For those confused about aperture and shutter speed.

[JeremyZ]

You might consider adding what an aperture actually is. (rather just say what it does)

An aperture is the opening that lets light through the lens. It is created by a multi-bladed opening.

You might also add bits about sensitivity (equivalent to ISO film speed from film cameras)and lens speed.

Aperture, shutter speed, sensitivity, and lens speed. Those are what make up the whole picture.

 

[legalily]

Most Excellent!

I am/was one of those. Love to shoot, get amazing shots, but half the time it is sheer luck. Thanks much.

 

[Phototini]

You might also add bits about sensitivity (equivalent to ISO film speed from film cameras)and lens speed.

Aperture, shutter speed, sensitivity, and lens speed. Those are what make up the whole picture.

Actually the "speed" of your lens has nothing to do with creating an image. As photographers all we are doing is painting with light. The more light you have the fast you are able to capture the image, and vice versa the less light available the longer it takes to capture the image.

The photographic triangle is Aperture, shutter speed and Sensitivity (ISO) always has and always will. The only thing a fast lens will do for you is enable you to capture images in lower light without increasing the sensitivity (ISO) without producing the increased "noise" that a higher ISO would normally introduce into the photograph. And if you are a bokeh junkie then it will also give you more of the effect than a "slower" lens.

 

[GILSAN]

You might consider adding what an aperture actually is. (rather just say what it does)

An aperture is the opening that lets light through the lens. It is created by a multi-bladed opening.

The aperture is like our eyes. When the sun is very bright we squint and virtually close our eyes, while in the dark our eyes are wide open. The pupils on cats eyes when day turns to night is even more evident.

 

[ceejay]

Some comments

What is Aperture? Intro to lesson.

A long exposure is normally considered a shutter speed of 1/50 of a second, meaning half a second. Some shutter speeds considered long exposures are 1/60, 1", 3", 5", etc.

Anything below 1/50 is considered a fast shutter speed. Examples of fast shutter speeds are 1/40, 1/1000, 1/400, and 1/2000.

Well ... 1/50 of a second is not a half second. That would be represented in camera speak as 1/2. Also 1/60 is faster than 1/40. The smaller the denominator, the longer the exposure. The ratio tells us the part of a second the shutter is open. (So, one-sixtieth of a second, one-fortieth of a second, one-one hundredths of a second, one-half a second and so on.)

But your post does a good job of describing the relationship between aperture and shutter speed. As others have pointed out, the third variable is film speed, or ISO.

There is an inverse relationship between aperture and shutter speed. Increasing the length of time the shutter is open, while decreasing the aperture will result in the same exposure or brightness. The difference in the shots will be how much is in focus. Larger apertures (smaller f-stop numbers) will give a larger depth of field and put more into focus. Smaller apertures (larger f-stops) will restrict the depth of field. So if you are using a large aperture like 1.8 or 2.8, you will isolate the subject nicely and the background will all be blurred. A much more 3-D effect and something that is hard to achieve with point and shoot cameras.

The very best description I have ever seen explaining f-stops (I did not write it) is copied and pasted below. Read this, its very very good!

What's Up With... F-Stops?
By Dan Richards May 2005

Remember taking your SATs? They had questions like this:

What is the next number in this sequence: 1, 1.4, 2, 2.8, 4, 5.6...?

At this point, you’d fill in the circle for “8” (or should have). Each number doubles by leapfrog. And so the next number after 8 should be 11.2. But let’s simplify things and round it off to 11.

This is the f-number sequence. Math-wise, it’s a geometric progression on the square root of 2 (1.414...).

OK, why such weird numbers?

First, what the f-number is: the focal length of a lens divided by the diameter of its diaphragm opening. A 100mm lens with an opening of 50mm is f/2. With a 25mm opening, the same lens is f/4. This explains 1) why the f-number gets larger when the opening gets smaller; 2) why long lenses with small f-numbers are so **** fat; and 3) why teeny-tiny lenses can have f-numbers like f/1.4 (tiny lenses—like those on digital compacts—are often very short focal lengths).

When you turn a dial to go up by one f-number step (say f/2.8 to f/4, called a full stop), you are cutting the light coming through the lens by half. If you go down the f-number sequence (from f/4 to f/2.8), you are doubling the amount of light coming through the lens.

Then why doesn’t the f-number itself double or halve for each single step?

Consider: to double the amount of light coming through an aperture (or double the volume of water through a pipe), you have to double the area of the opening. If you double the diameter of a circle, the area increases four times, not two. (Remember the math: area of a circle is p times the circle’s radius squared.)

So, to double the amount of light, you don’t increase the diameter of the opening by 2X; you increase it by the square root of two. Hence those f-numbers that bump up by v2 (about 1.4X) each step.

Each successive stop doubles or halves the amount of light over again. So if you skip from f/8 to f/4, you increase the light by four times (double, and double again). From f/4 to f/8, you’re quartering the light (half of half). Same for wacky in-between f-numbers. What’s two stops less than f/7.1? Easy: f/14.2, which your camera will show as f/14.

