Why learn about aperture and shutter speed?

Auto modes do a good job of capturing the world as you see it. Most of the time, though, these kinds of photos are seen as "snapshots". The semi-manual modes (the "priority modes") on your camera can give you considerable control over your photos to produce the end-result that YOU want rather than just taking whatever comes out of the camera as-is.

So, here's some inspiration. (You can click on any of the photos to view a larger version, the EXIF data, leave comments, etc.)

Aperture Priority Mode:

Small-numbered apertures (like f/4) will give you a more shallow depth of field. This can be useful when you have an ugly background like in the photo below where the background would have been a bunch of scrub brush in the distance at the local dog park:


Another thing you can do with a shallow depth of field is place the viewer's attention on one specific thing like in this photo where I picked one particular tulip as the subject. Keeping the rest in-focus would have made the shot too busy and this one tulip (backlit so beautifully by the sun) would have gotten lost:


Large-numbered apertures give you larger depth of field, which allows everything in the shot to be in focus from near to far like this:


When taking shots at night, using a large-numbered aperture will give bright lights a star-like effect:


Shutter Speed Priority Mode:

A fast shutter speed will freeze action like this:


A slightly slower shutter speed like 1/60th to 1/125th can be hand held and moved along with something that's moving fast to create a "panned shot" like this one:


A slow shutter speed can be used for all sorts of things. The downside is you'll need a tripod for all of the following types of shots.

First, at about 1/6th to 1/8th of second you can blur the water in a waterfall to create a silky, milky water effect like this:


Or if you use 5 to 10 second exposures you can do light painting like this:


Or "ghostly" photos like this:


And even longer exposures can give interesting results when you have lights that move like on ferris wheels or moving traffic like this:


I hope this gives you an idea of the kinds of decisions that are open to you when you know how to use the creative controls on your camera. Learning to use them isn't that hard, but the rewards are pretty awesome.

How aperture relates to shutter speed and vice versa

Learning how aperture and shutter speed (and ISO) relate to one another is an important thing to know when you're learning to use manual mode as well as the priority modes. But, this too is easy!

If you find a combination of settings that gives you the magic "0" reading on your meter (which means the photo should be exposed properly), and then you want to change the aperture value to get more depth of field, it's fine -all you have to do is some elementary math:

You may have heard of a "stop" of light? That's what those numbers on your exposure meter are -"stops" of light.

(Your exposure meter looks like this: [-2...-1...0..+1..+2] although Nikon flips the numbers around.)

The handy thing about measuring light in "stops" is the fact that when you half or double the number you use for ISO, aperture, or shutter speed -that's a "stop". So, in this example, if you remove a "stop" of light by using f/8 instead of f/4 your photo will come out too dark (at -1 on your exposure meter). But, by doubling the shutter speed to ADD a stop, you'll be back at "0" (correct exposure)! But if we want f/16, then you're doubling the number twice, so we have to half the shutter speed twice, which gives us 1/250 at f/16.

All you have to remember is how the settings effect the light that hits your film or sensor:
* Shutter speed: you gain a stop of light by halving the shutter speed.
* Aperture: you gain TWO stops of light by halving the number.
* ISO: you gain a stop of light by doubling your ISO.

So, as an example assuming your ISO is set to 100 and doesn't change, 1/1000th at f/4 would be the same as all of the following:
* 1/500 at f/5.6
* 1/250 at f/8
* 1/125 at f/11
* 1/60 at f/16
* 1/30 at f/22
...if you wanted a shutter speed of 1/15 you can't double your aperture to 1/32 -that setting isn't available on most lenses. So, you'd have to get that extra stop of light by doubling your ISO instead.

So, assuming your aperture was set to f/4 and doesn't change, 1/1000 at ISO 800 would be the same as all of the following:
* 1/500 at ISO 400
* 1/250 at ISO 200
* 1/125 at ISO 100

If you're not one for math you could even just count the clicks up from f/4 to f/16, then change the shutter speed down by the same number of clicks to get back to correct exposure. ...the math really isn't hard though.

This may be hard to read and understand, but it's really easy once you do it a few times. A great way to see this for yourself is with this camera simulator:
http://www.photonhead.com/simcam/shutteraperture.php


One reason that you may want to know how to do this is night shots. For exposures longer than 30 seconds, you need to calculate the settings yourself. More info on this can be read in Part II of this article here.

Getting sharp photos in low light

(Click on the photo for a larger version, the EXIF data, etc)

On Saturday I met Mike (ndisgr8) from my yahoogroup at Brookfield Zoo and we spent the whole day taking pictures. It was overcast in the morning, which made many of the indoor exhibits, which are largely lit up via skylights, very dark. As a result, it was extremely difficult to get high enough shutter speeds to get a decent photo in there. I figured this was a great example of low-light photography which everyone seems to run into as a problem from time to time, so here's a write-up about how I dealt with the situation and managed at least a couple decent pics from the ape house...

