UPDATED with video.
Voigtländer´s 17,5 mm Nokton is a handsome and well made lens in traditional fashion. It is a longish lens with 80 mm length and its full metal construction with 13 glass lenses makes weight rise up to 540 g. Thinking of its speed at a whopping f/0.95, its filter thread is surprisingly only 58mm. Many Voigtländer lenses are like this, relatively long but slender.
Nokton is a joy to handle with smoothly rotating focusing ring. Here another surprise is its closest focusing distance at 15cm, which gives an impressive magnification ratio of 1:4. I used Nokton solely with Olympus E-M5 camera with landscape grip attached. This is a well balanced combination with the right feel when shooting. Yes, this combination is also on the heavy and large side by mFT standards, but it feels like a camera should. Nokton is a native mFT lens, no adapters are needed with E-M5 or other mFT cameras.
One reason I enjoyed using this lens is its focal length. It has the same angle of view as a 35 mm lens in a FF 35mm camera. That´s my favorite focal length or, rather, angle of view. I have used these lenses so much during so many years that I can still walk where I want to take the picture, raise camera on my eye, frame without any need to move and shoot.
Nokton 17,5 mm is a manul focus only lens. No autofocus.
I have E-M5 configured for manual focus as seen in this picture. What´s originally a video button is now for choosing MF or AF in my camera. By pressing Fn2 I can magnify focusing spot in EVF. I works as a toggle where the second press gives me again normal view, but I get also normal view by touching shutter button. This configuration enables me to focus and compose quite fast. Enlarged area of EVF is of course a distraction no matter how easy or fast it is to do. That´s why I also have sharpness set to maximum, +2. It makes contrasty edges in EVF to kind of flicker when they come sharp. It is sort of focus peaking and is easy to see without EVF magnification. This feature should only be used while shooting still images as RAW files. It would ruin jpegs and video.
Nokton has also depth of field scale engraved next to distance scale. This makes zone focusing very easy. Aperture F5.6 with focusing set at 2.5 meters gives you a DOF starting from 1.5 meters and reaching to over 8 meters. That´s pretty much all one needs for street shooting with this focal length. There is no 2.5 m engraved in lens barrel. How do you set 2.5 meters? Now, 2.5 meters is hyperfocal distance for this lens at aperture F8, meaning that at these settings your DOF covers the distance from 1.3 meters to infinity. Just align infinity and rightmost 8-mark and use F5.6. If you want to work closer, align left 5.6-mark (between 8 and 4) at 1 m and your DOF extends from 1 to 2.5 meters at F5.6. I am no street photographer but it is good to know couple of focusing zones when the lens has a distance scale. This way you can shoot very fast without any need to worry about focusing.
This is a typical scene where zone focusing helps in getting the right moment.
In my previous blog I had nothing much to say about Zuiko M. 75mm lens´ image quality because it was just so perfect. Now we see a very different behaviour. This lens is very good when you know how to use it. But it also has an underlying nasty character which will kick you badly if you forget how to treat it.
Everything is very good at apertures roughly from F2.8 to F5.6. Image quality is very high across the frame, even if F2.8 is not quite up to F4 and F5.6. This lens has its aperture ring dented at full and half stops and you can hold it even at any intermediate setting. I only shot my test target at shown apertures which is a bit too sparse for a lens that has so varied characteristics. Anyway, there is some chromatic aberration and purple fringing also along this sweet range but those are easily corrected in Lightroom.
Before going to other apertures I must make a note on barrel distortion. That´s why corner crops of test target are slanted. I do not correct this kind of distortion unless I must. It does not show adversely in every image. My street shot above is one of images where I corrected it with Lightroom Lens Correction tool to straighten the upper edge of image. As you can see this geometric distortion makes center crops bigger than corner crops. Correcting this distortion evens them out and, by doing so, slightly lowers resolution in corners.
Another note must be made on focus plane. It is not straight but curved so that it curves closer to the camera towards image edges. This curviness does not show in these test target shots because I always focus center and corner separately. This lens is not meant for shooting brick walls unless you like them softer in the corners. With three dimensional subjects this curvature may keep subjects at image edges sharp or a little softer, just like a straight focal plane may do the same. It only depends how your subject lays three dimensionally. So, for me this is one of those need-to-know features of this lens while barrel distortion is a just a flaw.
Looking at test shots at F8.0 you can see that image quality starts to drop down. This kind of behavior is very typical for very high speed lenses. Some zooms are only struggling to get their act together by F8. You can use F8 but need to add a bit more clarity. But don´t go beyond this aperture. With this lens there should be no need to do it because you already have plenty of DOF.
And now I can´t avoid any more writing about largest apertures. I used the word character earlier. Some lenses have their special touch and then most do not. The latter ones can be "just" optically perfect performers, like Zuiko M. 75mm is, or barely mundane and so-so like most kit level zooms are. This lens has its special touch and charm which, as contradictory as it may sound, comes from the nature of its imperfections. When you look at the corners of my test target, you can see that they are not "good". No, they aren´t. This lens can´t get good MTF values wide open. Corners suffer more and more the wider you go with apertures. There´s chromatic aberration, ghosting and even strong purple fringing (RAW + LR4.1 process). CA is easily removed by keeping Remove Chromatic Aberration checked. Time to time fringing is not removed by just clicking with Defringing tool and you need to do manual correction with defringing Adjustment Brush. And then it is gone. But ghosting stays. You really can´t correct that. Centers can be brought up to standard by adding more Clarity there, mostly even corners at F2.0. Wide open you either like this dreamy ghosting or hate it. Because there is a large enough central potential for shapness and goodness, I could live with those corners. Even wide open. I actually like the touch of this lens and with some more practise could use it´s nature better as an advantage. Now I needed two weeks just for learning to know its traits. And like I said, this lens can be nasty and give you lousy pictures, if you try to do something against the nature of it. Nokton 17,5 mm is not a lens for casual snappers at larger apertures. Very fast lenses have always been enthusiast lenses and this is one of them.
Bokeh quality is one of issues with high speed lenses and here it is very likable. Part of it comes from smooth and round higlight reflections abtained by no less than 10 diaphgram blades. Only, again, you have to remember ghosting which gives every now and then its own elongated flavor.
I have a collection of sample images, which hopefully clarifies my opinion, in my samples gallery.
There is one problem with shooting video using E-M5. Alhough Nokton 17,5 mm lens is a native mFT lens, it is not giving that information to E-M5. So, there is no IBIS with video. I think that Olympus should tweak firmware to allow IBIS work with all lenses just like it does with stills. Other than that this lens seem to suit perfectly well for video work. Quality is great and because of aperture ring you can also control DOF while shooting video.
UPDATE: A sample video is now up at https://vimeo.com/45207144
I wanted first to have a full HD video at another site with better framerates and less compression. Didn´t happen yet. It may be better to download the video if there is problems with it. This video at vimeo is just a montage of clips, look at the touch of this lens.
Voigtländer Nokton 17,5 mm f/0.95 is a great lens, but only if you are prepared to learn its true nature and limits. It has potential to give you visually interesting images with its own touch. It has also potential for great image quality in strictest technical meaning. But it is not a good choice for a casual shooters. Street photography and moody images in low light are its own territory. Plus it is one of the most interesting lenses for video among mFT wide angles.