The Voigtlander Nokton 17.5mm f/0.95 lens is the second manual lens made by Cosina for the Micro Four Thirds (MFT) system. The first was the Nokton 25mm f/0.95 lens. It's a 35mm equivalent in focal length which is quite popular.
Design and build
The lens comes with a lens cap, a screw-on lens hood and the lens hood cap.
The build quality is excellent. It's basically metal and glass, and it's one of the larger and heavier lens compared to other MFT lens. It weighs 540g.
The heavy weight means it's better to use this lens on a camera with a good grip. It's still comfortable enough to hang around the neck the whole day because with camera and body, it's still under 1kg.
It's a big lens with a filter thread of 58mm, only smaller in diameter compared to the Panasonic 14-140mm lens.
This is a manual lens so there's no electrical contact points at the back of the lens. No EXIF data will be passed from the lens to the camera, so you'll not have information such as the aperture being used, but you'll still have info like shutter speed, exposure, basically the camera settings.
The aperture ring does 1 full stop with 2 clicks.
There's a new feature added to the aperture ring. You can now make aperture ring click-less by pulling back the dial just before it and turning it 180 degrees. A yellow dot will take the place of the white dot, and the aperture ring is now click-less. Very nifty feature for video.
At f/0.95, this is a fast and bright lens, good for low light photography. The other benefit of the f/0.95 aperture is the shallow depth of field (DOF) that can be used to blur out backgrounds. MFT with their smaller sensors required larger apertures to create shallow depth of field.
FocusThe lens is manual focus. You have to set the aperture manually and find the focus yourself.
Using the manual focus assist mode on the camera gives a zoomed in view for checking sharpness.
The shooting style of a manual focus and AF lens is different. Using AF, when it's not set to multi-area AF mode, you have to select the focus point yourself. If you're using multi-area AF mode, then there's a chance that the camera may not focus on the right subject you want. With manual focus, you can always be sure you're focusing on the right subject because you're the one choosing the subject to focus.
In terms of speed, it depends on how good you are detecting focus on the LCD or EVF. In actual usage, manual focusing is slower than AF because you have to make sure the focus is sharp, and that can be challenging.
The photo above is shot at f/1.4, 1/1250s, with a 8X ND filter.
Edge softness is quite evident at f/0.95 so I usually use the lens at f/1.4.
Vignetting is quite strong for this lens and only totally goes away at f/4.
Bokeh is quite wonderful. The 10 diaphragm blades render everything that's out of focus in a creamy manner. It's less harsh than the Panasonic 20mm lens with its 7 blades.
I love the way the lens captures subjects with its shallow depth of field. Shooting video at f/0.95 can result in footage that's quite unreal, e.g. people walking in a background of blur. You don't usually have people walking in a background of blur at wide angle, so that's makes the video quite unreal.
The same photo one stop slower at f/2. The image is much sharper, vignetting is still discernible but less so. The amount of detail is much easier to make out now.
This is the reference photo for the sharpness test below.
The corners are still soft from f/0.95 to f/5.6.
The centre is soft at f/0.95 and much better at f/1.4. Optimal seems to be f/2.8 but f/2 sharpness is quite good also.
In terms of sharpness performance, it's slightly better than the Voigtlander 25mm lens. Relatively speaking. For general use, it's definitely better to use it at f/1.4 and smaller apertures.
Close focusThe minimum focal distance is 15cm. That's very close and the depth of field is really shallow at this distance.
This was shot at f/0.95, 1/3200s, with a 8X ND filter.
Purple fringing is quite strong at f/0.95 and only goes away when you reach f/2.
The aperture ring enables you to change the depth of field manually, from shallow to deep, vice versa. AF lens can only move the focus plane with the focus, but it cannot change the depth of field once it is set.
There's no focusing motor so there's no noise to capture.
This is another video I shot, at f/1.4. With the 35mm lens, you have to get in quite close to your subjects. I prefer a 50mm equivalent lens for making videos.
Using this lens at night video is amazing. The softness at f/0.95 is not discernible in the video since the maximum resolution is not used. So overall, you can achieve relatively sharp video quality. In the video above, you'll see some flaws when using the lens with GH2's EX TELE mode which is not unexpected.
This is a challenging lens to use because you have to spend the time to ensure that the focus is on the subject. A high resolution EVF and LCD makes focusing easier.
Conclusion and who this lens is for
This is one of the fastest and brightest lens for MFT. It's for those who shoot often in low light and need the fastest lens possible. It's more than 1 stop faster than the Panasonic 20mm lens and 3 stops faster than the Olympus 17mm lens.
At 35mm, it's a great walk-around lens for purposes such as street photography. However, it's really quite big and heavy, which somewhat defeats the purpose of the MFT system. But compared to APS-C and full frame, it's still extremely portable.
It's a specialty lens due to the manual focus because of the ability to control for depth of field during video mode. That's probably the ultimate point in choosing between this or the Panasonic 20mm lens which is much cheaper and lighter.
For shooting stills, the compromise between image quality and depth of field means that this lens will be used more often from f/1.4.
Being a manual focus lens has its advantages. You can focus as fast as your hands can go, and as accurately as your eyes can see. The latter point on focus accuracy is a huge benefit when you're shooting in low contrast situations, where most AF lens will tend to start focus hunting.
At a glance
+ Excellent build quality
+ External aperture ring
+ Aperture ring can be made click-less
+ Manual control of depth of field during video
+ Bright f/0.95 aperture good for low light shooting
+ Beautiful creamy bokeh
+ Great image quality
+ Comes with lens hood
- Heavy at 540g
- Big at 80mm tall
- Edge softness when shooting wide open
- Corner softness from f/0.95 to f/2
- Visible purple fringing from f/0.95 to f/1.4
- Strong vignetting from f/0.95 to f/2