Problem in Night Picture

[irfanst]

First, the picture:
14676

Question:
Why does the picture have a green dot, because the dot shouldn't be there. I got this kind of problem a lot when I took the night scenary without flash. And the dot not always green, sometime blue or red :confused:

This picture was taken with my 350D using kit lens and UV filter (I always put UV filter all the time, because I want to protect my lens from unwanted scratch)

[JMWallace]

hhmmmm. is it always in the same location on every picture??

How long have you owned the camera body?

does it occur no matter what lens you put on?

Is it only in night pictures or does it happen in day shots too??

[coldrain]

If this is a 100% crop, it can be a hot pixel, a pixel that will not give correct values. But as you can see there is also a green circle around it. If it is not a 100% crop but a scaled down full picture, I have no idea what it is. And how can a lens get scratched exactly, when you are making a photo? I do not believe in the necessity of using an UV filter for anything else than filtering UV< or protecting the lens WHEN IT IS NEEDED (like when sand is blowing around, on a beach for instance).

[JMWallace]

it can be a hot pixel, a pixel that will not give correct values. But as you can see there is also a green circle around it.

Exactly what I was eluding too with the questions. The circle is what is throwing me too. First thoughts were ghost image from the lights, but there is only one. Hot pixel was second thought...but Coldy...do they sometimes pop in R or G or B like the OP is indicating? It thought they were ususally white...maybe I am thinking a dead pixel...

Think him answering the ?'s will help narrow it down.

JMW

[irfanst]

I bought that camera around 3 weeks ago, and I don't have other lenses yet. And this kind of problem only happen during the night. No daylight shoot produce unwanted dot. The funny thing is, not all the night shots have this problem and the dot is not always in the same location.

Regarding the UV filter, well... I'm a clumsy person, and I don't want to scratch the lens while I carry my camera around. So I would prefer to buy another filter rather that a new lens if it get scratch somewhere :p

Is it possible that the dot was there because of the filter or lens reflection? I don't think that it is because of dead pixel.

[coldrain]

is it a 100% crop or is it a downsized photo?

[TurboJim]

UFO maybe? Were you near area 51? :D

[forno]

Are the lens and filter 100% clean?

[DonSchap]

it looks like a reflection of some type.

I'd like to see some other examples. :)

Also, a shot with another lens. It could be a chip out of the rear element of the kit lens, if it got whacked by something else. I would say a closer inspection is necessary.

It could be an airplane wingtip lamp that the camera caught... and the photographer didn't. Green is an oddball color, to be sure.

[BonjiB]

I second the need for additional shots and if you can get your hands on one even for test purposes different lenses. It sounds to me like it's something to do with the lens perhaps. You never know though. Exhaust all your possibilities before you blame the camera. Try a different lens first of all and see what you get (another copy of the same lens would be best.) Maybe try a lens hood to rule out the possibility of flare?

[cdifoto]

Like Don said, maybe it's an airplane in the distance. Is there an airport nearby?

FWIW, that's not very cute scene anyway so if I were you I'd go try shooting something...prettier.

[coldrain]

*still waiting for the answer if it is a 100% crop or a full photo that is scaled down*

IF it is a crop, it may well be a hot pixel. IF it is a scaled down photo, I go with cdi.

[ktixx]

it looks like a reflection of some type.

I'd like to see some other examples. :)

Also, a shot with another lens. It could be a chip out of the rear element of the kit lens, if it got whacked by something else. I would say a closer inspection is necessary.

I second Don's opinion...seems like it is some sort of reflection or chip. Is it possible that the chip is on a part of the lens that spins when zooming or focusing and thats why it isn't always in the same location?
Ken

[irfanst]

This week end I went to Disney Lantern Festival, and I take the UV filter off. And the result, none of the pictures that I've taken having unwanted dots :)
So, I think the filter was behind this all the time, don't you think?
However, it leaves me a question, every filter supposed to have coating that preventing the reflection, right? :confused:
Do I bought a nasty filter or what (it is Hoya filter by the way)?

And for the unanswer questions:
- it is 100% crop picture
- the picture was taken very far away from the airport area
- yes it not a cute scenery, I thought it was a building with pretty light. But I was wrong, it's only a construction site :p . Seems that the lens is sharper than my eyes
- I'm sure that on that time the lens and filter were both clean.

I'll shoot again without filter during the night and try to be carefull not to bump my lens with something hard :p
I'll let you know if there something funny again captured from my kit lens or my new Tamron 18-50mm f/2.8 ;)

Thanks guys...

[coldrain]

Ok, if it is a 100% crop, what you are seeing is a hot pixel. hot pixels do not have to be stuck, they can start to operate normally again too. And that is why they seem to move from picture to picture then.

The green is just because it just happens to be a green photo diode that causes the "hot" pixel. And the aura just is a strange effect that i can not explain :eek: .

[Rhys]

I recognised that straight off. I took some night shots of Folly Pier. There were some horrible lights all over the photo so I whipped my UV filter off and re-shot. et-voila - no nasty lights. They were reflections from the back of my filter.