Sony Cyber-shot DSC-F828Sony extends their high end to encompass 8(!) megapixels and a sharp 7x Zeiss zoom lens. - And Sony's new RGB+E sensor technology for more accurate color!<<Viewfinder :(Previous) | (Next): Exposure & Flash>> Page 5:OpticsReview First Posted: 08/15/2003, Updated: 02/05/04 |
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The F828 is equipped with a super-sharp 7.1-51mm Carl Zeiss lens (equivalent
to a 28-200mm lens on a 35mm camera), an impressive 7x optical zoom ratio. Equally
important to the zoom ratio itself is that the wide-angle end of its range goes
all the way out to 28mm, wider than most digicam lenses offer. (Very handy for
Realtors and others who need maximum angular coverage for cramped shooting conditions.)
The aperture can be adjusted automatically or manually, and ranges from f/2-2.8
to f/8 depending on the zoom setting. An additional 2x Precision digital zoom
function (14x total zoom) can be turned on and off via the Record menu, but
remember that quality is always an issue with digital enlargement. That said,
the F828 employs Sony's Precision Digital Zoom, which seems to cause less quality
degradation than the normal digital zoom used by some other digicams. (One difference
seems to be that the required interpolation is done with raw CCD data, before
the JPEG compression is applied.)
The F828 also offers as much as 5x of "Smart Zoom" when shooting at the VGA resolution setting, effectively increasing the total zoom to 35x. (Smart Zoom is Sony's term for a digital zoom feature that limits its magnification to that which results in a 1:1 mapping of sensor pixels to final image pixels. Thus, at the full 8MP resolution, there's no Smart Zoom available, as the image is using all the sensor pixels already. A 640x480 chunk of pixels cropped out of the center of the 8MP sensor corresponds to a 5.1x linear "magnification," so that's the amount of Smart Zoom you have available when that image size is selected. Smart Zoom avoids the distortion produced by interpolating the image data back up to larger pixel dimensions. It's new to Sony's line, but Fuji's consumer cameras have worked this way for a few years now. - Overall, this is how I think digital zoom should work, so kudos to Sony for getting onboard with it.) When activated through the Setup menu, Smart Zoom and Precision Digital Zoom are controlled via the Magnify button on the rear panel.
The F828's zoom control is nice and smooth, with an adjustment ring around
the end of the lens barrel that is coupled directly to the lens elements
themselves. This provides complete control over optical zoom, with none of
the "fly by wire" uncertainty that characterizes most digicams.
The direct control makes it easy to make small adjustments to the zoom without
going too far in either direction, a nice feature for critical framing, and
is also much faster to use than the purely electronic controls on most digicams.
A zoom bar appears on the LCD screen, reporting the zoom position.
The rotating lens barrel of the F828 continues to be one of my favorite designs,
although the bulky lens takes some getting used to. (Actually, I'm a little
conflicted over the design. I love the flexibility it gives, but find it
a little awkward to hold in some situations. This is balanced by its making
certain shots very easy that would be either awkward or impossible otherwise.)
The lens pivots up and down approximately 100 degrees (roughly 70 degrees
up, 30 degrees down), greatly multiplying your shooting options. It's especially
handy for grabbing ground-level macro shots or when holding the camera above
your head to shoot over a crowd. The tripod mount on the bottom of the lens
barrel provides even greater flexibility when working with a tripod or monopod,
allowing you to tilt the camera's back panel for easier viewing. Sony offers
both wide-angle and telephoto converters as accessories for the F828, which
mount in front of the lens via the 58mm filter threads that line the inside
lip of the lens barrel. (The same thread diameter as the F717.) Having the
tripod mount on the lens centerline also makes it easier to align sequences
of shots intended for later assembly into panoramas.
Focus on the F828 ranges from between 9 and 27 inches (23-69 centimeters, depending on the zoom setting) to infinity in normal mode, and from 0.8 inches (2 cm) to infinity in Macro mode. (Note that the closest macro focusing occurs only when the lens is set to its maximum wide-angle position.) A Focus switch on the side of the lens selects either Auto or Manual Focus control. Manual focus is set by turning the focus ring at the end of the lens barrel, just as you would a standard 35mm camera lens. When using the Manual focus, a small indicator appears on the LCD screen that shows the current focusing distance in meters as you turn the ring. Also, an Expanded Focus option (activated in the Setup menu) automatically magnifies the image by 2x whenever you rotate the focus ring, providing just enough resolution to accurately set the focus based on what you see onscreen.
