What has happened to my sensor?

[Toggerman]

I was just cleaning my cameras ahead of an outing tomorrow and came across an unusual problem with my D750. It had a fair amount of dust but I also noticed a small group of bright red dots. They appear on every image regardless of aperture, shutter speed of ISO, and when I look at the sensor through my loupe I can see what looks like white specks of dust in the right area and formation that it would appear in the images. I have tried cleaning the sensor a couple of times (blower, lenspen and wet clean) and no change. I took some photos of fireworks last night and the spots weren't there. I put the camera in my bag after the fireworks where it stayed until I got them out to clean today. The lens hasn't been removed in between and the camera was switched off. What has happened?

Full image taken at 1/640th, F2.8, ISO100, red spots in top right quarter.



Crop of the image showing the red dots.



What is it and if it is damage to the sensor how has it happened during a time where it hasn't been touched?

 

[Dryce]

I've seen a few threads over the years on similar damage and the causehas tended to be exposure of the camera sensor to laser light - eg. at a disco light show.

 

[gramps]

Stuck pixels, generally would have to be re-mapped by a service centre.

 

[steve_lyt]

have you tried removing the lens and taking a picture of a white piece of paper , and is it still there then. it could be stubborn dust , and require a wet clean ,
calumet have open days and offer a professional sensor clean for a donation.

 

[4wd]

Stuck pixels, generally would have to be re-mapped by a service centre.

It's a bad case of this, does that camera have a way to map itself?
I know my 5Dii can do it though these look bad.

 

[gramps]

It's a bad case of this, does that camera have a way to map itself?

Possibly ... later cameras may be able to do this by just running a sensor clean manually twice in immediate succession.
@Toggerman may be worth a try, can't harm the camera.

 

[Toggerman]

Thanks for all the replies everyone.

I don't think they're stuck pixels as I can see something on the sensor as if it's debris but I'll give the mapping a try anyway.

I was using the camera this evening and I couldn't see them anymore. So I did a little more experimenting and it turns out that they are only red like above when there is a bright source of light, such as bouncing the flash off a white piece of paper. Bounce the flash off something darker and they look more like feint specks of dust, black with no hint of red. Indoors with no flash and they are barely noticeable for the most part.

Could they be small pits on the AA filter diffracting the light from brighter sources?

 

[gramps]

Could they be small pits on the AA filter diffracting the light from brighter sources?

I guess that would be possible but they do look very much like stuck pixels.

 

[Toggerman]

Possibly ... later cameras may be able to do this by just running a sensor clean manually twice in immediate succession.
@Toggerman may be worth a try, can't harm the camera.

I gave this a try and it hasn't made any difference .

I guess that would be possible but they do look very much like stuck pixels.

I would agree with the stuck pixels, especially given that changing aperture has no effect. But would you be able to physically see them on the sensor as you're looking at it?

I've also had a look through my photos out of curiosity and lo and behold they are in every photo that has sky in that area, all the way back to August when I bought it. I haven't used the camera much and I've never looked for dust before as I normally use it with quite wide apertures. It was 2nd hand but still under warranty so I'll contact the shop on Monday and see what they say. Otherwise I'll send it off to Nikon and get them to look at it.

 

[gramps]

would you be able to physically see them on the sensor as you're looking at it?

As the associated transistor is 'dead' the pixel is permanently on, so I guess you could see it illuminated but it's a guess not from the authority of experience.

I've also had a look through my photos out of curiosity and lo and behold they are in every photo that has sky in that area, all the way back to August when I bought it. I haven't used the camera much and I've never looked for dust before as I normally use it with quite wide apertures. It was 2nd hand but still under warranty so I'll contact the shop on Monday and see what they say. Otherwise I'll send it off to Nikon and get them to look at it.

I've never seen dust show up as red, it normally appears as black/grey.

 

[Toggerman]

As the associated transistor is 'dead' the pixel is permanently on, so I guess you could see it illuminated but it's a guess not from the authority of experience.

Never thought of that, it might be possible, I have no idea.

I've never seen dust show up as red, it normally appears as black/grey.

Same here. I once bought a 5D3 that had a scratch on the sensor and that only showed up as black. I only looked for dust on it today as I'm going to Brands Hatch with the family tomorrow and all of the cameras will be in use. Normally for motorsport I shoot with 2 D500s which are regularly checked and cleaned.

 

[snerkler]

I've never seen dead/stuck pixels look like that, usually it's just a solitary tiny dot so if it is dead/stuck pixels there's a hell of a lot imo to give that appearance. The fact that they are apparent even at f2.8 does suggest a flaw in the sensor though, whether it be dead pixels, physical damage or simply some debris well and truly welded on there

 

[realspeed]

If they were dead pixels would they not show up as small squares as in pixelation.?

 

[Fuzzdog]

Does sort of seem like stuck pixels, but I've never seen them in clusters like that before. Curious!

 

[gad-westy]

They don't look like stuck pixels to me either. Not as bright as a stuck pixel usually appears and they normally appear as solitary dots. They almost looks fibrous.