Which ND filter to buy

[tandeejay]

I keep on going on walks and finding waterfalls and wanting to get those photos with the long exposure, but I'm just not able to get that shutter speed low enough for my liking, so I have finally come to the realization that it is time to add an ND filter or 2 to my kit.

But the question is, which one do I need? Going away on a camp in June where I will likely meet some waterfalls so want to be ready when they do show up, so have until June to get my head around this question.

I have a CPL so it is likely that I would want to stack the ND filter with the CPL. This will be on my 16-80mm lens, so vignetting might be an issue at the wide end with stacked filters, so probably don't want to have to stack too many ND filters.

Any waterfall I'm likely to meet on camp would be close to the middle of the day (walk in/walk out/waterfall in the middle of walk, not practical to time walks for early/late afternoon waterfall meet... )

Looking at my local camera store, I can see ND filters ranging from 2 stops all the way up to 10 stops, so not really sure which one would best suite my need.

(happy to support the sponsors of AP when I do get around to purchase...)

Regards,
John

[arthurking83]

I remember seeing that a Nisi vari ND was a little better(overall) than a more expensive and similarly ND rated Lee type.
All quite expensive tho(depending on actual filter size).

72mm filter for the 16-80 would cost you about ~ $200 or so.
You can get cheaper fleabay types for more like $30-50.
I've been thinking about them, just to give them a go to see for myself that they're as crapola as you'd expect for those prices.

Even at midday, stopped down sensibly(I'm talking f/22 or smaller) and with a ND8, you should get what you're after.
AND!!! Don't let anyone tell you that you'll get too much diffraction at f/22 or smaller .. it's basically BS!
More likely at slower shutter speeds, you'll get movement in foliage, and or some flutter in the camera/tripod setup that will cause more sharpness loss, then diffraction will cause.
So the reality is that shooting in those conditions diffraction(as a cause for concern) is a moot point.

[Brian500au]

There is just no easy answer here. There are days when you will want a 3 stop, days when you want a 6 stop and days where you could use a 10 stop ND filter. I have never owned or used a variable filter - but I suppose if you are not going to use it much then that might be something to consider.

I have all three filters - but for years I only owned a 10 stop. If I had to purchase one today (and only one filter) I would go for a 6 stop as this seems to be a good compromise.

You also need to consider if you go to the Lee type of square slide in filters or just a screw in type. The advantage of the Lee type filters is you can stack them quite easily - and they have a graduated range as well but they are an expensive option by the time you buy the lens adaptor etc.

In my opinion filters can be a large investment for little real return. Mine spend more time in the bag than on the front of my lens.

[Geoff79]

Similar to some tales above. I have a whole collection of ND filters for both my lenses; barely use them at all. Lately I’ve been playing with a ND 100 -I think it’s called - filter. Got some interesting results on the middle of the day, without any distinct colour cast. That’s really the only one I play with as the results from the ND 2 to ND 10 filters never did much for me unless light was already low. Otherwise, I just prefer to use the CPL filter and lower aperture than I’d normally use, if trying to get some slowed motion.

The other function I used during the first holiday with my Canon 70D, and then never since, lol, was in camera stacking, or something like that. I’d take my 5 shots or whatever it was - all at same exposure, or not, if you wished, and then it would blend together in camera. This was effective for giving me some silky looking waterfalls in the midday sun, if you have something similar?

Regarding the cheap filters, some I’ve got are ok for their purpose, but I’ve noticed in the cheap ones it can be hit or miss with some pretty ugly colour casts.

If I remember/get time I could try and have a look what’s what, but I haven’t used them for so long. I think maybe the Citiwide ones were ok, for cheapies. I think...

[arthurking83]

I just had a gander at some of my midday water images shot some years back(took me this long to find them due to no keywording/catalogging!)

At f/20 something I was getting 2-6 sec shutter speeds at ISO100, at 12:55PM in July.
Only problem with filters is that unless you note down if you use them, there's no info as to what was used at the time.
I'd say most likely I used a CPL tho.

Obviously you can't make blanket statements about exposure needs as so many factors need to be taken into account, location being the priority factor!
ie. is it in a valley, with lots of tree cover. Tree cover makes shade, so even at midday you can achieve multi second exposures with small apertures.

Down to about f/22, I can't see any issues with diffraction(that can't be corrected), but on a series of shots at f/32 it was harder to recover some detail in some rocks.

I have some images shot in the open area of the river(f/32) ISO100 .. probably used a CPL, definitely no ND! ... doesn't look like a grad was used either, like I might use. Shutter speed was in the 3-5sec range.

So with that in mind, and using about 10-15sec as a shutter speed range(for that really smooth milky water effect), I'd estimate that an ND8(3 stop) would be about OK.

