Shutter speed with high ND filter---

FedEx

Hi
I got a ND filter (BW ND110 3.0) -- reduces light by 10 f stops..

as this blocks so much light the camera wont show what is the correct
shutter speed ... so what do i do ?

a test without the filter, so say w/o filter at f/16 1/100 s is the correct
shutter speed, what do i need to do to give the correct shutter speed w/ filter ..
double the speed 10 times ... so i get ... roughly 10 secs as the correct
shutter speed ?

Fenster

Honestly? Experiment. The purpose of an ND filter is to give you an arbitrarily controllable slow shutter speed. Adjust it until you get a result that feels right.

ThOnda

Errr, you've got it wrong.
ND8 decreases the exposure by 3 stops.

If the time without the filter was 1/125, you have to multiply it three times by two (is it six?). So you go to 1/60 (first time), then 1/30 (second multiplying) and eventually 1/15 of a second.
I took the 1/125s because it is from line of the basic exposure shutter speeds. most cameras with electronically controlled shutters allow times inbetween.
If your camera has TTL metering (through the lense), just set the exposure with the filter on the lense. If not, change the speed (ISO) to three times lower value (from ISO 400 -> 200 -> 100 -> final 50).

I would ask all other posters to correct/confirm what I had typed above.

CabanSail

The ND110 is in fact a 10 Stop ND Filter.

10 Stops from 1/125th is 8 seconds.

Mycroft H

FedEx wrote: »

Hi
I got a ND filter (BW ND110 3.0) -- reduces light by 10 f stops..

as this blocks so much light the camera wont show what is the correct
shutter speed ... so what do i do ?

a test without the filter, so say w/o filter at f/16 1/100 s is the correct
shutter speed, what do i need to do to give the correct shutter speed w/ filter ..
double the speed 10 times ... so i get ... roughly 10 secs as the correct
shutter speed ?

oooor you could increase the arpeture by three f stops

f16 - f11 - f8 ect ect

ThOnda

Oh, I was wrong, the 3.0 is version of the filter...

My bad, sorry.

Hugh_C

Agree with Fenster - I have a similar nd and first I try through-the-lens (ttl) and then adjust if necessary. Some examples here.

PaulieC

i would say around 120 seconds at F9 for a bright sunny day

FedEx

but is the formula correct ? do you double the shutter speed to
go one stop up ?

CabanSail

FedEx wrote: »

but is the formula correct ? do you double the shutter speed to
go one stop up ?

Yes.

1 Stop is a doubling or halving of light.

To change one stop you double or halve the shutter speed.

You can also go up or down one f stop of Aperture.

Doubling or halving the ISO will also vary one stop.

FedEx

Vielan Danke!

now its off to experiment!!!!

Mr. Grieves

Just to add to what CabanSail said, for aperture, multiplying or dividing the f number by square root of 2 (roughly 1.4) equates to 1 stop. Since most cameras have steps in between, it's not alway obvious whether you're moving a whole stop when changing aperture.

Handy to keep these numbers in your head. Starting at f/1.0 and multiplying by 1.4 gives:

1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22

Ballyman

See attached pdf for ND filter shutter speeds. It's not my document, I got it from someone else!