Aperture+Shutter Speed+ISO=Confused

[Overread]

Understanding Exposure by Bryan Peterson

I think a few more people in the thread need to get and read this book

 

[GeneralBenson]

Understanding Exposure by Bryan Peterson

I think a few more people in the thread need to get and read this book

Indeed. The thread should have been locked as soon as you answered correctly by saying, go read that book. After that there is nothing left to say, and so far everything else has just lead to more confusion.

 

[prodigy2k7]

ISO directly affects your shutter speed. Higher ISO = faster shutter speed.

No. Changing your ISO only under or over exposes your photo. You compensate with changing aperture or shutter speed. For example: If you are in Tv mode, you are set to 1/500 and you change your ISO from 100 to 200, your aperture changes, not your shutter.

Wow, that is the most absurd definition of ISO that I have ever heard. "ISO only under or over exposes your photo" - wrong wrong wrong wrong!!!! Changing ISO increases or decreases the sensitivity of the camera's sensor. Increasing or decreasing this sensitivity directly affects shutter speed.

Is you shoot in a shutter priority mode then yes the aperature would change. A high ISO is 99.9999% of the time used for faster shutter speeds.

Know what you are talking about before you tell others they are wrong ldman:

From wikipedia "Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. Relatively insensitive film, with a correspondingly lower speed index requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a slow film. Highly sensitive films are correspondingly termed fast films. A closely related ISO system is used to measure the sensitivity of digital imaging systems. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality (via coarser film grainimage noise of other types). Basically, the higher the film speed, the worse the photo quality." or higher

A higher ISO allows you to use a faster shutter speed, but it also allows you to change the aperture instead. Sure most people use higher ISO for faster shutter speeds, its very common, that doesnt mean ISO directly influences it. It doesn't. And YES your photo will become under or over exposed if you are in MANUAL mode, dont change your aperture/shutter and change your ISO.

Edit: I was talking about the end result if you change your ISO without changing your aperture/shutter, yes the ISO is the sensitivity to light, but the end result is, under or overexposure of your photo, if you don't compensate. Yes its most common to change shutter speed, but you are acting like its friggin physics, and it MUST change the shutter speed, like its a science. Its not. You are just confusing the guy more. I wasn't defining ISO. I said exactly what it DOES (in the eyes of the person) not the technical stuff...

 

[iskoos]

If a male newbie asked this question, he would get immediate advises on how to use the "search" function...

This forum is full of info about what you are asking. You do not need to buy a book immediately. Go to "Beginner's Photography" forum and type Aperture, shutter speed, ISO or simple "Exposure Triangle", and you will find lot more than you may expect.
I remember some members even started tutorial threads with sample pictures...

 

[icassell]

Understanding Exposure by Bryan Peterson

It's a book rather than a website but its well written and idealy suited to teaching you how to start using ISO, shutter speed and apertures both to achieve a correct exposure and going further to using the settings in a creative manner.

:thumbup::thumbup::thumbup:

 

[ghpham]

If I was a newbie, I wouldn't understand what half of you guys are saying. Recommending the book is about the best advice.

 

[RSPhotography]

I dunno...
They're fairly simple concepts. Not sure there's a need to spend any money to understand them!

... just my opinion!

 

[Rosshole]

ISO - this part determines how much light is needed to expose an image

Shutter speed - Determines how long light will be hitting the sensor

Aperature - How much light is let in when the shutter is open

Changes to each inversly effect the other two, and making changes to them will give you different effects on the exposure... ie, Frozen motion, depth of field, motion blur.

That's it.

 

[table1349]

I dunno...
They're fairly simple concepts. Not sure there's a need to spend any money to understand them!

... just my opinion!

Which is why Bryan Peterson wrote his book on Understanding Exposure and Ansel Adams wrote about the Zone System. The concept seems simple, however the application, given the physics of photography, is not.

 

[Dao]

I think one important point a beginner need to know is....

A photographer, most of the time, want to take a photo with "CORRECT EXPOSURE". Such as take a photo that it does not look too bright or too dark. There are exceptions of course.



How to obtain the "correct exposure", it is a combination of setting the "Aperture", "Shutter speed" and ISO/ASA (which is kind of like a light sensitivity value).


If correct exposure is 1 bucket of water.

To fill 1 bucket of water, I need to use a hose. Of course with a bigger hose (larger aperture), I can fill the bucket faster. Therefore I only need 20 seconds (Shutter speed) to fill the bucket.

Now, I can only use the smaller hose (smaller aperture) since the big one broke. To fill the same bucket, now it take 40 seconds. (double the shutter speed).

The problem is, I need to fill one bucket in 20 seconds, 40 seconds is too slow. To solve the problem, I use a smaller bucket (ISO/ASA) which is half the size.


The end result is the same, I have 1 bucket of water (correctly exposed photo)

Hope that make sense.

 

[bentcountershaft]

Understanding Exposure by Bryan Peterson

It's a book rather than a website but its well written and idealy suited to teaching you how to start using ISO, shutter speed and apertures both to achieve a correct exposure and going further to using the settings in a creative manner.

:thumbup::thumbup::thumbup:

The nice thing about that book is that it has photo examples of the same scene so that you can see how each of the variables affect an image independently. Seeing those images side by side really makes it easy to understand exactly what is going on in a picture and how to adjust to get the effect you want. For me as beginner it felt like an epiphany learning that and that book made it easy. It's been out a good while and is probably available at the local library if you don't want to buy it but it's really nice to have. I'd be willing to bet it's the single most recommend book on photography out there and for good reason. It's easy to understand even for someone that has never picked up a camera before.