User Review: APS-C 25mm f/1.4

The 50mm focal length is popular among many photographers due to its versatility, and the micro four thirds system now has plenty of 25mm lenses to choose from. Lusted after by many, the Voigtlander 25mm f/0.95 holds its rank at the top of the food chain in regards to speed, but is manual focus only and will set you back a whopping $1000 USD. Runner up in terms of speed and establishing somewhat of a cult following, the Panasonic/Leica D Summulix 25mm f/1.4 is also highly sought after because it is known to have fantastic image quality and the ability to render photos that are beautiful and unique to this lens. It can also auto-focus, but unfortunately all this amazingness does not come cheap and you will need to fork over about $600 USD to experience all of its glory. Another great option, albeit, not as bright, is the recently released Olympus M.Zuiko Digital 25mm f/1.8. Its image quality has been shown to rival that of the Pan/Leica and it comes in at about 2/3 of its cost. For those not willing to spend as much on a bright 50mm lens, one could opt to purchase a cctv lens and adapt it to a micro four thirds body. The most popular (and cheapest) cctv lens in this focal length originates somewhere in Asia and is made for 1" sensors. Although I never owned this lens (opted for the 35mm) it was seen to exhibit some unique characteristics such as vignetting and "swirly" bokeh.

Last month I was browsing eBay and came across another 25mm cctv lens which claimed to be new and could be used with cameras that had APS-C sized sensors. I figured since it was designed for a larger-than-M43 sensor, that the lens would not exhibit the artifacts that were present in other models and decided to make the purchase. This review comes from a user standpoint and since I am on a vessel bobbing around in the middle of the Caribbean Sea at the moment I cannot provide the most accurate tests on sharpness etc., but will try to give you more of an idea of what to expect if you decide to purchase this lens. Sample images come from scenes I encountered while traveling throughout airports and the city of Bogota, Colombia while on my way to board the Western Pride for work. Sharpness and bokeh tests in addition to a handful of sample photos were taken around the vessel since then.

Build and Ergonomics

The lens is extremely simple and comes with a generic pinch style front lens cover (a step up from the other versions) and a plastic back cover. The back of the lens screws on to a cctv to M43 converter (must be purchased separately) and if the lens lives permanently on the mount you can use a regular M43 back cover to protect the rear element when off the camera. In addition, the front of the lens is threaded and does indeed take 46 mm accessories (like the eBay listing advertises) which is handy if you want to add a hood or filter.

The lens is small (about 1/2 an inch shorter than the MZD 45mm f/1.8 and about as wide-see product shots below) and can easily fit into a pocket, however it is bigger than the 1" cctv lenses which makes it more proportional on the EM5. The aperture adjustment ring sits at the base of the lens near the mount and is marked with the simple increments of 1.4, 2, 4, 8, 16. The focus ring is all the way up front and is raised with grooves along the outside which adds a bit of texture. This is great because you can easily find the focus ring without having to look at the lens. When using the older 35mm cctv lens, I often accidentally adjusted the aperture instead of focus because the rings were right next to each other and it was hard to differentiate between the two. This lens also "feels" good and none of the rings on my copy are too stiff or loose. My only gripe regarding ergonomics was that when the lens is fully screwed into the adapter, the aperture and focus distance markings were not visible from above when it was mounted to the camera. This led to me having to flip the camera over in order to make precise adjustments to the click-less aperture. I had an "ah-ha moment" when I was performing the sharpness tests; once the adapter and lens are mounted to the camera you can slightly unscrew the lens until you can see the markings. This lens becomes a lot easier to use once this problem is solved and I am guessing the markings will end up in different places depending on the brand of adapter is used.

Using "Enfuse" for multiple exposures

Another option (or technique) I found useful with this lens was zone focusing and although the lens does not have a DOF scale, the rings are stiff enough to stay put after setting your aperture and focus unless you bump the lens. I used this method to discretely photograph people in the city of Bogota, and found stopping down between f/4 and 8 helped out in this arena.

Sharpness and Chromatic Abberation

I am sure the big question here is whether the lens is usable wide open and in short, the answer is yes. However, the extremely narrow DOF makes manually focusing the lens a bit challenging and it becomes necessary to enable the magnified view to achieve critical focus. As with all lenses, stopping down improves sharpness and at f/4 the center is very sharp. Like I mentioned above if you are using this lens for street photography stopping down between f/4 and f/8 will ensure the frame is sharp from corner to corner. During my trial run with this lens I refrained from stopping down past f/8 to avoid a loss of sharpness due to diffraction.

The following series of photos represent my attempt to showcase the difference in center sharpness and DOF throughout the usable aperture range. Since the scene was heavily back lit, this section also provides an example of the amount of chromatic aberration to expect (which is surprisingly minimal). It is worth mentioning that the examples were not taken at the close focus distance which is advertised to be 30cm (comes close to Olympus' 25mm lens) in order to give the image context and help showcase the difference in background rendering between the apertures. RAW images were imported into Lightroom and immediately exported as re-sized (1000 pixels-to help accommodate slow offshore internet) JPEGS. Center crops were exported without re-sizing and represent roughly 610 x 762 pixels.

F/1.4

f/1.4: RAW exported as re-sized JPEG

f/1.4: 100% center crop

F/2

f/2: RAW exported as re-sized JPEG

f/2: 100% center crop

F/4

f/4: RAW exported as re-sized JPEG

f/4: 100% center crop

F/8

f/8: RAW exported as re-sized JPEG

f/8: 100% center crop

Here are a few more examples of sharpness, however unless stated in the figure caption I cannot remember what aperture they were taken at (likely stopped down to f/4):

Hazy city

Hazy city: 100% center crop

The park

The park: 100% center crop

The park: 100% corner crop

Psalm 22: high ISO example, f/1.4

Psalm 22: 100% center crop

Buttons @ f/1.4

Buttons: 100% corner crop

Bokeh

The quality of bokeh from this lens is somewhat of a mixed bag. Overall, out of focus areas are pleasing but bokeh balls formed from point sources exhibit a bit of "roughness". In fact, I think overall the lens produces images with more grain than any of the Olympus offerings. I personally like the rendering (especially for street work), but consider looking elsewhere if you are looking for perfectly smooth bokeh balls. It is also worth noting that there is no swirl to speak of but starting at f/4 the shape of bokeh become rounded off hexagons. Below show examples from f/1.4 to f/8 with 100% crops (612 x 612 pixels).

F/1.4

f/1.4: RAW converted directly to black and white and exported as re-sized JPEG

f/1.4: 100% center crop

F/2

f/2: RAW converted directly to black and white and exported as resized JPEG

f/2: 100% center crop

F/4

f/4: RAW converted directly to black and white and exported as resized JPEG

f/4: 100% center crop

F/8

f/8: RAW converted directly to black and white and exported as resized JPEG

f/8: 100% center crop

Flare

The glass elements of this lens are recessed quite a bit into the body and I am guessing this helps to shield from flare. The 35mm cctv lens that I own is practically unusable in bright conditions due to excessive flare but this is not a problem with the APS-C version and during this trial run the lens never gave me flaring issues. I was able to force some out, but it took extremely bright conditions and I had to angle the camera. Wide open the lens produces this rainbow-y (and kind of awesome) flare accompanied by a pink and purple artifact. By f/2 the prism goodness goes away leaving the pink and purple, but again this was not a problem in real world use (see back lit sharpness test example).