 

[ceejay]

Aperture, shutter speed, sensitivity, and lens speed. Those are what make up the whole picture.

Aperture = lens speed

 

[1991-C4]

Here's a great post I ran into over the weekend that finally had it clicking for me.

It covers Aperture, Shutter Speed, and ISO.

Ben's Newbie Guide to Digital SLR Photography - Canon Digital Photography Forums

Crap! I have a Nikon and this stuff was written for a Canon!

 

[Doug b]

Just pick up Bryan Peterson's "Understanding Exposure". It covers the gamut in terms which laymen and advanced users will both understand. Perhaps one of the best written books any photographer should familiarize themselves with, and has been recommended across many an photography forum.

Amazon has it for 17$ Bargain for an investment. Amazon.com: Understanding Exposure, 3rd Edition: How to Shoot Great Photographs…

 

[Village Idiot]

Understanding what the aperture is and what it does is essential for knowing how to properly light using flashes and strobes. That's a whole 'nother ball game that deserves a post on it's own.

 

[decoman]

Here's a great post I ran into over the weekend that finally had it clicking for me.

It covers Aperture, Shutter Speed, and ISO.

Ben's Newbie Guide to Digital SLR Photography - Canon Digital Photography Forums

(Don't bother looking for part 3, it's not there yet. Yes, I read all 19 pages.)

thanks for the link!

 

[Slydude]

Excellent write up! Great for the newbs!

Ditto.

 

[patrick198]

What is Aperture? Intro to lesson.

This is a very common question among novices and amateurs alike. Isn't it about time someone puts it in simpleton terms anyone can understand?


OK, but how does the aperture size affect my photos?

Again, a very common question. Aperture will affect your photos in two ways:

-How bright or dark your photo is-

-How shallow or deep your DOF (Depth of Field) is (we will not cover that in this lesson)-

Let's talk about how it affects the brightness of your shots. Aperture rates are shown in units called 'ƒ-numbers'. What the purpose of the ƒ-number is is to show us the diameter of the 'diaphragm' in the lens, which means the opening in the back of the lens. The diaphragm allows the light into the camera's sensor or film, depending on if you use a film or digital camera. This creates the image. The higher the ƒ-number, the less light allowed onto the sensor or film, thus determining the brightness of the photo. Yes, the higher the lower. It is a confusing system, yes, but just don't let it mess you up. The standard aperture range on an SLR camera (digital or film) is ƒ/1.4, the highest aperture, to the lowest aperture, ƒ/8. The settings in between ƒ/1.4 and ƒ/8, known as ƒ-stops, are usually ƒ/2, ƒ/2.8, ƒ/4, ƒ/5.6. Aperture alone does not determine how the photo will come out, though. The other element is shutter speed, meaning how quickly the photograph is taken... and how much light is allowed in. But I thought aperture controlled that? It does. Lets get into detail (We can't explain aperture without talking about shutter speed!)

Shutter Speed In Detail:

Shutter speed dictates how long the shutter is open, which in turn means how much light is in the picture (how bright it is). Aperture determines the brightness of the light that comes in. You may need to read this paragraph over a few times, and think about it for it to make sense. The reason we need to talk about shutter speed in a lesson about aperture is simple: there is no avoiding them both when taking a photo manually. So, lets get started.

What's my shutter speed gonna do?

Your shutter speed will determine how long your shutter will stay open. Most cameras have a maximum shutter speed of anywhere from 15 seconds up to 30 seconds. You have probably heard of the term "long exposure" before. A long exposure is normally considered a shutter speed of 1/50 of a second, meaning half a second. Some shutter speeds considered long exposures are 1/60, 1", 3", 5", etc. If you want a sharp image, you need a tripod. To get an exposure above the preset setting on your camera's maximum setting (usually 15"-30") you will need to have a "bulb" mode. For a bulb mode, you will need a cable release, which can be set in the cable release socket on a film SLR or the hotshoe terminal on a digital SLR. You can have an exposure for however long your heart desires. This is especially useful when you want to do photos like star trails, because you can't get star trails with a 3" exposure. All this talk about long exposures, and no fast shutter speed discussion? Well lets talk about that now free online movies. Anything below 1/50 is considered a fast shutter speed. Examples of fast shutter speeds are 1/40, 1/1000, 1/400, and 1/2000. Most normal SLR's fastest shutter speed is 1/2000. If you took a photo at 1/2000 then the shutter would be open for 1/2000 of a second, allowing 1/2000's worth of light in. You will have a somewhat dark image at this speed, because 1/2000 will not allow as much light in as a longer would, such as 1" would. Here is an easy way to remember that: the higher the exposure, the more light that can enter the sensor or film, the shorter the speed, the less light. But, the quicker the shutter speed the quicker the picture is taken, meaning that moving subjects can be easily captured.


