Minolta Dimage F300A compact, stylish camera with a full five-megapixel sensor and clever autofocus system.<<Viewfinder :(Previous) | (Next): Exposure & Flash>> Page 5:OpticsReview First Posted: 05/22/2003 |
Optics
Learn how to use lens aperture to control depth of field - Visit our free Photo Lessons area!
Free Photo Lessons
The
F300 is equipped with a 3x Minolta GT, 7.8-23.4mm lens (a 38-114mm 35mm equivalent).
A shutter-like lens cover automatically moves in and out of place when the camera
is powered on or off, eliminating the need for a removable lens cap. When the
camera powers on, the lens telescopes outward an inch and a quarter into its
operating position, retracting again when the camera is shut off (or after the
camera has been left in Playback mode for a while). Aperture ranges from f/2.8
to f/8.0 (depending on the lens focal length, varying from a maximum aperture
of f/2.8 at wide angle to f/4.7 at telephoto), and can be manually or automatically
controlled. Focus also features either manual or automatic control, and ranges
from 1.6 feet (0.5 meters) to infinity in normal mode. A distance readout appears
on the LCD monitor in manual focus mode, with the actual focus distance controlled
by the up and down arrows of the Four Way Arrow pad. (I applaud the inclusion
of numeric reference points on the focus-distance display, but wish that there
were more than five of them, as an aid in setting approximate focus in situations
where you have to guesstimate the subject distance. - I also wish there were
some way to cause them to display in English rather than metric units.) Pressing
the center of the pad switches the up and down arrows back to controlling the
zoom lens. In addition to the distance scale, the F300 zooms the LCD display
by up to 2.5x (less if you already have the digital zoom function engaged when
you switch to manual focus) whenever you adjust the focus manually, as an aid
to achieving sharp focus. Macro mode changes the focus range for closer, smaller
objects, focusing from 0.7 to 2.0 feet (0.2 to 0.6 meters). While the 20 centimeter
minimum focusing distance doesn't sound all that close (many cameras focus much
closer), the F300's lens operates in telephoto mode in macro (rather than the
typical wide angle), so the net result is a good bit better than average macro
shooting, with a nice working distance that helps the flash function well too.
In addition to the F300's 3x optical zoom, the camera also features as much as 4x digital zoom (enabled through the settings menu). But digital zoom compromises image quality because it only crops out and enlarges the central portion of the CCD image. Thus, it directly trades off resolution for magnification. The more you enlarge the image digitally, the softer it gets. (Digital zoom is useful though, when you're shooting at a lower resolution setting to begin with.)
The F300 offers some unique AF options, including Single Shot, Manual, Full-time AF, and a sophisticated Subject Tracking system, some of which use Minolta's Area AF system to automatically detect the subject. The camera's large central autofocus area (indicated by a set of white brackets on the LCD screen) is made up of five separate AF regions, arranged dead center, and above, below, left and right of center. When you press the shutter button halfway, one of these five regions will lock onto the subject. When in Auto mode, the focus "box" selected by the camera is highlighted in red, and you can watch it track the subject as you move the camera around. Tracking AF is also available as an option when the camera is in Manual mode.
In Single-Shot mode, the camera simply locks focus when the Shutter button is half pressed, basing focus on one of the five focus areas. You can specify one of the five focus areas as the only active area by pressing and holding the center button of the Four Way Arrow pad. This displays the AF Area selection screen, where you can use the arrow keys to select a focus area and then press the center of the arrow pad again to confirm the selection. The camera will then base its focusing only on that AF area. In Full-time AF mode, the F300 continuously adjusts the focus, rather than waiting for you to press the Shutter button halfway.
Subject Tracking AF, which first appeared on several of Minolta's film cameras and then the F100, works with all five AF Areas, locking a moving subject to one of the frames, and then "handing it off" to an adjacent frame as it moves. This should be great for catching shots of an active toddler or a child's first little league game, as you just have to worry about keeping the subject somewhere near the middle of the frame, rather than whether or not focus is set. For best results, frame the subject in the focus brackets that appear on the LCD display, and halfway press (and hold) the Shutter button. As the subject moves, the active AF area will appear in red. The AF tracking isn't lightning fast, but Minolta says it's sufficient to track a subject moving at 9 mph (14.5 km/h) toward or away from the camera, or 3.4 mph (5.4 km/h) from left to right, at a distance of 12 feet (3.5 meters) at the wide angle lens position, or 33 feet (10 meters) at the telephoto position. To translate this to the real world, 9 mph is about the speed of a child running, (well, a small child, anyway) while 3.4 mph corresponds to a brisk walk. The tracking ability is more effective with the lens at its wide angle position than at telephoto, and also benefits from plenty of light and a subject with good contrast. It appeared to work pretty well in actual use though, and seemed like it would be useful in many situations.
I mentioned Minolta's "intelligent" AF system that is supposed to recognize and focus on people in preference to background objects. I had a hard time confirming that this was the case, as opposed to the camera simply selecting the closest object in its field of view. It did in some cases seem to show a tendency to focus on people's heads, although I found that it could easily become confused in low contrast situations, or if there was a bright object (a CRT, for example) in the frame with the subject. Also, if I moved the camera too rapidly, the tracking system would lose its "lock" on the subject and possibly end up acquiring a different element in the scene as its "subject." Despite its limitations though, I thought that the F300's intelligent autofocus capabilities were a significant step forward for consumer digicams.
Like other Minolta GT lenses I've tested recently, the one on the Dimage F300 seems to be of unusually high quality for a consumer digicam. It's very sharp across the frame, with little or none of the corner softness I've come to expect from consumer-level digicam lenses. It also shows almost no chromatic aberration, another common consumer lens failing. It did have higher than average barrel distortion at its wide angle setting, about 1.1 percent. (Most digicams show 0.8% or less barrel distortion, and amount I still consider too high.) I also found the zoom control rather slow to operate, it taking about 3.5 seconds to rack from telephoto back to wide angle. On the plus side although, the F300's lens provided pretty fine-grained zoom control, with fairly small steps between its "preferred" focal length positions. (As near as I can tell, the F300's lens has about 13 actual focal length steps along its zoom range, more than most cameras I've tested.)
Reader Comments! --> Visit our discussion forum for the Minolta Dimage F300!
Follow Imaging Resource: