The curious case of the green spot in the night

Started May 6, 2012 | Discussions
hewitt
hewitt Regular Member • Posts: 203
The curious case of the green spot in the night

Up this morning early to capture the moon and found a large green spot on most of my images. Can anybody tell me what may have caused this? I have seen the same thing on another image posted on this site taken with a Sony NEX.

darkref Contributing Member • Posts: 716
Re: The curious case of the green spot in the night

It's likely to appear if you are using a filter, or shooting through a window, or using a big aperture.

JustaBhoy Contributing Member • Posts: 796
Re: The curious case of the green spot in the night

Could be something on the lens surface or a touch of flare (it was a bright moon). If it really bothers you i'd try fixing it with Photoshop.
Nice images though.

dquangt Senior Member • Posts: 2,504
You mean like this?

Its probably flare from the bright moon just like I got from the sun in the following picture.

woodrim Forum Member • Posts: 77
Re: The curious case of the green spot in the night

I've seen something similar feom a Tamron lens which I think was the result of a flat rear element that reflected back light from the sensor.

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wll Veteran Member • Posts: 4,821
Re: The curious case of the green spot in the night

With the light coming in, it looks like lens flair.

wll

mikiev Senior Member • Posts: 1,092
You'll pickup a lot at 1/2-second

darkref wrote:

It's likely to appear if you are using a filter, or shooting through a window, or using a big aperture.

agree on window or filter, if shot outside.

With 1/2 or 1/5 shutter-speeds, you'll be picking-up any dim reflections that wouldn't even be visible to the naked eye.

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rrfischer Regular Member • Posts: 232
Re: You'll pickup a lot at 1/2-second

It's not lens flare. Flare usually has the shape of the aperture and is caused by light reflecting inside the lens. It causes the light to scatter, producing a shape that's not equal to the original object.

This looks like it's a filter or window issue, which is caused by a single reflection. That's why the shape of the moon is so well defined.

Photographing with a filter (cheap ones, specially) can cause this kind of things -- this is the strongest argument against using them.

D Cox Forum Pro • Posts: 29,372
Re: You mean like this?

dquangt wrote:

Its probably flare from the bright moon just like I got from the sun in the following picture.

The typical sign of lens flare is that the light source and the flare are the same distance from the centre of the picture, and in opposite corners. As is the case with the OP's picture.

With recent lenses we no longer see the spectacular lens flares that can be emulated in 3D ray-tracing programs.

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Richard A Novak Forum Member • Posts: 54
Re: The curious case of the green spot in the night

Do you have a skylight, UV, or other inexpensive filter on the lens to protect it? The filter may be causing some flare, especially if it does not have good multi-coating.
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Richard A. Novak

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D Cox Forum Pro • Posts: 29,372
Re: You'll pickup a lot at 1/2-second

rrfischer wrote:

It's not lens flare. Flare usually has the shape of the aperture and is caused by light reflecting inside the lens. It causes the light to scatter, producing a shape that's not equal to the original object.

This looks like it's a filter or window issue, which is caused by a single reflection. That's why the shape of the moon is so well defined.

Photographing with a filter (cheap ones, specially) can cause this kind of things -- this is the strongest argument against using them.

If you stick a filter or close-up lens on the front, it does effectively become another lens element (or elements), and the combination can have flare just like a plain lens. It is basically light reflecting back and forth inside the lens.

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hewitt
OP hewitt Regular Member • Posts: 203
Re: You'll pickup a lot at 1/2-second

The images were taken through an open window with a Hoya MC UV filter attached at 1/2 or 1/5 second.

Thank you for your comments. Next time without the filter.

Klipsen Veteran Member • Posts: 6,166
Don't expect miracles

hewitt wrote:

The images were taken through an open window with a Hoya MC UV filter attached at 1/2 or 1/5 second.

Thank you for your comments. Next time without the filter.

The green colour may be an indication that it's the coating on one of the lens elements that causes the ghost moon to appear.

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dquangt Senior Member • Posts: 2,504
Re: You mean like this?

do yo know what it is called in situations such as my picture?

D Cox wrote:

dquangt wrote:

Its probably flare from the bright moon just like I got from the sun in the following picture.

The typical sign of lens flare is that the light source and the flare are the same distance from the centre of the picture, and in opposite corners. As is the case with the OP's picture.

With recent lenses we no longer see the spectacular lens flares that can be emulated in 3D ray-tracing programs.

Tim Zhou Contributing Member • Posts: 611
Re: The curious case of the green spot in the night

I think they are lens flare and unavoidable if you shot into the light. Not long ago, I took two shots which had different types of flare. In the first one, you can see two green spots and a bit blue flare above the lamp. Then you see the same blue flare and a slight white flare in the middle of the photo. The lens was Contax G 28 with Nex 5n

I did try to avoid the green flare as I saw it on the screen, but it seemed at certain angle, they appeared. To keep the composition I wanted, I kept the green flare.

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Tim

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