LarryFB Loc: Depends where our RV is parked

The proper sequence of "whole f-stops) is f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, etc.

leftj Loc: Texas

BebuLamar

The ISO on my digital cameras can not be set to 10. Still when you put a 10 stop ND filter and you want the equivalent to ISO 10 you have to set the ISO to 10000. So if you set your ISO to 100 or 200 and put a 10 stop ND filter you can get much lower than 10. However I never use an ND filter.

leftj Loc: Texas

drum roll please!

Nymphadora

What are you trying to do that requires ND filters...?

gvarner Loc: Central Oregon Coast

That's the best plan at this point. You'll learn a lot about how cameras work.

James R. Kyle Loc: Saint Louis, Missouri (A Suburb of Ferguson)

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Get This -- READ IT..............

http://www.amazon.com/Understanding-Exposure-Fourth-Photographs-Camera/dp/1607748509/ref=sr_1_1?ie=UTF8&qid=1494602614&sr=8-1&keywords=Understanding+Exposure

treadwl Loc: South Florida

Yes you can put a three stop filter on top of a 10 stop filter and get a total of 13 stops. BUT (and this is a big but) First you might get shadows on the edges from stacking to many filters. The longer the focal length of the lens the bigger this problem becomes. Unless you get really high quality ND filters you will begin to get maroon color shifts which can be a real problem to get of in photoshop or lightroom. You will also have a much more difficult time trying to focus. (best to focus with the filters off the lens, then VERY VERY carefully screw them on before taking the shop. You will need a very solid tripod and a cable release to make this work out well.

Good Luck.

OddJobber Loc: Portland, OR

Did you borrow that from Yogi Berra?

ballsafire Loc: Lafayette, Louisiana

Now, this short answer makes more sense in understanding f-stops.

gessman Loc: Colorado

You know, one of the things we try to do here is be helpful and reduce wasted time and effort for people who ask questions. What you've just done is potentially send a lot of people to google to find out what "Lee" is. Those who don't know will have to potentially wade through a page or two of urls to make sure they know what Lee is and perhaps click on a link or two to get to the place where "Lee" reveals that information, all of which seems like a lot of wasted effort when you know the url or can find it easily since you were just there yesterday. Not just real helpful. Reminds me of junior high school teachers when I was younger who's role it was to teach kids the process needed to find an assignment in a book at the library - give just enough information so all her 35 students could go to the Library and dig through the card catalog duplicating the same effort 35 times when if they just knew the name of the book they only had 350 pages to go through to find the information. Not just real helpful but the role and mission was different than here. It would be my humble opinion that if your purpose in posting is to be helpful - then do it and don't just compound the confusion that already exists. Nobody needs to be taught how to use google and read indices for the right entry. They just want the answer or where they can find it with minimal effort and wasted time. Be helpful if you can... Everyone will appreciate it.

amfoto1 Loc: San Jose, Calif. USA

Hi and welcome to UHH...

To be brutally honest, if you don't yet have a good understanding of "stops", you probably shouldn't be looking at ND filters.

Do yourself a HUGE FAVOR... Head right over to Amazon.com and buy yourself a copy of Bryan Peterson's "Understanding Exposure". Read it, learn it.

"Stops" are absolutely critical for any photographer wanting to advance beyond fully automatic "snap shooting". If you want to take control of your camera, make accurate exposures and determine the "look" of your images, you need to work with stops.

"f-stops" are a means of expressing the size of a lens aperture. It's actually a ratio of the lens focal length to the diameter of the opening that admits light through the lens. In addition to the amount of light being allowed to pass through, lens f-stops also determine "depth of field" in images... i.e., how much is sharp versus the amount and degree of lens induced blur. (Note: videography uses "T-stops" instead of "f-stops", but they are similar enough for discussion here.) All lenses have a "maximum aperture" that's usually imprinted right on it. Small numbers indicate a large aperture: f/1.0, f/1.2, f/1.4, f/1.8, f/2. Those render shallow depth of field and stronger background blur effects. High numbers indicate smaller apertures: f/8, f/11, f16. These render greater depth of field and less strong background (or foreground) blur effect.

Shutter speeds are also commonly referred to in stops (though technically that's incorrect). Shutter speeds are important determining whether an image is sharply defined or blurred due to movement either of the subject or the camera itself. Shutter speeds on most cameras today range from 30 seconds to 1/4000 or 1/8000 of a second.

Finally, ISO or the light sensitivity of film or sensor is also often referred to in stops (again, technically incorrect, but common usage). It's the third factor you can adjust, along with shutter speed and lens aperture, to arrive at a "correct" exposure that renders an image in the manner of your choosing. ISO settings on most cameras today start around 100 and go up to 25800 or higher. For the best image quality, usually you'll want to use the lowest possible ISO that allows the shutter speed and aperture settings you want to be able to use.

This is often referred to as the "exposure triangle": lens aperture, shutter speed and media sensitivity to light (ISO). There are myriad possible combinations and a number of different ways to arrive at any particular "correct" exposure.... So once you understand and take control of these three exposure settings, you'll be able to make images that look the way you want them to, rather than just relying upon luck (i.e., automated point n shoot "snap shots") and hoping for the best.

