Photography Basics Archives - Page 9 of 16

Triage For A Dirty Camera Sensor

digital camera sensor — Your camera's sensor is the heart of your camera, treat it gently - By John Carney

The heart of any camera is the sensor. The computer is the brain but there isn’t a lot you can do as far as maintenance goes. Keep the firmware up to date and that’s about the extent of it.

But the sensor is another story. That’s where the images are being recorded and there’s a lot going on in the sensor bay. In most cameras there’s a mirror mechanism flipping up and down and those moving parts are lubricated at the factory. After that mirror flips up and down a couple thousands times, it sometimes happens that some of that sophisticated lubricant on the mirror mechanism ends up on your camera sensor.

Another way dust and dirt find their way on to your image sensor is changing lenses. No matter how careful you are changing lenses, short of a dust-free clean room protocol, sooner or later you’re going to get dust on your sensor. For some reason the most powerful attractive force in the universe for attracting dust is located in the sensor bay of your DSLR.

The day will dawn you start noticing spots in your photos. Little smudges that appear in the same spot photo to photo. The quickest way to check for grease and dirt is to go outside and shoot a patch of open sky at f/22. Then take the photo and jam the levels, you’ll see the smudges right away and clearly.

Sensor Triage

Okay, don’t panic. This happens to everyone sooner or later. You have several options for dealing with the problem, so just follow the protocol and you’ll be fine.

If you’re really worried, you can send your camera back to the manufacturer for cleaning. That will mean bouncing it across the country in a FedEx or UPS box and then the lab bounces it back to you. I’ve had cameras come back dirtier than they left, not because the factory guys did a poor job, but because of all the handling.

One gadget that’s indispensable is a lighted magnifier so you can see what you’re doing.

The other indispensable thing to have is a fully charged battery. If your battery dies in the middle of this operation, the mirror will drop back down, possibly on your cleaning tools. That will not make an improvement to the mirror mechanism. You will be sad.

Step 1 – Blower

The idea here is to see if you can dislodge the dust particle with a gentle puff of air. Do NOT get the tip of the blower too close to the sensor surface. Air at high enough pressure will mar the sensor cover. So just gently blow on the dust, it’s either going to come off or it isn’t.

Step 2 – Static brush

The next step is trying a specially made anti-static sensor brush. Do not use a lens brush! Sensor brushes are specially made.

Be really gentle. Anything that won’t come off with a gentle flick of the brush is probably lubricant.

Step 3 – Cleaning Kit

Lubricant is going to require a cleaning kit with methanol. Don’t mess around and try to cobble it together yourself. Spend the money and get a professional cleaning kit. There are detailed, step-by-step tutorials and instructions on their site. Follow them.

Take your time, don’t panic, and don’t try to cut corners and you’ll be fine.

Depth of Field and The Circle of Confusion

Understanding Depth of Field, or DoF, is one of those topics in photography that may not be as intuitive as it may seem.

Most people grasp the concept that the wider your lenses aperture is open, which translates to a lower f-stop number, the less distance is in focus on either side of the focal point. The narrower your lens aperture, which is a higher f-stop value, the greater the distance in focus on either side of the focal point.

That’s the simple explanation, it gets more complicated from there. The reality is the focal distance on either side of the focal point is not a clarity cliff that stays sharp until you hit the edge and suddenly falls off. DoF is actually a continuum where the focus gradually falls off to the point it’s visible with the human eye. There’s no critical point in transition, until you can see it.

There’s even a term for that nebulous spot, caused by the light rays not coming into perfect focus, it’s called the “circle of confusion”, also known as the disk of confusion, and the blur spot.

The standard to determine an acceptably sharp circle of confusion is the distance a single point becomes so out of focus it’s noticeable on a standard 8×10 inch print viewed at a distance of 1 foot.

The circle of confusion changes not only at every f-stop, but it also changes with the lens focal length (how far it’s zoomed) as well. At smaller focal lengths, the DoF tends to increase, all other factors staying equal. Another factor is the distance to the focal point, how far away the subject is.

