ND filter choice help

[Headshotzx]

Hey everyone! Need some help with ND filters.

I'm all for B+W and Hoya filters, so recommend me some for the following two situations:

#1 - Being able to shoot wide apertures (ƒ/2.8 and wider) outdoors in bright sunlight with strobes that will nuke either a lot of (or a little of) the sun's ambient. 58mm for my 50 1.4 or 85 1.8, and 77mm for my 70-200 2.8L IS. Needs to retain the ability to focus.

I'm thinking 3 stops ND might not be enough

#2 - Getting smooth silky water in daytime lighting without the need to get a timer remote (that is, more than 30 secs exposure). B+W's ND110 (10 stop) is a little overkill here, yes? I will be stopping down to ƒ/22 most of the time. No need to retain lens focus, but if it can, all the better. UWA will be the 17-40L (thus a concern about getting the edges of the filter in the shot, so stacking of filters is an issue). 58mm and 77mm.

#3 - Same as above, but at wide apertures such as ƒ/2.8 and wider for creative shots like isolating a particular subject in the water, with silky water around it and the far-away background thrown into a creamy blur. Max 30 secs exposure. Lens will be the 50 1.4 / 85 1.8 or 70-200 (58mm and 77mm)

Any help would be good (:

Note that I already have a Hoya 77mm CPL. Oh, another question is, what about stacking filters?

Cheers,
Zexun

[NYPhotog]

In bright sunlight at ISO 100, f/16, a 10-stop ND filter will provide about a 15 second exposure. With this information you can do the math with different ISO's and f-stops to determine your shutter speeds and ND filtration requirements.

[GoneTomorrow]

I use a B+W 1.8 ND (6 stop) for bright daylight water shots and it works very well, no need for ridiculously narrow apertures.

[NYPhotog]

I use a B+W 1.8 ND (6 stop) for bright daylight water shots and it works very well, no need for ridiculously narrow apertures.

I guess it depends on how long an exposure you want and whether or not you choose to use "ridiculously narrow apertures" (i.e. f/11, f/16/, f/22) to enhance depth of field for landscape work. ;)

[Scottes]

I'm just researching this too, so I have a few thoughts.

1. I took a bunch of shots yesterday in bright sunlight, and at f/11 my shots ranged from 1/125 to 1/250. At f/2.8 - 4-stop difference - that would have been 1/2000 to 1/4000. A 4-stop ND gets you back to 1/125 to 1/250, but that doesn't account for the strobes. So I'd be thinking about a 6-stop ND, though I'd also consider getting a 4-stop.

2. Going to f/22 brings those shutter speeds down to 1/30 to 1/60, without an ND. Getting 1/60 down to 30 seconds requires 11 stops of ND. I'd be worried about diffraction problems at f/22, so I'd consider f/16 and 12 stops.

3. Seems like about 8 stops would do here.

A CPL adds about 2 stops. You might not always want the effect of a CPL, so I'd save that for the times you need/want it.

Stacking screw-in filters, as you know, adds to the chance of vignetting. It's less of an issue with a 1.6-crop camera, but can still happen. And it's less of an issue if you're not at the widest - so you might need/want to zoom to 20mm on your 17-40.

To reduce the chance of vignetting, you can get those "super-thin" filters, but beware - you can't stack anything on top of them because they don't have female threads in the front. (At least mine doesn't, a Hoya.)

You have a 3-stop, so get a 4-stop and a 10-stop. With you CPL that will get you, with stacking a max of 2 filters: 2, 3, 4, 5, 7, 10, 12, 13, and 14 stops. Seems like a good range. And adding/subtracting a stop of aperture gives you everything in the range from 1 to 15 stops.

For your smaller lenses, you can get a step-up ring for about $7, allowing you to put 77mm filters on your 58mm lenses. Be warned that you can no longer use the lens hoods with a step-up, so you will then have concerns about flare.

[joosay]

Really good information there, Scottes.

I'm debating if I should get

1. 9-stop Hoya ND400 HMC filter
2. 9-stop Hoya ND400 HMC filter + Hoya HMC ND2
3. 9-stop Hoya ND400 HMC filter + Hoya HMC ND4
4. Hoya HMC ND4 + ND8
5. B+W ND 1000x 110 10-stop filter

I'm leaning towards option #1 or #2 and seeing if I need to get an additional ND filter from there. Also, what do you all prefer - B+W or Hoya?

Note: I have a CPL filter as well.

This will be used on a 450D + tokina 11-16. Hope two filters don't vignette.

Thoughts?

[Jon]

Well, your option 4, I believe, amounts to 5 stops, not the 9-10 of the otehr options. An ND2 adds 1 stop to whatever it's on; an ND4 adds 2 and an ND8 adds 3 stops. Note: adds, not multiplies.

[joosay]

Yeah, I know. I don't think 5-stops with two filters will cut it which is why I'm leaning towards a 9-stop filter and seeing if I would need another 2-stop filter or not.

[WINDY.]

I'd buy a Kenko 3stop ND8 and a B+W 10stop ND filter for different purposes. One for portraiture and one for landscape.

Definitely no 1 filter to do the job IMO.

[joosay]

Point taken. Thank you for bringing this to my attention. I'm still very new to this and didn't really think to use an ND filter for outdoor portraits.

[Scottes]

As a note, I bought the B+W ND 1000x 110 10-stop filter. It may be too much.

This was 4 seconds at f/11 - ISO 400. Equivalent to 16 seconds at ISO 100 - for a bright daylight scene.
http://www.itsanadventure.com/postimages/RockyGorge_104156.jpg

If I had to choose my first 2 ND filters - now that I know the effects of a 10-stop filter - I would get a 6-stop and either a 2-stop or 3-stop. Then I would fill in the blanks as time goes by, eventually having each one so that I don't have to stack.

[joosay]

Interesting, anyone else with the 10-stop or 9-stop filter? Thoughts?