This is where ND or "neutral density" filters finally might come into play. Sometimes light is just too bright to allow a slow enough shutter speed (used to deliberately blur moving water, for example) or to allow a large enough aperture (to strongly blur a background in a portrait, for example). The lowest ISO possible just isn't low enough for the photographer to be able to use the slow shutter speed or larger aperture (or both) that they want. When that's the case, putting a neutral gray filter in front of the lens - to further decrease the amount of light that can pass through - essentially "shifts" the range of usable exposure settings to what the photographer needs and wants. Usually for still photography one or two fairly strong ND filters are used... such as an single 8-stop or 10-stop filter... or a pair such as a 3-stop and 6-stop, which can be combined to make for 9-stop. Videographers have less flexibility with some of the other exposure factors, so might need a wider variety of ND filters (or a "variable" ND filter).

Any time you use a filter it's going to have effects on image quality. A low quality filter can cause all sorts of problems ranging from loss of sharpness, added flare, reduced contrast and color saturation, and more. The best filters have minimal negative effect on images under most conditions. So, don't scrimp on filters! Be careful and look for high quality, multi-coated glass from a reputable brand such as Hoya, B+W, Marumi, Heliopan, Singh-Ray or several others.

Assuming you're shooting digital images, there simply aren't many necessary filters any more. Not like there were with film. Today with digital imaging there are three primary types that remain useful: Circular Polarizers, Neutral Density and "Protection/UV". C-Pol are by far the most useful... they can serve a lot of purposes from reducing flare and haze effects to deepening the blue of the sky or green of foliage. ND are used as described above. Protection filters are largely unnecessary, probably greatly overused and quite questionable (with their pros and cons strongly disputed on forums like this), but might serve an important purpose in certain circumstances (i.e., when you're out shooting in a sandstorm!)

If shooting digital, so few filters are needed these days, spend more on them and get really good ones. Your images will benefit from doing this!

Do buy and read "Understanding Exposure" to learn the basics (we all were at the same place as you on the learning curve, at one time or another... I wish this book had been around when I was!). It sounds as if you're ready to move beyond "point-n-shoot snap shots" and start "making real photographs". It's a complex subject, far more than we can cover in posts to a forum. Peterson's book will be a huge help to you!

jeep_daddy Loc: Prescott AZ

Stops refer to f/stops.
An f/stop is a measured amount of light or the light sensitivity of a sensor for exposure of an image.
Each stop of light in the old days was measured in stops of light in equal amounts of light measuring 1 increment each. Now stops can be adjusted in 1/3 stop increments.

A stop of light can be adjusted by shutter speed by either doubling or halving the shutter time. So if your shutter is open 1/60th of the second and that is allowing too much light resulting in an overexposed image, you can double that to 1/120th of a second resulting in cutting the light by 1 f/stop.

A stop of light can also be adjusted by opening or closing the aperture which is referred to as stopping down (closing) the aperture, or opening up the aperture. Stopping down makes the aperture smaller so it lets less light through thus cutting the amount of light at the given shutter speed. So if that same example above is used with a shutter speed of 1/60th and your aperture was set for f/8 and your image is overexposed, you could stop down, make the aperture smaller, to f/11, which is one stop of light, thus darkening or exposing the image less. Whole f/stops aren't doubled or halved like shutter speeds. They are measured differently but easy to learn. Whole stops are f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, and so on.

That last way to adjust the exposure is to increase or decrease the sensitivity of the camera sensor. In the old days film was rated in it's sensitivity with a rating governed by ASA. ASA was the governing body that dubbed the film speed rating in various numbers. The numbers have stayed the same since digital cameras came out but a few years before digital, the governing body changed to ISO. You can look those up for the acronym they stand for but the point I'm trying to make is that ASA = ISO. So now they call the film/sensor light sensitivity rating by numbers like ISO 100, ISO 200, ISO 400 etc. Every time the number is doubled or halved, it is equal to on stop of light sensitivity.

Now for ND or Neutral Density filters. They are like sunglasses on your lens. They come in ratings and or numbers that affect how much light they will cut entering the lens to the sensor in increments of stops just like all the other ways to add or cut light talked about above. In other words, they sell ND filters that come in ratings of 1,2,3,4,5,6, and so on stops. ND filters may be stacked. So if you put a 1 stop filter on top of a 2 stop filter you have cut 3 stops of light from entering the lens.

ND filters are usually used to cut light so that the photographer can also use longer shutter duration so that they can achieve a desired affect which could include smoother water falls, streaking stars, or simply exclude people that walk through a busy scene.

This is a simplified version of what stops are and is not meant to other smarty pants people to critique my way of explaining to a new person. I didn't want to be too technical otherwise I would have just pointed the OP to a web site that would explain this in very technical terms. Sometimes simple is easy. So please, don't get picky about my wording or explanation.

photonutt1970

well stops can mean one of three things, aperture, Shutter speed or ISO each movement up or down is a stop

James R. Kyle Loc: Saint Louis, Missouri (A Suburb of Ferguson)

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Or.....

Harry Truman ....

"The Lens STOPS Here".