Let's put it all together

I should first start off with wishing everyone a happy holiday.

     In the last few posts, I've tried to explain what each of the three main parts of an exposure do individually and now I'll try to put them all together.

     It all comes down to controlling the amount of light entering into the camera. Say for instance it's a really bright sunny day, and you want to use a wide aperture to reduce your depth of focus. Your options would be to reduce your ISO setting number (I always shoot with the lowest number I can get away with), Or increase your shutter speed.

     In the above example, in the same light and same lens (Nikkor 85mm f1.4 D IF), I shot the image on the left with the aperture wide open to reduce the depth of focus, and got away with 1/50th of a second shutter speed. The image on the right was made with the aperture closed to the ideal minimum on my camera (I start to lose image quality smaller than f16), and the shutter speed reduced to 2.5 seconds- thank goodness for tripods, I never would have been able to hold the camera steady for that long. Due to the much smaller aperture, the image on the right is far more in focus from front to back, but due to the much longer shutter speed, it would have been the epitome of blurry because of camera shake if I had tried to hand hold it.

In this example, I was aiming for a clear image that was focused evenly from front to back, so I stayed with f16 on the same lens as before. At first glance, they're both reasonably decent shots. The first one, again, would have been impossible to hand hold at 2.5 seconds. I turned the ISO all the way up to 3200 and got a more respectable 1/10 of a second for the exposure, which still would have been tricky to hold, but not as much as before. The drawback to that is that with the ISO that high, I've introduced a good deal of noise to the image. If I were to hand hold it, I likely would have compromised a bit on the aperture (widen it a bit) to let more light in so that I could use a faster shutter speed.

ISO demistified.

     Most cameras these days have an adjustable ISO setting. The numbers relate directly back (like it was all that long ago) to the days of film, when the same numbers related to how quickly the film reacted to light. The lower the number, the slower the film was. Typically, slower films also gave much finer photographs. Most of the film typically found was rated at 100, 400, and 800; although there were many others available at higher end photography outlets (I actually still have a roll of Ilford 50 in the freezer I purchased for a shoot that never happened). The differences were both in the film carrier itself, as well as changes in the chemistry of the light sensitive layer. Back then, you had to have an idea of where you were going to be shooting, and load film accordingly. Bright, sunny day? load up a roll of 100. Family gathering at grandma's? Load up 400 (or sometimes 800, depending on how dark grandma's house is).

     Since you can always shoot at smaller apertures, or faster shutter speeds to reduce the amount of light getting to the film, you can always just have 800 in camera (or now, have it set for 800), right? There's the rub. Yes, technically you could, but there are a couple drawbacks. First off, decent high speed film got expensive. Second, due to the difference in chemistry, it was also much grainier. The following photo is actually a digital photograph that I ran through a graphic editing filter that does a particularly good job of simulating different films.

     The left half is simulating Kodak TMax 100 speed, which will be familiar to anyone who took a photography class. The right half is of Kodak TMax P3200, which was the fastest film you could typically find at the camera store. The difference could be used for the effect alone, I frequently did it myself on many occasions, depending on what I was shooting. Many times, though, the grainy effect would not benefit the final image.

     The same type of thing happens in current digital cameras, due to the fact that as you turn up the sensitivity of the sensor, you're trying to get the same amount of information from less input. An audio geek or musician would refer to the outcome by discussing signal to noise ratio. Unfortunately, the effect in digital cameras is less photogenic than in film. The next photo shows exactly the same image taken in my digital SLR at two different ISO settings... the left is at 200, which is the lowest native setting I have available; the right is at 3200, the highest setting.

At first glance, it's really not to bad (it was actually lit reasonably nicely, so there was plenty of information for the camera to process). If zoomed in, though, the noise becomes more prevalent.

     I feel compelled at this point to mention that I did no manipulation to the above photographs, other than zooming in on the chess board.

     This is one of the few occasions that having a higher end camera comes in handy. For the most part, as I'm sure I've mentioned before, a camera is a black box with a controllable hole in it. Higher end cameras, however, do have much better electronics. The above photos were taken with my Nikon D300, which is by all accounts a decent camera. If I could afford, say a D3S (I wish), the noise at ISO 3200 would be significantly reduced; but at three times the price of mine, I'll leave that one to the pros.

Shutter Speed is your friend

OK, It's been an obscenely LONG time since I've been able to actually sit and write anything. It's been a rough couple months.

Only slightly (in my experience) better understood than the effects of the aperture is the shutter speed. Using this is how you either freeze or blur motion, make the difference where you get a decent hand held shot over needing a tripod, or in some circumstances, actually get your camera's sensor to do some strange things.

I'll start with an amateur car race I photographed right around the time that I actually intended to write this post.

I have to admit that I broke one of my cardinal rules, and I think it's well worth mentioning here as a little side note: Always have a list of intended shots! Since I was photographing the race (at least partially) with this post in mind, I came up with a list of what I wanted to show, but didn't write it down. In the excitement of the day, which included running back to the hotel to change- shorts are not allowed track side, as it turns out; I forgot a couple. If  I'd had a written list, or at least a note on my cell, I would not have so easily missed them.

