shutter speed and aperture

[ken212]

I am used to always using automatic with my camera. I was hoping someone on here could explain to me what shutter speed is, what it does and how to use it (like when to use faster and when to use slower)? Also I was hoping someone could explzin aperture to me as well. What is it, what is it for and how to use it. I see number like f2.8 to f8.0. What do these numbers mean? Which is better and should the smaller or bigger number be used? Thanks.
Ken

[Honest Gaza]

I'll give it to you in simplest terms....for I am but a simple man :o :)

For any given photo opportunity, there is a correct exposure. This exposure is determined by a combination of a specific intensity of light, during a specific period of time.

An anology of this that is often used is the "tap over the sink".

Think of a sinkful of water as being the correct exposure. If you turn the tap on full blast, it won't have to be on for very long. If you turn the tap on slowly, the water will have to run for a longer period.

For this analogy, the tap opening is the "Aperture" and the water flow is the shutter speed.

The camera works in the same way. If you have a small opening in the lens (small Aperture), then you will need a slow shutter speed to allow enough light in for the exposure.

If you have a large opening in the lens (large Aperture), you will need a faster shutter speed so that you don't allow too much light into the exposure.

Once you get the grasp of this....it is time to get confused again.

Unfortunately, the Aperture values are represented by "inverse" values

....stay with me here

This simply means that F8 is in actual fact smaller than F2 (because you have to think of it in it's "inverse" form of 1/8 and 1/2....therefore "one-eigth" is smaller than "one-half").

Once you get the hang of this....you can then move on to what different affect these settings have (eg. capturing motion & changes in depth of field)

[AdamW]

Okay, it looks like you'd do well to read Bryan Peterson's Understanding Exposure. (http://www.amazon.com/Understanding-Exposure-Photographs-Digital-Updated/dp/0817463003/ref=pd_bbs_sr_1/104-9835028-5615146?ie=UTF8&s=books&qid=1182666055&sr=8-1) This is an excellent book to get the basics of how aperture and shutter speed work. But I'll give it a shot.

A camera uses light to capture an image, whether it's with light-sensitive film or a light-sensitive electronc sensor. There are three ways to adjust the amount of light that is captured. Each of these also affect in other ways the how the picture will look.

The first is ISO. With film, the ISO number indicates how sensitive the film is, and those numbers have carried over to digital photography. The ISO setting is how much light the sensor can grab. If you camera is set to ISO 200, it will capture twice as much light as ISO 100. The secondary effect of ISO is noise. With film, higher ISO meant a grainier image, because the film had larger grains of light-sensitive silver. With digital, higher ISO means more "noise," which can look similar to graininess, and can often be somewhat eliminated with software.

The second is shutter speed. This is simply how long the shutter is open. The longer it's open, the more light reaches the sensor. The secondary effect of shutter speed has to do with motion. If you have a moving subject, a fast shutter speed will "freeze" the movement. A fast enough shutter speed can show things the human eye can't see, like a hummingbird's wings in flight. A longer shutter speed causes motion blur, which can convey a sense of movement.

The third is aperture. This is how wide the opening of the lens is. It is measured in "f-stops," which is a fraction derived by dividing the size of the opening by the length of the lens. Newcomers are often confused by the fact that the larger the f-stop number, the smaller the opening of the lens. For example, f/4 is a smaller opening than f/2.8. The secondary effect of aperture is depth-of-field. This is the area of the picture that is in focus. The smaller the aperture (the bigger the f-stop number) the larger the depth of field. Taking a landscape and want the trees in the foreground and the hills in the distance to be in focus? Then you'll need a small aperture, like f/11 or f/14. Taking a portrait and want the subject to be in focus and stand out and the background to be blurry? Use a larger aperture like f/1.8.

A simple analogy is a water hose. The water is the light. The ISO is how much water pressure there is. The shutter speed is how long you turn the water on. And aperture is the diameter of the hose. If you change one, it will effect how the other two work.

Hope this helps!:cool:

[DonSchap]

Well said, gentlemen ... when I opened this thread, I was wondering how this might play out.

Just to offer a third line of thought ... :o

As has been offered, three major aspects concern most images ...

ISO - Shutter Speed - Aperture

The OP has been using automatic, so all these factors are decided upon by the internal calculator of the camera. Most DSLRs and several P&S cameras allow manual manipulation of ALL of these settings ... or some. I'm going to, for argument's sake, assume you have a lens or camera that has a maximum aperture of f/3.5.

ISO is the sensor's sensitivity. Normally, a couple genral rules apply when deciding on ISO:

ISO-100 for outdoor shooting (clear day)
ISO-200 for outdoor shooting (cloudy day)
ISO-400 for indoor shooting (with or without flash)
ISO-800 for indoor shooting (boosting the sensitivity)

Now, there are higher settings available in some cameras ... but they have drawbacks that beyond the scope of this immediate discussion.