I really like the feel of a digicam with a manual focus that works more or less like that on a standard 35mm camera lens. If you're making the transition from a film camera though, the F828's focus ring may take a little getting used to. It isn't directly coupled to the lens elements (like the zoom control), but rather just instructs the camera's CPU which way to move the focusing elements. This leads to a sense of disconnection between movements of the focus ring and corresponding focus changes that takes some getting used to. Also, the proportionality between focus-ring movement and focus adjustment seems to be a pretty strong function of the speed with which the ring is turned. If you move the ring slowly, it can take many turns of it to traverse the full focal range, while a quick twist will switch you from infinity focus down to a couple of meters with only a partial rotation. This variable proportionality is doubtless an attempt to deal with the slow slew rate of most "fly by wire" digicam focusing systems. It definitely improves the focus response relative to other cameras I've worked with, but I still find manual focusing on the F828 to be a slightly disconcerting experience. (I also noticed that the front of the pop-up flash housing obstructs the top of the focus ring, making it slightly awkward to turn.)
Similar
to the CD500 high-end Mavica model, the F828 features an adjustable AF area,
with a number of selection points available (one at dead center and the others
surrounding the center point). In straight autofocus mode, the camera uses
a multi-point selection, often highlighting two or three points on the screen
that it's basing focus on. You can also opt for a broader center AF selection,
as well as a smaller Spot AF area, or manually select the desired AF point,
to force the camera to focus on a particular subject and not be led astray
by other objects in the field of view. In any capture mode, the AF point
can be controlled by pressing the Multi-Controller until the Spot AF marks
appear, and then moving the AF point with the Multi-Controller in any direction.
A set of four corner bracket marks in the main viewing area indicate the
AF area.
Three AF modes in the camera's Setup menu control how often the camera adjusts
focus, including Single, Monitor, and Continuous. Single AF mode adjusts
focus only when the Shutter button is half-pressed, while Continuous AF mode
adjusts focus continuously as the subject moves, both before and after the
shutter button is half-pressed. Monitor mode is probably most similar to
the Continuous AF modes of most other manufacturers. It continuously adjusts
focus until the user half-presses the Shutter button, at which time the focus
is locked. Monitor mode slightly improves shutter lag for stationary subjects.
I've been a fan
of Sony's Hologram AF system for low-light focusing ever since I first saw
it. Hologram AF uses a laser diode and a tiny holographic diffraction grating
to project a crosshatched pattern of bright red lines on the subject. The
nifty thing about the hologram is that the projected pattern stays more or
less "in focus" almost irrespective of subject distance, so there's
always a sharp pattern for the camera to focus on. Hologram AF isn't only
for low light, as you'll see the camera resort to it in fairly normal lighting
as well, if there's not enough contrast in the subject to use the normal
contrast-detect AF system. Try pointing the camera at a blank wall in normal
home / office lighting, and you'll see the pattern. The screen shot at right
shows a camera's-eye view of the Hologram AF pattern, as the lens zooms from
wide to telephoto. (This shot was copied from my F707 review - Astute readers
will note the differences in the onscreen information display, but the Hologram
AF function works identically in the F828.)
In actual use, I've found that the Hologram AF system makes low-light and
low-contrast focusing practically foolproof. In fact, it literally was hard
to get an out-of-focus photo with the F828, in almost any situation. Hologram
AF is a significant innovation in AF-assist lighting!
Sony's "RGB+E" Sensor Technology
As I mentioned at the beginning of this article, arguably the biggest
news with the 828 is that it's the first vehicle for Sony's new "RGB+E"
image sensors, which use four different color filters, rather than the usual
three. (Most digicams distinguish color thanks to red, green, and blue color
filters over their individual pixels. The 828 adds "Emerald" (more
or less a cyan color) filters, replacing half of what would otherwise have
been green pixels on a normal CCD chip.) This new sensor color space dramatically
improves color rendition in some parts of the spectrum. In particular, it
reveals more shading and detail in highly-saturated yellows, reds, and oranges,
and more renders some shades of blue and blue-green more accurately. In early
samples I saw, the RGB+E technology looked like it held great promise for
significantly improving color accuracy and the ability of cameras to faithfully
render subtle hues in brightly-colored subjects. Now, after some time spent
with a production model, I have to say that it looks like the promise was
fulfilled. - The F828 does a much better job with highly saturated colors
of certain hues than any other digicam I've seen to date. (Interested readers
can peruse our original news stories covering the announcement of RGB+E technology
here and
here.)
I highly applaud Sony's innovation in exploring new camera color spaces to
improve image quality. Based on preliminary results, it looks like they've
achieved a real breakthrough in digicam color fidelity.
In their marketing literature for the F828, Sony touts the camera's use of
a true "Linear Matrix computing process" to convert the four-color
RGB+E data to conventional RGB. This is just a fancy way of saying that the
four colors are converted to the normal red, green, and blue values by multiplying
each of the four color values for each pixel by a coefficient, and summing
the results together for each of the target primary colors. What puzzles
me is that I thought this was how you always do color transformations.
Given Sony's hype over their use of this approach, it seems likely that other
digicams more often use a different technique that's less accurate, perhaps
trading off computational speed for accuracy. Regardless of the specifics,
it does appear that the F828 offers a new level of color rendition.
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