6 stops or 10 stops?

I'm thinking about getting a good quality (probably B+W) ND filter. I don't intend to use it too often, and they are rather expensive, so I want to buy only one. A 6-stop filter will slow the shutter speed by a factor 64. This is probably good for waterfalls and flowing water, where exposures of order of 10 s are good enough. A 10-stop filter gives a 1000-fold shutter speed slow-down and might be useful if I wanted to take a picture of a street in bright daylight and blur people away, by using an exposure of 5 or 10 minutes. Hence, they have different applications.

As I said, I want to buy only one. Which one would you recommend? Which one would be more flexible and would give me more opportunities for interesting photos apart from the examples above?

There are systems that are additive... IOW, the holder that attaches to the lens barrel, can accommodate more than 1 filter... 4 + 6 = 10...

I have a Cokin system, but the filter itself is a simple cheap square plate, not very good quality, and lets some light in around the edges.

I'd prefer a good quality screw-on filter.

If you're only going to get one of these filters then the Hoya NDX 400 HMC should get some serious consideration.

Simply put it's an all-around, excellently made, 9-stop ND filter that won't decimate your budget.

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What the Fish said. It's what I have and use.

Realize that it's much easier to compensate for an ND that is overly dark than it is to do so for one that's not dark enough, particularly when dealing with screw-on filters as you can quickly get unwanted vignetting.

B&W makes a circular ND filter...

I bought a Hoya (not real expensive) 9 stop ND a few years back and use it rarely. Here are two shots from 2012, one in bright sunlight (1 sec), the other in shade (13 sec). Both with D7000 and 17-55 2.8. If I used it more, I'd probably learn how to use it correctly.

I have both a 6 and 10 stop and, although I am using the 6 quite a lot lately if I had only one choice it would be 10 stop for sure. A lot more flexible IMO.

Also I would consider a system with a holder and slot in filters. I had a B&W screw on 10 stop and, while the quality of the glass was excellent, it was a pain having to screw it on and off repeatedly.

I pi ended up moving to the Lee system which has a lens adaptor ring, a holder and then the filters that slot in and out. They are expensive and you're eyes might water when you see the price but I got a lot of them second hand at a greatly reduced price. I did buy the Big Stopper(their 10 stop) new and that was €120, which is around $160 US I think.

One other bit of advice I would give is to make sure you shoot in raw as your filter may give a colour cast which will need to be fixed in PP and the more options you leave open to yourself the better.

My wife bought me a 3 pack of different stops that they all can be screwed together to add more stops. Don't know where she got it but I doubt it was expensive.

As I mentioned, I have a Cokin system myself, and I'm entirely impressed with it. I don't think it is any easier to put on and off than the screw-on filter (unless I keep the holder on all the time). Also, the square filter doesn't cover the lens completely, so I wouldn't trust it with a 10-stop filter. Maybe the Lee system is better designed than Cokin (it looks more expensive, for sure).

I have now three lenses with the same 77 mm filter thread, so I guess one 77 mm ND filter would do. I'd probably use it only occasionally.

Thanks, @adox66, this is the answer I've been looking for as to chose between 6 and 10 stops. Now I have to decide whether I want a B+W or Hoya.

Some Hoya reviewers complain about droplets of water (unavoidable when photographing waterfalls) damaging the coating. Horoscope Fish, BackdoorHippie, Singlerosa, did you experience any problems with water?

FredKingston said:

B&W makes a circular ND filter...

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...that I returned a day later. Only works well to about 6 stops, then it's a crap shoot regarding ghosting/dark spots.

Felisek said:

Some Hoya reviewers complain about droplets of water (unavoidable when photographing waterfalls) damaging the coating. Horoscope Fish, BackdoorHippie, Singlerosa, did you experience any problems with water?

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I can not say I've ever seen the coating on any filter *damaged* solely by it getting wet. Heck, I rinse my Hoya HD CPL under running water from the kitchen faucet on a regular basis, but those are Hoya HD's... I suspect what people may be complaining about is that trying to clean a typical multi-coated filter can sometimes be an exercise in the most extreme frustration. What I *have* seen, more than a time or two, are filters damaged by people who go crazy over-zealous with cleaning and in so doing damage the filter. Of course at that point it's all the filters fault somehow; it's "defective" or what have you. Never mind that acetone was never meant to clean a photographic filter. Anyway...

The key to effectively cleaning a multi-coated filter without losing your sanity is to use a real, legit, lens-cleaning paper and a real, legit lens cleaning solution. It's really just that simple but some people just don't seem to want to go that route. Get a freaking box of Uvex tissues and a bottle of Orion lens cleaning fluid and for $20 or so, you're set for a good looooong time.

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I can't see how water could damage a filter coating. More likely, the water dries leaving water marks. Then as Mr H Fish explains, they probably use some cheap or unsuitable cleaning procedure & damage the surface. Treat the filter as you would treat the lens. My cleaning system involves Rocket Blower, Lenspen, Eclipse fluid with Pec*pads. I use Hoya HD filters.

I'd scream "Balderdash!!" over that accusation regarding Hoya filters but I'd much rather say, "Poppycock!!"

Now, if the water they are talking about is coming from the ocean, complete with sand in tow, then you're on your own if all you're doing is wiping it off. And perhaps it could happen if you are shooting rivers in certain parts of West Virginia. Plain water? Like I said, "Poppycock!!!"

I've been using Hoya polarising filters for donkey's years and never experienced any problems. I didn't really expect Hoya's ND filter to be different, but just wanted to make sure.

It's kinda hard to recommend only one ND filter. Depending on the ambient light and the scene you want to shoot will depend on the amount of density of the filter. Unless you get a variable ND filter. And before someone jumps on the cross pattern issues with them, there are good one to be had that doesn't seem to have the issues.

I use a 3 stop and 6 stop, it really depends on what you shoot. I'm not crazy about super long exposures, but they have there place. Most of the time I'm using it for waterfalls and 3 or 6 does the trick for me. A 9 or 10 would limit me too much.