For this discussion, let's assume an indoor portrait shot of your Great Aunt Tilly. To fully aappreciate the control you have of your little light box, turn your camera to Manual Mode (M) and set the ISO to 400.

Shutter Speed is the camera's way of controlling time. Yep, powerful device, here. The higher shutter speeds (1/60, 1/125, 1/250, 1/500, 1/1000) reduce the amount of movement the camera will see. So, if Great Aunt Tilly has a problem with shaking or tremors ... you need to "freeze her." For some controlled lighting in this indoor scenario, we're going to use the camera's pop-up flash here (flash usually works best with three shutter-speeds due to syncronization with the shutter opening and closing - 1/60th; 1/125th; 1/250)... so you need to set your shutter speed to 1/125 sec. That setting pretty much assures us that useless she just plain falls over, we will have a good chance of locking her in position.

The Aperture setting, aside from allowing in light, is your way of controlling what is in focus and what is not, in your image. Obviously we want Great Aunt Tilly's face to be in focus ... and the autofocus should take care of that for use, if she is centered in your frame and has a the focus graticule (usually lights up in the display and signals you that you have acheived proper focus.) But, what I'm speaking about is everything thing else in the frame ... the couch she's sitting on, the bookcase behind her, the coffee table in front of her. To make Great Aunt Tilly stand out in the image, you need to defocus as best you can on these other items. This is called Depth of Field (DOF).

To explain: If you open the aperture to a setting of f/3.5, the DOF will be shallow, meaning there is a focal PLANE that is about four to eight inches wide. To expand, if you have Great Aunt Tilly's face in focus ... then anything four inches in front of her face and four inches behind it will be also. Anything further begins to soften and defocus to the camera.

If we close down the aperture ... to say f/5.6 ... this focal plane widens ... allowing objects one foot either behind her or in front of her to become focused. Close down to f/8 and almost everything you see in the viewfinder will be in focus ... and that sometimes makes it hard to determine what the "subject" was. This is also called the "snapshot." It totally defeats the reasoning behind having a better lens.

So, at f/3.5 ... we've got her face and beautiful blouse ... and the bookcase with the tattered books and trophies and that half-eaten cake on the coffee table are now a soft blur.

You pop the shutter ... the flash goes off ... you examine the LCD for your image ... "Not bad!" for the first time, you say. Okay, you can now determine if you need to cut down the light, because the exposure is too much and her face lacks definition. Simply set the shutter-speed to 1/250 (because it will still be synchronized with the flash at that speed) ... and you instantly cut down the light by half, by reducing the time (by half) that the light has to get to the sensor.

Trip that shutter release again ... examine Great Aunt Tilly's new image. It should be close.

Anyway ... it's a start at understanding, I hope.

BTW: Tell Tilly I said "Hi." ;)

[AdamW]

That setting pretty much assures us that useless she just plain falls over, we will have a good chance of locking her in position.

I find that bungee cords work well for this. :D:p

[Tim018]

shutter speed...

the smaller the number(1/30 vs. 1/250) the shorter the exposure...therefore light has less time to enter, and shorter speeds will also "freeze" moving subjects better

aperture...

the larger the number- the larger the opening- therefore more light is let in, but the depth of view is also smaller

the smaller the number- the smaller the hole in the lens- less light is let in but the depth of view is also increased

hope that is useful to you

[AdamW]

aperture...

the larger the number- the larger the opening- therefore more light is let in, but the depth of view is also smaller

the smaller the number- the smaller the hole in the lens- less light is let in but the depth of view is also increased


Tim, you've got it backwards. A larger f/stop number means a smaller hole. f/11 is a smaller lens opening than f/4.

And I think the correct term is depth of field, not to be confused with field of view.

[Tim018]

you are right AdamW. I apologize, i have never messed that up in my life. I guess i just thought one thing and wrote another- i am sorry

[AdamW]

No worries, Tim.:cool: It took me while to get it straight. And anyway, my fingers often type something different from what I'm thinking!:D

Oh, and welcome to the forums!

[DonSchap]

I'm curious as to whether the Original Poster found this helpful at all.

[zmikers]

I'm curious as to whether the Original Poster found this helpful at all.

Give him a few days for all of the info to sink in. It may take a while......LOL

[Rooz]

I'll give it to you in simplest terms....for I am but a simple man :o :)

For any given photo opportunity, there is a correct exposure. This exposure is determined by a combination of a specific intensity of light, during a specific period of time.

An anology of this that is often used is the "tap over the sink".

Think of a sinkful of water as being the correct exposure. If you turn the tap on full blast, it won't have to be on for very long. If you turn the tap on slowly, the water will have to run for a longer period.

For this analogy, the tap opening is the "Aperture" and the water flow is the shutter speed.

The camera works in the same way. If you have a small opening in the lens (small Aperture), then you will need a slow shutter speed to allow enough light in for the exposure.

