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Thread: a7s 3 mega hot pixel problem

  1. #1

    Join Date
    May 2020
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    Braydon

    a7s 3 mega hot pixel problem

    Hey everyone. I'm experiences crazy hot pixels on my new A7S 3. I sent it back to the shop, who agreed I shouldn't be seeing this degree of hot pixel noise in my images. They sent it to an authorised Sony service centre here in Australia. Supposedly a hot pixel fix was run on it, but I just got it back today (after 7 weeks at the service centre) and nothing seems to be any different. The hot pixels are just as bad. They are so much worse than the artifacting I get from the a7s 2 when using the same parameters.

    Here's a Flickr link to some tests I just ran, with a7s 2 photos to compare with. Particularly, pay attention to this one, which is a 30 second exposure. Then compare it with the same photo taken on the a7s 2. What a difference!

    My question is, is this normal for the a7s 3. I can't find anything online specifically about this problem for this model camera. Obviously, the artifacting gets worse the longer the sensor is in use (ie. the longer the shutter is open). It also only seems to be happening when I'm using the e-curtain. There are no hot pixels at all when the physical shutter is being used.

    If anybody out there has an A7S 3, could I please trouble you to do a test and see if the hot pixels are as bad as mine? I'm trying to decide whether to send it back again - but that could be another 7 weeks without my camera!

    Setting were:
    f4
    ISO 1600
    shutter 10 secs, and 30 seconds
    no picture profile
    electronic curtain

    PS, yes, I've done all the tricks to fix hot pixels like change the date by a month, and such. I suspect the problem is with the sensor itself and it needs the service centre to take a serious look at it (or, the problem is with me: maybe this degree of noise is now considered acceptable and I need to get with the program!)

  2. #2
    DanK's Avatar
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    Dan

    Re: a7s 3 mega hot pixel problem

    I couldn't find hot pixels with a quick look. I see some noise. Perhaps you could circle the hot pixels.

    To show hot pixels clearly, take two identical long exposures with the lens cap on. The image should be black other than hot pixels. Typically, they will show up in exactly the same place in both images.

  3. #3

    Join Date
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    Ted

    Re: a7s 3 mega hot pixel problem

    Quote Originally Posted by DanK View Post
    I couldn't find hot pixels with a quick look. I see some noise. Perhaps you could circle the hot pixels.

    To show hot pixels clearly, take two identical long exposures with the lens cap on. The image should be black other than hot pixels. Typically, they will show up in exactly the same place in both images.
    I wonder if a) said pixels are truly hot, i.e. always maxed out in raw, and b) are always in the exact same location.

    I say this because I've owned cameras (Sigma Merrill) that have pixels always in the same location but with significantly more gain than their neighbors and therefore didn't show up in a lens-caps-on test.

    Also they only showed up in the raw-only app RawDigger but not in converted images because they get interpolated out according to a "bad pixels" list passed in meta-data.

    Just a thought. I have no idea how Sony does it ...

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