As you can see there’s a lot of subjective observation in that standard and, indeed, human eye perception is much finer than the standard lens manufacturers use. If that isn’t confusing enough, the circle of confusion is different for every print size and viewing distance. So take the DoF marks on your lens with a grain of salt and understand that near the outside edge, you likely see the difference.

To bring this around to some practical application, if you need depth of field, a good rule of thumb is to use the aperture priority mode on your camera and use at least f/8 or f/11. In most lenses the circle of confusion falls off quickly at f/5.6 or lower. If you’re shooting for bokeh, deliberately throwing the background out of focus, you’ll be shooting at f/5.6 or below.

Ironically filmmakers were drawn to fast lenses for the very capability of throwing the background out of focus! It’s not just still photography where the subject comes up.

DoF is another one of those subjects where it’s important to experiment on your own equipment and understand where your lenses fall in the circle of confusion. Don’t trust the factory marks, get out there and shoot some samples.

There’s no substitute for gaining an intuitive grasp of your lenses DoF and the only way you can do that is get out and practice. Every lens will be different. This should be a ritual the first time you get a new lens.

Staying Motivated In Photography

photo walks — Photo walks and TFP shoots are great ways to network with other photographers

Staying motivated to take pictures is harder than it seems just sitting around thinking about it. When you first get a new camera, like many of you will this Christmas, taking pictures is easy. You’ll want to shoot everything in sight.

A month or two after the holidays, once the newness has worn off and the demands of daily life reassert themselves, your motivation will get worn down. It won’t happen all at once, it will be a gradual process that will sneak up on you. One day you’ll need your camera and the battery will be dead. It will dawn on you the camera has been in the closet for two years. That’s how it happens.

Whether you can keep your motivation for taking photos will determine if you make it as a photographer. There’s no better teacher than experience.

Here are some tips to maintain your motivation after the holidays.

Get Together With Other Photographers

Many local and regional photography professional associations have regular meetings where you can get together with professional photographers in your area and talk about equipment, technique, and the realities of the business. I would strongly encourage anyone thinking of going pro to do this. You will get a much more realistic idea of the realities of the business.

Many cities have photography clubs that meet regularly to take pictures.

Photo Walks

Photo walks are really just people getting together and walking around taking pictures. They can be free, group walks sponsored by a local club or the type you pay a guide to show you around.

Paid guides offer a lot of advantages, especially if you’re in a new city. They’ll know the best places to shoot and the right times to get the best looks. They’ll also sometimes know people and can get you into places you wouldn’t otherwise have access.

Photography Vacations

There are companies catering specifically to photographers for special events and photography vacations. Some combine the vacation with workshops to make it a learning experience.

Many times photography vacations can be had in exotic locations and come with accommodations and a local guide. Sure, it costs more but the peace of mind is invaluable. If I’m out taking pictures, that’s all I want to think about.

Take a Class

Another way to keep your motivation up is to take a class at a local university or community college. Many offer photography classes as adult education at night and on weekends. You’ll learn a lot and, in the process, meet other photographers in the area.

You might not need these tricks to keep your motivation up and, if you don’t, good for you. Otherwise, get out there and mingle with other photographers and you can help one another.

Here Come The Super Zooms

In the old days, zoom lenses were scoffed at by professional photographers. Zooms were the choice of amateurs and photojournalists, serious pros shot primes and that was that.

Fast forward a couple decades and zoom lens technology has made some amazing advances. Computer designed optics and advanced optical coatings combine to deliver astonishing clarity and color at price points unheard of a few years ago. Complete with high speed focusing motors and image stabilization, the zoom ranges are just insane. 18mm-200mm, 50mm-500mm, you start wondering why you need to pack a lot of glass around with you anymore. In many cases, you don’t.

Here are just a few examples of what’s out there and there are new ones coming out all the time.

