The Sony Alpha A100 is Sony's entry-level
digital SLR, competing with the Canon EOS Digital Rebel
and Nikon D40x. It's an evolution of the Minolta
DSLR line, which Konica-Minolta transferred to Sony in March of
2006. The A100 was introduced in June 2006.
The Sony Alpha A100 is compatible with all A-mount Minolta SLR and
DSLR autofocus lenses and accessories. Note that the Sony A100 cannot
accept Minolta MD-mount manual focus lenses. Though it doesn't directly
address Sony cameras, newcomers to the world of DSLRs might want to
start with the photo.net article "Building
a DSLR system".
The Sony A100 is
available in various packages from amazon.com:
Like many other low-end DSLRs, the Sony A100 lacks a dedicated LCD
for displaying image capture data. The large rear LCD is used for both
image and data display. This results in a simpler user interface
because there is only one place on the camera to look for
information. There are two main control dials on top of the
camera. The dial on the right controls the operating mode: Program,
Aperture priority, Shutter Priority and Manual plus multiple idiot
modes (Auto/Green, Portrait, Landscape, Macro, Sports, Sunset and
Night Portrait). The dial on the left of the camera controls a number
of functions which change camera settings for White Balance, ISO
setting, Metering Pattern, Flash mode, Dynamic Range control and
Setting color mode, saturation, sharpness and contrast. The various
options for each setting are displayed on the rear LCD and selected
using a four-way controller or the main control wheel located just in
front of the shutter release.
On the back of the camera is the 2.5" LCD used for both image
and data display. To the right of the LCD is the main four-way
controller with a center button, which can be used to select menu
options or navigate within an image. At the bottom right is the switch
to select "Super SteadyShot" mode, Sony's sensor-based image
stabilizer. To the left of the LCD are the controls for displaying the
menu, selecting which data are displayed, erasing images and recalling
stored images. There are also dedicated buttons for exposure
compensation (+/-) and Auto Exposure Lock (AEL).
The Sony A100 is responsive. The camera is ready for use within 1
second of being powered on. General operation is fast with no sense
of waiting for the camera to catch up. Transfer of images from the
data buffer to the memory card is fast. Image playback is very fast
for both JPEG and RAW images.
In continuous drive mode I was able to capture images at a rate of 2.9
frames/sec storing the images as JPEGs with the A100 set to ISO 100
and a shutter speed of 1/250s. With JPEG mode and a fast memory card,
you can keep on photographing until the memory card is full. With RAW
format, Sony specifies that the buffer will hold 6 frames. Using a
Lexar Pro 133x CF memory card, I captured 9 RAW images before the
frame rate slowed to around 1.7 frames/sec. High resolution JPEGs
varied between 2MB and 5MB in size, depending on ISO setting and
subject. Subjects with more detail and photographed at higher ISO
settings yielded larger files. RAW files, which come out with a .ARW
extension, are typically around 10MB each, though some were as large
as 13MB. This would indicate that the .ARW files are compressed,
presumably using a lossless algorithm.
The Sony A100 accepts Compact Flash memory cards, types I and II.
An included adapter enables the use of Sony Memory Sticks.
The Sony A100 uses 9 autofocus zones. The center zone has a cross-type
sensor, responsive to both vertical and horizontal detail. The
remaining 8 zones are line-type sensors, which respond to detail only
in one orientation. A sensor detects when an eye is placed against the
viewfinder and starts autofocus. With this function enabled, by the
time you get the camera to your eye, the AF system may already have
acquired focus. With eye-start focus off, AF is initiated with a halfway
press of the shutter release.
The viewfinder is quite bright despite Sony's use of a pentamirror
rather than a brighter (and more expensive) pentaprism. Part of the
brightness may be due to the fairly low magnification factor
(0.83x). Viewfinder coverage is 95 percent and there is a -2.5 to +1
dioptric adjustment. Though the viewfinder is on the small side, I
did not find this a problem when using the camera.
The in-viewfinder LCD display is presented just below the image. It
shows the usual stuff: flash exposure compensation, flash mode and
readiness, focus confirmation, shutter speed and aperture, exposure
compensation and/or metering, and the number of images that can be
stored in the camera's buffer memory. What is unusual about this
display is that it shows an indication of camera shake and the ability
of the anti-shake system to compensate for it.
The Sony A100 has built-in "Super SteadyShot" image
stabilization. Sensors in the camera detect motion and move the
digital imaging CCD sensor so as to compensate. This method of
stabilization was pioneered by Minolta in the Maxxum 7D and a similar
in-body stabilization scheme is used by Pentax.
There is some debate about the relative effectiveness of sensor-based
stabilization vs. Nikon and Canon's lens-based stabilization. To get
some idea of their relative performance, I tested the Sony A100 with a
16-80mm zoom set to 80mm and a Canon EOS 20D with an EF-S 17-85IS lens
also set to 80mm. I obtained a number of images with each camera at
shutter speeds from 1/80s to 1/8s. The standard rule of thumb is that
a photographer should be able to handhold an 80mm lens on these
cameras at shutter speeds of 1/125s and faster and get sharp
images. At lower speeds your chance of sharp images should drop
significantly. Photographing at 1/60s is 1 stop slower, 1/30s is 2
stops slower, 1/15s is 3 stops slower and 1/8s is 4 stops slower.