Equipment:
I was using my Sigma 50-500mm f/4-6.3 lens because this zoo gives the apes a lot of space to roam around and play, so I needed all the "zoom" I could get. For those who aren't familiar with the "f numbers" on lenses, it's included in the description of the lens for just this purpose (low light photography). The lower the "f numbers", the better the lens performs in low light. When you have a range of f-numbers like for this lens, it means that at the wide end (50mm) , 4 is as low of a number as you'll be able to choose for your aperture. At the long end (500mm), it's 6.3.

The reason this matters is as follows: The lower the aperture number, the faster your shutter speed can be. This is because as the aperture numbers get lower, you're letting more light into the camera, with more light via aperture, you can get faster shutter speeds (which allow less light to get in because the shutter doesn't stay open very long). -It's all a matter of balance.

Step 1: Aperture
This lens (the "Bigma") is not very "fast" (meaning it has relatively high f-numbers), so it really limits me when there's not much light. Because of this, I immediately put my camera on aperture priority mode and set it for it's lowest aperture number so I could get the most light possible via aperture (which would, therefore, allow the fastest shutter speeds possible).

Step 2: ISO
Before even bothering to begin looking for photo opportunities, I also set my ISO to 800. The higher your ISO number, the faster your camera will record the light when you take a picture. So, in low light you want to choose a high numbered ISO.

The cost for using high ISO numbers, however, is noise. Most noise can be removed in software later, but there's always an effect on picture quality. You should, therefore, always shoot in the lowest possible ISO setting for the lighting conditions you are in. In other words, remember to set it back down to 100 when you're shooting in daylight again.

Each camera is different as far as how much noise it produces at different ISO's, so it's a good idea to experiment and know how your camera behaves and how well you can remove the noise it produces at each different setting. This way, you'll know not to go above (in my case ISO 800) or you're risking not being able to remove the noise from the photo effectively. -I did end up moving to ISO 1600 later on in the ape house as a last resort because I wasn't getting any clear shots at ISO 800.

Step 3: Check your shutter speeds
Next, I lined up a shot and checked my shutter speed. With most SLR's you can see the shutter speed in your viewfinder. In this case, I was seeing shutter speeds ranging from 1/10 to 1/60 most of the time.

Remember, the rule of thumb is that you need a tripod if your shutter speeds are faster then the reciprocal of your focal length. That's just a fancy way of saying that if you're shooting with a 500mm lens like I was, your shutter speeds should be faster than 1/500th of a second. If you're shooting at 300mm, they should be faster than 1/300th of a second, etc. (Although 1/60th of a second is as slow as you should go with any lens because it's hard to hold the camera steady enough when your shutter speeds are slower than that regardless of how wide the lens is.)

So, I needed shutter speeds that were up to 50 times what I was getting!

Step 4: Put your camera on a tripod
I had a monopod with me just because my lens is so heavy, but I didn't have a tripod. So, I leaned the monopod against the railing and steadied it further by bracing it against side-to-side movement with my foot. A tripod would have made it more steady.

Of course, the monkeys and apes were rarely perfectly still, so even with a tripod, you'd still get blur unless they happened to stay still during the shot.

Step 5: Use burst mode
If you've done all you can with settings and steadying the camera, but your shots are still coming out blurry, your best bet is to take as many shots as possible. Many people aren't aware of it, but they jerk the camera a bit when pushing the shutter button to take a photo. That may be contributing to the blur, so if you put your camera in burst mode you can hold the shutter button down and it'll take several shots one after the other. Even if you're sure you don't jerk the camera, just by shear volume, this will increase your chances at a clear shot.

Step 6: Get creative!
I was doing all of that as well as trying to concentrate only on the apes that were in the best light and I was still having trouble getting clear shots. So, for a few shots I decided to try something different. I was shooting in RAW, so I knew that I'd have a good chance of getting most of the data out of a photo even if it was severely under-exposed (dark), so I intentionally under-exposed several photos as a last resort.

Your camera should have an exposure meter that looks like this: [-2...-1...0..+1..+2] and there's a small indicator that shows you your current exposure setting. "Zero" is normal exposure, but if you use exposure compensation to move the indicator towards the positive numbers, you're telling the camera to over-expose the photo by that amount. When you move the indicator towards the negative numbers, you're telling it to make the photo darker (under-exposed).

Darker photos are a result of letting less light into the camera, so when you move the exposure down into the negative numbers you should get higher shutter speeds. When you're shooting in RAW you're often able to lighten up the photo by up to 2 stops (which correlate with the numbers on that exposure graph on your camera).