Nikon Nikkor 18-200

On an APS-C or APS-H chip yields a comparable zoom range of 27.5-305mm. Fantastic range that can take you from a wide angle to right up close and personal. The 11.1x zoom range and silent wave focusing makes this lens a favorite among Nikon shooters.

Tamron 18-270

Designed specifically for APS-C chips, this 15x zoom by Tamron has a reputation for delivering sharp images through out the zoom range. It has internal vibration compensation features and is a great “single lens” solution when you only feel like taking one.

Sigma 50-500

Called the “Bigma” Sigma just might have come up with the perfect all around outdoor sport shooting lens. Fast focusing and sharp throughout the zoom range, the Sigma 50-500 gets 4.5 stars from Amazon users. It gets dinged for being a little heavy to carry around as a “single lens” solution.

Nikon 80-400

Getting high marks from wildlife photographers and bird watchers, the Nikon 80-400 is a solid performer at distance. It gets some criticism for not being wider on the low end.

Understanding Exposure

exposure photo — Correct exposure in this instance is in the mind of the creator, not the firmware of the computer

At the most basic level exposure is the relationship between the ISO, aperture, and shutter speed. When you push the button on your camera in automatic mode, there are a fantastic number of calculations going on inside your camera’s computer. Besides autofocus, your camera is analyzing the lighting, scene type, the light reflecting off the subject, the dynamic range, the contrast, and boiling all that down to a single set of numbers by balancing a fantastic number of variables.

In the old days you did all those calculations with a light meter in one hand an exposure guide in the other and, even then, you bracketed just in case. When you nailed the exposure it was part art, part science and part pure, dumb luck.

Now all that’s over. The sensor and computer inside your Canon 5D MKII or Nikon D300 camera combine to create an imaging device that is, by historical standards, absolutely mind blowing. But, even today, exposure is part art. While your camera is incredibly good at the science, the art still has to come from you. Part of what makes photographers worth the money is knowing when to trust the computer and when to take over.

Take the scene above for instance, a father and son sweeping out the engine bay at our old fire station. That is a classic “meter cheater”, meaning the proper exposure does not yield the most artistic expression of the scene. The first thing the camera tried to do was activate the pop-up flash so it could light the foreground subjects. I had to override the computer and tell it to expose for the outside light and ignore the foreground.

My opinion is that full manual shooters are kind of an anachronism these days. Manual shooting is slow, even when you really know what you’re doing. Do it long enough and you can get amazingly good at dialing in the settings, but you’re missing out on a host of functionality the sophisticated programming in modern cameras affords you. In controlled conditions, like a studio, you’ll be doing more manual shooting because the environment stays consistent.

More often these days, you’ll be telling the camera what you want to do either through soft menu settings or selectively managing certain components of the exposure. If you’re out shooting fast moving objects, you might tell the computer you need at least 1/500th of a second on the shutter speed and then let the computer manage the other settings.

You can tell the computer to make the exposure darker or lighter, to expose for a particular part of the picture while ignoring everything else, or to selectively change the contrast, color saturation, or sharpness. Knowing when to override the computer is one of the factors that go into becoming a great photographer.

In the old days that relationship was one way and dictatorial. You told the camera what to do all the time. Today it’s more of a cooperative relationship, more subtle. You and your camera work together. You do some things, the camera does some things. When you’re in a hurry, like chasing a story subject down the street outside the courthouse, or your camera is on the end of your monopod trying to get over the heads of the other reporters at a press conference, you trust the computer to do more because it can read a scene at the speed of light.

So, get out there and experiment with exposure and your camera menu settings. Use the AEB function (Automatic Exposure Bracketing) and compare the results. Experiment with aperture priority, shutter priority, and changing your camera’s presets. Do it until you can look at a scene and guess within an f-stop what settings your camera will choose.

Just because you don’t need to use all the manual settings all the time, doesn’t mean you don’t need to understand them.