What is this, and why it appears?

[Onera]

Hello everyone, I've took that 500-600 second exposure pic, and why this appears? Is it from overheating the sensor?

http://s22.postimg.org/6b2ood7vz/strange.jpg

 

[runnah]

Yup.

 

[amolitor]

It appears to be a tree. They're quite common.

 

[Onera]

thanks,

Is there any technique I can prevent that from happening? I want to try astrophotography it would be really bothersome

 

[table1349]

Dead vs Stuck vs Hot Pixels

 

[KmH]

Astrophotographers use cameras that have an on-board thermoelectric cooling (TEC) system.
Astrophotography Cameras | Orion Telescopes: Shop

Using a DSLR you need to make many, much shorter exposures and then stack the images.
Image stacking software - Bing

 

[16BitTons]

I used to take pictures with a fairly large telescope. Before taking your image, take a similar image with the shutter closed. Use the same exposure time, and do it under similar temperature conditions. Then you can subtract the "dark" image from the picture you want to keep. If I remember correctly, I was shooting in RAW and used GNU Octave or Python to do the subtraction, but there are probably more popular methods. Let me know if you try this, and how it works out! Shooting the stars is a lot of fun.

 

[480sparky41 40]

I used to take pictures with a fairly large telescope. Before taking your image, take a similar image with the lens cap on. .........

FIFY. You can't take an image with a DSLR when the shutter is closed.

 

[16BitTons]

Thanks, 480sparky, good point.

 

[18.percent.gary]

Nikon DSLRs do this automatically when "long exposure noise reduction" is switched on. It takes the intended exposure and then takes an equal length "dark frame" by recording the sensor output with the shutter curtains closed. It then subtracts the dark frame from the original exposure and removes any noise and hot pixels. Works great.