Posts Tagged ‘digital SLRs’

Working With DSLR Lenses

Those who own single lens reflex cameras suffer from a singular disease: Lens Lust. I didn’t make that term up. You’ll find references to Lens Lust all over the Internet, in user groups, and any gathering that includes two or more photographers. Lens Lust isn’t limited to digital SLRs;it infects anyone who owns a camera with removable lenses, including those of the film SLR and rangefinder persuasions.

I’ve fallen victim to it myself. I worked for two years as the manager of a camera store, and a hefty chunk of what I earned was diverted to my favorite vendor’s dealer personal purchase program, as well as to acquiring good used equipment brought to me for trade-in. I ended up with 16 different lenses for my 35mm SLR, including optics like 7.5mm and 16mm fish-eye lenses, a 35mm perspective-control lens, and other specialized lenses. Additional lens collections for my 120/220 SLR camera and Leica rangefinder followed.

These lenses served me well for a number of years and, in fact, should have been sufficient when I went all-digital because they could be used with my new dSLR, too. But then Lens Lust struck again. I wanted, needed newer lenses optimized for digital photography. My initial 27mm–105mm zoom (35mm equivalent), furnished with the camera, was soon supplemented by a 42mm–300mm (equivalent) zoom and an 18mm–36mm (equivalent) wide-angle zoom.

If enough of you buy this book, a better macro lens, another image-stabilized lens, and a 1.4X teleconverter will follow. Lens Lust is incurable.

Lens elements aren’t necessarily glass, in any case. Some very good lens elements can be made of plastic, and research into ceramic lens elements continues. If I happen to mention “glass” in this book, I’ll be referring to amorphous silica, not a lens. If I need a synonym to keep from using the word lens three times in one sentence, I’ll substitute optics, instead.

Storage

Once you’ve viewed your image through the viewfinder, composed and focused it with your lens, and captured the photons with the sensor, the final step is to store the digital image semipermanently so it can be transferred to your computer for viewing, editing, or printing. While the kind of storage you use in your camera won’t directly affect the quality of your image, it can impact the convenience and versatility of your dSLR, so storage is worth a short discussion.

Once converted to digital form, your images first make their way into a special kind of memory called a buffer, which accepts the signals from the sensor (freeing it to take another picture) and then passes the information along to your removable memory card. The buffer is important because it affects how quickly you can take the next picture. If your camera has a lot of this very fast memory, you’ll be able to take several shots in quick succession, and use a burst mode capable of several pictures per second for five or six or ten consecutive exposures.

Many digital SLRs provide a viewfinder readout showing either how many pictures can be stored in the remaining buffer or, perhaps, a flashing bar that “fills” as the buffer fills and gets smaller as more room becomes available for pictures. When your buffer is completely full, your camera stops taking pictures completely until it is able to offload some of the shots to your memory card.

The buffer is such a limitation on sequence photography that Nikon has introduced a dSLR that crops the center out of an image (creating an 6.8 megapixel picture out of a 12.4 megapixel photo) simply because the smaller images can be moved through the buffer more quickly. Nikon touts this feature as part of its faster burst mode.

The memory card itself has its own writing speed, which signifies how quickly it can accept images from the buffer. There’s no standard way of expressing this speed. Some card vendors use megabytes per second. Others label their cards as 40X, 80X, and so forth. Some prefer to use word descriptions, such as Standard, Ultra, Ultra II, or Extreme. I’m not going to tell you which cards are fastest here, because memory card technology and pricing is changing with blinding speed.

Google the Web for sites that have comparisons of speeds for various current memory cards before you buy. In recent months, the trend has been toward faster and faster memory cards at lower prices. That’s the main reason for the dropping price tags on those 1GB cards I bought. Both were older “standard” cards that were considered outmoded in a time when the leading vendors were pushing 2GB and larger “ultra” cards.

