articles/Lighting/dm-apertures-page2
by Dave Montizambert Published 01/08/2014
Since bigger aperture openings allow more light on to the imaging sensor and smaller aperture openings allow less, then f 8 is a larger opening than f 11 and f 8 allows twice as much light to strike the sensor than does f 11.
Conversely f 11 allows 1/2 as much light to strike the sensor than does f 8. If you look at an f 8 aperture next to an f 11 aperture (see Image 001) you will notice that the f 8 hole is twice the area of the f 11 hole and conversely the f 11 hole is half the area of the f 8 hole. Now compare an f 8 aperture to an f 16 aperture, the f 16 aperture looks smaller, it is exactly 4 times smaller and so it allows 1/4 of the amount of light on to your sensor than does f 8. Now let's try another comparison, compare f 2.8 to f 5.6, the f 2.8 aperture looks bigger than the f 5.6 aperture, it is exactly 4 times bigger and so allows 4 times more light on to your camera's imaging sensor.
Well that's pretty much it, so remember that an aperture is nothing more than a hole and that its name or designation is a measure of its area. In my next article, a continuation of this one, I'll dig deeper into holes (apertures) so as to create an understanding of metering for lighting and lighting ratios.
And finally, I realise that I dealt with some really basic stuff in the above, hopefully you have long since mastered these concepts but if not, please know that as basic as this is, it is not necessarily easy to understand straight off and so it does take some effort to truly understand these basic concepts, so if you find all of the numbers a little overwhelming, read a little, digest it, read again then read a little more. You probably won't get it all in one shot, so take your time, put your ego aside and allow yourself the space to learn and then practise, practise, practise.
To delve deeper into lighting, check out my free on-line lighting tutorial videos at www.montizambert.com (click on "Learn From Dave" and again on "!!!!!!!Free Stuff!!!!!!!"); my goal is to post a new one each month or two, time and energy willing!
On the modern digital SLR you are able to choose how to shift and display the aperture values. For example on the Nikon (D700) system it is in the menu as:
Custom Settings Menu b Metering/exposure b2 EV Steps for exposure control Choose 1/3, 1/2 or 1 stop
The values which sequentially appear will then be one of the rows shown above.
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