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Studio Tests

The 45mm performs pretty well in our studio tests. It can't match the stratospheric standard set by the Olympus Zuiko Digital ED 50mm F2 Macro (few lenses can), but it's decently sharp and has minimal distortion. Lateral chromatic aberration is being removed in software on Panasonic bodies, but this seems scarcely necessary as it's extremely low anyway. However the lens is not quite as sharp across the entire frame as the Lumix Vario G 14-45mm F3.5-5.6 kit zoom, which is outstanding at 45mm (but obviously doesn't open up to F2.8).

Sharpness Central sharpness is very high wide open, but the corners are notably softer. This pattern persists on stopping down; the highest central sharpness is achieved around F5, with the corners continuing to sharpen up until F8. As is often the case for Four Thirds, the optimum aperture is about F6.3. Diffraction starts to degrade the image significantly at apertures of F11 and smaller, with F16-F22 very soft indeed.
Chromatic Aberration Lateral chromatic aberration is being removed in software so is negligible in these tests. Uncorrected it's very low too.
Falloff We consider falloff to start becoming noticeable when the corner illumination falls to more than 1 stop below the center. There's 1.3 stops wide open here, which disappears rapidly on stopping down.
Distortion The 45mm macro is near-perfectly corrected for rectilinear distortion, with just a trivial amount of pincushion distortion detectable.

Macro Focus

The 45mm is capable of true 1:1 macro, and on a Four Thirds sensor that's quite something. You have to get close to your subject though - the measured minimum focus distance is slightly less than 15cm, giving a working distance of just 6.5cm from the front of the lens to the subject.

Central sharpness is high even at F2.8, but the corners don't come close - we suspect a degree of field curvature. Optimal central sharpness is seen around F5.6, although the corners are still a little soft. Apertures smaller than F11 inevitably start to suffer badly from diffraction, and should probably be avoided unless extreme depth of field is required.

(Click here for macro test chart shots at F2.8 and F22 - WARNING the latter is not pretty.)

Macro -17 x 12 mm coverage
Distortion: None
Corner softness: Low
Focal length: 45mm (90mm equivalent)

Software correction of lens aberrations

One of the more controversial aspects of the Micro Four Thirds system is Panasonic's decision to integrate software lens aberration correction as a fundamental component of the imaging chain. For most users this is completely transparent - the camera corrects both the viewfinder image 'on the fly', and the JPEG files it records. Also, both the supplied SilkyPix software and industry-standard alternatives such as Adobe Camera Raw convert raw files correctly too.

Geometric distortion

The Leica-badged 45mm F2.8 Macro is distinguished from all other Micro Four Thirds lenses by not requiring any correction for geometric distortion - a 'straight' conversion in dcraw is near-perfectly rectilinear, matching the camera JPEG exactly.

dcraw (-0.4%) JPEG (-0.4%)

Lateral chromatic aberration

The studio test data suggests that lateral chromatic aberration is being corrected in the ACR-converted raw files (out-of-camera JPEGs are the same). As usual we've used dcraw to process our studio test raw shots in order to determine the lens's true characteristics, revealing low levels of fringing (you'd have to look at images very closely indeed to have any chance of seeing it). This is illustrated visually using the top left checkerboard pattern from our lens test chart (as a 100% crop direct from the test image).

This fringing will be visible to owners of the Olympus E-P1 (which doesn't correct CA), but it's very unlikely ever to be objectionable in real life.

F2.8
F4
F5.6
F8
F11
F16
F22

Bellows factor

One characteristic of macro lenses not widely appreciated outside of enthusiast circles is the fact that, at large magnifications, the apparent aperture of the lens changes significantly. This means that you need to use longer shutter speeds than you might think (and would be indicated by an external meter) when shooting at macro distances. Of course the camera's metering system will deal with this automatically in normal use.

We've tested this effect by pointing the camera at an evenly illuminated surface and seeing how the exposure changes on focusing closer. Here we're comparing the Panasonic 45mm F2.8 to the Olympus ZD 50mm F2 macro for Four Thirds, and a couple of other new macro lenses. Values are given to the nearest third stop.

