The effect of a neutral density filter on black and white film

Ces1um · Apr 24, 2017

So I'm wondering specifically how a neutral density filter, usually used to improve colour saturation would translate to a black and white image? I know a nd filter allows you to use longer exposures to flatten waves on water, etc. I'm not looking for information on that. I'm wondering how increased saturation affects a black and white image. Does it increase or decrease contrast? Does it darken a photo overall? Is there no discernible effect? Is there any benefit to using one in black and white photography other than to purposely smooth moving subjects (water, etc...)?

MattKing · Apr 24, 2017

A neutral density filter does not, by itself, have any direct effect on saturation, it just decreases the intensity of the light reaching the lens. Decreasing exposure at the film plane or sensor will increase saturation for slide films and digital sensors. You can achieve that reduction of exposure at the film plane or sensor using the controls on the camera (lens aperture or shutter speed or both), or a neutral density filter, or a combination of all of the foregoing.
Some times you run out of choices when you want to achieve a reduction of exposure at the film plane or sensor - primarily when your shutter speeds don't go high enough to achieve what you want given the high light levels. Using a neutral density filter in effect lowers the light levels.

spijker · Apr 24, 2017

The OP's question may relate to the variable ND filters which are essentially two polarizing filters on top of each other. When the polarization of both filters is aligned, then the attenuation is at its minimum. When the polarization of both filters is at a 90 degree angle, then the combination blocks most light. I've never used these filters but given the nature of the thing they will act similar as a regular polarizing filter and thereby increase the colour saturation. Not sure how an increased colour saturation shows on black & white film except for blue skies with clouds. In that case it works well to get more separation between the two although it is dependent on the angle between of the sun and the camera lens.

Andrew O'Neill · Apr 24, 2017

No effect on colour saturation. I only use them to increase exposure time.

Sirius Glass · Apr 24, 2017

klownshed · Apr 24, 2017

The clue is in the title. They are supposed to be neutral and the only effect should be to reduce light.

Some are more neutral than others, but by design they have no effect on saturation.

Leigh B · Apr 24, 2017

The term "saturation" is not applicable to black&white images.

- Leigh

HiHoSilver · Apr 25, 2017

I don't dispute the posts about the effects on color, but do have some curiosity about the effects on mono. A glance through Ishutteratthethought's gallery will show alot of beautiful work while using a beefy ND filter in mono. I asked about it in one of the image comments & he mentioned it gave a somewhat different look or feel to the image. Whatever that is - certainly looks gorgeous. 'Maybe coincidence, but the results are impressive. 'Don't understand how or why, but it does leave me curious.

AgX · Apr 25, 2017

The only use for a neutral density filter, may it be colour or b&w, is gaining more freedom in choice of shutter speeds or apertures, opticwise.
Such filter acts as an accessory aperture, exposurewise.

Doremus Scudder · Apr 26, 2017

AgX said:
The only use for a neutral density filter, may it be colour or b&w, is gaining more freedom in choice of shutter speeds or apertures, optic-wise. Such filter acts as an accessory aperture, exposure-wise.

... well... I often use an ND filter or choose a long exposure to move the film down into reciprocity failure. The change in the distribution of tones due to reciprocity failure is hard to achieve with other methods and does have a unique look; heavy shadows and lots of separation in the mids, nice sparkly highlights. I do this often in place of N+ developments, often in conjunction with a red filter on Tri-X, which bumps up the contrast a bit too. This latter is due to the way 320TXP reacts to red light and doesn't work for other films.

I use ND filters to get really long exposures at times to "erase" the people or traffic in the shot. This falls into the category of choosing shutter speeds though.

As for increasing saturation in color films: An ND filter will do no more in this respect than reducing exposure any other way. And, if the ND filter is properly compensated for, it will not result in underexposure at all, and therefore, no increase in color saturation. For B&W films, underexposing does change the look of the final print, by eliminating shadow detail and requiring a higher contrast for printing... There's no color to increase saturation in. If this is not desirable then ND filters should be properly compensated for.

Best,

Doremus

ic-racer · Apr 26, 2017

ND filter on B&W film will make the negative lighter, fainter. Under-exposed, unless the compensatory factor is applied during exposure. Think of it as a non-diffracting aperture. In the old days there were photography books that explained these things.

Rick A · Apr 26, 2017

The movie industry used ND filters to simulate night while filming in daylight. Ever watch those cheesy B movie horror flicks? How do you think people were able to run through the woods without killing themselves in the darkness.

