What Does F-Ratio Mean?

This is part of the subject which was discussed in lesson 3, lenses, light and magnification of the Photo 101 course that I am following. It looks at brightness and f-ratio’s, magnification and field of view.

I found this lesson a harder one than the other two, although it is explained very well. I had to read through it a couple of times before I really got it. And this was partly because I had missed a key sentence, so it just shows it pays to reread an article!

F-ratio

My favourite part of the lesson though was the explanation of f-ratio, what it is and how it works. This is one of those photography terms that I hear people talking about and read about, but was not really sure what it was or what it meant.

F-ratio describes the relationship between the diameter of the lens and the focal length. F-ratio = focal length divided by diameter of the lens.

The f-ratio of a lens is always written on it somewhere. I always wondered what all those numbers on a lens meant!

If I put this information together with what I learned in the first two lessons then it is building a picture. Of how the design of a camera uses what we know about light and how it behaves to create an image. And we can then choose the right lens or settings for the situation, depending on how much light there is available to create the best image possible.

The different parts of the puzzle are starting to come together…

Homework

The homework this week was quite hard as most of the options were suited for DSLR’s, but that was fine because there was an option for point and shoots which was to use the macro setting on the camera.

My camera is a cheap point and shoot and I have been having problems getting the macro setting to work successfully. I keep it at the minimum distance that the camera suggest of 0.6m. And I found using a tripod and the self timer gives the best results. But I think I have done alright with the photos below (they are better than previous ones), although there is a bit of digital noise and they are not completely macro, but the best the camera will allow.

knives