I keep getting the message to consider long exposure mode when taking shots with my IQ3 80 back. From what I can see it sets a minimum ISO of 200 which is 2 stops of light difference, but typically when I'm shooting these long exposures I have 4 to 10 stops of ND in front of the lens, so the ISO increase isn't something I'm wanting.
What's "special" about long exposure mode? I can't find anything in the manual that really explains what it is about. I can see some circumstances were it would allow a 4 min exposure to be cut to 1, but is there anything to be gained by adding two more stops of ND and then enabling this mode?