Which 10 Stop ND Filter

I wasn't aware that Cokin has a 10-stop filter, but I can comment on the B&W and Lee. You've probably heard that each has a cast (blue with the Lee and magenta with the B&W), so choose your poison. They do require some color correction, but it doesn't get really bad unless you start stacking other filters on top of them.

I researched them both myself and went for the B&W. The Lee filter has foam edges that provide a fairly snug fit, and from what I understand it can be difficult to get it in and out of the holder without jiggling your camera. That might not be a problem for most people, but if you like to combine exposures, it's something to consider. With the B&W, I can screw it on lightly and remove it easily without jiggling anything. I have the 77mm filter and a step-up ring so that I can use it on a 67mm thread as well; six of my lenses are one of those two sizes, so I'm covered for pretty much anything.

As for metering, I just use an iPhone app called ND Calc. First I get the right shutter speed with the filter off, then I gently screw on the filter, calculate with the app, and take a test shot. If the exposure isn't right, then I just move the app's shutter speed dial accordingly and try again. I never need to take the filter off again just for metering.

Here are few long exposures I've taken with the B&W:

Summer Breeze

Trio

In the Moment


If you look carefully, you might be able to pick up on the magenta cast in these, since I often choose to leave it to some extent. I see a lot of people using the Big Stopper who likewise leave some of the cool blue cast in their photos, so like I said, you just have to choose which way you want your photos to lean. I like how the magenta adds to the effects of a sunset, but some people prefer cooler, steely colors.

Again, I don't know anything about the really cheap filters you speak of, but I would avoid them. If you really just want to play around with long exposures for little to nothing in the way of investment, you might consider a piece of welding glass from eBay, which will cost you only about five bucks. If you google it, you'll find some interesting threads with attachment advice and eBay seller tips.

Personally I like a variable ND. I shoot around woodland streams very often where a fixed ND can easily bee too strong. With my LightCraft VND I can dial in from 2-8 stops of light reduction.

I wouldn't recommend buying a cheap 10-stop filter at all. I mean, you will still get acceptable images, but you will probably have to spend more time in LR or PS cleaning up the image than you would if you invested in a quality filter.

With that said, I have a B+W 10-stop filter which I purchased for $125. It is worth every penny.

P is the ND filter expert, IMO. Here is a nice review article that I stumbled upon when trying to figure out if I wanted to add any of these filters to my camera bag. I had a .9 Tiffen ND screw on and a Lee GND filter. I eventually bought an inexpensive Vivatar VND filter (ND2 to ND 1000) for about US$ 42. I figured, I'd give it a try and if it didn't work out I'd only be out less that $50. So far it has worked fine.

I use the 9-stop Hoya HMC ND400 (the 82mm version is mentioned in that very good article you linked fcortese - thanks for that).

I've had no significant issues with color cast (then again, I probably correct for it in post without thinking about it), nor do I find the screw-in to be a problem. For shots using heavy ND filters, I always compose and focus without the filter on, set it all to manual, then place the filter on carefully. Exposure is usually determined by an external incident meter, a "EV calculator" (just a piece of card with equivalent EV values) and then bracketed around my target exposure.

$86 from Amazon, I've considered the Hoya to be a quality filter at a good price.

Agfa

I got a cheap Agfa 8 stop variable for £25 on Amazon. Not done loads with it so far, but seems to work OK and for the price is a decent product to test with.