Lumix Leica DG Summilux 25mm f/1.4 Review Part 2

In the first instalment of my review, I talked about the basic stuff, like the focus speed, sharpness and bokeh. Here, I take a closer look at other aspects of the lens.

Focus breathing

The Leica 25mm f/1.4 features internal focusing, like most other autofocus Micro Four Thirds lenses. This makes the focus fast and virtually noiseless. However, there is a downside: The field of view changes as the focus is shifted. This gives rise to the focus breathing problem: As the focus moves, objects in the frame appear to change size, to be breathing.

Lumix Leica DG Summilux 25mm f/1.4 Review Part 1

Back in the 1960's, when SLR cameras started to become available to the general public, one could essentially only buy prime (non-zoom) lenses. The cheapest lenses were the ones which were short, but still long enough, in terms of focal length, to be constructed without a complicated retrofocal design.

The cameras generally had a register distance of around 45mm, which means that any lens shorter than this will be more expensive to make. Hence, a popular segment became lenses around 50mm. These could be made fast, i.e., with a large maximum aperture, fairly inexpensively. For this reason, many bought their camera with a 50mm lens lens, which became known as the normal lens. It was the kit lens half a decade ago.

Wide angle lenses would require a retrofocal design, which was expensive. And longer lenses would require larger lens elements, again keeping the price high. So the 50mm lens was the most common (normal) lens to use on SLR cameras, simply because it was inexpensive.

At that time, to have a zoom lens which covers a range of focal lengths would be an unbelievable luxury. Today, it is the other way around. It is the zoom lens which has become the normal lens, the lens people buy in kits with their camera. While the 50mm (equivalent) prime lens has become the luxury item.

That is the case with Panasonic Lumix G Micro 4/3 LEICA DG SUMMILUX 25mm f/1.4 Leica Aspherical Lens. With the 2x crop factor of the Four Thirds sensor size, this lens corresponds to 50mm on a traditional film SLR camera, in terms of field of view. It has been co-branded with Leica, to underline the luxury, premium value of the lens.



Lumix 20mm f/1.7, Lumix Leica 25mm f/1.4, and Sigma 30mm f/2.8 DN

Video AF comparison, Lumix 25mm f/1.4 vs 20mm f/1.7

The Lumix Leica DG 25mm f/1.4 and Lumix G 20mm f/1.7 pancake are quite similar. Both are fast normal lenses. Still, they are different:



On both lenses, I am using 46mm to 37mm step down rings as lens hoods. If you go down the same route, you will also need a 37mm front lens cap.

Beyond the size difference, the 25mm lens features internal focusing, while the 20mm lens has an old style focus mechanism, where the whole lens array moves back and forth. The internal focus achieves faster focus, and makes less noise. The Lumix 20mm lens on the other hand is known to focus slowly, and for making more noise.

In this article, I aim to see if the difference in focus mechanisms make the Lumix Leica DG 25mm f/1.4 better suited for continuous autofocus during video.

Bokeh part 2

I previously wrote about bokeh, describing what it means (the nature of the rendering of out of focus areas), how it is commonly used, and I also looked into how the aperture setting affects the out of focus areas in the picture.

This time, I want to look more closely at how the bokeh differs by lenses. I've tested some common fast lenses from the Micro Four Thirds lens lineup, laid out here:



Second row: Olympus 45mm f/1.8, Leica Lumix 45mm f/2.8 macro, Lumix X 12-35mm f/2.8
First row: Lumix G 14mm f/2.5, Lumix G 20mm f/1.7, Sigma 30mm f/2.8 DN and Sigma 19mm f/2.8 DN