Assignment - Balance - Part 2

My last post was a bit of a teaser for the Balancing Assignment in the Lighting 102 course.  You can look back to that post for the specifics but basically this assignment was to take a photo that really meant something to someone using the basic skills that have been learned.  I planned to photograph my friends’ first child to satisfy the “special” part of this assignment. 

I had noted that I’m not what you would describe as a “baby person” so I feel the need to put out a disclaimer that no babies were hurt during this photography session.  No amateur photographers were harmed either. This was my first “baby shoot” and I can honestly say that it was vastly different than any other assignment I’ve ever been involved in.  Luckily the parents of this angel are good friends of mine so we could spend the whole day together without feeling rushed. 

This “shoot” took about six hours!  That may sound like an incredibly long time if you’ve never photographed a 4-week-old baby before.  I don’t think a 4-week-old understands schedules or cares about the goals of the guy behind the camera.  Between feedings, burping, changing, and a handful of NCAA Tournament games, we had lots of breaks that turned out to benefit everyone involved.  The baby needed its breaks, the parents needed the breaks to tend to the baby's needs, and I used the down time to review the photos we’ve taken.  The biggest benefit to all these breaks was that no one felt rushed.  Since we really didn’t have a choice, we worked around the baby’s schedule, and I think this put everyone at ease.

I would love to start showing all the wonderful photos that I was able to get of the baby and the parents but when I first began this blog I had to decide whether or not to make it public.  When I made that choice I also told myself that I would strictly adhere to anyone's request to not be included in it.  My friends that were the subject of this assignment have not been sharing photos of their baby on the internet and I was not about to without their approval.  But, since they are such nice people they did agree to let me post a few that keep their family anonymous.  I have even gone as far as to refer only to the baby as "it" instead of "he or she".

Let’s start out then by playing a game.  This is a photo of the baby’s feet; the first person to correctly identify this baby will win a prize!  Just kidding, I really do admire the reasoning behind their decision and respect it.

The entire shoot took place in my friends’ living room.  (Coincidentally, this was also the location of the largest television in the house.) This particular Saturday was pretty dreary so there wasn't an abundance of nature light in the room.  To compensate for this I set up two speedlites; one was set up with a shoot-through umbrella to lighten up the entire room and the second was set up inside a soft box.  Shoot-through umbrellas are sometime referred to as “light bombs” because they tend to throw light everywhere and I positioned it as high as I could in the room so it was away from the baby and it didn’t scare “it”. In this position it also wasn’t in my way as I moved around.  The soft box is slightly smaller than the umbrella and much easier to move around so I could easily bring it in nice and close.

I switched between two lenses that I love, the EF 50mm f/1.8 and the EF-S 60mm f/2.8 Macro, for the entire shoot.  I might have been able to shoot the whole session with the 60mm Macro but for some shots it was just a little too long (on a crop sensor camera) for the room we were in.  If you have a dSLR and are not familiar with the term "crop sensor" your camera probably has one.  Crop sensors have a built in crop factor that makes lenses seem more zoomed in than they would on a full-frame digital or a 35mm film camera.  Both of these lenses have much larger maximum apertures than the "kit" lens so they work much better with limited light.  

This is a second photo of the baby and "it's" daddy.  I tried to do a good mix of close ups and portraits so the parents had a variety of shots but of course I won't be sharing the family portraits.

For this being my first time photographing a baby I felt that it went well.  It really wasn't the baby's best day but with being able to take the entire day for the photo shoot I was still able to get numerous shots that will hopefully be memories for a very long time.  I want to thank my friends for allowing me to photograph their child and for allowing me to post these photos of..."it".  I hope that they feel the "something special" that was the point of this assignment.

As always, if you think that I stink, please let me know in the comments section and if you have any questions I would love to try and answer them.  The next method of control is "Restricting Light" so we get to discuss things like gobos, snoots, cookies and more!

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Assignment - Balance - Part 1

I am incredibly excited about the Balancing assignment.  It is something completely different than the previous ones and it ups the stakes in a very powerful way.  But before I can get into the assignment I'm compelled to do a brief summary of where we are and what's been learned in the Lighting 102 course.

Where are we?

