Focus and Depth of Field

The viewfinder of your SLR tells you almost everything you need to know about the shot you are about to take. One thing that it doesn't show you, however, is the amount of light that comes through at the aperture you specify. If you're one of the lucky few that have a depth of field preview button, you can actually see the difference in light when you change apertures by depressing it. What you'll also be able to see is the change in depth of field. And, now that I've been throwing that term around for a paragraph, I'll get to explaining what it is.

First, we need a bried explanation of focus. When you (or the camera) turn the focusing ring of the lens to focus on an object, the focal length of the lens (f') is changed to accomodate the following (simplified) formula: 1/f' = 1/Do + 1/Di. Di is the distance from the lens to the film surface, which is always fixed. Do is the distance from the lens to the object on which you want to focus. So, when a lens is set to a focal length of f' and the plane of the film is Di away from the lens, objects that lie in the plane that is Do away from the lens will show up in focus. Things that lie outside of that perpendicular plane aren't necessarily in focus.

Secondly, we need to understand a little more about the shapes of the glass elements of the lens. The surfaces of these elements cannot be flat because they most focus light on a particular distance. However, lens concavity and convexity (measures of the curvature of the surface of the lens) distort the image by bending the rays of light that they transmit.

And, this is where I started school... so no more time to write... :(

Aperture and F-Stops

Ever wonder why there is such a discrepancy in price between a 50mm f/2.8 lens and a 50mm f/1.4 lens? (The price of the former is typically at least a third of that of the latter.) The answer simply is that 1.4 is less than 2.8!
Well, you may have heard the lens with the lower f/ (f-stop) value called the faster lens. The reason behind this is that in the same lighting conditions, a lens at f/1.4 will be able to shoot an exposure that is shorter than what the f/2.8 is capable of. In other words, the shutter speed is faster. A bit of common sense and deduction can tell you that the faster lens must be able to let more light in than the slower one in the same amount of time. That's where the f-stop comes in. For the mathematically minded, f-stop = f/d, where f is the focal length of the lens and d is the diameter of the aperture. In the case of lens specifications, the f-stop (e.g. f/1.4) that is listed next to the focal length of the lens (e.g. 50mm) refers to f/D, where D is the largest diameter that the aperture can reach. Translated into practical knowledge, when you cut the diameter in half (or double the f-stop), you quarter the amount of light that gets through since it is the area of the opening that controls how much light passes.
So, there are a couple of things to consider with these so-called faster lenses. First of all, faster lenses are typically larger and heavier. Faster lenses need to be wider since they have to accommodate for the bigger diameter. They are heavier because they contain more or bigger glass elements. Secondly, because more glass elements result in more optical distortion, specially coated glass and aspherical elements have to be used. These factors add to the price of the lens.
But, if you can put up with the extra bulk in the camera case and the reduced bulk of the wallet, a faster lens can open up some creative portals. If anything, it will allow you to take more shots without having to pull that tripod out. The creative aspects are related to your use of depth of field.

Thinking of Going Digital? (Pt 2)

Beyond the top three factors, most consumers usually diverge in terms of what they look for. The following are things to consider, but not necessarily in the order I choose to lay them out.

Optical zoom - This ranges from 1 x (no zoom) to 10+ x and describes the amount of visible field that you can isolate with the lens. No zoom means that you're stuck with what the viewfinder sees unless you move closer or further away. Doubling the zoom (2x) means that an object will be twice as tall and wide on 2x as the 1x version. A common mistake is to confuse specifications for optical zoom with digital zoom, a method of zooming which simply involves cropping into the image, enlarging to the normal size, and the loss of resolution. Sometimes camera manufacturers will advertise, for example, a 12x overall zoom, with a 4x optical and 3x digital zoom. Since cropping and enlarging is something you can always do on a computer later on, the optical zoom will be the number to look at.

Size - The camera's size is something that will affect where you can bring it and how convenient it will be to bring along. If you expect to be travelling, you may want to consider that larger cameras make easier theft targets. Smaller cameras, while being very portable, also tend to have less features because there's less room for them. As technology is improving, smaller cameras are evening out in most fields of comparison, except optical zoom, which depends on physical parameters.

