Lumix 20mm lens and banding with the GH3

Recently, there has been a lot of talk about banding at high ISO with the Olympus OM-D E-M5 and the Panasonic GH3 in combination with one single lens, the Lumix G 20mm f/1.7. This is in fact also mentioned in the GH3 manual, "Stripes may appear in High ISO sensitivity [with the Lumix G 20mm]."

To test this, I took the same image using the Lumix G 20mm f/1.7 and Lumix X PZ 14-42mm f/3.5-5.6 @ 20mm. Both lenses were used on the GH3 camera, at f/5.6, with ISO ranging from 200 to 12800.

Lumix G 20mm f/1.7 pancake	Lumix X PZ 14-42mm @ 20mm

To investigate the banding problem, I have made 100% crops from the images at the ISO values 200-12800. Click to enlarge the image:

Based on these images, it is not easy to find any systematic difference between the Lumix G 20mm and Lumix X PZ 14-42mm lenses.

According to other people's findings, this problem can be seen in the shadows at high ISO. So, here are two more crops at ISO 12800, f/5.6, 1/80s:

Perhaps one can say that there is some more systematic banding with the 20mm lens, but it is certainly very hard to see. I don't think there are any significant stripes in the left image.

I tried a second shoot at ISO 6400, this time with the Lumix G 14-42mm f/3.5-5.6 as the alternative lens. The exposure parameters are: 1/60s, f/5.6.

Lumix G 20mm f/1.7 pancake	Lumix G 14-42mm @ 20mm

And a comparison at 100%:

Again, I don't see any problems with banding when using the Lumix G 20mm f/1.7 lens.

Finally, here is a comparison with the Sigma 19mm f/2.8 EX DN lens, with a similar focal length:

Lumix G 20mm f/1.7	Sigma 19mm f/2.8 EX DN
@ ISO 6400, f/5.6, 1/6s	@ ISO 6400, f/5.6, 1/6s

And here are 100% crops at both ISO 6400 and 12800:

The images are a bit dark, so I tried to use the curves tool to bring out more details:

In terms of banding or stripes, I am not able to see any significant difference between the two lenses. I can't see any significant banding when using the Lumix G 20mm f/1.7 lens.

Video

Here is an example video using the Lumix G 20mm lens on the GH3 at ISO 3200. I don't see any banding issues here:

Source of the problem

There has been some discussion about why banding problems were experienced with the Lumix G 20mm f/1.7 lens exclusively. Some have suggested it may be due to the focus construction of the lens. It is one of the very few Micro Four Thirds lenses which has a traditional focus mechanism, in which all the lenses move back and forth. This takes a stronger motor, and is slower and more noisy than internal focusing. The lens also has a large spiral spring in the focus assembly, and a lot of people have suggested that this might be the source of the problem.

Since the banding issue has been seen on the Olympus OM-D EM-5 and Panasonic GH3, some think this is a sign that their sensors are related, and share vital parts.

Conclusion

In my tests, I have not been able to find any significant negative effects due to banding with the Lumix G 20mm f/1.7 lens. My conclusion is that it is safe to use this lens, also at high ISO.

On the other hand, I have seen people posting example images where the banding problem can be seen, so I don't doubt that it can be a problem.

Another conclusion is that the ISO 12800 image quality of the GH3 is quite good. There is a lot of noise, of course, but still an amazing level of details. For web use, the images are usable.