Help me understand exposure...

[bango707]

Its funny how snippy people are getting these days. I am on a few other forums and the same is true on those as well. Somebody called it 'cabin fever' and I am beginning to agree.
Get out and take some pictures people!!!

 

[doobs]

http://www.amazon.com/Understanding-Exposure-Photographs-Digital-Updated/dp/0817463003

I should really bookmark this link by now.

 

[Tennessee Landscape]

http://www.amazon.com/Understanding-Exposure-Photographs-Digital-Updated/dp/0817463003

I should really bookmark this link by now.

Getting a lot of that, I'll be looking for that at the local bookstore tomorrow.......

 

[Happy Hour]

Did you even read my post? I said it was a "good book to have". I never said it "isn't good enough". I also never faulted him for not covering "every single detail or aspect of multiple subjects". I just said he "could have covered exposure in a much more concise manner". Yes he explains what the beginner needs to know but he takes most of the book to do it. The pictures are nice but you don't need them to get started.

I would prefer a rundown of the camera settings first. That's all you need to know to get a correct exposure. After that is covered, then the pictures and explanations are great for real life usage of the camera settings. That was all I was trying to say. I was not trying to discredit Bryan Peterson or his book in anyway. I would, however, prefer a more concise and to the point explanation of exposure as opposed to spreading bits and pieces of that explanation throughout a 150+ page book.

He does go over a rundown of the camera settings In his book understanding Digital. i thought the same thing about the pictures when I first opened the book. But while reading it I thought they were very helpful in understanding each process he was explaining. You read it then go how would that look and there you are it shows how it would look. I talked to him last week and he said his new book understanding shutter speed is much more detailed and will be out in stores in a few weeks.He also told me if I haven't already don't waist my money on understanding digital because it is already outdated and if your a Dlsr owner you probably know what he states in that book. And that his other books are much more informative than that one

 

[EOS_JD]

ISO ("film speed") - Sensor or film sensitivity. ISO is sometimes referred to as "film speed" since you can use a faster shutter speed with a higher ISO. ISO is not a measurement of shutter speed. Higher ISOs usually have more "noise" or graininess too them. If you double the ISO number, you double the brightness of the picture. If you halve the ISO number, you make the picture half as bright.

High ISO - Brighter, more noise or graininess.
Low ISO - Darker, less noise or graininess

See film speed for more information.

In digital photography, as you increase the ISO you increase the gain (sensitivity of the sensor to light). By doubling the ISO you make the sensor twice as sensitive so less light is required to make a correct exposure. You use the words brighter/darker and I don't like to do that as you may not want your image to be brighter...... You generally just want a correct exposure. So as you alter the ISO you need to adjust the shutter speed/aperture to suit.

Aperture
Large Aperture (small F-number) - Brighter, shallow depth of field.
Small Aperture (large F-number) - Darker, large depth of field.

Again you use brighter/darker..... Although kind of correct, I feel it's better to say that with a large aperture like f1.8 you need less time to get a correct exposure (so a faster shutter speed). Also as you say, larger apertures limit the depth of field.

With small apertures like f16 you need to have the shutter open for longer to allow the same amount of light in.

f2 : f2.8 : f4 : f5.6 : f8 : f11 : f16 : f22

The above shows a few common aperture values. Each f/stop means a doubling or halving of light. So f2.8 lets in 32 times more light than f16. If you get a shutter speed of 1/10th at f16, this would be 1/320th at f2.8 (so long as the ISO remained constant).

Shutter Speed - the amount of time the shutter is left open and the film or sensor is exposed. A shutter speed that is twice as long will make the picture twice as bright. A shutter speed that is half as long will make the picture twice half as bright.

Bright/dark again to me is not the best way to explain this. Better to say a shutter speed that is twice as long requires a smaller aperture (less light) and/or a lower ISO to get a correct exposure. A shutter speed that is half as long required a larger aperture (more light) and/or higher ISO to get a correct exposure.

[/quote]

Understanding exposure is perfect for the newbie to exposure. As you gain experience you will start to formulate your own views and your creativity will allow you to go beyond what you would read in the book but at all times the general rules do not change.