UPDATE [Nov 3 2015]: Laowa sent me a replacement copy of the lens, I did testing similar to the one above, and I can confirm that the new copy of the lens is obviously better: corners are sharper for both non-shifted and shifted cases, now very close to (but still a touch worse) than my Sigma 10-20mm lens.
UPDATE [Sep 30 2015]: I discovered that my copy of the Laowa 15mm lens has a subpar quality (see my second post below), and I am in the process of exchanging the lens for a better copy.
This is my review of Laowa (Venus) 15mm f4 lens which I finally received a few days ago. This fully manual UWA lens has a limited shift capability (up to 6mm, only vertically, and only for crop cameras) and 1:1 macro capability (the latter is achieved at 5mm distance from the front element - not entirely practical). This is the first UWA shift lens designed for crop cameras, and my primary interest in this lens was mainly about that. (I am also curious about the 1:1 UWA macro feature, which is also unique, but I will review it elsewhere.)
Judging from the MTF plots I've seen, a couple of published reviews (which admittedly were more focused on the macro feature of the lens), and the fact that this is a prime lens designed for full frame cameras, I had very high expectations for its optical qualities. I hoped that this would be my default UWA lens, to use for architecture, landscapes etc. The 1:1 feature would be just the icing on the cake.
Unfortunately this doesn't seem to be the case. I took this lens (along with my UWA workhorse Sigma 10-20mm f4-5.6 - a good lens, but not considered to be the best in its class) for a test drive under realistic landscape shooting conditions - a cityscape seen from a ~100m height. I used all the standard precautions:
- Used Live View to achieve the best focus at the frame's center.
- Used a tripod, 10s delay, mirror lockup, to minimize vibrations.
- Did my best to match the image produced by Laowa (both centered, and with maximum shift of 6mm) with that from Sigma (used at 15mm FL). It couldn't be perfect, as the two lenses have different shapes of radial distortion, but at least I made sure one extreme corner had a good match.
I used my Linux workstation as it is much easier to fully automate the processing. In particular, I used the following command line tools (ask me for details if interested):
- dcraw: RAW image processor.
- tca_correct and fulla (part of Hugin package): automatic chromatic aberration correction.
- convert and montage (part of ImageMagick): automatic cropping, normalizing, and montage of the tiles.
- gimp (image editor): to add labels. BTW, I managed to find the newer gimp version which is finally (after many years of promises) works with full color photos (up to 64 bit per channel). Just google for "gimp 2.9 goat invasion". E.g. here: http://www.partha.com/ . This is an experimental version, but seems to be working fine (under Linux at least.)
A side comment: both Sigma and Laowa exhibit very little CA, but it was still very useful to get rid of it, for the sake of comparing the corner sharpness. I used my idea described elsewhere (https://photography-on-the.net/forum/showthread.php?p=17618193) to automatically remove CA from shifted photos. It worked great.
Here is the main result (click on the link under the image to view it at 100%, to see the difference in sharpness): extreme corner sharpness for
- Laowa at maximum 6mm shift (left column),
- Laowa with zero shift (center column), and
- Sigma (right column).
The photos were made with my crop camera Canon 50D.
IMAGE LINK: https://farm6.staticflickr.com …68272956_ff4e4386ee_o.jpg
Overall impression: Sigma 10-20mm lens is much sharper in the extreme corner than non-shifted Laowa 15mm lens, especially between wide open and f/11. Sigma's corner is the sharpest around f/8 (though it is totally usable even wide open, at f/5.0), while Laowa's corner sharpness is best around f/11 (but substantially less sharp than Sigma at the same f-number).
When shifted to the max (6mm), the extreme corner sharpness of Laowa gets even worse (the left column). It is barely usable only around f/16.
Even better way to compare the two lenses is to choose the sharpest aperture for each case, and then display them side by side (sharpest apertures were f/16 for Laowa with 6mm shift, f/11 for Laowa with zero shift, and f/8 for Sigma):
IMAGE LINK: https://farm6.staticflickr.com …28506532_064d02472d_o.jpg
For completeness, I also made the same comparison for the frame center:
IMAGE LINK: https://farm6.staticflickr.com …07663449_2a01780fd2_o.jpg
As expected, the difference in central sharpness is much smaller. Both Laowa and Sigma do a good job here, even the 6mm shifted case.
To give you an idea how small these areas are on photographs, here is the Laowa photo (zero shift) shot at f/11, with CA removed, and the two red squares showing the comparison areas (click to see the full size photo):
IMAGE LINK: https://flic.kr/p/xTba4B Laowa 15mm shot at f/11 by First Last, on Flickr
Here is the example of how little chromatic aberration these two lenses (Laowa and Sigma) exhibit, in the extreme corner at f/11 (where CA is the strongest); it also shows that automatic CA correction works very well, including Laowa shots with maximum (6mm) shift. (I am using my trick to correct CA in shifted photos.)
IMAGE LINK: https://farm6.staticflickr.com …25523128_9a626f227a_o.jpg Chromatic aberration test for Laowa 15mm f4 lens
At the end, I am not sure whether I should be impressed with my old and trusty Sigma 10-20mm performance, or be very disappointed with the Laowa's corner sharpness. Likely both.
From my tests it does appear that the new Laowa 15mm f4 lens was primarily designed for its unique UWA 1:1 macro feature; and it should be mostly used as such. Its qualities as a general purpose UWA lens were obviously sacrificed for that primary goal.
- The mechanical quality seems to be excellent. It is hefty, all-metal, with no loose movements.
- The aperture blades are beauty: 14 rounded blades produce almost perfectly circular opening at any f-number. Not surprisingly, the published macro shots have very nice bokeh.
- The shift feature is very hard to use, so it was obviously an afterthought, and almost a gimmick. One has to push up the small metal lever pretty hard, and then move the whole lens with your hand (very stiff motion). This is gonna be very hard to use on a tripod.
- The lens cap has a great design, works much better than the Sigma's, or the Canon lenses I have (135L etc).
- The lens shade has small plastic parts, and is pretty hard to put on and remove. It likely won't last.