Above: the GH1’s sensor and related circuitry
A DPReview forum user from the UK was unhappy with the amount of banding on his Panasonic GH1
[url]http://forums.dpreview.com/forums/read.asp?forum=1041&message=35221454He called Panasonic in the UK who asked to see samples of the banding. After analysing his photos, they replied that the problem with too much chroma banding, in vertical and horizontal lines – was outside of the usual tolerances. They suggested he return the camera to the reseller for a replacement, which he duly got.
Surprise – the new replacement was much better.
This should offer some comfort for new GH1 owners who experience banding for the first time. What’s more difficult to say, is how to scientifically test and to know how much is too much?
At least now quite clearly we have proof that the performance of the CMOS sensor in the GH1 varies between batches, or even on a unit by unit basis. As revealed on EOSHD.com last month, the older generation of the GH1 and the PAL model made in China is also made in a different (and older) factory to the one Panasonic commissioned in Japan in late 2009, that now makes the latest batches of the GH1 which may explain why some units perform better than others.
Banding has always been a divisive issue amongst GH1 shooters, some see it – some don’t as much. I had two models whereby one behaved much better than the other (older) unit.
This theory has been backed up time and again by observers. Your eyes haven’t been deceiving you. Different owners really are getting different results.
If you already have a GH1 with high banding, it may be too late to return it to the place of purchase, and just because Panasonic are now issuing this advice, they themselves do not action the replacement. It’s entirely up to the reseller. My advice would be to new GH1 owners – if you suspect your camera footage or photos have more banding than content you compare it to from other GH1 shooters online, immediately ask for a replacement at place of purchase and see if the other unit performs better. Don’t wait a week or 2. Do it within the first 3 days of purchase.
Most GH1’s will be absolutely fine and it’s possible to see banding as a fault where it might actually be in the normal range – all CMOS based cameras have banding, even the 5D Mark II.
But situations like that on DPReview and my own experience with two differing GH1 units over the last year, do suggest that Panasonic are right to advise people into seeking a replacement if they feel they’re affected by a poor unit.
Now if they could take the matter into their own hands, and replace affected units themselves – that would be a much better solution for all concerned!
The EOSHD.com Banding / Fixed Pattern Noise FAQ
• Banding is caused by fixed pattern noise (FPN) – a CMOS sensor phenomena
• It aligns with the read-out channels on the sensor, in static horizontal and vertical lines
• On the final image, it can cause discoloured banding, like faint lines in a fixed position over the image
• It appears most noticeably on under exposed shots, at high ISOs
• But it can appear even at ISO 100
• It is less noticeable in good lighting, but at high shutter speeds can be noticeable if the shot is underexposed
• Fixed pattern noise is not the same as the usual high sensitivity noise
• It is not generated by the photo-sites reacting to light, rather being excited by nearby electrical circuitry and heat
• Even with the lens cap on and no light entering the sensor, fixed pattern noise occurs
• The GH1’s image processing is collaborated to reduce it as much as possible
Variations in FPN results from GH1 units may be caused by any of the following
• Environment – temporary heat build up inside and outside of camera
• General manufacturing variations
• Variances in the CMOS sensor wafers
• Factory / processing issues
• Testing – manufacturing Q/A, missing affected sensors
• Calibration issues with the noise reduction routines and image processor
Note: for people linking to this article on DVXUser.com forums please use the following URL:
[url]http://www.dvxuser.co.uk/content.php?175-Panasonic-recognising-GH1-banding-issue
