Neutral density filter: 2-stop or 4-stop?

[paulzoom]

Ihave a Fuji S1 Pro and need a ND filter for outdoor flash. If you had to choose just one filter to buy, would it be the two-stop or 4-stop?

 

[Matt Chroust]

It really depends on how much ambient light you have available and how much DOF you want. You should be able to use the "sunny f/16 rule" to help you out.

ex#0: If you are using iso 100, the "sunny" rule predicts an exposure of f/16 at 1/100 (about 1/125 sec.) at noontime in full sun.

ex #2: A 2-stop ND filter will let you set your camera to f/8 @ 1/125 and
maintain the equivalent exposure, and

ex #4: 4-stop ND filter would have you at f/4 @ 1/125 for an equivalent exposure.

If you are shooting in open shade, evening or morning, your mileage will vary.

Now, to the question of fill, if you wanted your fill about 2 stops under ambient, you'd be able to set it to f/8 in each "sunny" example, and be right in line. So you should know that you need a flash that can make at least f/8 light at the subject distance & ISO 100.

Hope that helps.

Regards,

Matt

Ihave a Fuji S1 Pro and need a ND filter for outdoor flash. If you
had to choose just one filter to buy, would it be the two-stop or
4-stop?

--
Matt

 

[paulzoom]

Thanks for the reply. I guess my dilemma is that I don't know what my flash (an SB-24) can handle. If it can handle f/8 on a sunny day I'm set. But if it can't I would have to go to the 4-stop ND filter. However the problem, is what if it is 1/125 at F/11 and I use a 4-stop ND filter which would bring me all the way down to F 2.8 which would be not enough depth of field.

I guess I'm saying that ideally, they would make a 3 stop ND filter which would be perfect. I'm wondering what most Fuji S1 owners are using for ND filters and what flash they are using.

It really depends on how much ambient light you have available and> how much DOF you want. You should be able to use the "sunny f/16> rule" to help you out.> > ex#0: If you are using iso 100, the "sunny" rule predicts an> exposure of f/16 at 1/100 (about 1/125 sec.) at noontime in full> sun.> > ex #2: A 2-stop ND filter will let you set your camera to f/8 @> 1/125 and> maintain the equivalent exposure, and> > ex #4: 4-stop ND filter would have you at f/4 @ 1/125 for an> equivalent exposure.> > If you are shooting in open shade, evening or morning, your mileage> will vary.> > Now, to the question of fill, if you wanted your fill about 2 stops> under ambient, you'd be able to set it to f/8 in each "sunny"> example, and be right in line. So you should know that you need a> flash that can make at least f/8 light at the subject distance &> ISO 100.> > Hope that helps.> > Regards,> > Matt> > > Ihave a Fuji S1 Pro and need a ND filter for outdoor flash. If you> > had to choose just one filter to buy, would it be the two-stop or> > 4-stop?> > --> Matt

 

[ajs2]

Thanks for the reply. I guess my dilemma is that I don't know what
my flash (an SB-24) can handle. If it can handle f/8 on a sunny day
I'm set. But if it can't I would have to go to the 4-stop ND
filter. However the problem, is what if it is 1/125 at F/11 and I
use a 4-stop ND filter which would bring me all the way down to F
2.8 which would be not enough depth of field.

I guess I'm saying that ideally, they would make a 3 stop ND filter
which would be perfect. I'm wondering what most Fuji S1 owners are
using for ND filters and what flash they are using.

I am not quite sure what you are trying to do. I asume you are trying to keep the camera within the flash sync rate and a f/stop of around f8.

If the sun is very bright it's also likely to be harsh too. A N/D filter is not going to fix that. You might be better trying to find some shade or use a large brolly if no shade is about. The would solve both problems. Plus a little fill flash on top!

Hope thats helps
Alex

 

[paulzoom]

I'm trying to use fill flash at the beach to shoot group portraits. I guess I'm asking is whether an SB-24 will have enough power a F/8 to fill or whether I should get the 4-stop ND Filter to bring the F-stop to F/4.0

coltrane wrote:> > Thanks for the reply. I guess my dilemma is that I don't know what> > my flash (an SB-24) can handle. If it can handle f/8 on a sunny day> > I'm set. But if it can't I would have to go to the 4-stop ND> > filter. However the problem, is what if it is 1/125 at F/11 and I> > use a 4-stop ND filter which would bring me all the way down to F> > 2.8 which would be not enough depth of field.> > > > I guess I'm saying that ideally, they would make a 3 stop ND filter> > which would be perfect. I'm wondering what most Fuji S1 owners are> > using for ND filters and what flash they are using.> > > I am not quite sure what you are trying to do. I asume you are> trying to keep the camera within the flash sync rate and a f/stop> of around f8.> > If the sun is very bright it's also likely to be harsh too. A N/D> filter is not going to fix that. You might be better trying to find> some shade or use a large brolly if no shade is about. The would> solve both problems. Plus a little fill flash on top!> > Hope thats helps> Alex

 

[Matt Chroust]

If I understand what you're asking, it doesn't matter much. The ND filter won't change the intensity of the required fill. Check this out:

0) If you set your fill at two stops under (for example) with an exposure of f/16 your fill would be f/8

2) If you use a 2stop filter, you open the lens to f/8, but the fill would still be f/8 light because it gets a 2-stop drop penetrating the filter (8> 5.6> 4)

4) If you use a 4 stop filter, you open the lens to f/4, but the fill is still f/8 because it loses 4 stops (8> 5.6> 4> 2.8> 2.0) going through the filter

Bottom line is there's no free lunch

Regards,

Matt.

