Dust, sensor problem, or something else?

M

matt fury

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So, I'm looking at the test shots from my new refurb R-D1, and there's little spots on the photos that I would describe as dead pixels (if I was talking about an LCD). Is this dust? Or is this a sensor problem? Just noise? Happens in every photo I took, it's just more visible in the dark and always in the same places, which is what makes me nervous.

They're more colorful before uploading, so let me know if you can't tell what I'm talking about from this picture...

http://gallery.mac.com/thisismafiot#100020/EPSN0023&bgcolor=black

Thanks in advance,
 
That photo is rather difficult to evaluate. Based on your description, it may be hot pixels. Try using the Dead Pixel Correction in the Basic Setup menu.

Best regards,

-Jason
 
Dust should theoretically show up as dark spots (as it is blocking light from reaching the sensor), so I doubt that dust contamination is your problem. Hot pixels sound like the most reasonable answer.
 
Yeah, it's definitely not dust. I'd like to say it's just noise, but it doesn't seem like there's enough of it. That could just be me, though.
 
OK, tried shooting the inside of my lenscap at iso 200, 400, 800, 1600. it still shows up and gets progressively brighter/more numerous as the isos climb. The spots stay in the same places, getting more noticeable and more start coming in. Doesn't sound like noise to me, but I'm not very experienced here.

Here's the one at 1600.... http://www.thisismafiot.com/gallery/v/users/EPSN0198.JPG.html
 
Hot/stuck pixels - my R-D1 did that when I first got it on long exposures. (In fact, there were a couple of especially annoying ones that persisted at 1/15 s.)

Depending on how noticeable they were in a photo, I'd either ignore them or remove them - I only bothered doing the latter if I thought they would be intrusive (e.g. in areas of flat, dark colour).

I got rid of them in Photoshop - there's a technique whereby you shoot your lens cap to obtain a black image showing the pixels, called "dark frame subtraction":

• Description and examples
• Instructions

I created a Photoshop action so that I could do this using a key press.

Most cameras - certainly dSLRs - do this in-camera, usually automatically. Why Epson omitted this function is a mystery!

However, the best solution is to upgrade the firmware to the second version, the same as in the R-D1s. This adds a menu item for dark field subtraction that maps out these stuck pixels, and works perfectly: my camera does not show a single aberrant pixel now!
 
It's happening even at 1/125th! making me really nervous. I'm waiting for my battery to charge to full and then I'll try the firmware upgrade, but this really worries me.

Thanks for the very detailed instructions, Rich. Your website has also been a huge help...

We'll see what happens here, but I'm not feeling too lucky atm..
 
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