Shape & Layout - This is something that a lot of people consider without even thinking about it. How a camera feels in your hand is vital to how much you enjoy shooting with it. It shouldn't be too big, too small, too heavy, or even too light. Even if you don't intend to buy your camera in a store, you should compare the feel you get from your top choices before purchasing. Examine especially how all the buttons, dials, and switches are arranged on the camera body. Do you turn the camera off when you were intending to zoom? Do you press the shutter button instead of the power button? The layout you are comfortable with usually depends on what you're used to, from older cameras you've used.

Scene Modes - Scene modes are preprogrammed settings that are tailored for a specific type of shot. Of these, the most common are macro, portrait, landscape, sports, and night portrait. Scene modes are an easy way to take a shot without having to know how to change the settings to get the best results.
Macro is a setting that usually only works at the lowest zoom (or widest angle of view). It allows you to be able to focus on a subject that is just inches away. It's so great for flower shots that that is usually the symbol that this mode is given.
Portrait modes usually set an auto flash with red-eye reduction. It determines the exposure near the middle of the frame (where the face should be) and uses a larger aperture to focus more attention on the subject.
Landscape modes use a small aperture to get as much of the picture in focus as possible. The flash is set at off because the flash won't be able to reach most of the landscape anyway.
Sports mode lets you take shots at the fastest shutter speed allowable by the amount of light.
Night portrait is the same as portrait except that the flash will go off at the end of the exposure instead of the beginning. This allows more light from the background to hit the digital sensor before capturing the subject.

Other Features - Cameras can come with many features that you may not need on the camera itself. Some offer a panoramic mode that helps you piece together adjacent shots. This is very handy if you love landscapes. You may be able to find black and white and sepia modes, which aren't unique if you can also do that on your computer. Cameras with a focus-assist light are helpful if you take many pictures in low-light conditions. The key to a lot of these extra features is figuring out which ones you'll use and which ones you're just paying money for.

Attachments - Higher end point-and-shootor SLR-like digital cameras feature a threaded lens that allows you to attach wide angle adaptors, tele-photo converters, filters, and other accessories to the lens. These parts are usually sold separately and can be quite costly, but, if you want to be more creative with your pictures on the camera, they are a good investment.

There are many other things that you can consider, and I've only listed the most common ones. I could write forever about how I would pick my next non-SLR digital camera, but that would give you too much to read. Besides, my next digital camera will, I hope, be an SLR!

Thinking of Going Digital? (Pt 1)

Digital cameras seem to be the trend of the future nowadays. People from almost all areas of photography are jumping onto the digital bandwagon - wedding photographers, amateur enthusiasts, and especially point-and-shooters. Digital photography truly has its advantages for most photographers. Despite the higher initial investment, you can imagine how much money and time you can save when you don't have to worry about buying and processing film. Especially with the Internet as the preferred form of communication, digital files become much more convenient than paying for scans or scanning pictures yourself.

So, if you're that average point-and-shooting consumer, are you ready for a digital camera? One of the first things to consider is how much and how often you shoot. If you take your camera with you everywhere, you're sure to save on film and developing costs. If you tend to take one or two shots and forget your camera for a year, a regular film camera isn't for you. However, whether you chose digital or an instant camera, in this case, is up to your wallet. For those that already have a film point-and-shoot that they are very happy with, perhaps investing in a negative scanner (remember they also make attachments for the cheaper flatbed scanners) would be the better route. There are many factors to consider beyond just how you use your camera and your budget. In the end, if you feel you're ready for it, you're ready to start looking for your digital camera.

Having sold cameras for several years, the most common question I got was "well, which camera do you recommend?" This was one question I always dodged because what works for me and what I like in a camera is quite individual. There are many aspects of a camera to consider before making your purchase. It's up to you, the consumer, and not the salesperson to figure out what has priority over the other details. Three factors, however, tend to be the top considerations.

First, how much do you want to spend on this purchase? Keep in mind that the camera will probably not be the only item you'll be getting. Digital cameras come with a miniscule starter memory card (8-32MB), so the chance of you buying something bigger (128MB+) is very high. Also, unless you already have a case or don't intend to take the camera outside your house, a case or bag to carry and protect the camera will be very helpful. Digital cases, as I've experienced, tend to be more padded, and consequently more expensive, than similarly sized and featured analog camera cases. Additional warranties, extra batteries, AC adaptors, extra battery chargers, tripods, etc. There are many things you can add to this purchase, so figure out beforehand what you need so you can have an accurate measure of how much of your budget remains for the actual camera.

