Panasonic Lumix G 20mm F1.7 II (H-H020A) - Banding

Started Aug 6, 2013 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: Panasonic Lumix G 20mm F1.7 II (H-H020A) - Banding

tsi wrote:

This is just for Anders. Most others will find the following pretty boring.

Many thanks for keeping me entertained! I am.

And don't underestimate the audience here. Not a whole lot of people seemed to be all that interested in DM's and mine lengthy discussions nine months ago. But then some joined the party and helped us out with additional knowledge, fresh ideas, and/or new evidence, among them you. Something similar might well happen again because there are some new people here after all.

I don't know if we are ever going to quite nail the cause(s) of this problem. Even if we nail it/them, we cannot be sure that the answer will help us accomplish a practical solution that will eliminate the problem or work around it by any means other than the already known (but painful) one of lowering the ISO and/or avoid pushing in post. But hope springs eternal so who knows.

I didn't know we were ever going to nail the problem with purple flare with the 7-14 on the E-M5 (and other Olys) either or whether it would be of any practical help if we did. But we eventually came up with an answer as well as a decent solution.

And since you have done a nice systematic effort to link specific parts of the electronic circuitry to the resulting banding, it would be a real shame if you didn't document it publicly, as you now have.

It may be a while before I have fully digested these results and I don't know at this stage if I will have any more comments or questions at that point. But if I do, I'll post them here.

In the meantime, thanks again for your efforts.

The compilation shows 9 images with the aspect ratio changed.

From left to right:

f2.8, ISO6400, contrast +100 (from today)

1.) 10 flex removed

2.) 4x4 flex removed

3.) 4 flex removed

4.) 6 flex removed

5.) all connected

f2.0, ISO6400, exposure +1, contrast +100 (9 months ago)

6.) 10, 4x4, and 4 flex removed

7.) 4x4 flex removed

8.) all connected

9.) 4x4 and 4 flex removed (f2.8)

9 images of old panasonic 20mm f1.7. Aspect ratio changed. Red lines indicate change of band pattern.

No bands are visible when all three flex wires are disconnected (Image 6). There remain some modulations but these are at a much lower level than the typical 20/1.7 bands. These residual effects can probably be seen with any other lens.

Type 1:

The image area where bands can be seen changes with the set aperture. The bands do not necessarily disappear, but do always exhibit a change of their frequency which in turn changes their visibility. The position where the frequency of the bands changes is indicated by the red lines in images 1,3,4,5,8. This is about at the same position for the images taken at f2.8 and slightly upward for the image taken at f2.0.

Type 2:

The bands can be seen from top to bottom and have a more or less constant frequency. This is the type of banding which can be seen at f1.7. It is also observed when the Aperture flex is removed (see image 2 and image 9). Image 2 is not a good example since the frequency of the bands is very high, which makes it difficult to see them at all. Today was not a good day.

Type 3:

Less than 20 bands can be seen from top to bottom. In some images the bands have a color such as in the image of the spring. In other images the width of the bands is irregular. It seems to me that this is Type 2 banding at a relatively high frequency. The visible bands are a kind of beating pattern.

Type 4:

Image 7 is different from Type 1 and Type 2 in that the bands appear and disappear several times while the periodicity of the bands is more or less constant. I have seen this only on that day 9 months ago. It has nothing to do with the dissection of the lens since it was visible before it started. This may be a beating pattern or an active loop of the lens.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
Post (hide subjects) Posted by
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
tsi
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow