Zeiss 50mm f1.4 Planar focus shift issue. Understand and avoid it
Anyone buying the Zeiss 50mm f1.4 Planar (ZE, ZF, C/Y) should be aware of its Focus Shift issue. It is a well documented issue with this lens (and several others like the Canon 50 f1.2 L, Zeiss 85mm f1.4 etc) which can render this lens pretty much unusable for closeup shots. Fortunately with the right technique and a little bit of practice this issue can be mitigated easily.
Focus Shift Explained :
So what is this focus shift issue exactly ? Basically it means that means that that lens's focus shifts as you stop down. Normally (with any lens) you will focus with the aperture wide open and then while pressing the shutter the camera will stop down the lens to its desired aperture value to take the shot. But sometimes (with some lenses) stopping down shifts the focus to a different point resulting in an Out Of Focus (OOF) shot.
In the above example, the left image shows the desired focus (without any shift) and the right image shows the result of focus shift when the shutter is pressed.
The focus shift issue is reduced if your subject is far away or if you use smaller apertures with larger DOF to compensate for the focal shift. So that means that if you shoot closeup and with larger apertures (f2.0, 2.8, 3.2... etc) and focus through the viewfinder or through liveview then you might end up getting an OOF shot. Ofcourse there will not be any focus shift while shooting wide open.
So while this lens was brilliant for landscapes, i found myself unable to take any good closeup pictures with it. This was a real let down for me and i went as far as deciding to sell off this lens and buy the Zeiss 50mm f2.0 Makro Planar which does not exhibit this focus shift (and costs about double the price).
Fortunately i came across some good advice which helped me mitigate the focus shift issue with the lens and now i'am really happy with the closeup shots im getting with this lens.
Method 1 : Use the DOF preview button (Viewfinder Focussing) :The DOF (Depth of Field) preview button is used to stop down the lens to the selected aperture value, showing you a preview of how the final image would look like. So by focussing your lens with the DOF preview button pressed you can easily avoid the focus shift issue.
Depending on the handling of your lens, it might be a cumbersome process to hold the camera steady, press the DOF preview button and turn the focus ring at the same time. Fortunately the Zeiss 50mm f1.4 ZE has a buttery smooth focus ring which can be easily turned using just a single finger. I hold the camera in my right hand, cup the lens using my left hand with my left thumb pressing the DOF preview button and my left middle finger operating the focus ring. It is a pretty straight forward process and you'll get the hang of it after a few times.
Tip : Stopping down the lens makes the viewfinder darker making it difficult to focus. So i start focussing with the lens wide open, then when i find my focal point i press the DOF preview button and make the necessary fine adjustments to nail the focus while stopped down. This method works like a charm every time.
Method 2 : Live view Focussing - Use the DOF preview button or use Still + Movie mode:
If you like shooting through live view, then things get a bit easier. There are 2 options here.
Use the DOF preview button : You can press the DOF preview button to stop down the lens and adjust the focus accordingly. But there is a possibility that sometimes you might forget to do this and end up with a OOF shot.
Use Still + Movie mode in Live view : By setting the Live View mode to Still + Movie (with the screen setting option selected as Movie Display) we can ensure that the lens is always stopped down to the selected aperture level while in the Live view mode.
If your camera supports this feature, then you should definitely shoot with the Still + Movie mode setting enabled.
Method 3 : Use AF micro adjustment (Viewfinder Focussing): Canon cameras which support AF micro adjustment can register the AF adjustment settings for ZE lenses. So if you are comfortable with the AF micro adjustment feature then you test your lens using a focal chart and set its AF micro adjustment value accordingly.
WARNING: I'am not sure if the AF micro adjustment will work for multiple aperture values. I.e if the focus shift varies for different apertures then we cannot use AF micro adjustment to cover all of them. I personally am not comfortable with this and i prefer using the DOF preview button while focussing through the view finder.
The below image shows a series of crops from the images i took while focussing through the viewfinder before and after using the DOF preview button for focussing. It makes a world of difference and i do not worry about focus shift from the Zeiss 50mm f1.4 Planar anymore.
So to wrap up, it is definitely possible to mitigate the focus shift issue with the Zeiss 50mm f1.4 Planar by using the right techniques. So do not let this discourage you from buying this wonderful lens, its performance is exceptional for landscapes and when the right techniques are used, it can be pretty great for closeups as well.