Secondly, figure out what you'd want to do with the pictures you take. Will they only be posted on websites? Will they be emailed to friends? The 5MB jpg file that can come out of a 4-MP camera may be bulkier than you want. But, if you wanted to print these pictures out or make enlargements, you'll need that extra resolution. In any case, a higher MP camera will give you more leeway in terms of editting, resizing, etc. And, the resolutions available to you will usually be determined by your budget.

Lastly, what others think about a camera after having used them tends to indicate which ones are more reliable, easier to use, etc. Consumer reports are a good way to start but also ask around among friends, coworkers, and even salespeople at the camera store. Salesmen have a lot of time to play with every camera in stock, and, if they didn't, you may not want to be talking to them about what camera is best anyway. But, as with any kind of advice, take it all with a grain of salt. What the photography geek behind the counter likes in a camera may not be what you want or need, so there are personal preferences to consider. Part 2 covers the other common variables that can influence your decision.

Red Eye

I'm not referring to the airline flights - it's the evil looking bloody pupils that I'm referring to. I'm sure you've all had an otherwise great shot ruined by the malicious fiery dots that pretend to be eyes. (This topic also happened to be the one that I taught at a 5-minute audition for a Kaplan teaching job that I did earlier today... or rather, yesterday...)

First of all, how does it happen? Direct light from a flash shines into the eye, through the pupil, bounces off the blood-vessel-rich retina, and reflects back out toward the camera's lens. The film or digital sensor records this reemitted red light as the color of the pupil. Therefore, the devilish gaze. Are there any solutions at hand? Can the devil's work be stopped in the realm of photography?

Firstly, camera manufacturers have all introduced something called "Red Eye Reduction" flash. This is basically a set of pre-flashes that go off before the actual flash goes off with the pressing of the shutter button. The additional light before the shot tricks the brain into thinking that it is brighter than it really is. The eye's response is then to constrict the pupil. So, when these pre-flashes go off, the pupils shrink, letting less light from the flash into the eye and, more importantly, less reflected red light out.

Unfortunately, as the name reminds us, the use of pre-flashes only reduces the amount of red eye in our pictures. Some faint hints of red may still peek through, and sometimes it may not work at all. A solution that a lot of photographers use is to change the angle that the incident light (the light from the flash) comes in at. When the incoming light hits the retina at a larger angle, the reflected light doesn't bounce out of the eye towards the lens. (You can see this for yourself with an approximated diagram of the eye, the camera, and a light source that is far from the lens.) This technique can be accomplished in several different ways.

The easiest way is to move the flash further from the lens. You can either mount a taller speedlight unit to the camera or use a sync cord to remove the flash from the camera body altogether. Another way to change the angle is to use a speedlight that has an adjustable head. This allows you to bounced the light off a nearby surface, usually the ceiling or a reflector placed near the subject. If you don't want to change the angle that the flash is coming from, something to consider is the use of a diffuser. In this way, rays of light are much less likely to get into the eye and reflect directly out to hit the lens.

Now, I know all this information is helpful if you have a camera with a sync-cord port or a hot shoe for a speedlight, but if you're a point and shooter, you're probably wondering what you can do other than using the red eye reduction feature. Fortunately for the digital users, a lot of manufacturer's now package photo editting software with their cameras, software that often has tools to rid yourself of the gruesome twosome. Some programs now even have a one-click feature which uses an algorithm to identify faces and locate red spots that exist where the eyes are calculated to be. Whether automatic or manual, clicking red pixels away is a lot easier and simpler than drawing dots on a picture with a red-eye removal pen.

For the film shooters out there, this solution involves several more steps but is quite worth it for an otherwise great shot. You can have your negatives (or slides) scanned to CD at the photo-processing lab, or you can scan the prints at home with a flatbed scanner. Some scanners come with a negative/slide attachment so that you can scan those in your underwear as well. Once you have a digital file, you can use photo-editting software as described above. If you want to avoid using the software yourself, you can bring your negatives into a digital photo-processing lab that has comparable technology on their printer. The newest generation of digital printers have software that not only removes red eye but also balances the highlights and shadows of the picture for better contrast.

Now that you know the cause of red eye and how to fight back, go out there and kick some demon eyed butt!!