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DSLR News - June 2007 To those of you who are new to the Digital SLR Guide newsletter this month - I apologize. Here's the thing: this month's installement is going to be a little lightweight compared to past issues. While this means that you won't get QUITE as much information about digital SLR cameras this month, I do have a perfectly valid excuse. At the end of last month, there was a new arrival in our household: Catherine Roberts graced us with her presence. We're very happy to finally meet her, but she's resulted in a lot of very busy days and sleepless nights for me and my wife. As such, I haven't had the same amount of time that I usually do to devote to this newsletter. Oddly enough, there also hasn't been a lot of news to report in the world of digital SLR cameras. 2006 was a banner year for the development of new cameras, and I had a very tough time keeping track of them all - there weren't enough issues of the newsletter to feature every single new camera. 2007 has seen a remarkable slowdown - the only new digital SLRs released are the Olympus E-410 and E-510. Canon, Nikon, Pentax and Sony have all been remarkably quiet (despite Sony's bold claims when they first started to take over 25% of the digital SLR market share). This lack of new cameras means that the portion of this newsletter for camera buyers is going to be a bit thin for the next couple of months. On the plus side, that just means that there will be more information for existing digital SLR camera owners, and I know that there are plenty of you out there reading this newsletter. That's enough for the quick state of affairs - let's get on with it!

In This Issue New Arrival Which Camera to Buy? Middle Gray Free Canon Workshops When to Over-Expose Top Rated SLR Photo Links Latest SLR Guides Nikon D80 Canon Rebel xTi Nikon D40 Sony ALPHA A100 Digital SLR Terms Megapixels Anti-Shake ISO / Image Noise Sensor Dust Crop Factor RAW vs. JPG Continuous Photos Autofocus Points Aspect Ratio Lens Terms Focal Length Prime vs. Zoom Maximum Aperture First vs. Third Party SLR Lens Features Canon Lens Glossary Nikon Lens Glossary

Digital SLR Q & A

Digital SLR Technique

I've spent the past several issues of this newsletter digging into the three camera controls that let you acheive a balanced exposure: aperture, shutter speed and ISO.

In the next couple of issues, I'm going to talk about some situations where you want to take manual control of these settings, and why leaving your camera in AUTO mode isn't going to get the shot right.

Important point: your camera wants all of your photos to turn out gray.

This is an over-simplification, but let me explain how it works. Let's say that you're taking a photo of a friend in front of a famous landmark, and you've got the camera set to AUTO mode.

In this case, the camera selects an aperture/shutter speed pair so that you get a balanced exposure.

In order to do this, the camera must evaluate the entire scene striking the sensor and make some decisions about the amount of available light. At high noon on a clear day there is plenty of available light, and at night there is very little.

But take the following scene: your friend is standing in the shade, but the landmark behind her is bathed in sunlight.

Light and dark are competing within the same image, and the camera must strike a balance between the two so that you get a photo that looks OK. In order to do this, the camera takes the middle ground. This middle ground is also called middle gray.

If you point your camera at a pure white wall and snap a photo in AUTO mode, it won't turn out white - it will look gray instead.

Your final photograph is actually under-exposed. If you open the photo in a photo editing program and use the "auto adjust" feature, you'll see the gray wall change to white.

This is an interesting point for anyone out there obsessed with taking photos of white walls, but let's find a more practical example: snow.

Virtually every photo I have ever seen of people in the snow is under-exposed. Once you realize that your camera wants to make everything in the photo close to middle gray, this makes perfect sense.

The camera's sensor detects that there is a HUGE amount of white in the photo and automatically assumes that it needs to drop down the exposure to compensate. Unfortunately the end result is not quite what you want: snow winds up looking gray, and anyone standing in it appears too dark in the final image.

So what's a snow-bound photographer to do?

The answer lies in taking manual control of your camera, and adjusting the aperture, shutter speed or ISO to intentionally over-expose the photograph when you take it.

Let's say that to take that snow photo in AUTO mode, your camera chooses the following settings:

• Shutter Speed: 500 (1/500th of a second)
• Aperture: f/8
• ISO: 100

These are the settings that the camera thinks will create a balanced exposure. But remember, the camera is being fooled by all of that white and is actually under-exposing the image (too little light is striking the camera's sensor).

Our goal then is to let MORE light into the camera.

