What to do about long exposure artifacts?

TJ K · Nov 24, 2009

Ok so I like taking pics of star trails and all that fun stuff but when I examine the photos there are always a ton of green,blue, and red dots. Is the only way to get rid of all of these is to use the spot removal tool and go by and individually click each dot to get rid of it? Thanks here is a pic example:

tj

KmH · Nov 24, 2009

Noise reduction software like Noiseware Pro.

What astronomers do is they cool their image sensor. The pro astronomers use liquid nitrogen. Amateur astronomers use digital cameras made specifically for astronomical imaging that have built in cooling systems.

Like this one.

TJ K · Nov 24, 2009

Alright awesome. If i had some spare cash laying around that would be pretty cool to buy! I'm sure some amazing photos would be guaranteed out of that thing.
tj

icassell · Nov 24, 2009

I believe an alternate way (although I don't know how it's done) is to stack many shorter exposures in order to both average out the noise and to allow the sensor to cool down.

TJ K · Nov 24, 2009

Ya that is another way but at the time I was up at our little weekend getaway spot and wanted to open the shutter and go have fun. Once I get the d300 I can put it on a timer mode and it will do it all for me. Then i need something to stack them haha.
tj

djacobox372 · Nov 24, 2009

Use film....

icassell · Nov 24, 2009

Adobe Photoshop CS4 * Creating an image stack (Photoshop Extended)

icassell · Nov 24, 2009

djacobox372 said:
Use film....

Then you have reciprocity failure issues. Nothing is perfect.

TJ K · Nov 24, 2009

djacobox372 said:
Use film....

Only if you buy it for me

icassell said:
Adobe Photoshop CS4 * Creating an image stack (Photoshop Extended)

Gotta get cs4 first lmao. Thinking of getting it if I have money left over after this d300 deal.
tj

astrostu · Nov 24, 2009

Take a photograph with the lens cap on for the same length of time as your star trails photograph. Then subtract it from the one with the star trails. That's what astronomers do, it's called "dark subtraction." You can do this in Photoshop by putting the dark in a layer above the star trails and then setting the layer blending mode to "Difference."