Panasonic FZ2500 Optics

Zoom
A generous 20x zoom, with decent to very good far-field performance.

The Panasonic FZ2500 is equipped with a 8.8-176mm lens, offering a zoom ratio of 20x for a very versatile 35mm-equivalent focal range of about 24-480mm.

Maximum aperture is a relatively fast f/2.8 at wide angle but that drops to f/4.5 at telephoto, starting from about 250mm equivalent. The following table reflects the maximum and minimum apertures as reported by the camera at various focal lengths:

Far-field performance appears to be decent to very good at f/5.6, with sharpness and contrast ranging from very good at wide angle to good at telephoto near the center of the frame, though there is some softening, chromatic aberration and coma distortion visible in the corners particularly at the wide end.

The camera also offers standard digital zoom up to 4x (shown above), a higher quality Intelligent Zoom up to 2x, and Extended Optical zoom which just crops the image to the image size selected.

The above series is meant primarily to show zoom range so it isn't great for judging optical performance. See below for our lab results on macro performance, geometric distortion, corner and center sharpness, etc.

Macro
A slightly larger-than-average sized minimum coverage area, with very good detail near the center. Flash is mostly blocked by the lens at minimum focus distance.

The Panasonic FZ2500 captured a slightly larger-than-average sized minimum area in Macro mode, measuring 2.68 x 1.78 inches (68 x 45 millimeters) at full wide angle. (Maximum reproduction ratio is specified at the wide end.) Detail is excellent across much of the frame although corners are quite blurry even at f/8 (most lenses show some softening in the corners at macro distances but the FZ2500's corner blurring appears to be higher than average). The lens blocked the flash across the majority of the frame, casting a large shadow. You'll likely need to use external lighting for your closest macro shots.

Geometric Distortion
Low to moderate distortion in camera JPEGs, very high in uncorrected RAW files at wide angle.

Geometric distortion in JPEGs is fairly well corrected, with about 0.5% barrel distortion at wide angle, and less than 0.3% of barrel distortion at at full telephoto. Note that some intermediate focal lengths may produce a bit of pincushion distortion. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle) or inward (like a pincushion -- usually at telephoto).

Uncorrected RAW files show high geometric distortion at wide angle. We measured almost 3.9% barrel distortion at maximum wide angle which is one of the higher distortion results we've seen. The image circle also doesn't cover the entire frame, so there's a lot of correction and interpolation applied to in-camera JPEGs at wide angle. At full telephoto, barrel distortion appears to be identical to in-camera JPEGs, so there's no geometric distortion correction being performed at the tele end. Note that most RAW converters will automatically correct for distortion, however strong correction can lead to interpolation artifacts and additional softness away from the center.

Chromatic Aberration and Corner Sharpness
Low to moderately high chromatic aberration in the corners. The lens produces soft corners across the focal range, even stopped down.

Chromatic Aberration. Lateral chromatic aberration in camera JPEGs is fairly well corrected at intermediate focal lengths, though some moderately high amounts amounts are visible in the corners at both maximum wide angle and maximum telephoto when wide open. The center shows very low to low levels of chromatic aberration.

Corner Softness. Sharpness in the center is very good for the type and speed of lens, though corners show some significant softness at most focal lengths we tested when wide open. At maximum wide angle, all four corners are soft, with the left corners just slightly softer than the right, and softening extends fairly deep into the frame. This is no surprise, though, considering the amount of the distortion correction being applied. The center however is very sharp when wide open. All four corners performed quite well at 70mm equivalent, only being slightly softer than the center which itself is fairly sharp, though not quite as sharp as maximum wide angle (though it's difficult to compare as the camera applies stronger sharpening at wide angle). At 200mm equivalent, the center is again fairly sharp, but corners are noticeably softer with lower contrast. It's a similar story at full telephoto (480mm eq.), with the center being reasonably sharp, but all four corners showing some softness, but this time the right side is the softest. (Be aware that our telephoto target for long-zoom cameras like the FZ2500 is smaller than our wide-angle target, so resolution between wide and tele isn't directly comparable. Also note that the corner USAF resolution chart in our long-zoom telephoto target isn't in the extreme corners for 3:2 cameras like it is for 4:3 cameras, and the color is cooler than our standard target.)

Vignetting. As you can see from the slightly darker crops, there's some minor corner shading ("vignetting") at full wide angle when wide open, but it's negligible at longer focal lengths.

Stopped-down: Stopping down to f/5.6 at 24mm equivalent unfortunately didn't improve corner performance, but actually degraded sharpness a bit (f/4 isn't quite a bad, but still not as good as wide open). The center also degraded a bit compared to wide open due to diffraction, but was still quite sharp. Corners also degraded at 70mm equivalent, although sharpness in the center improved slightly. At 200mm equivalent, corners did improve when stopped down to f/5.6, but not by much. The center was also a bit sharper stopped down. At maximum telephoto, stopping down to f/6.3 improved corners and the center very slightly, but again corners are not as sharp as the center, and the center is not quite as sharp as at wide angle. Interestingly, there is still some minor corner shading visible at wide angle.

Chromatic Aberration Correction. As you can see from the uncorrected RAW crops (above right), lateral chromatic aberration is actually quite high and bright at maximum wide angle when wide open, and a little higher at full telephoto wide open (the worse-case scenarios), so the Panasonic FZ2500's processor does a pretty good job suppressing a lot of it in JPEGs, but it still leaves some visible fringing behind, especially at the telephoto end. Also notice how much distortion correction and sharpening is being applied to JPEGs.

Overall, good though not great performance for a reasonably fast 20x lens. Performance near the center of the frame is quite good across the focal length range, however corners are weak even when stopped down, and color fringing is visible at both ends of the zoom, especially at full telephoto.

Coverage
Excellent accuracy from the electronic viewfinder and very good from the LCD monitor.

The Panasonic FZ2500's electronic viewfinder showed just under 100% coverage at wide angle and at full telephoto in our tests, which is excellent, especially given the amount of geometric distortion correction that is being applied at wide angle. Interestingly, the LCD was a little looser at closer to 99% coverage in our tests, thought that's still very good.