GH2: Magnified focus with legacy lenses

The Panasonic Lumix GH2 represents an evolution from the original GH1, which not only includes better video quality, but also better ergonomics. One example is the possibility to use the click wheel to select magnified focus assist mode when using legacy lenses. With the GH1, this mode was available through two button presses: Left arrow key followed by the down arrow key.

On the GH2, it is much simpler. Normally the rear control wheel controls the aperture (in A mode), and the exposure compensation. Switching between these two is done by pressing the click wheel.

When using a legacy lens, however, the camera cannot control the aperture anyway, so the default function of the control wheel is to adjust the exposure compensation. However, Panasonic has added a new function on the GH2: Pressing the control wheel once brings up the magnified focus assist view. You can exit the magnified view by pressing the control wheel again, or by half pressing the shutter release button.

I will demonstrate how to do this.

To use a legacy lens, you will first need to make sure the camera operates when a non-compatible lens is attached. This is done by setting the "Shoot without lens" option. You'll find this option under the custom options (with the "C" and wrench symbol). Here is the location in the menu:

As an example, I am using the manual focus Nikkor 50mm f/1.8 AIS lens. This is a classic, cheap and light lens. It has a pancake characteristic, however, with the adapter it is still not very compact.

To attach such a lens, you will also need a Nikon to M4/3 adapter. Here's how to attach the adapter and the lens to the GH2 camera:



In the next demonstration video, you can see that I use the magnified focus assist view. In this mode, rotating the control wheel changes between 5x and 10x magnification. You can also use the arrow keys to move the enlarged area.



The magnified view can also be brought up by pressing the touch screen. However, since I usually have the thumb near the rear click wheel, I find it much easier to use this function for focus assist.

When focusing, you will normally want to use a large aperture. E.g., f/1.8 for the Nikkor 50mm f/1.8 AIS in my example. It is easiest to verify that the focus is correct when the aperture is large, since the depth of focus is the smallest.

On the other hand, when actually taking the photo, you'll often want to close down the aperture for extra sharpness. Hence, you end up adjusting the aperture ring on the lens back and forth all the time.

Virtually all cameras do this process automatically. But when using legacy lenses on a Micro Four Thirds camera, you must set the largest aperture manually when focusing, and then stop down the aperture before taking the picture.

Future use of MFT lenses

One of the fun things with the Micro Four Thirds (MFT) format, is the short flange distance (20mm), which enables the possibility of making adapters for a number of formats. There are cheap, abundant adapters for many legacy formats, e.g., Nikon F and Pentax K, to name a few.

When MFT becomes legacy

However, the flip side of the coin is that some day, inevitably, MFT is also going to become a legacy format. What happens with your gorgeous, and expensive, MFT lenses then?

Let's say that the worst case scenario is that, due to competition, the MFT system loses so much volume that it is abandoned by Olympus and Panasonic. It doesn't seem likely now, but stranger things have happened.

You can still use your old cameras and lenses, of course, but at some point you will want a newer camera, due to new features and better image quality. Can you still use your MFT lenses on some camera from another system?

If Samsung NX becomes dominating

The Samsung NX format is one of the competitors in the mirrorless system category. Let's say this format becomes dominating. Can you use your old MFT lenses on this format through an adapter?

In short: No. It's not possible. The Samsung NX format has a longer flange distance (25.50mm), meaning that even if you made a very short adapter, the MFT lenses would not be able to focus to infinity. You could only use them as short focus macro lenses. Which is not very useful.

If Sony E becomes dominating

The Sony E format was introduced for their new NEX series. It has a flange distance which is 2mm shorter than the MFT format. This is good news, because 2mm, while pretty short, is probably enough to make an adapter for using MFT lenses on Sony E. The Sony E format also has a wider flange diameter, which makes it easier to design an adapter.

However, the MFT lenses are pretty useless without the possibility to operate the focus and the aperture. And both are operated electronically, controlled by the camera. So an adapter must have the relevant software to interpret the Sony E signals, and translate them into something that the MFT lenses understand.

This kind of electronic communication might sound easy, however, it is probably far from trivial. And at best, your autofocus would probably be very poor, both the speed, and, possibly, also the accuracy.

For a comparison, let's consider the Canon EF system. There are adapters for using Canon EF lenses on MFT cameras, but none of them can control the aperture or the focus. So the probability of getting future adapters that provide this feature for MFT lenses seems pretty slim, given that there are many magnitudes more Canon EF lenses out there than MFT lenses.

Conclusion

The conclusion is that if the MFT system is abandoned, your lenses are more or less useless.

On the other hand, there are some rumors now that the modular Ricoh GXR system will include a Micro Four Thirds mount/sensor module. If launched, this will enable mounting a MFT lens to the Ricoh GXR camera, with an adapter mount/sensor module.

Update December 2010

Since I wrote this article, an adapter for using MFT lenses on Sony E cameras (NEX) has actually emerged.  However, since it has no electronic contact, it can not control neither the focus nor the aperture.  So you're stuck with a focus around infinity, and the max aperture.  You can, however, use it with the Cosina Nokton 25mm f/0.95, which is a completely manual lens, with a mechanical focus ring, and a mechanical aperture ring.