How to get long exposure in daytime?

[newguy]

I found a nice waterfall on the way home from work last night and I want to get some shots of it in the day. How do I get that cool murky/misty flowing water look? I have a Lumix G1 camera.

[ohenry]

You need a neutral density filter which will reduce the amount of light transmitted to the sensor. Additionally, use the smallest aperture you can and the lowest ISO.

[scoundrel1728]

Besides a neutral density filter, you will also need a tripod, which you should have anyway for landscape photography. In this case, you will absolutely need one because to get the effect you want, you will need exposure times much too long for handheld shots, even those steadied by a monopod or image stabilization (or whatever Panasonic calls their version).

Neutral density filters come in a variety of densities, the densities being designated in several ways. One is the attenuation or filter factor, such as 2x, 4x, 8x, and so on. The other is a logarithmic scale, which can be related to the number of "stops" of attenuation, each stop corresponding to 2x. Instead of stops, filter attenuation is more often given in bels, each bel representing 10x power/energy/intensity attenuation. Each bel equates to 3-1/3 stops of attenuation and each stop is 0.3 bel.

For your purpose, the most useful attenuation is 1.8 or 2.0 bels: 6 or 6-2/3 stops; 64x or 100x attenuation. To use these filters effectively, you must control your ISO rating and your exposure manually. Otherwise, the camera will think that it is shooting in dim light and will try to increase the ISO and open up the lens, and speed up the shutter. Because the idea is to lengthen the exposure time to where you get that smooth effect, the camera's effort to speed up the shutter works against the effect you are trying to achieve. The higher ISO rating also reduces the dynamic range and general image quality, both of which are objectionable in landscape photography. You may or may not want to open the lens, but on landscapes you usually want to shoot at a fairly small (high-numbered) aperture if you can.

In bright sunlight, you can expect an exposure of 1/200 to 1/400 second at f/8 and ISO 100. With an ND 2.0 (bel) or 100x filter, this becomes 1/2 to 1/4 second. You can at least double these exposure times if you also use a circular polarizer, which you should have anyway if you shoot a lot of landscapes. You can double them again by shooting at f/11.

One other thing to watch about these neutral density filters: filters this strong are often not really neutral in color. Therefore, you cannot depend on the white balance presets. You must do your own custom preset or you might be able to get by with the Kelvin or auto white balance, though I have been let down often by auto white balance and try to avoid using it.

[highbarger]

If you have two polarizing filters, you can stack them together and by rotating each separately, create a variable neutral density filter. This can cause color shifts, but it's fun to try...

[Benji]

In order to blur the water you will need a shutter speed of at least 1/2 second. You WILL need a tripod to hold the camera. Also shoot when the sun is NOT illuminating the falls. Use as low an ISO as your camera will allow. Use as small an aperture as possible,( like f/22.) Use a ND filter and/or a polarizer filter. Shoot in Raw, shoot a gray card first, shoot in manual.

Benji

[SNAPaPHOTO]

Originally Posted by Benji

In order to blur the water you will need a shutter speed of at least 1/2 second. You WILL need a tripod to hold the camera. Also shoot when the sun is NOT illuminating the falls. Use as low an ISO as your camera will allow. Use as small an aperture as possible,( like f/22.) Use a ND filter and/or a polarizer filter. Shoot in Raw, shoot a gray card first, shoot in manual.

Benji

What do you think of the Tiffen filters, I know with the UV and such, one needs to spend the extra money on a decent quality of glass. I guess my question is, is Tiffen good for ND filters? Or Polorizing

[scoundrel1728]

In my own experience with crossed polarizers, the light that does make it through has been very blue.

Here is the B&H Photo list of neutral density filters, including some variable attenuation models.

[Mike_PEAT]

Originally Posted by highbarger

If you have two polarizing filters, you can stack them together and by rotating each separately, create a variable neutral density filter. This can cause color shifts, but it's fun to try...

One of them HAS to be a LINEAR polarizer, it WON'T work with two circular polarizers. Also if one of the polarizers you use is circular, you have to have them attached to the lens in a particular order.

Originally Posted by scoundrel1728

In my own experience with crossed polarizers, the light that does make it through has been very blue.

Here is the B&H Photo list of neutral density filters, including some variable attenuation models.

Actually, the "variable attenuation models" (variable ND filters) are basically a linear and circular polarizer in a compact design, and YES you still get the colour shift at the extreme end of the range.

[scoundrel1728]

Originally Posted by Mike_PEAT

One of them HAS to be a LINEAR polarizer, it WON'T work with two circular polarizers. Also if one of the polarizers you use is circular, you have to have them attached to the lens in a particular order.

You can make a variable attenuator from two circular polarizers; but the one facing the subject must be mounted backward with a macro coupler. Then the quarter wave plate of the first polarizer faces the subject. This will make the system sensitive to circularly polarized light instead of the more common linearly polarized light. Because circularly polarized light in nature is rare but not entirely unheard of, the result as far as the image is concerned will be almost the same as if a nonpolarizing attenuator were attached instead.

The linear polarizer on (what is now) the back of this first polarizer will allow light of only one linear polarization to pass, regardless of that comes in. This linearly polarized light then comes into the second polarizer, which is mounted normally on the camera lens. This second polarizer acts like any other circular polarizer, attenuating the linearly polarized light striking it according to the relative attenuations of the two polarizers. The quarter wave plate on the back of this second polarizer then turns the transmitted light into circularly polarized light, to which the internal optics of the camera reacts the same as if the light were not polarized at all.

In fact, you might even want to make such a variable attenuator if your camera's optics is sensitive to the direction of incoming polarized light but you don't want a polarizer along with your attenuator. You also might use one of these front-to-front circular polarizer assemblies if you wanted to photograph subjects under circularly polarized light. You could fabricate a circular polarizer more cheaply if you could eliminate one of the sheets of linearly polarizing material and the rotating mechanism and sandwich the remaining polarizing material between the two quarter wave plates if there were enough demand to make circular polarizers commercially.

[Mary Robinson]

My personal preference is ND filters for the milky water look. I believe you can stack them if you need it really dark. However, you'll have to set up the focus beforehand as the viewfinder shows very dark or black on a lot of cameras. And then as mentioned, set your ISO to the lowest possible setting, 50 or 100 and aperture between f/16 and f/22. You can adjust either of those as needed to get the final image you like. Also check the noise levels as longer exposures also mean more noise.