so you have to halve the diameter when calculating the area.

[Dafydd Eveleigh]

I wished this video had closed captions. It looks really good wish I could understand it more. I am Deaf so it is difficult to follow :-(

[Dylan Bennett]

I will close-caption it for you.

[Dylan Bennett]

Done. I have close-captioned the entire video for you. I hope that helps. :)

[honitsten]

Thank you for this explanation. I used this to help me with my algebra final. We needed to take something that the student uses everyday and explain it in class like a math lesson. I earned an A for my math class.

[bkhanka]

very good explanation.

[Lakshabir Debnath]

lucid explanation helped a lot. thank you.

[magdalene512]

awesome! 

[مصطفى منير]

thanx a million !!!

that was sooooooooo informative n fun

but still one question

on the lense i see numbers written this way

"18-55 mm 1:3.5-5.6"

what does that ratio means?

[haiggoh]

What I still can't wrap my head around is WHY there is a maximum opening of the iris that is set to e.g. 2.8 - how can there be physical limitations to opening? Wouldn't a f/1.0 lens not simply be a lens with an iris that can open the aperture so wide that it won't affect the light coming in? That should be not much of a technical challange. So is the maximum just a limitation to allow them to charge higher prices on faster lenses?

[Jim Miller]

I am glad I found this video. It explains some confusing issues in simple terms. Thanks...

[Matt Smith]

SIMPLE?