What kinds of filters do you need for longer exposure times?

[stormchaser]

I know for an exposure time of at least four seconds a neutral density filter

will work, but what if you wanted, say thirty seconds? Five minutes? What kind

of filter would you need to use?

[pico]

What filter? An ND, of course.

 

An ND 64 filter (1.8) will give you 6 stops. You can get way versions to get hours of

exposure time, too.

[albert_richardson1]

It would help to have more of a background explanation of the circumstances for his question. Ordinarily long exposure times are the result of the subject being too dark to use a faster time. Pinhole camera users have to use long exposure times because the small size of the aperture lets in too little light for anything else. I haven't heard of someone using a ND filter to artificially darken a scene just to be able to use long exposures.

 

Use the smallest aperture the lens has and stack on the strongest ND filters you can find to the point that vignetting doesn't ruin the shot. Don't forget to adjust for reciprocity failure if necessary. Anything moving will be blurry.

[brucecyr]

Lower the ISO setting. ND filters come in a range of densities. I've seen 3.0 rating, which is good for 10 stops! I don't use them, but I suppose you could stack a pair of 10's if you're willing to accept some potential image degradation. N.b., 10 stops equates to a light diminution of 1 divided by 2 to the 10th power! So a 1 second exposure would be drawn out to a 512 second = 8.5 minute exposure behind a 3.0 ND filter.

 

There may be more specialized gear available.

[brucecyr]

PS: Each ND 0.3 units = 1 stop.

[pico]

<i>Use the smallest aperture the lens has</i><p>

With 35mm and smaller formats, diffraction will be a real issue.

[brucecyr]

ND 3.0 would be 10 stops, but that's not 2 to the 10th power -- its a log-scale. BTW, I searched and found B+W offers ND 6.0's.

[akajohndoe]

Weren't there pictures of an empty LA freeway taken with extremely long exposures with ND filters so that the cars were not in the image long enough to register?

[phule]

DN,

 

Don't know about LA but I've seen some of Chicago:

 

[stormchaser]

Sorry, I'm not sure about this "stops" stuff. My camera is a Nikon EM that used to be my dad's, and the only setting for longer exposure time is B(as long as the button is held down).

[brucecyr]

Kieran,

 

You need to catch up on the basics! "Bulb" setting is indeed how you expose for an indefinite time.

 

What you need to learn now is about exposure basics, reciprocal relationships between aperture and exposure time, etc. Click on "Learning | Tutorial" at the top of this or any photo.net page and go through the online book there. It also provides a short bibliography of supplementary texts. It should be fun!

 

HTH

[mark_houlder2]

<p>check out some of <strong>rut blees luxemburg</strong>'s work - she does very long exposures of night scenes which results in, for instance, strange looking skies (as clouds drift past, lighting changes, etc). there's also a guy who did a project on people sleeping - the exposures were done overnight, and the resulting image is a bed with all their movement while sleeping recorded as one area of varying blurred-ness.

</p>

<p>

i tried to emulate this for a college project, using 2 ND graduate filters and exposures of 10 minutes each (35mm). it worked well enough, although for my purposes i found that 30-sec. exposures worked just as well, so I ditched the grads and opened up the aperture a little in the end (i got fed up of spending hours outside in manchester, in january. very cold!). this is a 10-minute, f16 exposure with 2 ND filters (0.3 and 0.6 i think): <a href=" [flickr]</a>

</p>

<p>

as someone else has stated, it's easier to do long exposures with large format/pinhole, as you effectively have the use of much smaller apertures (my limit was f16 and 10 mins - i think luxemburg uses f64 and several hours on a view camera, but not sure).

</p>

[William Michael]

Bruce C Wrote:

 

> What you need to learn now is about exposure basics . . . etc

 

Also once you understand about exposure read up on RECIPROCITY EFFECT.

 

The Nikon EM is a film camera, at the very long exposure times you are attempting, most film behaves differently, outside normal `exposure` rules.

 

Regards,

 

WW

[stormchaser]

Thanks for your help, guys. I think I'll be good using a neutral density filter for now, and clearly your advice isn't worth much to me until I get a camera that actually supports stops. :P

[William Michael]

> clearly your advice isn't worth much to me until I get a camera that actually supports stops. <

 

Mr (I assume) Nottelling,

 

There is confusion demonstrated by this response.

 

You seem to not understand what the `stops` are: stops are referring to the aperture setting on the lens.

 

The Nikon EM is a basic, 35mm (refereeing to the film size = 35m)) SLR (Single Lens Reflex camera that supports interchangeable lenses (ie you can swap the lenses on the body.

 

Each lens has an aperture ring with numbers on it, in a progression like 2; 2.8; 4; 5.6; 8; 11; 16; 22. (see photo attached Nikon EM and Lens showing aperture or `stop` numbers.)

 

These are commonly called `stops` because they `stop down the lens` which means the bigger the number selected the smaller the hole made inside the lens by the aperture blades and the less amount of light is let through.

 

Get a good basic photography text from the library and read about exposure, aperture, lenses, shutter speed etc, or get involved with a camera club or speak face to face with a friend who is into photography, (and knows about the basic technical aspects). Or read the beginners basics on this site.

 

Armed some better basic knowledge you will be able to ask more specific questions on this forum and you will benefit a great deal more from the responses.

 

Regards,

 

WW<div></div>

[stormchaser]

Oh, really? I always thought there was a little dial or something about exposure time. But mine doesn't say, as far as I know, what the absolute "correct" exposure is. Hey, wait a minute. That aperture adjusts the amount of light reaching the lens, doesn't it? What does it have to do with shutter speed?

[dangoldman]

the way i understand it, which may or may not be right is that: a stop is the amount of light that is being allowed onto the medium. So, you stop down 2 stops, you take away 2 stops of light. Whether it be aperture or time.

[stormchaser]

Okay, I just figured out f/stops. I'm not sure about exposure stops, but I know that when I step the f/stops on my camera up or down, it automatically adjusts the shutter speed for it.

 

I loves my camera. :D