Filters for Long Exposure.

[calebk]

I see some landscape photos, whereby even though they are shot in daylight, there is extreme motion blur seen in clouds/sea spray. I'd like to know what filters actually cut light by that many stops.

[yyD70S]

I would think the cheapest method would be to firstly use the smallest aperture opening -- baring in mind the factor of defraction, of course...

Second would be using the polariser as a stop-gap measure -- I assume most would have a polariser vis-a-vis other filters...

Thirdly, I guess, more to the point of your question, would be the Hoya NDx400 (one of the several brands) -- which would cut off 9-stops of light.

[thingie]

i don't know if this will help as my conditions were not as extreme as described.



shot at f22 with 0.8 sec and ISO 50. i used a polarizing filter as well.

[FilterFunk]

using the smallest aperture + slow shutter + tripod (and optional ND filters?) should be able to do the trick.

[cantaresg]

Perhaps use more than one ND filter? 2x ND8 or 1x ND4 + 1x ND8? That'll cut 5 stops of light.

[ExplorerZ]

Originally Posted by cantaresg Perhaps use more than one ND filter? 2x ND8 or 1x ND4 + 1x ND8? That'll cut 5 stops of light.

I would suggest the use of a ND400 or even higher instead, stacking that much of filter will
1. cost pretty bad vignette for wide angle
2. much higher chance of degrading the image quality

[CS TAN]

Originally Posted by cantaresg Perhaps use more than one ND filter? 2x ND8 or 1x ND4 + 1x ND8? That'll cut 5 stops of light.

Correct me if I am wrong. Neutral Density filters reduce light transmission by x f stops as follow:
ND8 = 3 f stops
ND4 = 2 f stops
ND2 = 1 f stop

In the above example you have stated, it should have a total 6 f stops instead.

There is a one half (1/2) ND filter with one half of this filter is Neutral Density and the other half is clear, with a soft boundary between the two. It is used to control bright/dark contrast by reducing half the shot by x f stops. Particularly useful in landscape photography, the rotating mount allows bright skies to be easily controlled for dramatic effect.

[calebk]

Thanks to all.

I reckon I'm pushing the aperture limit already. Shooting anything smaller than f/13 would result in diffraction.

I have a ND8 and a CPL already, and now I've heard of a NDx400. However, I've never seen this before.

[yyD70S]

I personally have not used it but have seen some pics with the NDx400 filter -- check out with our forum member Azure.

[Del_CtrlnoAlt]

how long do you need?

ND2,4,8 combine, or maybe a NDX together?

[GilbertGoh]

Originally Posted by Del_CtrlnoAlt how long do you need? ND2,4,8 combine, or maybe a NDX together?

how to shoot with a NDX?
i tried several times, found that it only works for shooting the sun for subjects with strong time source.

please direc me to any sites teaching the use of such a filter.
thanks in advance.

[CS TAN]

ND filters have four main uses:

1. To enable slow shutter speeds to be used, especially with fast films, to record movement in subjects such as waterfalls, clouds, cars, seas etc.
2. To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background.
3. To decrease the effective ISO of high speed film (ie: above ISO400) and allow it to be used outdoors in bright situations.
4. To allow video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which would normally cause over-exposure.

Take a look at this simple write-up: http://www.cs.mtu.edu/~shene/DigiCam...filter-ND.html
and this one: http://www.outdoorphotographer.com/c...2006/oct.shtml

[GilbertGoh]

thanks for the links as i seen them, they are for general ND filters. NDX is it is not really the same as it bring it down by 13-f stops.
anyone used this and shoot before?

[Yatlapball]

Why is it not the same? If you understand the concept, it will apply to any ND filter. Even if it cuts light by 100 stops.

Do note that after cutting light by so many stops, you might very well have to end up manually calculating the exposure time and shooting in bulb mode (a cable release with timer would come in useful here. Unless you fancy using a stopwatch). Since most DSLRs nowadays only accomodate up to 30seconds.

[GilbertGoh]

sorry but i do not undertand what kind of concepts you are refering to.

if you could please show how you calculate the timing for -13F ND filter

i do have a timer remote control. but i have tried biggest aperature and smallest with timing up to 15 mins, all i got was internal diffraction or black pic.
i am still short of a external power source to try timing up to 1 day or 2.

the only pic i got out of it was that sun.
sorry i am very noob in this area.

[Yatlapball]

f1 - 1.4 - 2 - 2.8 - 4 - 5.6 - 8 - 11 - 16 - 22 - 32 - 45 - 64 - 91

For example a scene requires 1/8000s at f/1.0
After cutting the exposures by 13 f-stops, it would be something like shooting at f/91 and to get the correct exposure you need 1s

[ExplorerZ]

Originally Posted by GilbertGoh sorry but i do not undertand what kind of concepts you are refering to. if you could please show how you calculate the timing for -13F ND filter i do have a timer remote control. but i have tried biggest aperature and smallest with timing up to 15 mins, all i got was internal diffraction or black pic. i am still short of a external power source to try timing up to 1 day or 2. the only pic i got out of it was that sun. sorry i am very noob in this area.

its easy to calculate... let say without filter you are getting 1/200 then +13stop would be (do note the +, because you are going to compensate for the decrease in light by the ND)

1/200 > 1/100 > 1/50 > 1/25 > 1/12... until you get roughly 60s or so... by that time, you probably need to count in your heart when doing bulb mode

[GilbertGoh]

Originally Posted by Yatlapball f1 - 1.4 - 2 - 2.8 - 4 - 5.6 - 8 - 11 - 16 - 22 - 32 - 45 - 64 - 91 For example a scene requires 1/8000s at f/1.0 After cutting the exposures by 13 f-stops, it would be something like shooting at f/91 and to get the correct exposure you need 1s

as stated in my previous post at -13F stops, i set bulb mode for 15 mins still blank.
i just i need to try harder and more.
i also read at after 19 or some thing, the F stops are exponencial in power.

[GilbertGoh]

Originally Posted by ExplorerZ its easy to calculate... let say without filter you are getting 1/200 then +13stop would be (do note the +, because you are going to compensate for the decrease in light by the ND) 1/200 > 1/100 > 1/50 > 1/25 > 1/12... until you get roughly 60s or so... by that time, you probably need to count in your heart when doing bulb mode

i did use a timer but not result, Maybe Cokin's Filter NDX is not a -13F stops
if ND4 = 2 Fstops
13 F Stops = ND8192 filter?

[AdyH]

I've been tryin to get e Cokin ND100 filter. Anyone knows where i can get them? e usual shops not carrying them unfortunately