According to the L102 course there are seven ways to control light:

1. Varying the position - previously discussed
2. Varying the Apparent Size of the Light Source - previously discussed
3. Altering the Relative Intensity (i.e. Balancing) - We are here! 
4. Restricting Light
5. Refraction and Reflection
6. Altering the Color
7. Time

What's been learned?

I'll keep this list condensed to what has been learned about balancing light.

1. By altering the aperture we lighten/darken both the ambient and flash exposures (the whole scene)
2. Altering the shutter speed lighten/darkens only the ambient exposure. Think of flash as instantaneous, it does not care about how long the shutter is open (as long as you are working within the max. sync speed).
3. To alter the flash-lit area and not the ambient light you have to do a little dance;

                        i.     The ambient light cares about both the aperture and the shutter speed while the flash only cares about the aperture, so to alter the flash and not the ambient you need to adjust the aperture to the desired setting and then compensate the shutter speed the equal and opposite amount.

Simple, right?  Well, maybe an example might help.  Say you were shooting a couple maracas (see below) at f/4 at a shutter speed of 1/25 but the flash is too bright.  You have a couple options.  You could walk over to the flash and manually reduce its power, you could move the flash away from the subject, or you could control it all from inside your camera. 

To control it in-camera you can stop down the aperture, say to f/5.6 (1-stop, 3 clicks on your camera). Now the whole scene darkened so you need to bump up the ambient by slowing down the shutter speed by an equal amount, 1-stop, which in this case would be 1/13.

Photo on the left was taken at 1/25 @ f/4, photo on the right was taken at 1/13 @ f/5.6.  This isn't the best example but you can see that the ambient exposure remains the same in both photos.  The easiest way to tell is by looking at the specular highlights caused by a window in the foreground (the big ones are caused by the flash, but there are smaller ones just to the left it them).  These aren't changing because the ambient exposure is constant.

1/25 @ f/4 = 1/13 @ f/5.6, simple, if try it and practice.  To make it easier sometimes I just count clicks, 3 clicks this way (1-stop, on my camera) means I have to do 3 clicks the other way.  To be honest, I just brought my camera out to make sure I got the stops named correctly.  The absolute numbers don’t really matter all that much to me; the balance between the ambient and flash is what matters.  When I first read that in the L102 course I thought, “Dude, you’re crazy!” but after working through this course I realized that it’s true, and quite liberating.

The Assignment

As I stated above, I am pumped for this assignment.  David Hobby (a.k.a. The Strobist), author of the blog strobist.com (which includes the Lighting 102 course) has tens of thousands of readers, maybe more, and he aims to mobilize this mass of humanity into an army of well-doers.  The framework of the assignment is simple; photograph someone in mixed ambient/flash light using the techniques that we’ve learned.  The special part, taking inspiration from his friends’ project the Thank You Calendar, is to “produce a photo that makes a difference to someone.”  The Thank You Calendar was a 2008 project to benefit soldiers and veterans in residence at the Walter Reed Army Medical Center in Washington.

To borrow a line from Marty McFly, “Whoa.  This is heavy, Doc.”  Sure, this whole time I’ve been working through this course I’ve been photographing my family or others, even did a Christmas card shoot for my brother and sister-in-law, but making a difference to someone?  I’m sure I have, but that was never the actual goal when I got the camera out of the bag.  The goal typically is to just, “get some good shots”.  I’ve definitely thought of using one of my previous “sessions” as the focus for this assignment but I’ve decided to make this as special as I can.

Recently I’ve been asked to take photos of my friends’ 1-month old baby.  Go big or go home, right?  This family isn’t “special” in any societal “special” way, but they are special to me.  They are a wonderful family that I’ve known for quite some time.  To build on the pressure, I don’t believe that they have done a photo shoot with an actual professional so this will be the baby’s “first photo shoot”.  

Oh dear Lord, what have I gotten myself into!

To explain that last thought a bit you first need to realize that I believe that photos of someone’s children (I don’t have any of my own) and even photos of yourself as a child are pretty important.  Whether they hang in a living room, sit on a desk or lay in an album that hasn’t opened in 20 years, they are special.  They capture a moment in time that you can ever return to (unless of course you are Marty from above).  I have yet to experience a mother looking through an old photo album and not see her shed a tear.  They are powerful, so I’m taking a bit of responsibility into this shoot.  I do not want to be remembered as the guy that ruined this kid’s first shoot.