For standard shooting, I’ve never found the speed of my digital film to be much of a constraint, but if you shoot many action photos, sequences, or high-resolution (TIFF or RAW) pictures, you might want to compare write speeds carefully before you buy. A card that’s been tested to write more quickly can come in handy when you don’t have time to wait for your photos to be written from your camera’s buffer to the memory card. What I always recommend is to buy the fastest memory card you can afford in a size that will hold a decent number of pictures.

Then, purchase additional cards in larger sizes at bargain prices as your backups. For example, if you’ve got a lot of money to spend, you might want to buy a 2GB “ultra” card as your main memory card for everyday shooting, and stock up on slower, but dirt-cheap 1GB cards to use when your main card fills up. Or, if your budget is limited and you don’t need a high-speed card very often, spend your money on a 1GB or larger standard card, and treat yourself to high-speed media in a more affordable size, such as 512MB. That way, if you do need the extra-fast writing speed of an ultra card, you’ll have it without spending a bundle on a high-speed/high-capacity memory card. And you’ll have plenty of capacity in your standard digital film at an economical price.

You certainly won’t be choosing your digital camera based on the kind of storage it uses. Digital SLRs generally rely on CompactFlash for the most part, because CompactFlash media is small enough to be carried around easily and always seems to be on the leading edge of capacities.

Smaller form factors, such as the postage stamp-sized Secure Digital card, are not found in as many advanced cameras, and are annoyingly easy to misplace. However, SD cards are rapidly catching up to CompactFlash in capacities, and I’d expect many digital SLRs to have slots for both in the future, similar to the Canon EOS-1Ds Mark II. Among non-SLR, point-and-shoot digital cameras, the various film card formats are proliferating at an alarming rate. Only the first three formats listed below are likely to see widespread use in digital SLRs, however.

■ CompactFlash. Among all digital cameras, CompactFlash is the second-most-favored format in the United States and first among digital SLRs. Although larger in size than Secure Digital (SD) cards, CompactFlash cards are still very small and convenient to carry and use. As larger capacities are introduced, they usually appear in CF format first. As a bonus, the CompactFlash slot can also be used for mini hard drives, such as those from IBM, with capacities of a gigabyte or more.

■ Secure Digital. The SD format overtook CompactFlash as the most popular memory card format in digital cameras with one of the last bastions, Nikon, finally adding an SD card camera to its compact point-and-shoot line. Most other vendors had long since converted for their compact digitals, although Canon continues to offer beginner cameras that use CompactFlash. The postage-stamp-sized SD cards allow designing smaller cameras, are available in roughly the same capacities as CompactFlash, and cost about the same. The chief drawback (to date) is that there are no mini hard drives in the SD format. If you want to use a mini hard disk, you’ll need a camera with a CompactFlash slot. Some digital cameras can also use the similar, but slower Multimedia Memory card (MMC). Figure 2.18 shows both CompactFlash and SD memory cards.

■ Mini hard drives. For a long time, mini hard drives were your only option when you needed more than a gigabyte of storage. If you’re using a 6 megapixel or better camera and like to save your images as TIFF files or in another lossless format, you need more than a gigabyte of storage. However, with CompactFlash cards now available in 4GB to 8GB sizes, the mini hard drive is losing its capacity edge, and they have always cost more than the equivalent silicon memory card. Although not excessively prone to failure, mini hard drives do have moving parts and must be handled with more care than memory cards.

Understanding Histograms

One of the best things about digital SLRs is the ability to review your captured images on the back of the camera, in order to assess whether or not you’ve got your shot. Composition and colour are relatively easy to evaluate by glancing at the LCD screen, and sharpness can be determined by zooming in on your photos. Judging the exposure,
however, is a little harder, as it’s not always easy to tell if your images are too bright or dark on the LCD screen. The same picture will appear bright and vibrant viewed in the dark but much duller if you look at it in direct light. A more reliable way to check your exposures is to use the histogram.

What’s a histogram?

It’s not always easy to tell if your images are too bright or too dark on the LCD screen. A more reliable way to check your exposures is to use the histogram.

