Resolution
Here is the true head to head. Both cameras come with the same 12.3-megapixel Live MOS sensor and TruePic III+ image processor. The sensor measures 17.3 x 13mm and promises “more detail than ever before in your pictures,” according to Olympus. Indeed, the cameras produced clear, detailed images most of the time. We tested the cameras using their modest 14-42mm zoom lenses. Although the lenses differ in size, they have the same zoom and max aperture of f/3.5.

 

 

The E-P1 shows better definition in the vertical lines on the resolution chart. Its smaller kit lens, however, exhibited more chromatic aberration than the DSLR's optic, showing as orange-colored lines that creep in where black should be. 

 

The two cameras performed similarly on the horizontal lines in the resolution chart. At higher ISOs though, JPEGs from the Olympus E-620 show splotches of smoothed pixels; this can be seen when you magnify the chart to 100%. The smoothing is less apparent in RAW files, but it is still more pronounced than similar shots from the E-P1.

 

Color
The two Olympus digital cameras provide different renderings of color. Both map tones similarly across the gamut, but the E-620 offers a more neutral reproduction of JPEGs, while the E-P1's colors are more saturated across the board. Below are two untouched JPEGs of a blue hydrangea flower – the first one by the E-P1 and the second by the E-620.

 

Olympus E-P1, JPEG from camera

Olympus E-620, JPEG from camera

 

As you can see, the E-620’s colors are significantly paler in the samples. Interestingly, the opposite is true for RAW files. Below are shots of an X-Rite ColorChecker chart, photographed by the Olympus E-P1 and Olympus E-620 in RAW, then processed neutrally in Adobe Camera RAW):

 

Olympus E-P1

 

Next, is the same chart photographed by the Olympus E-620 (also shot in RAW, processed neutrally in Adobe Camera RAW):

 

Olympus E-620

 

In the following graphics, we can see that when the white point is set on both files in Adobe Camera RAW, the E-620 offers the slightly more saturated mapping.  In these illustrations, the squares correlate to the 24 tiles of the X-Rite ColorChecker chart, while the circles represent the actual depiction by the Olympus cameras. The longer the tether between the two shapes, the greater the color error.

 

Olympus E-P1

 

Olympus E-620

 

The tethers tying the E-P1’s colors are longer, and thus more inaccurate, than the E-620’s. This will make a slight difference when shooting JPEGs (as evident in the hydrangeas above) and other common subjects, but isn't significant enough to sway opinion in either direction. 

 

Below is a further breakdown examining how the cameras reproduce common subjects. In every situation, the E-P1 offered a stronger, more saturated reproduction.

 

 

Generally speaking, shooters looking for punchy colors straight out of the camera will be more pleased with the E-P1. Conventional editors, however, may prefer the E-620's faithful reproduction.

 

Speed
The Olympus E-620 has the edge when it comes to pure capture speed, but the E-P1 has better endurance. The E-620 can shoot 4 frames per second, up from 3.5 fps in the E-520, while the E-P1 maxes out at 3 fps. The E-620 stopped after just five shots to recover, while the E-P1 buffer could handle up to 10 shots.

 

 

The E-620 has another advantage. It has two continuous shooting modes: high and low. The high is set for 4 fps, but the low can be set between 1-3 fps. For its versatility and speed, the E-620 wins the sprint.

 

The E-620's AF advantage also plays into a much faster shooting experience using the DSLR. 

 

Both cameras also include Picture Modes (such as “Vivid” and "Muted") to adjust the 'look' of the reproduction in-camera. 

  

Noise & Dynamic Range
The imaging sensor within both interchangeable-lens cameras is much larger than a standard point-and-shoot digicam, allowing for better performance in low light without the flash.  The E-620 and E-P1 both come with wide ISO ranges and multiple noise reduction settings. The chart below shows how each setting fared:

 

In every setting, the Olympus E-P1 maintained lower overall noise levels. It does, however, come at the expense of some detail at higher ISO settings. 

 

Olympus PEN E-P1 - ISO 1600

Olympus E-620 - ISO 1600

 

The lower noise levels in the RAW files help the the E-P1 realize a bit more overall dynamic range. The graph below shows the Olympus E-P1 offers about a tenth of an EV stop more than the E-620 at base settings.