Fuji FinePix 4900 ZoomFujifilm extends its consumer digicam, with a 6x optical zoom lens and extensive exposure controls.<<Viewfinder :(Previous) | (Next): Exposure & Flash>> Page 5:OpticsReview First Posted: 10/7/2000 |
OpticsA 6x, aspherical glass, 7.8 to 46.8 mm lens (equivalent to a 35 to 210 mm lens on a 35mm camera) is built into the 4900 Zoom. As we mentioned earlier, the lens seems to take up a large part of the camera body, and is much larger than the lenses typically used on FinePix digicams. This is doubtless partly due to the longer than normal zoom ratio as well as the lens' fairly large maximum aperture at full telephoto (f/3.1 at 210mm equivalent). The lens telescopes out from the barrel when the camera is powered on, and returns when the camera is shut down. Focus ranges from 1.6 feet (50 cm) to infinity in normal shooting mode, and from 3.9 to 32 inches (10 to 80 cm) in macro mode. In addition to the contrast-detect autofocus system, focus can also be manually controlled by the notched focus ring at the end of the lens barrel. A switch on the side of the lens controls whether the camera is in auto or manual focus mode..
In the past, we haven't been too impressed with the manual focus options on most digicams we've tested, unless they included an explicit distance readout. This is because the LCD resolution is typically so low compared to that of the CCD
that it's almost impossible to tell whether the subject is in focus, based on how it appears in the LCD: There just aren't enough pixels on the LCD to tell if the image is sharp or not. Thanks in part ot their SuperCCD technology, Fuji has come up with an excellent solution to this problem for the F4900: A focus check button on the back panel (just below the power button) enlarges the center of the image to about twice normal size. Surprisingly, this seems to be enough to make accurate judgments about image focus, and worked quite well in our own testing. Besides this focus-assist "magnifier" function, there's also a focus indicator that appears in the LCD, next to the "MF" icon. This indicator takes the form of two arrow icons, with a solid circle between them. It only appears as you adjust the focus in manual focus mode, and indicates by the arrow direction which way you need to turn the focus ring. In practice, we found this focus indicator a little unreliable, particularly in the case of low-contrast subjects, where we felt visual inspection of the magnified LCD view actually worked better.Don't get us wrong though, as much as we liked the manual focus option on the F4900, it can't remotely be compared with manually focusing a 35mm SLR: The response time of the manual focus adjustment itself is rather slow, and it takes a bit of scrutiny to decide when you've really achieved optimum focus. (The manual focus ring on the F4900 is actually a "fly by wire" control, since its motion doesn't control the lens directly, but instead just instructs the camera's processor to move the lens elements appropriately. This gives very fine control when you're zeroing in on a focus setting, but is rather slow when making major focus changes.)
Aperture can be manually or automatically adjusted, depending on the exposure mode, from f/2.8-f/3.1 to f/11.0 with 13 steps in 1/3 "f" increments. The f/2.8-f/3.1 specification refers to the fact that the maximum effective aperture varies as the lens is zoomed from wide angle to telephoto. This variation is documented in Fuji's specs for the lens. It's likely that a similar variation occurs for smaller apertures as well (meaning that the minimum aperture at the telephoto end of the lens' range is likely some number higher than f/11.0, but Fuji doesn't provide this specification, nor does the camera report it in its JPEG file headers.
A zoom toggle button is located on the side of the lens, but you can also control the zoom with the up and down arrows of the rocker toggle button on the rear panel. The 4900 Zoom also offers a digital telephoto function that works with all file sizes except for the 2400 x 1800 setting. The amount of digital zoom allowed depends on the actual image size, with the largest amount of zoom equalling 3.75x for the 640 x 480 image size. Because the digital telephoto option just crops-out the center of the image, quality is compromised in the form of higher noise levels and/or lower resolution. Fuji's implementation of it is really done the way we like to see though: It never interpolates the image beyond what the sensor would normally deliver. Thus, no digital telephoto is available at maximum image size, and the amount of digital telephoto available at any chosen image size always corresponds to a simple cropping of the selected image size out of the maximum-resolution file. Digital telephoto will thus be slightly less sharp than the pure optical telephoto image at any image size, but won't degrade to the extent seen in some cameras.
Digital telephoto is activated by zooming past the optical zoom range. A zoom status bar appears on the LCD display, showing the amount of digital and optical zoom available with the current camera settings. There's no provision to disable the digital telephoto function, but you don't have to worry about inadvertently zooming too far and triggering digital telephoto when you don't want to: The zoom stops at the end of the optical range, and doesn't proceed into digital telephoto territory unless you release the zoom toggle and press it towards the telephoto setting again.
A set of threads on the inside lip of the lens barrel accommodate a wide angle lens conversion kit, available as an accessory from Fujifilm. We'd like to see the thread adapter part of this kit sold separately from the wide angle lens itself, so you could use it to attach filters or macro lenses to the camera, without having to purchase the whole kit. (Perhaps Fuji will read this review, and decide to package the adapter accordingly...)
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