M8 Sensor Flaws - How to Detect?

[cobbu2]

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So I tried to sell one of my M8s, and (true confession) I shoot mostly with it set to JPEG Fine. I never once noticed any flaws for as long as I had the camera until the buyer came back to me complaining about some vertical lines making their way about halfway up from the bottom (he sent images to me and sure enough they were there). I was really surprised... I checked the images on the memory card I had in the camera last, and on the very last image I took with it, there was a very faint vertical line starting at the bottom about a third of the distance from the right edge extending about a third of the way up. In any case, it was nowhere near what the buyer was experiencing. I'm assuming he was shooting in RAW, but I'm not sure. In any case, I now have the camera back and issued a refund.

I tried a few shots at fast and slow shutter speeds, mostly wide open at both dark and light surfaces (again in JPEG Fine), but couldn't find anything. What's the best systematic or standard procedure to test the sensor for flaws? I tried searching for this; many folks talk about what they find, but not how they found it.

Thanks, Allan

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[david strachan]

Well Allan you might like to do your tests in DNG, (RAW) umm, just as the buyer did, as well as JPG. I think you'll see the difference then.

Some of the processors put their own affects into the image, hiding the true DNG values, to give a more polished final image, and therefore eliminating "faults"...particularly when going to JPG's.

...

Edited February 20, 2022 by david strachan

[cobbu2]

9 minutes ago, david strachan said:

Well Allan you might like to do your tests in DNG, (RAW) umm, just as the buyer did, as well as JPG. I think you'll see the difference then.

...

Thanks… I just assume he did his tests in DNG, he wouldn’t reveal that to me one way or the other. In any case should I concentrate on high or low ISOs, or both? I was just wondering what is the most effective approach. I didn’t realize in-camera JPEG compression would mask those defects so much if at all.

[david strachan]

Hi Allan, in editing during your post, perhaps reread my post.

 

You can test at all sorts of extremes...including high ISO particularly.  That usually shows banding, for example.  The M8 is not good at high ISO, with banding and plenty of digital noise.

If you are selling they will be looking for faults,  just as i would if buying. If my camera i use workarounds or pretend it's not there. 

All best. 

PS I have two M8's...I love 'em.

Edited February 20, 2022 by david strachan

[farnz]

Hi, Allan,

The flaw your buyer mentioned is relatively common and is caused by a stuck or dead pixel.  The sensor is 'logically' split into halves and reads the pixel data from the centre outwards in lines.  If one pixel dies then it can't pass on power or data to the next pixel in the line and the whole line looks like it's 'died' and shows up as a black line mentioned by your buyer. 

The fix is simply mapping out the dead pixel and Leica used to offer that service but I'm not certain whether it still does.  Ideally Leica should do because it's a defective part of the camera and the dead pixel has probably not met its designed service life.   Tricky to prove but might be worth mentioning if you contact Leica and the initial answer is "No.".

Pete.

[cobbu2]

11 hours ago, farnz said:

Hi, Allan,

The flaw your buyer mentioned is relatively common and is caused by a stuck or dead pixel.  The sensor is 'logically' split into halves and reads the pixel data from the centre outwards in lines.  If one pixel dies then it can't pass on power or data to the next pixel in the line and the whole line looks like it's 'died' and shows up as a black line mentioned by your buyer. 

The fix is simply mapping out the dead pixel and Leica used to offer that service but I'm not certain whether it still does.  Ideally Leica should do because it's a defective part of the camera and the dead pixel has probably not met its designed service life.   Tricky to prove but might be worth mentioning if you contact Leica and the initial answer is "No.".

Pete.

Thank you, Pete for the info! Turns out, there are actually several lines, at least three. The shutter count is a little above 12,200 so there should be a lot of life left; the camera works exceptionally well in every other respect (rangefinder accuracy, display, etc.) so I'll be researching the remapping option.

[youyouFR]

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On 2/24/2022 at 3:08 AM, cobbu2 said:

Thank you, Pete for the info! Turns out, there are actually several lines, at least three. The shutter count is a little above 12,200 so there should be a lot of life left; the camera works exceptionally well in every other respect (rangefinder accuracy, display, etc.) so I'll be researching the remapping option.

Hi, i have the same pb with a recently bought M8. dis you find a solution ?

[chris_livsey]

On 7/1/2024 at 9:15 AM, youyouFR said:

Hi, i have the same pb with a recently bought M8. dis you find a solution ?

I suspect the case above was an illustration of the jpeg in-camera "fixing" the dead pixels. It is possible to run a program on a RAW file to remove them then regenerate a jpeg in your chosen software if you don't want to use the in-camera option.

Pixel Fixer | Hot pixel removal utility