I hope this helps some of you!

Great post! It's very nice. Thank you so much for your post.

 

[Manuductor]

Good posts and answers. Here is a quote I took from PopPhoto Magazine last month related to DoF.
Hyperfocal Distances: Changing with lens and aperture, the hyperfocal distance is the nearest focusing point that will produce sharpness at infinity -- in other words, the maximum depth of field that includes infinity. Lens depth-of-field scales help you set it: in manual focus, turn the focusing ring so the working aperture (e.g., f11) on the depth-of-field scale lines up with infinity on the focusing scale (the one on the lens that you can rotate with your hand). Now, every distance from the opposite working aperture to infinity will be sharp." (I added the stuff in parentheses.)

In your Depth of Field post, could you help with the following, please? On the old lenses I used with film cameras, I could follow those directions, but on my new lenses for my digital camera, I can't because the lenses don't have the same aperture display on the rings. So, how do I set the hyperfocal distance using my digital with a zoom lens?

Thanks.

 

[VaughnA]

In your Depth of Field post, could you help with the following, please? On the old lenses I used with film cameras, I could follow those directions, but on my new lenses for my digital camera, I can't because the lenses don't have the same aperture display on the rings. So, how do I set the hyperfocal distance using my digital with a zoom lens?

Thanks.

There are quite a few DOF/Hyperfocal calculators for the iPhone/iPod touch. I use iDOF calc and it works great. Play with it and get a feel for the numbers. You can do pretty decently by generalizing. For instance a 16mm lens on a APS-C Camera will be in-focus from about 1 meter to infinity at F5.6. When I'm shooting wide and want it in focus I just set to 5.6, focus about 1/3 into the shot and shoot.

 

[Chris....]

My son is taking a photography class in high school and I found this simulator very helpful.

SLR Camera Simulator | Simulates a digital SLR camera

 

[SteveJobs@Apple]

Great write up! Helped clear things up a bit.

 

[BCRose]

I know I am late to this thread but if I can add the following it may give this a different perspective and perhaps make it easier.

Exposure is controlled by three different settings on your digitaal camera. Aperture, Shutter speed and ISO. This is often referred to as the exposure triangle.

A very basic way to understand this is to keep the following in mind;

1. Aperture controls the VOLUME of light available to the sensor.
2. Shutter speed controls the amount of TIME the light is available to the sensor.
3. ISO controls the sensors sensitivity to light.​

There is of course much more to understand how all three of these work together to create a 'correct' exposure but in a nutshell the three items above are what control the exposure of your images.

 

[paul_77]

Hi,
Just wanted to point out a couple of things that are not quite right:

"A long exposure is normally considered a shutter speed of 1/50 of a second, meaning half a second "

1/50 of a second is not half a second - it means what it says: it is a 50th of a second (divide a second up into 50 increments and it's one of those increments.

"If you took a photo at 1/2000 then the shutter would be open for 1/2000 of a second, allowing 1/2000's worth of light in. You will have a somewhat dark image at this speed, because 1/2000 will not allow as much light in as a longer would, such as 1" would."

That is actually misleading. It's always relative to available light/ISO/aperture. 1/2000 shutter speed in the right lighting conditions will give you a correctly exposed photo.

 

[BCRose]

The original poster may want to do a little research on this matter and edit the post. It is not accurate and not explained particularly well.

As a professional photographer I shudder when I see people who mean well but do not understand the basics try to explain the relationship between Aperture and Shutter speed.

As Paull_77 explains, you can have a correct exposure at any shutter speed, I have taken many at 1/8000th that were not 'dark' as suggested. It all depends on the volume of light exposed to the sensor that is controlled by the Aperture. That in turn can be affected by ISO setting.

Try this real world experiment. If you have a lens that will open up to 2.8 or larger Aperture go outside on a sunny day and open your lens as wide as it will go. You will more than likely require a shutter speed of at least 1/4000 to create a correct exposure, depending of course on your subject.

The 'Sunny 16' rule is a tried and true method of determining a correct exposure. This rules says that on a sunny day a correct exposure will be f/16 at 1/125th of a second. So given that you can determine what the settings will be for any other shutter speed or aperture because they both divide exactly in half or double with each increment.

For example;

If the sunny 16 rule says that f/16 and 1/125 is correct then so will:

f/8 and 1/250
f/5.6 and 1/500
f/4 and 1/1000
f/2.8 and 1/2000

All these settings will give you the exact same exposures. As the Aperture increases in size and allows double the volume of light to reach the sensor then the shutter must match by doubling its speed and allowing the volume of light to be exposed to the sensor for half the time. The only thing that will change is the depth of focus. But that is another story

 

[Dysfunction]

I doubt the OP will edit anything.
Last Activity: 07-27-2010 07:30 PM

I think pretty much all the inaccuracies have been pointed out in the last two years. Then again, I'm lazy and would simply point people to The Camera, The Negative, and The Print anyway.