02-03-2016 08:02 AM
Yes, you can. I recommend setting your camera to manual, "M", mode to do it, though.
However, you will find it easier to do initially if you set the camera to Aperture Priority, "Av", mode. Dial in settings for ISO and f/stop, and let the camera calculate the length of th exposure. This can get you into the ballpark of where you want to be. You would then change to Manual mode and fine tune the final composed shot.
02-03-2016 12:37 PM
Keep in mind how long exposure noise reduction works...
Suppose you take a 30 second exposure. When noise-reduction is used, the camera will take the normal exposure (the "light" frame), then immediately follow with a 2nd exposure but will keep the shutter closed (the "dark" frame). This allows the sensor to build up "noise" for a dark-frame in conditions identical to your light-frame. The dark frame noise is then subtracted from the light frame to produce a new light frame with less noise than you would otherwise have had... but it will take 1 minute to shoot a 30 second exposure (because it has to shoot 2 exposures.)
This sometimes makes people think their camera has locked up... when in reality it's just busy taking the "dark" frame.
02-03-2016 11:01 PM
Thannk you for all reply,
if i tune on both long exp noise and high iso speed, when i shootong night long exp, do i need to tune off the high iso speed ? and indoor shoot for high iso speed, so need to tune off the long noise exp ?
02-04-2016 12:27 PM - edited 02-04-2016 12:41 PM
If you mean High speed ISO NR you don´t need to use it together with raw. What I know it doesn´t matter if you have it turned on or off. Only if you shoot jpg.
With raw, you can always turn on or off High speed ISO NR in Canon Digital Photo Professional or noise reduction in another raw converter.
Like TCampbell wrote Long exp. noise reduction will take two images and remove all hot and dead pixels. Raw converters often have hot pixel remover.
Another thing to do to get less noise is to keep your camera sensor cold. This is in Swedish, but you will understand the temperature in Celsius. Live view will heat the sensor, so don´t use Live view for minutes before taking a longer exposure. You can check the temperature inside your camera with an exif viewer. I don´t know where in the camera the temperature is measured.
02-04-2016 03:15 PM
"Another thing to do to get less noise is to keep your camera sensor cold"
Yes and old trick. We used to freeze film to make it more sensitive.