So, I moved the exposure meter down to -2 and took a shot. I reviewed the photo on my LCD and turned on the option to view the image's histogram. I made sure the data didn't run off either side of the graph (because that indicates that you're missing data, which you can't get back even in RAW). The photo was very dark, but the histogram looked ok, so I tried a few shots like that and hoped I'd be able to "save them in software" later.

Summary:
The photo above is one of the ones I took on ISO 1600 and under-exposed by 2 stops, then "saved" in the RAW software that came with my camera (Digital Professional Pro). The "right" solution to this kind of a problem is a "faster" lens (meaning a lens with lower f-numbers), but everyone eventually finds themselves in a situation where they didn't expect to have a low-light issue and they need to do what they can with what they have. Hopefully, this write up has given you some ideas for the next time you're shooting in low-light.


Extended reading / other resources:

• How to read histograms here: http://blog.muddyboots.org/2009/02/histogram-basics.html

Making backgrounds blurry

Intro:
Sometimes, when we want to take pictures of something, the background is rather ugly or maybe it's too complex and overwhelms the viewer. In these cases, if we can get the background blurred, the subject stands out better and the photo looks more professional. Some examples: Taking a picture of a person in front of a city street or taking a closeup of a flower without having mud or weeds showing in the background. A blurred background will lead to a much nicer photo in both of these cases as well as many others.

For Beginners:
If you are using auto modes, try the two below. They'll both lead to blurred backgrounds in most cases.

• Portrait Mode: For people pictures, monuments, and other work where your subject will be fairly large ("person-sized" plus or minus a few feet), "Portrait Mode" works well. The icon for this mode usually looks like a woman's head.
  
• Macro Mode: For smaller subjects, like flowers, where you'll be pretty close to the subject when you take the picture (within a foot or so), use Macro Mode. The icon usually looks like a flower.
  

For Intermediate Photographers:
Aperture is the setting that controls "depth of field" or how much of the photo is in-focus. Low numbers (up to about "8.0") will create more background blur than higher numbers (around "16" and above). Try putting your camera in "Aperture Priority Mode" (usually marked with an "A" or "Av"), select an aperture, and the camera will automatically choose the shutter speed to match it so your photos will come out properly exposed. (This mode may take some experimenting with to get used to, but it's really quite easy and it's a great way to get familiar with aperture before moving into learning full Manual Mode!)

Some things to watch out for:

• Overly dark photos: This will happen if there's not enough light and you're trying to use too big of a number for the aperture. You can lower the aperture number or increase your ISO number (for example, if you were using ISO 200, turn it up to 400 or 800), or move to an area where there's more light (if possible).
• Overly bright photos: This will happen if there's too much light and you're trying to use too small of a number for the aperture. You can increase the aperture number, or decrease your ISO number (for example, if you were using ISO 400, try turning it all the way down to 100), or move to a less bright area (if possible).
• Weird or blurry photos: This happens when you choose a high numbered aperture in conditions that are too dark. The camera had to use a slow shutter speed, so if you move the camera at all you get a blurry mess. Either put your camera on a tripod or use one of the tips for an overly dark photo: choose a smaller aperture number, increase the ISO number, or you'll need to find a way to get more light on your subject.
  

For Advanced Photographers:
Once you spend a little time using different apertures in different conditions, you'll notice that using an aperture of "8.0" might result in a lot of blur in a flower photo, but almost no blur in a photo of a mountain range. This is because aperture isn't the only thing that determines depth of field. The other conditions that effect how much blur you'll get are:

• Distance to subject: The closer that you are to your subject (the thing you are focusing on), the more blurred your background will be.
• Your lens: The longer your lens is, the more blur you'll get. (A "long lens" means one with more "zoom" -more technically, a long focal length, as in a 300mm lens rather than a 28mm lens)

For Photo Geeks:
For more information, see my depth of field tables below:

• For subjects 10 or 20 feet away.
• For subjects 50-75 feet away.
• For subjects around 100 feet away.

(* Again, by "subject", I mean "what you are focusing on".)

You can print those tables and keep them with you to get an idea for how much blur you'll get with a given lens, and a subject a given distance away, or you can just experiment. An interesting thing to note is that the change in distance and focal length go hand-in-hand. In other words, if you want a photo framed a certain way, you can't use a longer lens to get more background blur -you'll have to back away too far and those two changed conditions will cancel each other out so that you'll get about the same amount of background blur either way. The only way to get more blur in these situations is to use a smaller aperture.

Conclusion:
This is one of the secrets of pro photographers -be aware of your background. If it's ugly or busy and you can't change it, do what you can to take the viewer's attention away from it by blurring it (or in more technical language, using a shallow depth of field). ...and (hopefully) now you know how to do it too!

If you don't understand something or have trouble with any of my tips, feel free to contact me via a comment on this (or any) article, or see my website for my email address and I'll be happy to help you out!