The results showed that the effectiveness of the Sony Super SteadyShot
system was quite similar to that of the Canon lens-based stabilization
system, at least at mid-range focal lengths. Giving numerical results
is difficult because photographs can range anywhere from sharp to
blurred - and all degrees of sharpness in between. However at 1/8s
about 50 percent of the images were acceptably sharp with the Canon
system and about 40 percent with the Sony system.
Whatever the relative merits of the two stabilization systems, it's
clear that the Sony Super SteadyShot has the huge advantage of
stabilizing all lenses mounted on the A100 body. In
addition you only have to pay for stabilization once because it is
built into the body.
Remember that any image stabilization system stabilizes camera motion,
not subject motion. If your subjects are moving, e.g., at a sporting
event, you need a fast lens (f/1.4, f/2, or f/2.8) and/or good image
quality at a high ISO setting.
The Sony A100 uses a 10 megapixel CCD sensor with an ISO range from
100 to 1600. Noise levels are pretty well controlled up to ISO 400,
with noise becoming intrusive at ISO 800 and ISO 1600. The images
below are 100 percent crops from images captured at ISO settings from
100 to 1600 with the Sony A100 and from ISO 100 to ISO 3200 with the
Canon EOS 20D. The noise levels of the EOS 20D are very similar to
those of the Canon Rebel XT and XTi and all three Canon DSLRs use a
similar CMOS sensor.
As you can see, the noise level of the Sony A100 is somewhat higher
than that of the Canon EOS 20D. The 20D appears to have an advantage
of one ISO level, i.e., the 20D noise at ISO 800 is equivalent to the
Sony at ISO 400. This test (a grey card at 100 percent cropping) is
designed to reveal noise. In a typical image printed at 8x12, both
cameras would be fine up to ISO 800. Below are crops from images taken
at ISO 800 and ISO 200. These are 50 percent crops, so if you are
using a 17" monitor at 1280 x 1024 resolution (a typical system),
they'd represent sections of a 12" x 18" print.
Maximum shutter speed for syncing with flash is 1/160s or 1/125s with
Super SteadyShot enabled. The built-in flash, which must be manually
raised and lowered, has a useful range of about 10 ft. (guide number
of 12 in meters at ISO 100; higher ISO settings result in longer flash
range). The built-in flash can operate as an autofocus illuminator in
low light conditions, but it has to be manually raised. The built-in
flash covers the field of view of a 16mm lens (equivalent to that of a
24mm lens on a full frame camera).
There are seven flash modes: Automatic, Fill, Red-eye reduction, Rear
sync, Wireless, High-speed sync, and Slow sync. In wireless mode the
built-in flash sends a series of optical pulses to an external
flash. The external flash first fires a metering pre-flash, which the
camera uses to determine exposure. The built-in flash then sends a
second series of pulses, which tell the external flash how much power
to use. Contrast this with the Canon system, which requires a hot shoe
flash such as the 580EX II in order to fire and control a wireless
slave such as the 430EX.
The Sony system currently offers several external flash units, the
HVL-F36AM, the more powerful HVL-F56AM and the
HVL-MT24AM macro twin flash.
A series of test images with the HVL-F56AM and were all well-exposed,
both with the flash mounted directly on the camera and with it being
controlled wirelessly. One somewhat puzzling feature of the HV F56AM
is that there is a menu option allowing a flash ratio to be
set. However, the manual states, "This indicator is displayed, but
this function is not available. Use the OFF setting." Perhaps Sony is
planning a multi flash system with ratio control in the future?
The zoom range of the flash is specified as 24mm to 85mm for full
frame coverage, which means that it will cover lenses from 16mm to
57mm on an APS-C camera like the Sony A100. A fold down panel
increases the coverage of the flash to illuminate the area covered by
a 17mm lens (11.3mm on the A100).
The Sony HVL-F56AM Flash, (buy from Amazon) supports
Sony's ADI (Advanced Distance Integration) flash. This means that the
flash power calculated to give optimum exposure may be adjusted based
on the focus distance of the lens to compensate for unusual
background or subject reflectivity. It's similar to Canon's ETTL II
flash metering. Not all Sony lenses return focus distance
information, and ADI is not available with the following Sony lenses:
16/2.8 fisheye, 20/2.8, 28/2.8, 135/2.8, and 500/8.
The F56AM has most of the features you'd expect in an advanced flash
including high speed sync, manual output control, stroboscopic operation, auto or manual
zoom head control and a tilt and swivel head. The flash measure about 3.1" x 5.3" x 4" and weighs
just over 13oz.
3fps continuous burst speed (maximum 6 frames in RAW mode)
Anti Dust system to shake dust off sensor
40 segment metering system
Image Stabilization in body "Super SteadyShot"
Eye Start AF
9 AF zones, 1 cross type, 8 linear type.
Flash sync 1/160s (1/125s with Super SteadyShot on)
95 percent viewfinder (0.83x)
Uses Compact Flash memory cards
Shutter speeds 30s to 1/4000s
Weight 545 g
The Sony A100 is competitive in performance with the cheapest Canon
and Nikon bodies. The Sony system of lenses and accessories is
smaller than Pentax's and much smaller than Canon's and Nikon's. The
A100's main advantage over similar priced bodies from Canon and Nikon
is the built-in image stabilization. The A100's main weakness is
objectionable noise at higher ISO settings.