Secondly, I’m not so much of a “baby” person.  I love being an uncle!  Give me that kid after they are about a year old and we will have a blast, but babies?  I wouldn’t go as far as to call is a phobia but…it’s something.  Toddlers are pretty tough to break.  In all reality they can take a bit more punishment than I can.  I’ve seen kids fall down on their knees and get back up like nothing happened.  If I fell straight down on my knees, unless I was on a trampoline, someone’s gonna have to help me up, that hurts.  But babies, especially before they can hold up their own heads’... I feel like I’m holding a slinky, w-whoa-Whoa.  I always see headlines in my head, “Man who held baby wrong now in custody”, “Study finds that the majority of politicians did not have their heads’ properly supported as babies”.  “…and then my poor meatball, rolled right out the door.”

How about this plan, you hold the baby, I’ll take the photo.

Check back in a week or so to see how things turned out.  Until then remember, you don't get better by leaving the camera in the bag.

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3.1 & 3.2 – Balancing the Sun

If you have been following this blog you may have noticed that there has been an extended delay in new postings.  What began as a brief pause during the end of the year holidays turned into a several month long break.  A once a week pace was becoming far to difficult to maintain and before I could recognize the warning signs I had become burnt-out.  Luckily this break has recharged me and I will continue to log my progress through the Lighting 102 course.  I can however guarantee that it will not be on a post a week pace anymore.

The last post was about balancing flash with indoor ambient light.  In this post I’ll be dealing with balancing flash with the sun outdoors.  Even though I'm moving outdoors, the principals of balancing flash remain the same; modifying the shutter speed affects only the ambient exposure, and modifying the aperture affects both the ambient and flash exposures.  Using a flash in the sunshine is commonly referred to as “fill flash” because the flash is used to fill in the shadowy areas caused by the sun.  For some beginners it might be a strange concept to use a flash in bright sunshine but doing so can make a dramatic difference in your photography.

The Lighting 102 course broke balancing flash with the sun into two separate segments.  The first segment was about balancing flash with twilight and the second was balancing with the full afternoon sun.  While my wife and I were traveling through California we stopped off at a roadside park to try out some “fill flash” techniques.  Since both segments were done on the same day so I had to switch up the order.

1/200, f/6.3, 42mm, speedlite low camera right
(El Matador State Beach)

The first photo, to the right, is my attempt at cross lighting technique during the full afternoon sun.  The sun was high, behind the subject and to the left.  A speedlite was added low and to the right.  The two light sources were set up opposite each other, hence why it is called cross lighting.

Take a look at the subject's left shoulder.  The top of her shoulder is in shadow due to the speedlite's low setup.  If this shot was taken without the speedlite entirely, the left side of the subject's face would also be in shadow.   That isn't to say that it would be "wrong" to do so but that wasn't my intent in this particular photo.  My intent was to have the subject's face entirely exposed and separate her from the background.

Fill flash is also a technique that you can also use with an on-camera flash so you shouldn't feel like you have to do a lighting setup to use it.  Any time that you are shooting a subject with a bright background you should consider using some fill flash.  Using flash on a bright sunny day will ensure that your subject is properly exposed without blowing out the sky in the background.  Blowing out a portion of a photo is when part of the frame is so over-exposed that it becomes pure white and all detail is lost.  Typically this is bad.  Clouds, snow, and white haired dogs are examples of things that are notorious for being easily over-exposed.

The second part of balancing flash with a setting sun or at twilight.  The "problem" with this is that we had some time to kill between mid-afternoon and sunset.  As mentioned in the first photo's caption, it, and all the photo's in this assignment were taken at El Matador State Beach in California.  It's a bit off the beaten track but it was well worth the drive and this is how I ended up spending the afternoon...

The series of photos above really have nothing to due with the L102 course directly but El Matador was so beautiful and I had such a good time that I felt I needed to share them.  There are a few places in the world where I have experienced pure peacefulness; perhaps it was a reaction to the hustle and bustle of Los Angeles or the excitement hangover from the Rose Bowl (Go Green!) but this was one of those places.  I could have stayed here for days.