On with the examples... First, stopping action. Generally speaking, the faster your shutter speed, the less time will be allowed for your subject (or in some circumstances you) has to move during the shot. Easy, right?

In the first example, I cranked up my shutter speed a bit (1/1600th of a second), and got an otherwise decent frame of this car.

The trouble is that you can't tell that this car is actually in the middle of the race. The wheels aren't turning, the grass is clear, as is the corner worker's truck in the background. I might as well have shot it sitting still in the paddock.

For the next frame, as well as turning down the shutter speed, I used a technique called panning. I was attempting to swing my torso in the exact direction as the car, at the same angular speed, keeping the car in the same spot in the viewfinder. At first it sounds reasonably straight forward (I know I thought so anyway), but the more I thought about it, the trickier it became. I have to admit, the first few frames didn't work out so well, but after a couple attempts I started to get the hang of it.

This Corvette was taken at 1/200th of a second- quite a bit slower than the first one.This time, you can actually tell that the guy was actually moving.

To be filed under the photographer moving category, as well as under poor technique, the next frame (taken at 1/320th of a second) shows what happens when the photographer (me) is moving during the frame. To be honest, I can't quite tell if I was swaying too much, or just wasn't panning with the car properly- I haven't looked at it that closely yet.

You'll notice that the car is totally blurry. We all get shots like this, especially when starting out. Considering that I had never even seen a car race before, let alone photographed one, I'm surprised I didn't get a greater quantity of these. There is a reason that every photographer I know goes through every shot from the shoot, and picks out the best ones. Nobody (except for a couple wedding photogs I've seen- and they should learn this rule, too) shows the client everything.

Also in the category of subject and photographer moving is the next one. About a decade ago (in the days of film), I was doing a lot of work with local bands, usually in night clubs. It was a lot of fun, and I had the opportunity to learn how to work in some of the most difficult lighting conditions I could think of. Anyway, I was looking through some prints from back then, and came across this one. Clearly, Wayne and I were both moving (notice the movement in the microphone stand- that's me moving), and due to the nearly total lack of light, I had my shutter speed way to slow to hand hold, but I actually kind of like the nearly surreal way this came out. I likely set it aside back then because it's technically very bad, but have grown to like it in a way. This is why I don't delete (or toss) anything, except for the worst of the worst, even if nobody else sees them.

Deviation from the plan.

This was originally going to be the next part in the "exposure" series, which was actually mostly written. An opportunity has come up that will allow me to get (hopefully) some decent frames showing different things you can get varying your shutter speed. Unfortunately, that's going to be in a couple weeks.

In the meantime, I've been playing with my new-ish macro lens. At some point, I'm going to have to put something together about lens length, distance to subject, and depth of focus (how much of the frame is in focus, and how your distance from it and lens choice will affect it).

First evening playing with Ferro Fluid

The above photo was taken during my first evening playing with ferro fluid. It's a suspension of tiny magnetic particles (their size is measured in Ångstroms) in oil. If you've ever done the iron filings on paper over a magnet trick, this is very similar, except it works in three dimensions, following the flux lines of the magnetic field. I'll be playing with this more later.

from wandering around the back yard

The frame above was from the first day after I had gotten the macro lens, and just wandered around the back yard, trying to get a feel for it (the lens, not necessarily the yard).

Aperture

The first, and possibly the part of the trinity with the greatest effect on the final image is the lens aperture.

Each model lens has a different minimum and maximum size aperture, usually referred to by a decimal number, sometimes following a lower case f; like f2.8. The first image is a lens with an aperture adjustment ring, like I mentioned in my last post. The second is a newer lens built strictly for digital cameras, on which such manual controls are obsolete.

traditional, manual aperture control

new style, digital only lens

 

The number is referring to the size of the opening in the lens. It's actually inversely related to the length of the lens. In the case of my 85mm lens, the largest aperture is f1.4 so its diameter is 1/1.4 x 85, or 60.714 mm. None of this is necessary to know.

The size of the hole is controlled by a group of leaves that open and close based on the setting. The shape of the leaves can also affect the price of the lens- lower end lenses will typically have a straight profile, where higher end ones will sometimes have both more and curved leaves, creating a more circular aperture.

aperture wide open

same lens as above with its aperture at its minimum setting

Usually, more expensive lenses will also have larger maximum apertures (usually referred to as "faster," or “brighter”). This comes in handy for the ability to hand hold (not use a support like a tripod) a decent exposure without having to use a flash, and also the depth of focus, which I'll get to shortly.

Several years ago, I was doing a lot of work with local musicians, usually at live performances. At the time I was using a lens common to the off the shelf kits- a zoom telephoto lens with a maximum aperture of f4-5.6 (it varied based on how far I had zoomed in). The lens itself is decent; but with the extremely low light levels, it was difficult at best to get a decent exposure. When hand holding long exposures, you always run into a problem with you moving; and when photographing living subjects (people, pets, etc....), they will move as well. In contrast, I've done some similar work with newer, faster lenses recently, and found it much easier to get a decent shot due to the availability of more light.

