Nightime, Long Exposure, help meeeee

[Benphall]

ok First try at long shutter speeds i like the idea but obviously would like a bit of pointers if anyone out there in DPS land uses this method trow a couple tips my way.

nikon D40
Sigma 10-20
f5
20 min

[jujitsu1]

Well I'm no pro but for long exporuses you really should have something that is moving and have abit of light to it. Thats why your picture only as the stars that have moved. Hope this helped. Try going to a bridge over a road and shoot the traffic come towards and away from you.

[OsmosisStudios]

Youve got some great startrails, that's for sure. Is that the intention?

[Benphall]

yes the star trails is what i was going for (secretl i was hopeing for a boat or 2 to go by as well. i somewhat like the way it turned out however it seems to be a bit noisy i photoshopped it to turn the sky more blue. raw image was more warmer colors. Need some advise. i had white bal set to tungsten due to the lighting comeing from the rear because of the cottages nearby.

[OsmosisStudios]

Noise is caused by 2 things: ISO and exposure time

What was your ISO?

20minutes of exposure is going to cause Long Exposure Noise, which is the caused by the buildup of heat in the sensor from being exposed and active for so long. It's the modern version of reciprocation.

[Benphall]

my ISO was set at 200 ( the lowest my D40 can go to) any helpfull hints. short of buying a new body

[ALSto]

Maybe try f20-f22 or higher if your lens can handle. This may help a little but 20min exposure will yield noise probably no matter what you do.

Allen...

[bongomon]

I know with my Canon there is a setting accessed through the menu that is supposed to help cut down on noise from long exposures. It works by taking a second "blank" exposure for the same length of time as the first and sandwiching them together.

This can be a hassle sometimes because for every 10 second exposure you take you have to wait 10 more seconds for the camera to record this other blank image and combine them. That turns your 20 minute star field image into a 40 minute experience (time for a blanket and some hot chocolate).

I don't know if the Nikon offers a similar ability or not, but it's something to look into...

[b]

[CaptainNH]

The noise comes from the long exposure - the longer the exposure the more noise.

You can cut down noise by taking a series of shorter exposures and combining them in PP.

I try to limit my exposures to 2min at a time - you can still get great star trails if you shoot back-to-back.

[OsmosisStudios]

Originally Posted by ALSto

Maybe try f20-f22 or higher if your lens can handle. This may help a little but 20min exposure will yield noise probably no matter what you do.

Allen...

How would this help? Stopping down from f/5 to f/22 is 5 stops: that'd make the shutterspeed something around 10hours.