Soon enough, the sun began to sink into the western horizon and it was time for me to get back to "work".  This wasn't my first time taking photos at sunset but it was my first time trying to do so with a off-camera lighting setup.  I describe the experience as frantic waiting.  With a setting sun the ambient light is constantly changing which adds a very different variable to contend with.  The bonus to the changing light is that you get quite a variety of photos in a very short amount of time.  It took me a while to decide but I finally ended up selecting this photo out of the bunch.

The lighting set up for this shot was very simple.  I attached my flash to a tripod and had it positioned it camera left at about the same height as the subject's face.  

On this trip I was traveling light.  I had my camera, a tripod, and a couple speedlites.  I would have loved to bring my light stands, umbrellas, soft boxes, etc. but for a trip across the country to watch a football game and do some photography on the side, the airlines extra bag fees seemed steep.  In both the daylight and the sunset shots I had a bare speedlite setup on my tripod (bare = no modifiers (umbrella/softbox etc.)).  Typically I try to keep the flash as close as reasonably possible to the subject.  This does two things: 

1. It makes the apparent light size larger and, 
2. Due to the inverse square law, it makes the light more powerful.  

I don't go crazy with closeness because nobody likes to have  a flash right up in their grill, but typically the flash is set up closer to the subject than the camera is to the subject.  An added bonus to making the light more powerful is that I can reduce the output of the speedlite.  Instead of having to run the flash at full power, which eats through batteries, increases recovery time, and reduces the life of the flash bulb, I can typically at 1/4-1/8 power or less.

I learned in this photo shoot that taking portraits at sunset is fairly easy to do but incredibly difficult to master.  In my experience, photography takes a lot of practice and this sunset portrait assignment was the toughest so far.  Thank you for continuing to follow my blog and remember that the Lighting 102 course can be found on strobist.com.  Please feel free to use the comments below to ask any questions you may have, tips you'd like to share, and words of encouragement or criticism are always welcome.

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3.3 - Balancing Flash/Ambient Indoors

In last week’s post I discussed the basics of exposure with ambient light (i.e. without the use of a flash).  I wanted to give a basic overview of exposure before jumping into balancing multiple exposures.  As the Lighting 102 course explains, when shooting with ambient light the idea of exposure is fairly rigid.  There is correct exposure for a given setting.  Straying much from this correct exposure and the photo becomes either under- or over-exposed (too dark or too light). 

In contrast, flash photography has multiple exposures: an exposure for the ambient light and an exposure for each flash used.  The idea of “correct” exposure gets a little murkier because each lighting source has it's own exposure.  Is the “correct” exposure based on the overall ambient light exposure, the subject, the background, or any combination of these?  There isn’t really a simple answer as it is completely up to the photographer to decide what they are trying to create.

As a general rule of thumb for any photo is that the main subject should be fully exposed. That is to say that if the subject is a person, the person’s face should be properly exposed.  The exposure of everything else in the photo is then free to be manipulated to the desires of the photographer.

The following exercise will illustrate the balancing act between flash exposure and ambient light exposure with a simple one-flash setup.  The aperture, ISO and flash power are held constant (f/5.6, 200, ¼ respectively) and the shutter speed alone is used to balance the exposures.   Remember that aperture affects both the ambient and flash exposures; shutter speed only affects the ambient exposure.  Therefore by modifying only the shutter speed the flash exposure remains constant but the ambient exposure can be modified.

The first shot of the exercise is to the left.  I think it's a wonderful example of taking the ambient light out of the equation.  This is a base line for the exercise, and assures that no ambient light will be affecting the shot as the flash is first introduced.  This wonderful first shot is taken at 1/200 at f/5.6 and the ambient light is approximately 6 stops under-exposed.   How do I know that it is 6 stops under-exposed for ambient?    I took a second test shot in Av and the camera calculated that a correct ambient exposure would be at a shutter speed of 0.4 seconds.  Then it is just a matter of counting up the stops.