 
1:2
1:1
Panasonic 45mm F2.8 Macro OIS
-1 stop
-2 stops
Olympus ZD 50mm F2 Macro
-1 stop
n/a
Tamron 60mm F2 Macro
-1 stop
-2 stops
Canon 100mm F2.8 L IS USM Macro
-1.3 stops
-2 stops

All of these lenses behave in pretty much the same way, losing about a stop of light (and therefore requiring a stop slower shutter speed for correct exposure) at 1:2 magnification, increasing to 2 stops at 1:1.

Optical Image Stabilization

The 45mm macro incorporates Panasonic's grandly-named 'MEGA O.I.S.', which the company describes as 'Advanced Hand-shake Correction Technology'. The IS group audibly rattles around inside the lens until it's mounted on a powered-up camera, at which point it locks into place. Operation is near-silent, but if you listen closely you can hear a slight whirring noise when the unit is running.

Panasonic makes no specific claims about the unit's effectiveness, and with good reason. Image stabilization systems almost universally work by detecting slight tilts in the angle the camera is pointing, and moving lens elements (or the sensor) to compensate. However camera shake also slightly changes the position of the lens relative to the subject, and while at long distances this is unimportant, as the subject gets closer (or more correctly the magnification increases) this effect contributes progressively to overall blur; at macro distances it becomes dominant. Only Canon's latest 'Hybrid IS' technology claims to address this problem, using sensors which detect both tilt and shift movements of the camera, and moving lens elements appropriately - other systems become considerably less effective at close distances.

'Normal' range test

We've generally found the stabilization units in SLR lenses to be pretty effective in real-world use, and to quantify this, we subjected the 45mm to our studio image stabilization test. With its effective focal length of 90mm, we'd normally expect to be able to get good results handheld at 1/125 sec. The subject distance for these tests was approximately 2.5m, and the test camera was the Panasonic G1.

We take 10 shots at each shutter speed and visually rate them for sharpness. Shots considered 'sharp' have no visible blur at the pixel level, and are therefore suitable for viewing or printing at the largest sizes, whereas files with 'mild blur' are only slightly soft, and perfectly usable for all but the most critical applications.

IS OFF IS Mode 1 IS Mode 2

Panasonic's in-lens image stabilization is doing a reasonable job here, although it doesn't seem as effective as the current state-of-the-art from the likes of Canon and Tamron. There's a distinct difference in effectiveness between the IS modes available on Panasonic bodies, with 'Mode 1' (in which the IS unit is running continually) clearly doing better than 'Mode 2' (in which it's only activated after the shutter has been depressed). We suspect this may be due to the relatively massive IS unit Panasonic is using in this lens (it's clearly bigger than those used in the various zooms). Our experiences in the field also reflected this studio test result, so it's best to set the camera to Mode 1 (however this does come at the expense of battery life).

In Mode 1, we see an almost three stop advantage using IS; in Mode 2 somewhere between one and two stops. Unusually the drop-off in effectiveness beyond this is pretty severe; at slower shutter speeds there are few sharp shots. This is definitely better than nothing, but some way short of the best systems currently available.

Close range test

To see how effective OIS is at dealing with shake during macro shooting, we repeated our test at a much closer distance, with an image magnification of approximately 2:1. In this case we looked at just IS Mode 1. The results from this test are pretty stark - at such close focus distances, IS is giving next to no advantage at all (which again reflected our experience in the field). It's not quite time to put away your tripod yet.

IS OFF IS On (Mode 1)

On the subject of image stabilization for hand-held macro shooting, it's also worth pointing out that no stabilization system even attempts to correct for the inevitable slight back-and-forward sway of the photographer relative to the subject, which is a major cause of blur (although in this case through incorrect focus). Switching the camera to continuous autofocus can improve your hit-rate, but a tripod is definitely preferred.

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