# urgent qn!! hoya nd4 = 2 or 4 stop?

#### nysheng

##### New Member
hi all! my research indicates that it's a 2 stop. but some sources have insisted it's a 4 stop. anyone kind enough to confirm?

##### Senior Member
It only allows 25% of light through... That's 2 stops.

#### nysheng

##### New Member
the guy I'm getting a filter from. haha that confused me a little.
so basically a b+w nd102 is equivalent to a hoya nd4 rite?

just curious, in what instances do u use a nd4 and when would use a nd8 for example.

#### night86mare

##### Deregistered
the guy I'm getting a filter from. haha that confused me a little.
so basically a b+w nd102 is equivalent to a hoya nd4 rite?

just curious, in what instances do u use a nd4 and when would use a nd8 for example.
yes, i think B+W classification is 1xx, where xx is the number of stops added.

for example, nd110 is 10 stops. nd106 is 6 stops.

i would use a nd4 when i want 2 stops extended shutter speed. i would use a nd8 when i want 3 stops extended shutter speed.

the light is not always the same, there are so many factors to consider.. hence.. that is the only thing i can think of. :sweat:

#### nysheng

##### New Member
yes, i think B+W classification is 1xx, where xx is the number of stops added.

for example, nd110 is 10 stops. nd106 is 6 stops.

i would use a nd4 when i want 2 stops extended shutter speed. i would use a nd8 when i want 3 stops extended shutter speed.

the light is not always the same, there are so many factors to consider.. hence.. that is the only thing i can think of. :sweat:
hmmz can u give me an example of a scenario when you would a 2 stop versus maybe a 6stop? and vice versa.

#### miaoteh

##### Member
hmmz can u give me an example of a scenario when you would a 2 stop versus maybe a 6stop? and vice versa.
it is all depends on how many stops of light that YOU want to cut.

#### sfoto100

##### Senior Member
a few of my frens think nd4 is 4 stops, nd8 is 8 stops...

wow... b+w got 110 stops nd leh... dun play play...

#### miaoteh

##### Member
for example, you are shooting portraits outside with flash, after you set to max flash sync shutter speed and lowest iso, the aperture the camera give you is, say, F11 to get a proper exposure, any aperture larger than tat will result in overexposure, but hor, you wan to use F2.8 to get nice background blur.

so in this particular case, you need something that can cut the light, so that you can use F2.8, F11 to F2.8 is 4 stops, so IN THIS CASE, you will need a 4 stops ND filter.

etc etc.

#### night86mare

##### Deregistered
hmmz can u give me an example of a scenario when you would a 2 stop versus maybe a 6stop? and vice versa.
simple.

i would want a 2 stop filter say, 30-40 minutes after the sun has set.

at that time, light is low, without any filters optimal exposure is maybe f/8, iso 100, 4 seconds.

4 seconds will not give me smoothed out waves. 2 stops gives 15 seconds, that will give me smoothed out waves.

compare this to a 6 stop filter in such a situation. 2 stops 15 seconds, add another 4 more stops.. 4 minutes. same effect, possibility of hot pixels, long wait that is not necessary..?

now, in the earlier timing, when the sun has just set, maybe this same optimal exposure without any filters is f/8, iso 100, 0.5 seconds. with 2 stop filter that is 2 seconds, not enough. with 6 stop filter it is 30 seconds.

it is not that hard to see mar. just think out of the box, it is a matter of targeting SHUTTER SPEED, and getting there based on the amount of light available to you.

#### nysheng

##### New Member
for example, you are shooting portraits outside with flash, after you set to max flash sync shutter speed and lowest iso, the aperture the camera give you is, say, F11 to get a proper exposure, any aperture larger than tat will result in overexposure, but hor, you wan to use F2.8 to get nice background blur.

so in this particular case, you need something that can cut the light, so that you can use F2.8, F11 to F2.8 is 4 stops, so IN THIS CASE, you will need a 4 stops ND filter.

etc etc.
simple.

i would want a 2 stop filter say, 30-40 minutes after the sun has set.

at that time, light is low, without any filters optimal exposure is maybe f/8, iso 100, 4 seconds.

4 seconds will not give me smoothed out waves. 2 stops gives 15 seconds, that will give me smoothed out waves.

compare this to a 6 stop filter in such a situation. 2 stops 15 seconds, add another 4 more stops.. 4 minutes. same effect, possibility of hot pixels, long wait that is not necessary..?

now, in the earlier timing, when the sun has just set, maybe this same optimal exposure without any filters is f/8, iso 100, 0.5 seconds. with 2 stop filter that is 2 seconds, not enough. with 6 stop filter it is 30 seconds.

it is not that hard to see mar. just think out of the box, it is a matter of targeting SHUTTER SPEED, and getting there based on the amount of light available to you.
ahhh....i see...it's much clearer now..thanks!!! i got myself a b+w nd102. will go experiment and see what other nd filters i might need in future

#### wildcat

##### Senior Member
ahhh....i see...it's much clearer now..thanks!!! i got myself a b+w nd102. will go experiment and see what other nd filters i might need in future
All the best :thumbsup: I also find a similar Hoya ND8 (3 stops) filter one of the most versatile.

#### ziploc

##### New Member
For outdoor portraitures, beside using ND filters you can also get a flash capable of high speed sync to overcome the max sync limit.