Besides allowing for a shorter shutter speed, the size of the aperture also has a huge effect on the depth of space that's in focus. Don't worry, I'm not going to get into the physics behind this trick, I'll just give a couple examples.

In the image on the left (forgive me, but for a frame of reference, you'll be seeing this same series of shots several times), I shot the chessboard with the lens wide open, at f1.4. Notice the fact that most of the frame is progressively more out of focus, both toward and away from the camera, with just an extremely short section that's in focus- right at the knight's ear. The right image was taken with the same lens, except that the aperture was what I call "slammed shut," at the smallest setting, in his case f16. Much more of the frame is now in focus, including the back edges of the poorly assembled background.  The larger out of focus area comes in handy when you want to bring attention to only a small portion of the scene, but one has to be careful, because it's very easy to reduce the depth of focus too far, like in the second photo. I was focusing on the moth’s mouth area, but the front of the head is completely out of focus.

Another thing to keep in mind is that at the widest and smallest settings, even the "best" lenses on the market lose sharpness. One advantage they have is that the optics are almost always better, and a lens with a maximum aperture of 1.4 is natively going to be sharper at f4 than a lens with a max aperture of f4. Almost all lenses lose sharpness at their minimum and maximum settings.

Intro to photography 1

This will be the first installment in a series of posts intended to be an introduction to photography. I'll try to keep it as simple as possible, but being a geek by nature, I may go on a bit of a tangent here and there, so please bear with me. Also, I'm a Nikon guy, so most of the time, I'll likely using their terms.

Before I really get started, I have a quick note. I was recently asked by someone who is looking at getting their first digital SLR for recommendations on how to learn to use it. This was, not surprisingly, the final push for me to start writing these articles. My initial reaction was to say, "get out and use it." Since then, I've thought of another one. Read the manual. Don't expect to remember anywhere close to all of it, just get the basics of the controls, and know where to look for answers. I've had my current camera for a couple years now, and know the controls I use all the time like the back of my hand. Sometimes, though, I come across the need to use a feature that I've never used before, or one that I use so rarely, that I still have to look it up. That's OK. Modern cameras a so complicated, there are features that few people ever use.

On to the original point of this post...

A wise man once said that a camera is just a black box with a controllable hole in it. This is entirely true, and learning exactly what's going on when you change the controls opens up a whole new world of images. Most people never get past the "program" setting, which allows the camera's computer to make all the decisions. This is fine in some circumstances (I still use it on occasion), but the quality of the output is limited.

My intent in the next few (maybe several) posts is to help people get past this.

When I first started playing with cameras, once the film was loaded, there were two things in the camera that affected the exposure: aperture and shutter speed. With the advent of digital photography, a third thing was entered into the mix- ISO (film speed). Together, I'll refer to them as the trinity. I'll be explaining each of them individually later in separate posts.

Aperture refers to the size of the hole in the lens that lets light through to the sensor. If someone is discussing the details of an exposure, you'll see it as a decimal number: 3.8, 16, 5.6, etc. On lenses not made specifically made for digital cameras, there's a ring just in front of  where it mounts to the camera (not surprisingly called the lens mount) with the same numbers on it. This is where we used to adjust the aperture. There is some math you can do to figure out what the size of the hole is, and I'll touch on that later. For now, all that needs to be understood is that the smaller the number, the larger the hole in the lens, so more light will be reaching the sensor all at once.

The second part of the equation is the shutter speed. This refers to the amount of time the sensor is exposed to the light, usually refered to as a fraction, e.g. 1/250(th of a second)in the camera's viewfinder, it will likely be listed as a whole number with a quotation mark after it. This is an important thing to notice. When the viewfinder says 250, that's 1/250th of a second; when the viwfinder says 250", that's 250 seconds- huge difference. The longer the shutter speed, the more light will hit the sensor; it also means a greater amount of time that neither the photographer nor their subject can move without blurring.

Third is the ISO. This is actually a holdover from the days of film (which aren't actually dead yet); when we would have to think about what the light levels would be like where and when we would be shooting, and choose a film speed accordingly. The differences were in the chemistry of the film itself, up to and including the size of the light sensitive crystals. The lower the ISO number, the slower it reacts to light. Digital photography has made this a variable option.

There are a couple reasons that all of this is necessary to understand. First and foremost, digital sensors act the same way as film. If you send too much light at them all at once, your image will be either way too light, if not full white. Not enough light has the opposite effect, everything fades to black.

Now that I've thoroughly scared off anybody even slightly interested, I'm going to stop to allow for a reread. I swear I'll do my best to explain how all this works together.

It's been a strange few months.

I realized the other day that it's been a while since I've written anything.

Since my last post, I've gotten a new job. After eleven years, I decided I needed a change. I now have a better schedule (I'm not working until 1 AM anymore), and the people I work for are MUCH nicer. My blood pressure is still coming down, and I've now been there almost seven months.

Which leaves me wondering about a project I was working on. A former coworker was talking about holding some photography classes, and asked if there was anything I would like to do. I thought about doing a couple about the trinity of exposure-  aperture, shutter speed, and ISO; and even shot some example frames. Since I no longer work there, What do I do with them? I guess I can put it here.