If you have a large opening in the lens (large Aperture), you will need a faster shutter speed so that you don't allow too much light into the exposure.

Once you get the grasp of this....it is time to get confused again.

Unfortunately, the Aperture values are represented by "inverse" values

....stay with me here

This simply means that F8 is in actual fact smaller than F2 (because you have to think of it in it's "inverse" form of 1/8 and 1/2....therefore "one-eigth" is smaller than "one-half").

Once you get the hang of this....you can then move on to what different affect these settings have (eg. capturing motion & changes in depth of field)

well said grasshopper.

[AdamW]

well said grasshopper.

Can I be the cricket?;)

[Rhys]

It's like driving a car....

The speed limit is the amount of light.
The gearstick controls your aperture
the accelerator controls your shutter speed

By varying gear and accelerator you can control your overall speed.
1st gear and foot right down - 60mph
4th gear and foot lightly pressed - 60mph

You can't use 4th and your foot all the way down and expect good results in a 30mph limit zone. Just as you'd spend time in a black jail cell, your images will be all black too.

ISO is the power of the car. For example, 50ISO is about the equivalent of the Citroen 2CV with its 2 cylinder 2 stroke 500cc engine and 3200 ISO is about the equivalent of a McLaren F1.

A with ISO, a 2CV will hold a lot more cargo than a McLaren F1. In terms of grain/noise, the lower the better.

[BKKC]

I'm curious as to whether the Original Poster found this helpful at all.

I dont know about the Original Poster but I sure did. Your post which talked about the distances that would be on focus was of great help. It explained a problem I have been having while trying to focus 2 birds at once with one closer then the other, I could only really get 1 bird in sharp focus at once. So I just need to use a smaller aperture then I guess I would need to slow down my shutter to allow more light

[DonSchap]

I dont know about the Original Poster but I sure did. Your post which talked about the distances that would be on focus was of great help. It explained a problem I have been having while trying to focus 2 birds at once with one closer then the other, I could only really get 1 bird in sharp focus at once. So I just need to use a smaller aperture then I guess I would need to slow down my shutter to allow more light

RIGHT ON! - You got it, now.

Tightening the aperture, although cutting down the light, causes the depth of field to expand (or deepen). At about f/64 ... you would think that everything coming in through the lens should be sharp ... there is a physical property problem, that was with film ... with digital, you no longer have that luxury, because of the sensor's sensitivity to diffraction. This begins to significantly occur at about f/22 on the digital lens, causing the edges to begin softening as visible light begins to interfere and scatter at the sensor.

To fully appreciate this issue, please use this link: DIFFRACTION (http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm)

When you get to f/16, it's time to call it quits for available sharpness, in the digital world. It is what it is, at that point. Focus as you can, but do not cut that aperture down any further.

There are some fun lens filters you can use that allow two subjects at different ranges to be focused on, simultaneously. (Similar to a bi-focal) one half of the lens is clear and the other is a x2 magnifier. So ... if one subject is at 8 feet ... the other subject could be at 16 feet. You focus on the one ... and the other comes right in, too, with this device. Oh yeah, use Manual Focus with this ... cause it will drive autofocus right out of its mind.

It really is designed more for set-up shots or something you can control (other than nature shots), but it can give you some entertaining moments in your photography.

[ken212]

While this is all a lot to take in, it has been very helpful to me in understanding this subject better. Of course it will probably take me plenty of time and practice to get it all correct. But I do want to thank everyone for their help.

Ken

[Honest Gaza]

Can I be the cricket?;)

It's Master Po that we need

[AdamW]

It's Master Po that we need

"If you can snatch this nd filter from my hand..."

[DonSchap]

Personally, I want to walk across the Canon Glossy Paper ...
.
.
.

and not leave a trace, then ...
.
.
.
I will have run out of ink. :p

But not only that ... some other thoughts on training:
"In the Shaolin temple there are three kinds of men: students, disciples and masters. Development of the mind can be achieved only when the body has been disciplined. To accomplish this, the ancients have taught us to imitate God's creatures.... From the crane we learn grace and self-control. The snake teaches us suppleness and rhythmic endurance. The praying mantis teaches us speed and patience. And from the tiger we learn tenacity and power. And from the dragon we learn to ride the wind. All creatures, the low and the high, are one with nature. If we have the wisdom to learn, all may teach us their virtues. Between the fragile beauty of the praying mantis and the fire and passion of the winged dragon, there is no discord. Between the supple silence of the snake and the eagle's claws, there is only harmony. As no two elements of nature are in conflict so when we perceive the ways of nature, we remove conflict within ourselves and discover a harmony of body and mind in accord with the flow of the universe. It may take half a lifetime to master one system." -Master Kan

I suppose the same could be said of Photography ... Zen Photography - close your eyes and pray when you hit the shutter release?


25889

[Honest Gaza]

So it would be fair to say he would never suffer from "red-eye" ? ;)