Hoya HMC ND8 question

[Thaash]

I am buying this filter to my Sigma 17-70.

For example if I used 1/500 shutterspeed ISO 100 and F / 11 aperture without the filter what shutterspeed can I use at ISO 100 and F /11 with the ND8 filter (so that picture has the same lighting)?

Is there a way I can calculate this? I know it ND8 means 3 F stop but how can I calculate F stop to Shutter speed only, if everything else is constant?

 

[Gaerek]

You just need to learn how to determine full stops for both shutter and aperture. Shutter is easy. Since a stop is a halving or doubling of the amount of light per stop, if you were at 1/500 (assuming you didn't change anything) and you put that filter on, you would be at about 1/60. (500/2= 250, 250/2= 125, 125/2=62.5 or rounded to 60).

Aperture is a bit harder. Starting at f/1.0 (and there's very few lenses that fast out there) the order of full stops goes like this:

f/1
f/1.4
f/2
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22

So since you started out at f/11, assuming everthing stayed the same, your new aperture value would be f/4. People who have been in photography for a while usually learn how to calculate this in their head. But you can find f/stop calculators online, and for your smart phone.

EDIT: I should note, since I don't think I explained this well enough, don't do both of those adjustments at the same time, unless you want to overexpose by 3 stops. Pick one, or a combination of both. For example, you could do f/4 at 1/500, or f/11 at 1/60. You could also do f/5.6 at 1/250, or f/8 at 1/125.

 

[kundalini]

Don't forget you can throw ISO settings in the mix as well.