сряда, 2 септември 2015 г.

Lesson 2 - Get moving -part 1- Aperture

Lesson 2 - Get moving -part 1- Aperture 


Image taken from https://sites.google.com/a/sduhsd.net/mr-jordon/photography

Welcome to lesson 2 where we'll look at another very important aspect of photography - aperture and shutter speed. If you have read lesson 1 you already know that aperture is important for getting the correct exposure but you may wonder what it is. But first things first. 
So what is aperture and why do we need it? According to Wikipedia (again!) aperture is:
'The iris of the lens that controls the size (diameter) of the aperture is called “diaphragm” in optics. The sole purpose of the diaphragm is to block or stop all light, with the exception of the light that goes through the aperture. In photography, aperture is expressed in f-numbers (for example f/5.6)' 
OK, we started with the Chinese again... Still, let's try to break that into pieces - meaningful bits if possible. 
But before we do that we have to know ho the camera works...

Image taken from https://blog.cameralends.com/2014/07/21/8-photography-terms-that-commonly-confuse-beginners/

In the picture above you see a normal lens (OK, I know that some of you who have compact cameras can't exactly imagine what that is but don't worry - the built-in lens of your camera has the same thing). So - see that strange shape in the middle - pentagonal - like hole? Well, in plain English the HOLE that is formed is called the APERTURE of the lens and the  THING  that forms it is called the  DIAPHRAGM
Remember in lesson 1 where I told you about exposure and there was a diagram? If you don't - here it is again: 

Image taken from http://www.dreamstime.com/royalty-free-stock-photography-exposure-diagram-photography-image25034157


So - in that diagram under APERTURE it says SIZE OF THE OPENING THROUGH WHICH LIGHT TRAVELS TO THE SENSOR. Basically the aperture controls how much light would get to the sensor and the diaphragm controls the size of the aperture. So far, so good. But as with anything else in photography (I guess in anything else as well) there is a catch. 
THE LARGER THE APERTURE THE LESS THINGS ARE IN FOCUS! In our diagram that is said in photographic as DEPTH OF FIELD  or as photographers love to abbreviate things to get people confused - DOF. Chinese again, hah?  Here is the point - aperture is measured with F numbers. THE BIGGER THE F NUMBER, THE BIGGER THE DOF. You still don't get me, do you? 
OK, imagine you're shooting a portrait - and you know, portraits have those nice blurry backgrounds - so you'll need a SMALLER F NUMBER (say f/2.8; f/3.5 or something of the sort) to GET THE BACKGROUND OUT OF FOCUS. Here it gets a little messy because SMALLER F NUMBER MEANS BIGGER APERTURE. That is so because you need a lot of light to go through the lens in order to blur the background (in photographic that's called 'out of focus'). See what I mean below:

Image taken from Google images - forgot where I downloaded it from, sorry to the author - meant no offence - If you recognize the author - contact me to change the caption


By analogy, if you want to take picture of that vast landscape you'll want everything in focus (photographic for that - 'pin sharp'). So you'll need a BIGGER F NUMBER (normally ranging between f/8 and f/22) to GET IT ALL IN FOCUS. Confusion continues because BIGGER F NUMBER MEANS SMALLER APERTURE. That is so because the hole needs to be very small in order for the sensor to get it all OK - like the method of camera obscura (I'm not gonna explain that here, just Google it).


Image taken from http://www.freelargeimages.com/landscape-2332/

So let's try to recapitulate what we know here:
Image taken from http://www.robertmackin.com/tutorials/photography/camera-aperture-explained/
Image taken from http://www.crafthubs.com/f-stops-apertures-for-beginners/12520


If you wonder where to find that in the camera menu - look below:

There is only one thing you should know about aperture - THE BIGGER THE APERTURE THE MORE THE LIGHT AND VICE VERSA. That means that at f/2.8 you'll not need abundance of light whereas at f/16 you'll do.


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