Big stopper question

How would I know what shutter speed to use with a 10 stop nd filter at night. I don't really want to waste my time firing off 5 minute exposures just to find out they're overexposed. Is there some sort of formula to calculate what shutter speed to use? Thanks.

I'm on my phone so I don't want to type out the reply I probably should, but in short - there's an app or two for that!

I think I have a freebie called ND Filter Calc

Varneeezy wrote in post #17400369
How would I know what shutter speed to use with a 10 stop nd filter at night. I don't really want to waste my time firing off 5 minute exposures just to find out they're overexposed. Is there some sort of formula to calculate what shutter speed to use? Thanks.

Try some shots without it to dial in an exposure. Once you have it looking the way you want, adjust for the ND filter.

Hey thanks guys! Life savers! I should have known though that there would be an app for that. After all there is an app for everything.

If you went to school more than 30 years ago then you probably learned something called 'mental arithmatic'. If you went to school later than that you can still give it a try, it's sort of like a calculator, but you use your brain.

Take the shot without the ND and note the shutter speed. Now multiply that by 1000.

1/100s becomes 1000/100 = 10/1= 10s

1/250s becomes 1000/250 = 100/25 = 4s

1/30s becomes 1000/30 = 100/3 = 33s (but 30s will be close enough)

Your Big Stopper should've come with a chart which already does the shutter speed calculation. You may be missing it if you purchased your Big Stopper used.

thanks guys. Ya I just ordered a b+w 10 stop. Hopefully I like it. I heard its one of the better ones. Should be here on Thursday.

If using a 10-stop ND filter at night, I think a calendar would be the most suitable tool for working out shutter speeds!

Seriously though, this thread is quite helpful. There is a handy chart on page 2 as well: http://www.cambridgein​colour.com/forums/thre​ad9316.htm

Mike