A histogram is a simple bar chart showing the distribution of pixels in an image, based on brightness. The left-hand side represents the darkest pixels, the middle corresponds to the midtones and the right-hand side the white pixels. The higher the graph is at a given point, the more pixels of that brightness are present in the image. For an average image with no strong highlights or shadows you can expect to see a peak in the graph in the middle, showing an average distribution of tones. With a darker image, such as a lowlight scene, you can expect to see a peak to the left. A peak to the right would denote a high-key image. That said, there is no such thing as a perfect histogram. You can only judge it to see if the graph looks how you’d expect it to and adjust the exposure to correct it if things don’t tally up.

How To Reduce Noise In Your Photos

Noise is that grainy look digital photos sometimes get, usually noticeable as multi-colored speckles most visible in the dark or shadow areas of an image. Although you can sometimes use noise as a creative effect, it’s generally a bad thing that destroys detail in your image and might limit how much you can enlarge a photo before the graininess becomes obtrusive.

The most common types of noise are produced at higher sensitivity settings. That’s because cameras achieve the loftier ISO numbers by amplifying the original electronic signal, and any background noise present in the signal is multiplied along with the image information.

One reason why point-and-shoot digicams often don’t have ISO settings beyond ISO 800 is that the noise becomes excessive at higher ratings. However, you can boost the information that the bigger dSLR sensors capture to higher ISO settings with relatively lower overall noise. I’ve used digital SLRs that had less noise at ISO 800 than some poor-performing point-and-shoots displayed at ISO 100. Obviously, the larger sensors found in dSLRs score another slamdunk in the noise department and make high ISO ratings feasible when you
really, really need them.

Noise doesn’t always result simply from using high ISO settings: Long exposures can cause another kind of noise. Although some techniques can reduce the amount of noise present in a photo, by and large, digital SLR cameras are far superior to their non-SLR counterparts when it comes to smooth, noise-free images. Thanks to the disparity in size alone, all sensors of a particular resolution are not created equal, and sensors with fewer megapixels might actually be superior to higher-resolution pixel-grabbers.

For example, most older 8-megapixel dSLRs produce superior results to the newest 10-megapixel non-SLR digicams. I’ve seen results from one $3,000 4.3-megapixel pro-level dSLR that runs rings around the best images possible from an $800 EVF model with an 8-megapixel sensor. So no matter how many megapixels a point-and-shoot camera’s sensor can hoard, that sensor isn’t as big as a dSLR’s. And when it comes to reducing noise, the size of the sensor is one of the most important factors.

How To Improve Your Photography with a dSLR

The differences between digital SLRs and the camera you were using before you saw the light depends on where you’re coming from. If your most recent camera was a point-and-shoot digital model, you know the advantages of being able to review your photos on an LCD an instant after you took them, and, if you’re serious about photography, you also understand the benefits of fine-tuning them in an image editor. If you’re switching to a digital SLR from a film SLR, you’re likely a photo enthusiast already and well aware that a single lens reflex offers you extra control over framing, using focus creatively, and choosing lenses to give the best perspective. And, if you’re making the huge leap from a point-and-shoot non-SLR film camera to a digital SLR, you’re in for some real revelations.

A digital SLR has (almost) all the good stuff available in a lesser digital camera, with some significant advantages that enable you to take your photo endeavors to a new, more glorious level of excellence. Certainly, you can take close-ups or sports photos with any good-quality film or digital camera. Lowlight photography, travel pictures, or portraits are all within the capabilities of any camera. But digital SLRs let you capture these kinds of images more quickly, more flexibly, and with more creativity at your fingertips. Best of all (at least for Photoshop slaves), a digital SLR can solve problems that previously required working long hours over a hot keyboard.

Despite the comparisons you can make to other cameras, a digital SLR isn’t just a simple upgrade from a conventional film camera or another type of digital camera. A dSLR is very different from a film SLR, too, even though some vendors still offer film and dSLRs that look quite a bit alike and share similar exposure metering, automatic focusing, and other electronics, as well as interchangeable lenses. If you look closely, you find that the digital SLR camera is different, and how you use it to take pictures is different.