Neptune Aquatics

Neutral Density Filters

A_Lee

A_Lee

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I understand that the general purpose of these filters is to reduce the amount of light that enters the lens of a camera. On really bright sunny days, using a neutral density filter can allow you to use slower shutter speeds.
But aside from this, does a neutral density filter affect the color [saturation, and/or contrast] of a picture? I notice quite a handful of folks use ND filters when taking landscape pictures. I am not sure if it is to just to blur water more easily, or something else. I have got a 10-20 UWA lens, and am pondering if it is really worth my while to have ND filters in my arsenal at the moment. I currently have a circular polarizer, for what it is worth.
Also, if ND filters are recommended, out of curiosity, would anyone happen to have any experiences with certain brands of ND filters?
Any feedback is appreciated :)
 
A true ND filter only does attenuation. I have seen a handful of ND gradient filters which are often used when there is a horizon (like if the sky is too bright relative to land, the ND dims the sky but not the land)
 
Thanks Tony; I've heard of GND's, but I don't think they would be all that useful to me (not as much as I would like anyways) because I don't run in to too many situations where I am shooting under conditions like you mentioned. Well, not yet anyways ;)
So, from what I gather from what you said, a ND filter will not alter any colors or such in a picture, correct?
A large part of the reason I ask is because I see many peoples landscape photos, and they mention they utilized a ND filter (not a GND all the time). They don't have any water in the picture either, so I am a bit puzzled as to why they might be using a ND filter?
 
ND vs. GND filters. The filters that you're thinking of are gradual neutral density filters, Tony. It's the case where there's a gradient and either a sharp or soft transition (2-3 stops hard GND vs. 2-3 stops soft GND).

Here's a shot that I took awhile back. Shot was taken with 3 stops soft GND IIRC. Taken as the light was fading; shutter speed was like 15 sec.
54616095.jpg


Another picture taken with GND.
56067029.jpg


As for ND filters, they cover the entire lens and allow you to slow your shutter speed down. Why would you use one? To slow down shutter speed of course and to produce softer/manageable light.

You can also use them in the shade. Why would you want to do this? When you need a slower shutter speed but at times when you do so, you blow your exposure. This is when ND shines. Take for example the following:

56067420.jpg


56067423.jpg


Exposure time on both of the above was 30 seconds, in the shade. 5 stops ND were used (+2 and +3 stacked).
 
Thanks Eric for taking the time to type all of that up, and for providing examples. Beautiful pictures I might add :)
How does one determine whether to get hard GNDs, of soft GNDs? Do you have a brand bias, or preference?
 
Anthony,
The ND filter just attenuates the entire spectrum going into the lens. It's purpose is to allow for a longer exposure in order to catch motion blur. For instance, to blur a waterfall or waves without overexposing the area around. It should have no effect on colors. I have no idea why anyone would use one without any motion involved.

This does not apply to a gradient ND. For a gradient ND, Tony is correct.

-Russell
 
ND filters can be used w/out water movement as well. How does it come into play?

Say you were shooting someone out on a bright day, like today. It allows you more latitude on exposure. How so? With so much light, your shutter speed either jumps way up or you have to stop down considerably. So you could possibly end up with the following scenario:

ISO: 100
f/stop: f/11
shutter speed: 1/2000

Say, you wanted to separate whatever you are shooting from the background. To do so, you want a narrower, DOF, meaning you have to tweak with the f/stop. If you want to shoot at f/8 and keeping the above settings, you actually end up at: ISO 100, f/8, ss 1/4000. Well, say that isn't narrow enough for you and you want to go as far down as say f/2.8 (highly plausible if you're shooting with a prime lens, such as the 50mm f/1.4 or even the 50mm f/1.8). This is where the issue comes in. Most cameras only allow you to shoot at a max shutter speed of 1/4000, your ISO is as low as can be and there's not much you can do now (there are other ways to get around this, but that's for another time :) ). Even say you were to use a camera that is capable of doing 1/8000 at max shutter speed. From the above settings, it'll get you to ISO 100, f/5.6, ss 1/8000. Here you cap out.

So...ND filters. Say 2 stops, what it means it that with that on the lens, and your max shutter speed allowable on camera is 1/4000, then you're looking at: ISO 100, f/4, ss 1/4000. If you use a 3 stop ND filter, then effectively, you're looking at ISO 100, f/2.8, ss 1/4000.

Hope the above makes sense. If not, let me know and I can elaborate. :)
 
I am actually leaning towards GNDs now ... seems ND filters may not be what I am looking for after all, as I will be using it mainly on my UWA for landscape purposes and things of that nature.
Eric, can you point me in the direction of a website that sells a nice selection of GNDs at a reasonable price? I've seen some of the prices for individual filters, and they're definitely quite pricey! :) If I were to get just one GND, is there a GND "strength" you might recommend?
Thanks again!
 
Brand wise, for GND, take a look at Cokin. There are other mfg'ers out there, such as Singh-Ray (the gold blue filter is awesome), as well as Hitech. Hitech is a step up from Cokin, but both will work. The Hitech GND filters and holders are larger than the Cokins.

As for ND filters, take a look at the usual suspects such as B+W or Hoya HMC (Kenko are the same).
 
You can find Cokins adapter on like eBay for relatively cheap. If you use a multitude of different lenses for landscape, go w/the largest filter size and use step down rings (I use 67mm and 77mm lenses, so I picked up a 77mm holder and then use step down ring to 67mm when I need to use it on the other lens). I actually might have an extra set of P holder; let me check when I get home.

As for the filters themselves, gonna have to dig that up. I remember a vendor that was based out of Oakland that had decent prices. Unfortunately, I can't recall it off the top of my head...

I'd take a look at 2 or 3 stops soft edge and maybe a 3 stop hard edge GND for landscape uses.
 
Really depends on your subject matter and what you want from the image.

Here's a picture that does show the difference:
filters.jpg


The one on the left is the 3 stop hard vs. the one on the right which is the 2 stop soft. The composition from your subject will sort of determine whether you should use a hard vs. a soft GND filter.
 
A-Did you ever end up getting a GND? tagging along on this thread to learn.

also do you know anything about variable Fader Filters?

Joe
 
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