Shutter Speed: 1/200 second

Now the flash is added (through an umbrella).  The couches and wall in the background are being lit by spill light from the flash.  The shot was still taken 6 stops below the ambient exposure so the light has to be coming from the flash.  From this point forward I will slow up the shutter speed to start bringing in the ambient light.

Shutter Speed: 1/125 second

This is the same shot taken at 1/125 (2/3 of a stop slower).  It doesn’t look all that different from the shot at 1/200 and there are two reasons for this:

1.     Since I started so far below the ambient exposure 2/3 of a stop isn’t enough to begin to bring in much ambient light, and

2.     Shutter speed does not affect flash exposure.

Shutter Speed: 1/40 second

The ambient light doesn’t begin to be exposed until about 1/40^th of a second.   This is the shutter speed that begins to allow the ambient light to fill in the flashes shadowy areas.

To the right is the shot taken at 1/40^th of a second.  The difference between this shot and the one at 1/125 is very small but the ambient light is (just barely) beginning to be exposed.  Again, everything is staying consistent (aperture, ISO and flash power) but with the slower shutter speed more ambient light is allowed in.

Shutter Speed: 1/6 second

Here it is again at 1/6^th of a second.  You can start to see why there isn’t a single “proper” exposure for the ambient light.  The subject is exposed and the amount of ambient light exposure is completely up to the photographer’s discretion.

Shutter Speed: 0.4 second

Again at 0.4 seconds, which is what the camera calculated as the "correct" ambient light exposure.

Shutter Speed: 0.6 second

And again at 0.6 seconds.  I could keep cranking up the ambient exposure but I think you are starting to see the point of the exercise.  I hope that you can see that the idea of proper exposure is quite different when working with flashes.  As long as the subject, the cameras in this case, are properly exposed, the background exposure can be anything you want it to be.

If you decide to try this exercise out on your own be sure to set the subject in an area that is less exposed to the ambient light than the background.  Place it in a "shaded" area if you want to think about it that way.  Doing this prevents the ambient light from over-exposing the subject as you open up the shutter.  This concept works just the same outdoors where you have to compete with the sun.  Also please check out the Lighting 102 course by David Hobby here.

Below is a photo of the basic lighting setup that I used for this exercise.  I originally had the curtains opened during my first attempt, an instruction that I missed in the L102 course, and had to redo the exercise.  Hopefully you can learn from my mistake.

If you have been following my blog you may be confused on why this post wasn't about working outdoors.  In last week's post I explained the difficulties of working outdoors in Michigan during December.  In fact, the high daytime temperatures are struggling to get above freezing, and there is 6-inches of snow on the ground now.  This does not mean that I'm blowing off the two exercises dealing with balancing flash with the sun.  Instead I have something special planned for these two outdoor exercises that won't require me to suffer out in the cold. This "something special" is going to take a little bit of time, and with the holidays quickly approaching, there is going to be a small lag in the posts.  Look for the post on these exercises shortly after the New Year.

Until then,  thank you again for reading and I hope that you have a wonderful holiday season.

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Exposure Basics

The next exercise in the Lighting 102 course deals with balancing flash exposure with twilight.  Completing this exercise has been difficult for me because of the time of year.  We are nearing the winter solstice and where I live that means that twilight is around 4 in the afternoon.  Since I work a day job, that happens to support my photography hobby, the time of day the sun sets limits me to working on the weekends.  This is my long-winded way of saying that I can’t write a post about my progress through the next Lighting 102 exercise because I haven’t actually done it.  I also thought that before I write a post about balancing flash exposure with ambient light exposure that I should give a quick overview of exposure in general. 

When I began this blog a few months ago, I had told myself that I wouldn’t write a post about exposure.  It’s not that exposure is a complicated concept but it takes a while to discuss and there are literally hundreds of books on the subject.  I convinced myself that there wasn’t a need to repeat a subject that has been so thoroughly covered by others.  I have since thought differently but today’s post will only be a little review on exposure and will be in layman's terms. 

Simply said, exposure is the quantity of light captured on your camera’s sensor (or film if you’re old school).  Regardless of the type of camera, only three things determine exposure: Aperture, Shutter Speed and Sensitivity.  If you understand these you can say good-bye to full-auto modes and "creative modes" forever. 

