Dont use the inbuilt noise reduction - its useless and will take about an hour to process your picture after you have taken it.I'm not sure, but i read somewhere that long exposure introduces some noise ( it seems CCD produces random noise as a result of long exposure).
Not sure how effective is the inbuilt noise cancellation function
The inbuilt function work as followingDont use the inbuilt noise reduction - its useless and will take about an hour to process your picture after you have taken it.
Noise builds up due to the sensor getting hot. Longer the exposure, the warmer the sensor gets.
In my experience it gives no result, and after a long exposure of 30 minutes plus i do not want to sit around waiting for another 30 minutes for it to clean the photo when about 30 seconds in PS will do the trick.The inbuilt function work as following
After the shutter closes, it clears the charges on sensor, and exposes it for same time ( with shutter closed), so as to get the noise floor, and does some processing based on that data........ but yes....... as per my experience it gives good results
but you would then have to account for reciprocity failure for long exposures with film...Use film camera. That's the best for long exposure. Especially those fully mechanic one (that not required any battery to operate).
Knowing your gear limitation is a must.
within the limits of photography, CCD and CMOS seems to be able to hold reciprocity well enough... I'm sure there are limits to it (isn't there always) but not for how we would normally use digital cameras... noise is of course a different story, especially when taking really long exposures where heat from the sensor itself can build up... but current sensors should be able to take it, especially with darkframe subtraction to reduce such noise, and there is always noise reduction software...With digital camera no need?