[serious]Photography - ND filters

[wossname]

Has anyone used ND filters before? I was thinking of getting one so I can use some new techniques I've not tried before, like long-shutter shots of waterfalls and so forth.

What rating is best to go for? I was thinking of a 6-stop one to start with.


...but now I've just seen this:

Tip: use a polarising filter
A polarising filter offers a similar light reducing option as a Neutral Density 4x filter. Add two polarisers together and you can get an infinitely variable ND from 4x to very strong (almost black) by rotating the front one.

Your thoughts please.

[penagate]

I haven't heard of stacking CPLs before but I can imagine you might have problems with uneven exposure (perhaps more pronounced vignetting with wide angle lenses) and maybe colour shifts.

I would go for an 8-stop ND filter which will give you a reasonable increase in exposure times when shooting at say f/11 or smaller.

Let me know how you go as I would like to get one for myself too.
Are you looking for a screw-on or a drop-in?

[penagate]

Alternatively you could try something like this:
http://www.singh-ray.com/varinduo.html

I am assured that its quality matches its price.

[abhijit]

Go for a partial ND filter. They are useful for shooting waterfalls. You can rotate the black part to reduce the light thrown by the sky and the white part to capture the waterfall. That's the only use I can think of.

Also, do not buy cheap filters. I have made that mistake and it is a waste of money.

[mendhak]

I'm looking at the URL in your first post. It looks like the ND is simply making the whole shot blurry. Is that what it does? Maybe you could find a page that shows lots of before and after examples?

[abhijit]

I'm looking at the URL in your first post. It looks like the ND is simply making the whole shot blurry. Is that what it does? Maybe you could find a page that shows lots of before and after examples?

http://www.flickr.com/photos/awfulsara/51300446/

[mendhak]

Ah interesting. So how about his next shot:

http://www.flickr.com/photos/awfulsa...n/photostream/

Would that have been taken with an ND (two shots, layered)? (They should just call it HDR!)

[mendhak]

I understand penagate's comment on this photo now:

http://www.flickr.com/photos/mendhak/3153203893/

It does look like something an (G?)ND could do. However, this was the result of using a circular polarizer. I've been ignorantly using the circular polarizer to get various sky effects without knowing that it could sorta kinda maybe do the same thing as an ND.

[wossname]

No Mend, an Neutral Density filter merely restricts the amount of light entering the sensor, it doesn't make anything blurry. The motion blur is a result of the camera being forced to use a longer exposure time - which is the goal.

A polarizer merely limits certain rays of light that are vibrating the wrong way, there's obviously an associated drop in light levels in side the camera but CP filters are still designed to let as much light through as possible.

Right, I've just tried the "two CP filter" trick and it doesn't work in the way that they above article (see the first post) describes. I'm not sure if this is because my two CP filters are from different manufacturers or what. All I really saw was a very mild darkening of the shot, BUT the really eye-catching effect I did see was a wild change in colour cast between blue (an almost cyanotype effect) and yellow. As if the colour balance had gone insane.

That's a neat effect in it's own right but I'm not interested in that right now.

I'm quite disappointed that it didn't work though, I wouldn't want to pay £80 (or whatever) for a proper fixed ND if I can fake it out for free with the two CP filters I had already. Oh well.

Pena, thanks for the tip, I'm looking for a screw-in type, mainly because it's easier to handle. I don't think I'd be using it often enough to warrant a drop-in adaptor.

[schoolbusdriver]

I'm not sure of the EXACT effect you're after, but here are a couple of experimental shots I took in the local park. Trees & shrubs make taking pics of this conservatory difficult, and the orientation is such that the sun is never behind you, so a ND filter is needed - more specifically a graduated ND filter - rotated to darken the sky in this case. These aren't edited, apart from resizing. You can stack GND (& ND) filters to darken, say, the top & bottom of a shot, leaving the centre section lighter etc. To blur flowing water without blowing the sky you'd probably need a longer exposure time, and a stacked GND / ND filter combination, with exposure compensation. Oh, and a bit of patience.

1) No filter. Sky is blown.



2) Graduated ND filter. Darker, and a much better sky. Now all the information is available for editing - far easier than trying to recreate a realistic blue sky. Could also have stacked a CPL to get the sky bluer - but it may have looked silly on a winter snowy shot. Note how more detail stands out in a horizontal bar across the centre where it's at it's brightest (minimum filtering).



I know the perceived wisdom is to get the best filters that you can - which usually means the most expensive, but you can get good results from something 1/100th of the price - or costing next to nothing with a little ingenuity (motherboard anti-static bag perhaps ?)

[wossname]

I'd rather have a ND than a GND, because I can always underexpose slightly and lighten areas in software later if need be. I thought GNDs were becoming less popular for that very reason.

[Merrion]

Has anyone used ND filters before? I was thinking of getting one so I can use some new techniques I've not tried before, like long-shutter shots of waterfalls and so forth.

What rating is best to go for? I was thinking of a 6-stop one to start with.


...but now I've just seen this:


Your thoughts please.

I like the two polarisers idea although it may have funny results on things that do polarise light such as water or the sky. For infinte stops a lens cap is the cheapest option

[wossname]

Yeah, the 2 CP filters didn't work at all for me. Perhaps I'm not doin' it rite.

So anyway I went and asked at Jacobs about prices for ND gear and I ended up buying on the spot!

I got a Cokin 52mm adaptor plate, a filter holder and a Cokin ND8 filter, all for the rather small sum of £42!

The kit looks a bit large and unwieldy but it doesn't feel that way once it's on the camera. The construction is solid but not heavy. I've got my CP filter between the ND and the lens, so I can still spin the ND filter around to make sure my CP filter is orientated correctly. Actually it makes the CP easier to manipulate because it's a larger item to grab hold of.

And another little bonus is that the small amount of added weight on the front end should help to reduce camera shake slightly.

Comparison photos here...
http://www.flickr.com/photos/adamneilward/4500646902/

So Pena, I'd recommend the slot-in type actually, it's not as much hassle as I thought it'd be.

[Shaggy Hiker]

What kind of polarizers? The effect is pretty dramatic for linnear polarizing filters, but it may not work at all for circular polarizers (haven't tried). The linnear polarizing filter is filtering out light that is not parallel to some plane. If you put a second one in front of it, then rotate it 90 degrees, then the two of them filter out almost everything. You can see the effect with two pairs of polarizing sunglasses if you look through both, then rotate one 90 degrees relative to the other. Just for your information, it is generally easier to rotate the pair that is NOT on your face. You can see a similar effect if you look at most LCD displays through polarized glasses, though in that case it is easier to rotate your head.

[wossname]

With my CP filter I can black out any LCD screen, but when I double them up and sloooowly rotate the front one 360 degrees, the most that happens is that I get either an extreme blue or yellow cast. The brightness barely decreases at all.

[Merrion]

I have a UV filter as well - that with the cicular polariser is what is needed for all the cloudless sunny days we get here in Dublin :-)

[Shaggy Hiker]

I'm not familiar with how CP filters work, just linnear polarizers (LP? or has that already been used to death).

[schoolbusdriver]

I'd rather have a ND than a GND, because I can always underexpose slightly and lighten areas in software later if need be. I thought GNDs were becoming less popular for that very reason.

GND filters are almost mandatory in landscape photography - they can eliminate the need for editing. Although software editing is part and parcel of digital photography, I'd rather make a correct exposure and post process as little as possible.

The trouble with using just polarisers is that light reflected off many materials - particularly biological matter - is polarised, so you end up with unusual tints in in one area while trying to enhance another.