Very Very Long exposures

[JoshBoy]

Hi,

In the past I have done 60 second exposures at night however I have been playng around with longer exposures to get the movement of the stars in the sky, my issue is the super large amount of noise that comes into the shot. I have seen some great shots that have been exposed for hours with no noise, how is it done?

If it helps im on a Canon 7D.

Cheers

Josh

 

[Tomple]

Off topic sorry
but

How do you like the 7D?
Im looking into getting one

 

[JoshBoy]

Off topic sorry
but

How do you like the 7D?
Im looking into getting one

Love it. I have moved over from Olympus ( I have been using for the past 5 years.

Canon just seem to have a much better feel to them.

 

[mattyb240]

Alot of people stack lots of 30 second exposures, to get ones longer you need to go to an area of low light pollution.

Not the best example:

But this was over an hour or so single exposure.

 

[Techhie]

I have seen some great shots that have been exposed for hours with no noise

They usually set the ISO speed at around 100-400, which is why the exposures take so long and come out clearly. The same exposure could be attained in much less time if you are able to do some decent noise reduction in post, but many people also enjoy the "shift" effect from long exposure.

To do exposures over 30 seconds on the 7D you must buy an external shutter button, or connect the camera to a computer while on set to control it.

If you happen to be in an area of low light pollution, cranking up the ISO can do wonders for a 30 second wide-open exposure.

Taken with my 5D mk II, 30sec at f/4 and ISO 25,600 (I didn't have anything but the bare camera with me)

 

[FrankieTDouglas]

Shoot with your camera set to its lowest ISO. Also, don't stop all of the way down... otherwise you get defraction, which while more is in focus, it's actually less sharp (think pinhole photography).

Also, be sure to turn ON your long exposure noise reduction. Your camera produces two types of noise. ISO noise, like what you're used to, but also long exposure noise, which shows itself as blue dots in your image. This is a glitch of digital cameras. By turning on LE NR on, basically once the image finishes exposing, it spends an equal amount of time processing it and eliminating all noise created by being open for so long.

 

[JoshBoy]

Cool thanks, I will have a play around tonight as I think I left my ISO on auto last time (just realized) however I would also like to try the option of stacking the photos, I am trying to find a tutorial on the web but if anyone knows of a good one I would be grateful, (I am using CS5)

Cheers

josh