Colored dots in night photos?

What would be causing the colored dots to show up in long exp. photos? I took some shots of a storm in AZ over the weekend with the following settings....see pic. It showed up in about half of them all with different exposure times. Some are a lot worse than others, at first I thought it was stars, but they appear below the horizon as well, and they are red, blue, and green.

Nikon d-5018-55mm @ 34mm
color rep. sRGB
no flash
f/13
exp time: 83.9 sec.
metering: pattern
exp. comp: 0step

If the dots are in the same place in different photos, it is probably hot pixels because of the long exposure.

Jeff

Larry, I don't know if your camera has it, but see if there is a Long exposure noise reduction setting. my D70 has it, so I would imagine the D50 would as well.

Well I thought of that, (the NR setting), but why would it only be in certain photos? Would this also be why some of my dark areas in daytime photos are very grainy? I do have the camera set to the largest size.

I have a few hot pixels in my Fuj S2. I almost never notice them except in the rare cases when I shoot jpg. Because you list the colorspace as sRGB, I assume you shot jpg. The compression and any built-in sharpening seems to make my hot spots more obvious, maybe that is what you are seeing too. Maybe when the offending pixels (if that's what it is) fall on a brighter area they don't get emphasized as much. I believe that is what I see. For something as spectacular as that lightening storm I would shoot RAW files. So, did you turn on aperture priority and just let the camera decide when to shut the shutter? Interesting, surely 83.9 seconds came from the EXIF data, not from an exposure time you set. Sorry. I guess I asked more questions than I answered. That happens with me sometimes.

Pete D.

When you say you have a few hot pixels on your fuji s2, is this permanent, something fixable, because i did notice that most of the lightning shots from that night are all burned.....

Were the spots in the same place for every exposure? They look very similar to spotting I occasionally have.

I'm leaning to what I have come 'microdust.' Very fine dust on the sensor which, when the camera goes into a cooler area or weather, causes round marks which may be condensation when moisture is attracted to it. That a storm is approaching may have resulted in cooler moist air causing it to do this.

There seems to be no method of controlling it. If the spots are in identical places on all the shots, it may be mechanical. If they are not, it may be dust.

Dave

I think my hot pixels are set in stone. I accept this as a normal failure rate. The beauty of fillm is/was/always will be that the recording medium is continuously refreshed. I still won't go back to film.

I also found hot pixels on a few images I took at night,, then did a search on it. If you are taking long exposure shots and you have the noise reduction function set on your camera this will happen. Turn the noise reduction function off to see if there is a difference.