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04-26-2013, 10:26 PM   #1
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Night time picture has a green aperature dot

Hi:
I need help.
I am new to the DSLR world. This was taken using K-r and 18-55 kit lens. I think the problem is quite obvious to you guys.
What can I do next time to avoid the green dot and how do you guys name it?
Also, can I use software to remove it?

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04-26-2013, 10:31 PM   #2
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The clue with this is it is symetrical around the centrepoint of the photo with the bright light.

Most likely the result of multiple reflections from sensor to the centrepoint of the lense rear element and back to sensor.

Frustrating! It is not visible in viewfinder before pushing the button.
04-26-2013, 10:38 PM   #3
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Yes very frustrating. Even worst thing is it is visible in the viewfinder. I moved around and tilted the tripod. Couldn't get rid of it from the viewfinder no matter what. Just took some shoots regardless. Hoping there is some post processing way to fix it.
04-26-2013, 10:40 PM   #4
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...and, yes, it is possible to remove it with just about any image processing software, using a "clone" or "healing" tool.

04-26-2013, 10:52 PM   #5
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QuoteOriginally posted by dmnf Quote
I think the problem is quite obvious to you guys.
What can I do next time to avoid the green dot and how do you guys name it?
It is simply a reflection - I would ask for three guesses but probably only need one - you have a filter on the lens, correct? Next time you want to shoot at night the green dot will magically disappear - just take the filter off. If you're shooting at night and see a reflection that is at a reverse mirror opposite to the strong light source, a filter is almost always the culprit, guaranteed.
04-26-2013, 10:56 PM   #6
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I only have the UV filter. Is this what you suspect?
If that is true, then you really help me a lot. I would never suspect that is the root cause.
I will certainly remove it next time.
04-26-2013, 11:13 PM   #7
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QuoteOriginally posted by dmnf Quote
I only have the UV filter. Is this what you suspect?
If that is true, then you really help me a lot. I would never suspect that is the root cause.
I will certainly remove it next time.
I would virtually guarantee it - I don't generally use filters anymore myself, but know that this exact issue in low light shots with strong light sources will result in the mirrored ghosting we are seeing in your photo above. An easy fix for next time!
04-26-2013, 11:15 PM   #8
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Thanks for the "clone and heal" suggestion. It works beautiful.
I learn a lot tonight. Any other PP suggestions?
Just one last question. Can I use FastStone to make the cross on top of the pyramid brighter and dim down the moon.
I am so amazed by how much I can do with PP.

04-27-2013, 01:00 AM   #9
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QuoteOriginally posted by dmnf Quote
UV filter. Is this what you suspect?
Yep, my monies on that too, remove it, usually issue goes away.

I run naked these days and use hoods for protection.

Well without filters I mean.
04-27-2013, 01:18 AM   #10
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QuoteOriginally posted by dmnf Quote
Just one last question
You can use FastStone to do that possibly in two ways:

open the image, then Adjust Lighting > globally boost the shadows and dim the highlights

or (harder) open the image, hold down Ctrl then select the area of the image you want to apply adjustments to with the mouse (usually by drawing a rectangle or circle or freehand around the item). Then adjust the lighting for that specific selection.

And yes, UV filters can cause havoc with night-time shooting. Best to avoid them unless you need them.
04-27-2013, 03:33 AM   #11
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QuoteOriginally posted by dmnf Quote
I only have the UV filter. Is this what you suspect?
If that is true, then you really help me a lot. I would never suspect that is the root cause.
I will certainly remove it next time.
Being green, it is likely to be a sensor reflection and taking the filter off probably won't help.
04-27-2013, 03:43 AM   #12
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QuoteOriginally posted by kh1234567890 Quote
Being green, it is likely to be a sensor reflection and taking the filter off probably won't help.
Except if it is a reflection off the sensor which is being bounced back by the inner surface of the filter. Then removing the filter will help.

The OP should do some tests to prove or disprove this.

Regards

Chris
04-27-2013, 04:52 AM   #13
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QuoteOriginally posted by kerrowdown Quote
run naked these days and use hoods for protection.
Darn Not the image I was wanting first thing in the AM
04-27-2013, 04:56 AM   #14
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QuoteOriginally posted by seventhdr Quote
Except if it is a reflection off the sensor which is being bounced back by the inner surface of the filter. Then removing the filter will help.

The OP should do some tests to prove or disprove this.

Regards

Chris
Didn't OP say, in the 3rd posting in this thread, that he saw the green dot in the /viewfinder/?

If so, and if the viewfinder is optical, then it can't be the sensor, as that'd be covered by the shutter & mirror.
04-27-2013, 05:26 AM   #15
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QuoteOriginally posted by patrick9 Quote
Darn Not the image I was wanting first thing in the AM
You'll be less choosy when you get to my age.
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