We can do this in one of three ways:

1. Slow down the shutter speed (shutter stays open longer)
2. Open the lens aperture wider
3. Increase the ISO (more light is absorbed by the sensor)

This means that any one of the following changes will result in more light in the final image:

1. Slow down the shutter speed from 500 to 250
2. Open the aperture from f/8 to f/5.6
3. Increase the ISO from 100 to 200

For the purpose of this exercise it doesn't matter which setting you change, but the important point is that you only change ONE of the three. You'll have to set your camera to manual mode because this is the only mode that allows you to change one setting at a time without affecting the others.

Also realize that by changing this one setting, the camera will think that you are over-exposing the photo.

In most cases, it's not OK to over-expose (the photo will appear washed out) but in this case it is. With white snow a camera set to AUTO mode will under-expose, so if you intentionally over-expose the image what you'll wind up with is a balanced exposure that doesn't require any adjustment after the fact.

So when should you intentionally over-expose? I'll talk about that in just a moment.

Learning Resource

This month's learning resource comes to us from Canon.

Throughout the Summer, Canon is hosting free photography workshops at Yosemite, the Grand Canyon and Yellowstone National Park.

You get to borrow the latest Canon digital SLR cameras (and lenses!) and a professional photographer will then lead you to some prime photography locations to try it all out. Canon printers will be on hand so you can take away some memories, and participants will also receive CDs with images downloaded from the memory cards.

Here's the schedule:

• Yosemite - sorry, this one's already over
• Grand Canyon - July 9-29
• Yellowstone - August 6-12

You can find out more about these free workshops at Canon's Photography in the Parks web site.

How and When

This month's topic is When to Intentionally Over-Expose.

In the Technique portion of this newsletter, I introduced the idea that there are certain times when your camera set to AUTO mode is going to under-expose your photos.

I also provided one example of when you want to intentionally over-expose the image for best results: when taking photos in the snow.

But deliberate over-exposure can be used for a lot more than just taking balanced photos in the dead of Winter.

Here's a quick list of some of the most common times that you'll want to intentionally over-expose the image, plus the reason why the camera doesn't quite get it right:

• Snow - the camera wants to expose the white snow as if it were a gray tone instead of white
• Baby on a white blanket - this is quite similar to the snow situation so the camera will under-expose
• White sand beach - again, this creates conditions similar to snow
• Architecture - if the structure is predominantly white (like a lot of capitol buildings in the U.S.) then you'll want to over-expose just a bit
• Subject in shade - colors are muted in the shade, and the camera's desire to expose for middle gray typically requires some manual over-exposure

In short, the best time to take manual control of your camera and intentionally over-expose your images is when the subject of the photo is predominantly white.

However, there are many other times where intentional over-exposure might yield a more interesting photograph than one that is perfectly exposed.

This technique doesn't work as well for landscape photography, but is often used in portrait and glamour shots.

The next time you're out and about in a big city with a lot of billboards, pay special attention to they way most clothing ads are lit. You'll find that the subject of the photograph is often over-exposed.

This technique is also used to great effect with celebrity photographs.

There's a simple reason: when you over-expose a portrait, areas of the person's face that would normally have tone and texture appear as pure white in the final photograph. This is a great way to hide skin blemishes and other flaws (no makeup required!) that would otherwise show up in a correctly exposed photo.

If you're taking a portrait of a friend who's self-concious about his or her skin, just intentionally over-expose the portrait for best results.

For those of you into photography jargon, portraits taken in this style are called high-key.

Example Photos

The following sequence of photos illustrates how you can compensate for middle gray

The image below was taken in AUTO mode. You can see that the predominantly white background looks gray and that the main subject is under-exposed. Aperture: f/4, Shutter Speed: 1/125, ISO: 400.

In image #2, I made ONE change: I slowed down the shutter speed to 1/60th of a second to let in more light and over-expose the image. Aperture: f/4, Shutter Speed: 1/60, ISO: 400.

For image #3 I left shutter speed and ISO alone, but opened up the aperture to let in more light. Aperture: f/2.8, Shutter Speed: 1/125, ISO: 400.

For the last image, I increased the ISO but left the aperture and shutter speed alone. Aperture: f/4, Shutter Speed: 1/125, ISO: 800.

This not only illustrates the compensation required to correctly expose a white background, it also shows you that you can adjust ANY one of the three settings of aperture, shutter speed and ISO, and get very similar results.

Cameras and Accessories

Links

The following collection of links will help to keep you posted about what's new at the Guide and in the world of digital SLR cameras.

In Conclusion

That's all I've got for June - I'm going to go take a much-needed nap now.

Thanks for reading and happy picture-taking!

--Chris Roberts, Your Digital SLR Guide