Aperture

Aperture is the opening in a lens that allows light to enter the camera.  Aperture works much like the iris (colored portion) of an eye.  As an exercise, stand in front of a bathroom mirror and stare at one of your eyes. Then cycle the bathroom light on and off and watch how the iris expands and contracts as it adjusts to the changing light. Camera lenses do the same thing except instead of a pretty iris they have a series of fins, or the diaphragm, to restrict the incoming light.  If you have an SLR with a “depth of field preview” button you can see the lens’ diaphragm by looking through the front of your lens and hitting the button (as long as your aperture isn’t set to the lens’ maximum). *  Below is a series of shots to illustrate.

 

f/2.8                                    f/5.6                                       f/11

Depth of Field Preview Button

Aperture is expressed in f-stops and they are fractions. Therefore, f/2.8 is a larger aperture than f/11.  A larger aperture (smaller number) will allow more light to enter the camera than a smaller aperture (larger number).  Aperture affects more than just the amount of light entering the camera but I'll discuss that later in this post.

*The “depth of field preview” button is on the front of the camera to the right of the lens just under the lens lock release button (at least on my Canon).

Shutter Speed

Cameras have a shutter made up of multiple little doors. The shutter is opened for a given amount of time and allows the light to expose the camera sensor (or film).  You can think of the camera’s shutter as your eye lids if you’re like me and love analogies.  On a SLR you can see the shutter by taking off your lens and lifting up the pentamirror or pentaprism.  If you choose to do this just be careful, that’s a sensitive piece of machinery that you’re sticking your finger into.  If you don't know what a pentamirror or pentaprism is, I don't suggest doing this at all, just trust me that the shutter is made up of multiple pieces. 

Shutter speeds are measured in seconds or fractions of seconds.  Longer shutter speeds allow more light in and shorter speeds less light.  The important thing to remember is that shutter speeds, much like aperture, are also expressed in “stops”.  I’ll get into why after I get through a little sensitivity training.

Sensitivity

Remember this stuff? (wiki)

Sensitivity is measured in ISO.  The sensitivity of a digital camera’s sensor is adjustable.  In contrast, a roll of film has a set ISO sensitivity rating.  On film cameras the only way to adjust the ISO is to remove the roll of film and load another with the desired ISO rating.  ISO actually stands for International Organization for Standardization, (I figure that if I took the time to look that up on Wikipedia I might as well share it) and is a way to measure how much light a type of film needs to become exposed. When digital cameras were developed someone smart decided to measure the digital sensor sensitivity using the same system.  ISO is measured in whole numbers, finally whole numbers!  What’s even better is that a lower ISO value is less sensitive than a higher ISO number so it’s intuitive.  This means for instance that ISO 100 needs more light to get proper exposure than ISO 400.  You also may have guessed that ISO, just like aperture and shutter speed, is expressed in “stops”.

Stops

The reason Aperture, Shutter Speed, and ISO are all expressed in stops is because each stop affects the exposure equally.  This means that opening up the aperture by one stop effects the exposure the exact same as slowing down the shutter speed by one stop.  Below is a table of full stops for all three:

Aperture (f-stop)	Shutter Speed	ISO
f/2.8	1/1000	50
f/4	1/500	100
f/5.6	1/250	200
f/8	1/125	400
f/11	1/60	800
f/16	1/30	1600
f/22	1/15	3200

Moving down the table each f-stop allows exactly half as much light into the camera as the previous setting, each shutter stop allows twice as much light, and each ISO setting needs twice as much light for a given exposure.  For instance, if the correct exposure in a given situation is f/5.6 with a shutter speed at 1/125 and an ISO of 200 and you wanted to open up the aperture to f/4 (1 stop), what could you do to get the correct exposure?  If you only opened up the aperture, the photo would be one stop over-exposed so to correct it you could either speed up the shutter by 1-stop (1/250) or decrease the ISO by 1-stop (ISO 100).

f/5.6, 1/125, ISO 200 = f/4, 1/250, ISO 200

and

f/5.6, 1/125, ISO 200 = f/4, 1/125, ISO 100

Dave this is so confusing, why can’t I just leave my camera in auto mode and let it figure it out?  The camera’s auto modes stink because they doesn’t allow any changes to the camera's built in functions.  I compare it to forever driving with an instructor, sitting shotgun that has his or her own brake and tells you where to go.  I’d say get the f-stop outta my car!  Digital cameras have sophisticated built-in light meters built and they should be taken advantage of but not in the auto mode or any of the "creative" modes!  Those darn “creative modes” drive me just as crazy!  Most digital SLRs (DSLR), however, have three semi-auto modes that are great to use. 

