I need to shoot a time lapse sunrise for an internal promotion. This will consist of a one minute interval from 3:00 (black) to 8:30 (day) and I want the sun in the frame. Is this a situation where using an neutral density filter is a good idea? I've never used one before but there are coworkers who own them so I could borrow if need be...
If you are asking about using an ND filter to limit potentially damaging light from direct sunlight then you should be fine as long as you use a wide-angle lens, especially near sunrise where the sun is shining through a dense slice of atmosphere, scattering the light.
Shooting the sun with a telephoto lens is strongly discouraged, and would certainly require a strong ND filter to prevent damage to the camera, or your eyes (if using an optical viewfinder).
A graduated ND filter may help tame the dynamic range of the scene, which can still be very high around sunrise. If the foreground is unimportant to the look of the shot then expose for the sky and you should be fine without a filter.
I'd guess you'd need a GND or partial ND, else the sky would be seriously overexposed. Put the ND over the sky, expose to have the total of the exposures cause the ground to be correctly lit, should help keep the sky look reasonably normal. Or just compose the final image in Photoshop using the ground from one and adding sun positions from all the others.
One or the other is what I'd try (likely using several cameras to take both sequences together, and with different ND gradations, especially if I can't reliably come back to reshoot the sequence on other days).
ND filter makes the scene really dark and lets you use a longer shutter speed in bright light without blowing out the scene. Assuming that in your situation, you need the whole scene and not just the sun, you won't need an ND filter.
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