Also note with making guesstimations: the faster the motion of the subject, the more blur effect you get with (relatively)faster shutter speeds too.
ie. with a vertical water fall water speed(velocity) is basically at terminal velocity, or quite fast. So a 1 sec shutter speed will give a smooth-ish milky effect. 2 sec a bit more .. etc.
But trying to get a 30sec shutter speed is an almost futile endeavour to get it the water flow more milky. Obviously it will be, but not 30x more milky. There's a limit.

Also where this info comes in useful tho, is that if you want a milky smooth effect on a slower moving subject, eg. a slower moving river, then obviously the slower the shutter speed, the more milky the effect of the water.
So, lets assume you have a vertical waterfall, and a slow-ish flowing stream beyond that.
At 1/4 sec exposure, the waterfall itself will be milky smooth(vertical water moves quickly) .. but the slower moving stream will be captured in stop motion freeze frame .. ie. not milky smooth.
So your target shutter speed for that situation would be at least 2sec or so.

I'm fairly sure that even in full sun, at f/22 ISO 100 and a ND8 filter, you should get around 3 sec exposures easily. Add some cloud, some shady cover, etc .. and you're probably into the 5+ sec range.

I'd also say that another aspect of trying to achieve a similar effect could be to use image stacking.
That is, take you shots in the typical unfiltered manner(f/22 ISO 100, 1/5sec or whatnot). Take a few shots(tripod, minimal movement, etc.
Stack those images(you can get free image stacking software that works OK).
The idea is that because the water movement is dynamic and pretty much sure it's never going to be the same, the stacking process will render it blurred.
Same with foliage movement too tho, but this is going to happen whichever way you go anyhow!

On the same train of thought, and assuming you use Photoshop of some form(ie. layers) .. you could even try using that feature as a pseudo stacking technique. Have no idea if it'd work, as I don't use it.
That is, again a series of exposures, and in PS, you could layer the part of the water(fall or flow) over and over, but if the exposure is quite fast enough to freeze foliage motion, leave them alone.
This way you'd get the milky water effect, but not the (sometimes annoying) moving foliage effect.
Would be interested to see if this would work.

[arthurking83]

Just a heads up:

While I had a bit of time to waste(just now) .. stumbled onto Matt Grangers website, and he's also recently done a test/review on ND filters.
Didn't see any vari ND filters(and note that they are expensive and more prone to anomalies!) .. but he's done a recent test on ND3(0.9 or 3 stop filters) and on 10 stop(ND1000 or 3.0) set as well.

note that a 10 stop filter is always going to be more expensive(relatively) than a 3 stop filter .. etc. etc.

Reason I post this info is that it's about the most current(in terms of time).
My earlier reference to ND filter tests would have been many years ago and both tech/quality/performance changes over time as manufacturers improve their products. So I'd recommend if you seek out any other reviews, look for the most recent.

FWIW: 3 stop test MG rates the most expensive as his first choice, but I reckon in terms of value for money, the Hoya HMC version at about $50(ish) would be about ideal.
for the 10 stop test, and maintaining a sane price point! ... Hoya Solas seemed to be about right. ~ $120 or so.

[Boo53]

Relatively new on the market are the NISI range. I like them and Dylan Toh has done reviews on them.


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[Liney]

I don't know the answer to the technical question, but I picked up a set of three ND filters as well as a bunch of other filters and stuff from a company called Neewer. Check out ebay, a set of three ND filters comes in at just over $20 depending on which size of filter you need. I'm not sure if this is AUD or USD but its still a decent price and the filters I've used have been good quality.

[Jaded62]

I use a Lee 4x6 GND 0.9 on my 77mm Canon lens. It is a bit fiddly trying to get the the holder attached to the lens so this is something best done early and not on the spot when you want to shoot. Once fitted to ability to slide the 4x6 up and down to suit the shoot helps a lot. I also use a Lee 4x4 ND 1.2 for slowing things down. Both great filters and are worth the money.

[Nick Cliff]

Have a set of Nisi filters and they are fine for my purposes. Nisi is possibly a mid price filter using a schott glass equivalent manufacturing process. You will lose some sharpness with tests I have done however for sunrise shots over the sea a reverse grad is great or in difficult lighting conditions in rain forests sometimes an ND grad is a worthwhile compromise.
https://live.staticflickr.com/618/23008363916_cf5f581b68_h.jpg (https://flic.kr/p/B4aSZA)Row of ancient Antarctic beach tree buttresses in the mist. (https://flic.kr/p/B4aSZA) by Nick Cliff (https://www.flickr.com/photos/126962485@N05/), on Flickr
This photo was taken using an ND soft grad filter used vertically with the dark side on the lighter side of the tree buttress in light rain and fog.
cheers Nick