Canon EOS shooting modes (wiki)

In Canon world, the "semi-auto" modes are P, Av, and Tv.  These are Program, Aperture priority and Shutter priority (T for time, I guess), respectively.  All three allow you to use all the built-in functions of your camera that you paid good money to have: White Balance adjustment, Picture Style, ISO adjustment, focus point selection, etc. and even whether or not you want the built-in flash to fire.

Program

In Program once you depress the shutter button half way it will select an aperture, a shutter speed and ISO (if ISO is set to auto) that will produce correct exposure. Then by turning the selector wheel you can scroll through aperture/shutter speed combinations that will produce a proper exposure.  The disadvantage to Program mode is that if you want to keep shooting in a specific aperture or shutter speed you need to crank on that wheel each time you take a shot.

Av
Aperture also affects a photo’s depth of field.  In laymen’s terms this is how much of the photo is in focus and how much of the photo is out of focus.  As a rule of thumb for portrait work you want to shoot with a large aperture (small number) to blur the background and make your subject stand out.  For landscape work you want the entire scene (foreground and background) in focus and by “stopping down” your aperture (larger number) you increase the depth of field to accomplish this.  To shoot with a consistent aperture, use Av mode.  In Av mode the camera will adjust the shutter speed as the light changes to give you correct exposure without changing the aperture.

Tv
Shutter priority (Tv) works much the same way as Av mode, except you set a shutter speed and the camera adjusts the aperture and ISO (if ISO is set to auto).  For instance, this mode is helpful when shooting sporting events.  In this situation you know you want a fairly fast shutter speed to freeze the motion but you don’t want to keep adjusting the aperture as the amount of light changes.

Helpful Tip:  As a rule of thumb the inverse of your focal length is the slowest shutter speed recommended if the camera is hand held.  In layman's terms, with a 50mm lens one can shoot at 1/50 without worrying too much about camera shake.  With a 250mm lens that shutter speed drops down to 1/250.  The more zoomed in the lens is the more susceptible it is to camera shake.  If you have a steady hand, or your lens has vibration reduction (VR-Nikon) or image stabilization (IS-Canon) built in, you can slow up that shutter speed slightly.  Shooting with shutter speeds largely slower than the inverse would require a tripod, or other means, to steady the camera.

Manual Mode (M)

DSLR’s also have a Manual mode.  In this mode the user manually sets the desired aperture and shutter speed.  All of my photos that I’ve taken for the Lighting 102 course have been shot in Manual (M) mode.  Shooting in Manual does not somehow make one photographer superior than another so I don’t say this to be egotistical.  I shoot in Manual for this class because some of these exercises require that photos be taken purposely under- or over-exposed.  Also while I am learning off-flash photography I need to be able to control everything and modify one thing at a time until I get my desired exposure.  However, I will take a test shot in Program priority to take advantage of the light meter and get me in the ballpark of where I need to be for an ambient light exposure.

ISO

Most DSLRs have the ability to set the ISO setting in either Auto or a specific ISO setting (200, 400, etc) in any of the semi-auto modes or manual mode.  In Auto, the camera will set the lowest ISO possible to achieve proper exposure.  As another rule of thumb, the lowest possible ISO should be used for any shot.  The lower the ISO the better quality the image will have.  Quality cameras will have great photo quality up to ISO 400 or even 800.  Beyond ISO 800 and image degradation will begin to be noticeable, but don't be afraid to crank up the ISO if you are shooting in very low light situations. A grainy photo (loss of image quality due to high ISO) is better than a fuzzy out-of-focus one. 

If this hasn’t confused you enough in the next post I’ll be discussing multiple exposures which complicates matters even further.  In flash photography not only do you have the ambient light exposure but you also have an exposure for each of the flashes used.  It’s madness but its so much fun!!!

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