What ND filter strength?

[Indigo November]

I know that you can use a neutral density filter to allow longer shutter speeds for waterfall photos.
I saw somewhere the number "eight" in correlation with the strength ND filter that you want for waterfalls.
Some ND filters are labeled 0.3 or 0.6 or 0.9, but some are labeled with the number of stops of light it cuts down.
So, what number should I be looking at, and can anyone tell me what ND filter is good for taking photos of waterfalls in daylight?

Thanks.

[RichardTaylor]

Re the numbers.
See this.

How To Use Graduated Filters

What to use all depends on
(1) light levels
(2) What minimum aperture do you want to use?.
(3) What is your camera's minimum ISO?
(4) How slow do you want the shutter speed to be. In other words how "milky" do you want the waterfall to look. That also depends on the waterfall.

Personally I would go for a ND 8 for maximum flexibility.

Here is an example:
Taken at 1 second in daylight (very light cloud) , but in a forest where the light levels were low. I did not like the pics taken at longer exposures as they were too milky.
A ND filter was not used.

Camera Canon EOS 5D
Exposure 1
Aperture f/13.0
Focal Length 200 mm
ISO Speed 400

I can post pics at 2 & 10 seconds and stream closeups of 6 seconds if you like.

[Indigo November]

Okay, when you say "ND 8", what exactly is that number? That is the part I am having trouble with.

Found this:

2x = ND.3 (exposure adjustment = 1 stop, reduces ISO 1/2)
4x = ND.6 (exposure adjustment = 2 stops, reduces ISO 1/4)
8x = ND.9 (exposure adjustment = 3 stops, reduces ISO 1/8)

So do you mean the 8x ND 0.9? Or do you mean that I should find one that cuts down 8 stops of light?

[RichardTaylor]

Three stops NDx8 (in Hoya terminolgy.)
(2 is one stop (1/2 the light comes through))
(4 is 2 stops (1/4 the light comes through))
(8 is 3 stops (1/8 of the light come through))

See this page from Hoya.
HOYA FILTERS - The Difference is Clear


B&W terminology is different
See this PDF (from B&W site)

https://www.schneideroptics.com/info...dbook10_11.pdf

[Indigo November]

I see, different manufacturers have different terms. So confusing.
Thanks for setting it straight for me.

[OsmosisStudios]

Even if most manufacturers use different nomenclature, they'll all at least give you how many stops of light it blocks.

I have a 3-stop as a general-use filter for certain things, but have a 10-stop for super long daytime exposures. I sometimes stack them.

[nemesis256]

another thing you can use is a polarizer. I find this useful when shooting waterfalls because there's often wet rocks around the waterfall, and a polarizer can remove the reflection. Then if I need to reduce the shutter speed so more, I add a neutral density filter on top.

[dakwegmo]

Originally Posted by nemesis256

another thing you can use is a polarizer. I find this useful when shooting waterfalls because there's often wet rocks around the waterfall, and a polarizer can remove the reflection. Then if I need to reduce the shutter speed so more, I add a neutral density filter on top.

Yep, a polarizer will generally cut two stops of light. I find that when shooting during the golden hours, the CP is more than enough to get the shutter speed I want. If I do have to shoot during the day, which I try to avoid, I'll stack a .9 (3 stop) ND to cut 5 stops. Though, you have to be very careful with color casts when stacking filters, especially the less expensive ones.

[sk66]

I use a variable ND (Light Craft version) 2-8 stops....
They are on the expensive side, but get a large one and step up rings and one filter does it all.

[Thunder_o_b]

I use the Cokin system Welcome to COKIN.COM. I have 1,2 and 3 stop NDs and a CP, I can combine up to three at a time for the effect that I need. I have read people saying that there is a color cast to them, but I have been using them for many years and have never had that problem.