Image Help Wanted

[lightlord]

Hi All,

I wanted to shoot some star-trails from my backyard with my sony a350 and got some wierd results.
I shot this picture with no lights around in pitch black surroundings.
Settings where 18mm Manual f8 iso-100 30minute exposure
I expected an black picture with star trails instead i got ALOT of purple.
And look at the left an right hand corners???
Is this the norm for sony dslr camera's ?

original shot.



auto-level in ps to get rid of the purple to no avial ;(



Any ideas or help please

greetings Lightlord

[KevinBarrett]

Did you have the optical viewfinder covered? I may not know much else about the problem, but with long exposures, any ambient light can creep in through an unguarded viewfinder.

[David Kilpatrick]

This effect is quite common - it happens in just one corner on the A100. It seems to be caused be proximity of electronic components to the sensor. Experienced astro shooters just crop the frame - the 14 megapixels allows you to do this and still have a good resolution.

David

[lightlord]

Tiny update from my side

Itook my camera lens cap on and put it into my vault inside my closet and took another picture..i totatly forgot about it so after an hour and 40 minuten i rememberd i had my camera on

With this result.

[marktuma]

Isn't this what the long-exposure noise reduction is for? I thought the purple is noise caused by the sensor heating over time, but it's repeatable, so you can take a frame with the shutter closed and subtract it.

[lightlord]

Thats my next step thanks..