Nodda Duma · Apr 26, 2017

ND filter neutrally (theoretically) affects the transmission through the optical system. It does not affect depth of field, aberrations, or diffractive effects. So you can use an ND filter to reduce the throughput by several stops while keeping the lens wide open.

I use them a lot at work when testing laser systems.

Sirius Glass · Apr 26, 2017

Rick A said:
The movie industry used ND filters to simulate night while filming in daylight. Ever watch those cheesy B movie horror flicks? How do you think people were able to run through the woods without killing themselves in the darkness.

Actually the movies use very dense blue filters, not ND filters, to get the "day for night" effect. Thus they can shoot scenes during the day making the scene dark blue. People are fooled into thinking that the scene is at night. Fooled because they think that light is blue when there is low light. Low light is not blue, they just think it is blue.

SteveT · May 8, 2017

I am in the process of getting a 2 stop (0.6) ND filter for use with my CFE f/4 40mm Distagon lens to use with my 501cm. Question - if I spot meter for light and shade and get readings that are 13EV TO 6EV in dynamic range I am either going to lose detail in the shadows or have blown out highlights because Provia 100 has a latitude of 2 to -4. If I place my ND filter on my lens will this balance my picture in terms of tonal range or am I barking up the wrong tree?

Rick A · May 8, 2017

Sirius Glass said:
Actually the movies use very dense blue filters, not ND filters, to get the "day for night" effect. Thus they can shoot scenes during the day making the scene dark blue. People are fooled into thinking that the scene is at night. Fooled because they think that light is blue when there is low light. Low light is not blue, they just think it is blue.

Actually, different filters were used, depending on film and situation. I merely pointed out ND's were common with low budget B&W horror films. Dark red filters were also used, film was also tinted blue early on in motion pictures.

Mainecoonmaniac · May 8, 2017

Do you mean graduated ND filters to saturate the sky? Here's an example.
http://shotrockers.com/graduated-neutral-density-filters-photo-tips/

Leigh B · May 8, 2017

SteveT said:
If I place my ND filter on my lens will this balance my picture in terms of tonal range or am I barking up the wrong tree?

A neutral density filter is identical to closing the aperture by the same number of stops.

These are often used when folks want to use a slow shutter, e.g. to smooth turbulent water's surface.

- Leigh

AgX · May 11, 2017

Leigh B said:
A neutral density filter is identical to closing the aperture by the same number of stops.

Not quite...

ND filters have such a transmission effect.
The aperture in addition has a optical effects (DOF, diffraction)

(Depending on situation ND filters may yield optical effects too, but that are rare cases.)

JBrunner · Oct 12, 2017

Rick A said:
The movie industry used ND filters to simulate night while filming in daylight. Ever watch those cheesy B movie horror flicks? How do you think people were able to run through the woods without killing themselves in the darkness.

Actually, we don't. We use to use a blue filter and under expose. ND might have come in to the picture to contribute to a using desired stop. The big secret was to avoid showing the sky. Today it can largely be done in post, and you should still, of course avoid the sky. You still might use an ND filter to reach a certain stop.

ND filters have no effect on saturation (hence the neutral part of "neutral density" or ND). They do alter transmission (the reason of their existence), which if not compensated for, can have an effect on saturation. In regard to the OP, they have no effect on saturation because black and white film does not (for practice purposes) "saturate".

ND filters are not the same as closing down the aperture. As a matter of fact, they are often used (particularly in cinematography, because of fixed shutter speeds) to avoid just that.

pentaxuser · Oct 12, 2017

I wonder if we have convinced the OP yet and he has abandoned the idea of an ND filter for saturation?

pentaxuser

E. von Hoegh · Oct 12, 2017

ic-racer said:
ND filter on B&W film will make the negative lighter, fainter. Under-exposed, unless the compensatory factor is applied during exposure. Think of it as a non-diffracting aperture. In the old days there were photography books that explained these things.

There still is, for those who read....

Gerald C Koch · Oct 12, 2017

Filters have no magical properties as they can only do what is allowed by the laws of physics. ND filters only decrease the amount of light reaching the film. Therefor no other change for a B&W image.

Filters in general are one of those subjects misunderstood by many. You will hear the statement that "filters increase contrast." This is true for polarizers and to a limited extent color filters. However a color filter does not increase contrast across the entire spectrum only a portion of it. A green filter will darken reds but actually lighten greens. Therefore there is an increase in contrast only for red objects.

The effect of a neutral density filter on black and white film

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The effect of a neutral density filter on black and white film

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