Thanks for the reply. I guess my dilemma is that I don't know what
my flash (an SB-24) can handle. If it can handle f/8 on a sunny day
I'm set. But if it can't I would have to go to the 4-stop ND
filter. However the problem, is what if it is 1/125 at F/11 and I
use a 4-stop ND filter which would bring me all the way down to F
2.8 which would be not enough depth of field.

I guess I'm saying that ideally, they would make a 3 stop ND filter
which would be perfect. I'm wondering what most Fuji S1 owners are
using for ND filters and what flash they are using.

I am not quite sure what you are trying to do. I asume you are
trying to keep the camera within the flash sync rate and a f/stop
of around f8.

If the sun is very bright it's also likely to be harsh too. A N/D
filter is not going to fix that. You might be better trying to find
some shade or use a large brolly if no shade is about. The would
solve both problems. Plus a little fill flash on top!

Hope thats helps
Alex

--
Matt

 

[Rinus Borgsteede]

Ihave a Fuji S1 Pro and need a ND filter for outdoor flash. If you
had to choose just one filter to buy, would it be the two-stop or
4-stop?

Neither would work unless you have a very powerfull flash gun. it is true that you open the lens and get a larger lens opening but the light from the flash has now been reduced by two stops as well so it is (except for depth of field control) a waste of time and it can only cause more problems.

I have an SB24 and it has a guide number of about 110. That means that at ten feet I can use f-11.0. The exposure to fill the shadow side of the subject (on a sunny day) that needs the fill, would 1/125 @16. The flash would be good to about 8 feet.

With a 2 stop ND, the exposure drops to 1/125 @ f-8.0 and the flash is now good for half the distance which is 4 feet. As you can see, you are better off to not use the ND filter and get a much more powerful flash unit.
Rinus of Calgary

 

[paulzoom]

Thanks all for that info. I had read previous posts about the S1, flash and the 1/125 sync speed and the need for using ND filters and had assumed it was for optimizing fill flash. So I guess the only negative of having a 1/125 speed flash setting is having too much depth of field.

coltrane wrote:> > Ihave a Fuji S1 Pro and need a ND filter for outdoor flash. If you> > had to choose just one filter to buy, would it be the two-stop or> > 4-stop?> Neither would work unless you have a very powerfull flash gun. it> is true that you open the lens and get a larger lens opening but> the light from the flash has now been reduced by two stops as well> so it is (except for depth of field control) a waste of time and it> can only cause more problems.> I have an SB24 and it has a guide number of about 110. That means> that at ten feet I can use f-11.0. The exposure to fill the shadow> side of the subject (on a sunny day) that needs the fill, would> 1/125 @16. The flash would be good to about 8 feet.> With a 2 stop ND, the exposure drops to 1/125 @ f-8.0 and the flash> is now good for half the distance which is 4 feet. As you can see,> you are better off to not use the ND filter and get a much more> powerful flash unit.> Rinus of Calgary

 

[Negative287]

Can't you stack a -1 and -2 ND?

--
http://www.pbase.com/elterrible

I guess I'm saying that ideally, they would make a 3 stop ND filter
which would be perfect. I'm wondering what most Fuji S1 owners are
using for ND filters and what flash they are using.

ex#0: If you are using iso 100, the "sunny" rule predicts an
exposure of f/16 at 1/100 (about 1/125 sec.) at noontime in full
sun.

ex #2: A 2-stop ND filter will let you set your camera to f/8 @
1/125 and
maintain the equivalent exposure, and

ex #4: 4-stop ND filter would have you at f/4 @ 1/125 for an
equivalent exposure.

If you are shooting in open shade, evening or morning, your mileage
will vary.

Now, to the question of fill, if you wanted your fill about 2 stops
under ambient, you'd be able to set it to f/8 in each "sunny"
example, and be right in line. So you should know that you need a
flash that can make at least f/8 light at the subject distance &
ISO 100.

Hope that helps.

Regards,

Matt

Ihave a Fuji S1 Pro and need a ND filter for outdoor flash. If you
had to choose just one filter to buy, would it be the two-stop or
4-stop?

--
Matt

 

[Rinus Borgsteede]

Correct! Picking the right background will sure help in making that a non issue unless you really need to kill the depth of field, then the ND filter should be at least the ND 4 for a 2 stop reduction. You now know that the flash may not reach but it is still good for those bridal close ups.
Rinus of Calgary