Sebastien Ross Posted September 29, 2014 Share Posted September 29, 2014 Hi guys, I've been testing a lot the a7s in low light and I've ran into some purple noise issue coming from the sensor. Sony canada is pretty useless about that... https://www.youtube.com/watch?v=zpvACzU1Nj0&feature=youtu.be I've tested it with 5 different A7s, they all do the same...In video mode, going under 1/50th with iso higher than 12 800, always give me that purple fringing (not as bad as the youtube video...witch is at the worst setting, but still, it's a bit frustrating) Technically, i know it doesn't respect the 180degree rule going under 1/50th for 24p/25p...but it could be useful is certain situation. At first, they blame the metabones ...just like everyone (ex: Quote Link to comment Share on other sites More sharing options...
mojo43 Posted September 29, 2014 Share Posted September 29, 2014 Ya it happened to me this weekend as well. I haven't done further testing, but it seems to be happening in my camera as well as high isos. Quote Link to comment Share on other sites More sharing options...
andy lee Posted September 29, 2014 Share Posted September 29, 2014 12,000 iso is well hot!! I never shoot over 1250 iso I think you are asking alot for 12000 iso to be 'clean' on any camera not just a Sony use a faster lens and lower iso setting its nothing to do with 1/50 shutter just very very hot iso Quote Link to comment Share on other sites More sharing options...
mojo43 Posted September 29, 2014 Share Posted September 29, 2014 Naw, it's only happening on one side of the frame. I agree that it's a high iso though. Quote Link to comment Share on other sites More sharing options...
Administrators Andrew Reid Posted September 30, 2014 Administrators Share Posted September 30, 2014 Let's call it a purple vignette. Purple fringing is something else, to do with lenses. The purple vignette I've not had yet, how long was the camera running for when it happened? Quote Link to comment Share on other sites More sharing options...
mojo43 Posted September 30, 2014 Share Posted September 30, 2014 Not long. We should call it purple half vignette. It only seems to show up on the left half. Quote Link to comment Share on other sites More sharing options...
fuzzynormal Posted September 30, 2014 Share Posted September 30, 2014 Think maybe it's a light leak through the body of the camera somehow? johnnymossville 1 Quote Link to comment Share on other sites More sharing options...
Sebastien Ross Posted September 30, 2014 Author Share Posted September 30, 2014 Alright purple half vignette hahah Been running for 2min before. Like I've said I tested it in store too, with brand new one, demo, etc... Lens or Body cap on. It as something to do with the shutter speed for the a7s specifically... The purple noise is minimal or absent at 1/50 and 1/60...but keep increasing when you go under those shutter speed (at very high iso) I know It is hot iso, not asking it to be clean...i'm curious why it is left top and bottom corner mostly. Might have something to do with the sensor readout or fuzzynormal could be right. Quote Link to comment Share on other sites More sharing options...
richg101 Posted September 30, 2014 Share Posted September 30, 2014 mine also does this. However it only really shows when i rag the hell out of the camera. just because the camera goes up to 400,000iso doesnt mean it's useful at that speed. anything below 16000 is as clean as a whistle I am finding. andy lee 1 Quote Link to comment Share on other sites More sharing options...
Sebastien Ross Posted September 30, 2014 Author Share Posted September 30, 2014 Totally true...Just tested the crop mode... super clean up to 25 000. Sweet :P It act also differently in slog2 than other profile ...huh! andy lee 1 Quote Link to comment Share on other sites More sharing options...
mojo43 Posted October 1, 2014 Share Posted October 1, 2014 I tested last night and it has nothing to do with shutter speed. The half vignette is there at high isos period. Strange that it is only on one side and that all cameras have it. Quote Link to comment Share on other sites More sharing options...
Quirky Posted October 2, 2014 Share Posted October 2, 2014 With the purple colour put aside, vignetting would suggest it has something to do with the lens and/or the lens adapter used, wouldn't it. Especially if/when the vignette disappears in crop mode. I wonder if the vignette appeared with any lens and any lens + adapter combo, or just with one particular lens? Or, if the vignetting happens on one side only, that would suggest it has something to do with a de-centered lens array inside the lens in use. So does that lopsided vignette happen with any lens or just one lens? A dumb question, perhaps, but just to make sure, as the story didn't reveal that little tidbit. Quote Link to comment Share on other sites More sharing options...
mojo43 Posted October 2, 2014 Share Posted October 2, 2014 I'll be able to test more once I have I get my other adapter, but it sounds like it is happening to all cameras in the same way. Not sure though... Quote Link to comment Share on other sites More sharing options...
Quirky Posted October 2, 2014 Share Posted October 2, 2014 I'll be able to test more once I have I get my other adapter, but it sounds like it is happening to all cameras in the same way. Not sure though... All cameras with any lens? Or all cameras with that one particular lens/adapter? If the lens or the adapter is dodgy, it will happen the same way with each individual camera. As for the purple vignette, suppose that would not be too surprising with a "suitable" legacy or another non-native lens, a wider angle lens in particular, under "suitable" conditions. One would think the vignetting is likely to disappear or at least happen less frequantly with a native lens. Unless one wishes to shoot under some extreme conditions. But after testing it with sony native FE lens.... ...the vignetting is still the same? Or does it appear only with one FE lens, or any FE lens? Or only during some unusual conditions, regardless of the lens? Just curious, too, as I don't own an A7s, and wondering if it's about a given lens, or could it have something to do with uneven internal heat buildup or something... or whatever. Hoping it was about a given lens, rather than an internal issue. Quote Link to comment Share on other sites More sharing options...
mojo43 Posted October 2, 2014 Share Posted October 2, 2014 I just read in the comments of the vimeo video posted above: "I've also observed the "purple fringing" on three different A7S. It's no light leak. There is one or the other sensor out there with similar problems. "Black shading" calibration is the keyword." I have a different adapter than the metabones and I am using FD glass. I don't have any native lenses to test unfortunately. This only happens at really high isos. But it is still unfortunate as it looks like the rest of the image is pretty clean except for this part. Quote Link to comment Share on other sites More sharing options...
johnnymossville Posted October 2, 2014 Share Posted October 2, 2014 Think maybe it's a light leak through the body of the camera somehow? That was my first thought when I saw it. I'd try other lenses and see if does the same thing. Quote Link to comment Share on other sites More sharing options...
Danyyyel Posted October 2, 2014 Share Posted October 2, 2014 Perhaps it is better to test with no lense and a cap on the mount. In this way you are eliminating one variable. It does happen that depending on the electronic arrangement in cameras, some component might cause interference. I did happens on Dslr (forgot Nikon or Canon) that lens or VR or non motor or motor lense caused some noise etc, long time ago. Quote Link to comment Share on other sites More sharing options...
Sebastien Ross Posted October 2, 2014 Author Share Posted October 2, 2014 It's happening with a cap on the mount also. Lense with metabones, FE native lense or cap on the mount the vignette it's always the same. Quote Link to comment Share on other sites More sharing options...
Sebastien Ross Posted October 3, 2014 Author Share Posted October 3, 2014 I tested last night and it has nothing to do with shutter speed. The half vignette is there at high isos period. Strange that it is only on one side and that all cameras have it. Agreed, but i've find it more present at 1/4 compare to 1/60 at equivalent iso. Quote Link to comment Share on other sites More sharing options...
mojo43 Posted October 3, 2014 Share Posted October 3, 2014 Are you sure that the exposure is the exact same when you change the iso or is it changing when you drop the shutter and see it more clearly. Whether it is buried in the shadows or not is maybe why you don't see it? Quote Link to comment Share on other sites More sharing options...
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