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DSLR Guide News - Cameras Past and Present
February 26, 2009
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Digital SLR NewsWhile several new digital SLRs have been rumored for release in 2009, nothing is official yet.
Throwing caution to the winds, I'm going to provide you with more information about these rumored cameras, since many past rumored cameras that I've seen have all eventually been released.
As such, they have been releasing new camera models for photographers of all skill levels: beginners (A200), Intermediate (A300, A350) and Advanced (A700, A900).
Now the rumor mill is abuzz about a new 15 megapixel Sony digital SLR (the A800 maybe?) that sounds like it will be a competitor to Canon's 50D (also a 15 megapixel DSLR). Expect this new camera from Sony to include: dust control, a live view LCD (that might flip out from the camera body), built-in image stabilization, dynamic range control and face detection autofocus. It might even have Sony's smile detection shutter release (if they really pack on the features).
The other new cameras are not actual digital SLRs: they fall into the hybrid class of camera known as Micro 4/3rds.
In 2009, expect to see a second Micro 4/3rds digital camera from Panasonic (their first was the DMC-G1) but this time with the addition of a video capture feature.
Also expect to see some new Micro 4/3rds digital cameras from Olympus (partnered with Panasonic) with a very unique look. The new Olympus cameras will look much more like compact cameras, but with all the advantages of a digital SLR (minus the optical viewfinder).
Look for many new cameras to be announced right around March, since that is the month for PMA - a massive annual trade show that often includes a slew of new camera announcements.
Beginner Tutorial - ApertureIn last month's newsletter, I provided an introduction to aperture.
Here's a quick summary of that information:
The aperture f-stop scale looks like this:
f/2.8, f/4.0, f/5.6, f/8, f/11, f/16, f/22
(note: I just noticed that the scale that I provided in last month's newsletter is NOT correct - it contains f/3.5, which is not part of the standard scale)
Now, this particular scale shows each aperture number changing by something called a full stop of light.
When the aperture changes by a full stop, the amount of light landing on the camera's sensor is either doubled or halved.
Once you realize that the lens aperture can be changed by full stops, a question arises: what about half stops?
Yes, aperture numbers can also be broken down into a half-stop scale:
f/2.8, f/3.5, f/4.0, f/4.5, f/5.6, f/6.7, f/8.0, f/9.5, f/11, f/13, f/16
While a simple half-stop scale might make the most sense, most digital SLR cameras are actually set up by default to change aperture in third-stop increments:
f/2.8, f/3.2, f/3.5, f/4.0, f/4.5, f/5.0, f/5.6, f/6.3, f/7.1, f/8.0, f/9.0, f/10, f/11, f/13, f/14, f/16
Let's take a quick break from the numbers and talk about HOW you actually change the lens aperture using a digital SLR camera.
All main command dials don't just spin freely: they "click".
Let's say that your digital SLR is one of the many where aperture numbers are broken down into third-stops. Let's also say that currently your aperture is set to f/8.0.
Now, if you want to OPEN the lens by a full stop, you click the main command dial three times in one direction to go from f/8.0 to f/5.6. If you want to NARROW the aperture back down to f/8.0, you click the main command dial three times in the opposite direction.
The reason that you have to click three times is because of the third stops.
Before we wrap things up on aperture control for this month, a word about customization: the factory default setting for most digital SLR cameras is to use a third-stop aperture scale.
However, some cameras allow you to customize the scale and change from third-stops to half-stops if you so desire. Both work equally well, the third stop scale just provides you with a slightly finer level of aperture control.
Intermediate Tutorial - Depth of FieldLast month, I talked about how changing the aperture helps you to control the depth of field in your photos.
This month, we'll talk about the other two variables that have an impact on depth of field: the focal length of your lens and the distance between the camera and the subject.
Here's the high-level overview for lens focal length:
Let's take a look at a photographic sample to make this clear. In both images, the other two variables that affect depth of field (aperture and distance) are kept constant. The lens aperture is set to f/5.6, while the distance from camera to subject is about 5 feet (1.52 meters).
The left image is taken with a lens focal length of 28mm while the right image is taken at 135mm. Note how the background is significantly more out of focus in the image shot at 135mm than at 28mm.
Now that we've illustrated how focal length affects depth of field, let's take a look at the impact of camera-to-subject distance.
For these two images, the lens focal length was set at 28mm. The lens aperture was set to f/5.6.
The left image is taken from 5 feet (1.52 meters) away from the subject while the right image is from about 1 foot (0.3 meters) away. Again, you should see a pretty big shift in the depth of field.
Now, let's combine the three variables together into an integrated whole.
Imagine that you are taking shots of a subject from about 10 feet away (3 meters) and that your lens is set to an 18mm focal length. In this case, both the focal length and the camera-to-subject distance are working to create a lot of depth of field.
Key Point: changing your aperture setting in this case won't have a pronounced effect on your image.
This is for all you folks out there who change aperture values constantly and have yet to clearly see how the aperture affects depth of field.
If you change just ONE other variable in the scenario above, you should immediately see how different apertures affect depth of field. Let's say that you keep the focal length constant at 18mm, but you move to within 2 feet of your subject.
Now, a change from aperture f/4.0 to f/16 should have a pronounced impact on how your image appears.
Conversely, you can also stand in one spot and zoom in on your subject. Once the lens focal length is 55mm, an aperture change should be quite easy to spot.
Every shot you take involves an on-the-spot judgement about what these three variables should be.
If you're limited by one variable (say you only have a wide angle lens attached to the camera) then you must achieve the depth of field that you desire by using the other two. Deep depth of field is pretty easy to achieve with a wide angle lens, but if you want to blur a background, you'll have to set the aperture wide and get right up close to your primary subject.
Other Photography Sites
Recommended Digital SLR Retailers(These are the three online stores that I use to purchase all of my digital SLR photography gear)
In ConclusionThe PMA trade show is right around the corner here (March 3-5) and I'll be writing up all of the new cameras announced in next month's newsletter.
I've also reviewed the results of my Camera Guide Poll and the cameras that everyone would most like to see reviewed are the Canon Rebel XS and the Canon 50D. I hope to get my hands on both of those soon, and will announce when the guides are available in this newsletter.
Until then, happy picture-taking!
--Chris Roberts, Your Digital SLR Guide
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