View Full Version : ND filter to blur water, clouds, people ...

Mark McCarvill
10-May-2005, 07:42
Hi folks. Which level of ND filter would you recommend for someone who wants to experiment with (a) blurring water, clouds, etc., David Fokos style and (b) “erasing” people from busy tourist attractions?

I use B+W filters and their midrange ND1.8 has a 6-stop exposure factor. I looked up the reciprocity information for my film (T-Max 100) and assuming an initial meter reading of 1 second, applying a factor of 6 would (I believe) mean 64 seconds before reciprocity correction and 207 seconds after reciprocity correction. Based on your experience, is 3.5 minutes in the ballpark for accomplishing what I want to do?

The strongest B+W filter I found is ND6 (20 stops). What would one use a 20-stop filter for?


Steve Hamley
10-May-2005, 07:53

This looks like just what you need, although pricey - a Singh-Ray vari-ND.



10-May-2005, 09:14
The super heavy duty ND filters (like the 20 stop one you mentioned) are used for solar astronomical photography.

Paul Butzi
10-May-2005, 09:37
I have two ND filters I use to extend exposure times, one B+W 103, a three stop (8x) filter, and one B+W 106, a six stop (64x) filter. I had to special order the 106.

I've used them often. Examples at www.butzi.net/newgalleries/pacific/slowtime.htm (http://www.butzi.net/newgalleries/pacific/slowtime.htm).

I don't know what reciprocity departure table you're using for TMX. I would use an exposure of about 130 seconds for an indicated exposure of 64 seconds.

In practice, with the 8 stop filter, I meter the exposure, calculate the exposure in second, multiply by 60 to get minutes, then interpolate roughly based on the little chart glued to the top of my meter. The difference between 60 seconds and 64 seconds is slightly less than 0.1 stop - smaller than the resolution of my meter.

Jeff Dyck
10-May-2005, 09:56

You may also consider changing your film for these long exposure shots. T-Max has excellent reciprocity characteristics as films go - "older" style films like Tri-X or FP4+ require a lot more reciprocity correction at long exposure times that you can take advantage of. I too shoot a lot of T-Max, but always have a couple holders loaded with Tri-X in my bag for just these kind of shots. The reciprocity characteristics are such that after your metered (uncorrected) exposure hits about a minute, your T-Max 100 is actually "faster" than the Tri-X (and it just goes downhill from there...). There is a whole other discussion about the differences of the "look" of Tri-X vs. T-Max, but you can read back in the archives for that!

Mark McCarvill
10-May-2005, 10:08
Beautiful work, Paul. And particularly relevant examples, since I will make some long exposures on the beaches of Prince Edward Island. The reciprocity data I used in my example is from http://home.pacbell.net/mkirwan/Reciprocity_Tables.htm. I will try your suggestion as well, which matches what I got from Kodak. And of course I will experiment.

Andrew, thanks for the 20-stop information.

Jeff, good point about trying Tri-X. Hadn’t thought of that.

And Steve, the Singh-Ray filter looks amazing, but you’re right about pricey – “only” $340!


Paul Butzi
10-May-2005, 10:28
"beaches of Prince Edward Island"

Oh, sure. Go ahead and taunt us all mercilessly!

Seriously, I haven't been to PEI since the bridge opened. How have things changed?

Mark McCarvill
10-May-2005, 11:02

I haven’t spent much time in PEI since the bridge opened, but my understanding is that the doomsayers and the bridge boosters were both wrong. PEI hasn’t lost any of its charm, nor has there been a sustained economic boom, apart from the mini-boom during the construction period. Some Island businesses suffered because Islanders can more easily shop off-Island, while tourism (especially golf courses!) benefited since visitors “from away” can get to the Island (and back home) faster.

A bigger change to the look of the Island has resulted from erosion – the Cavendish beach area for example loses about 3 feet of shoreline annually. And the beautiful dunes at Panmure Island (which you may have seen on the cover of a past PEI visitor guide) are essentially now gone.

11-May-2005, 05:20
Hi Mark, where are you from, if not PEI? I didn't know of any LF users on the Island! If you are ever over in Moncton, let me know and perhaps we can grab a coffee or something!

Anyway, I would say if you are looking to get moving clouds etc, the weakest filter you'll use is a 6 stop (64x). A 10 stop (1000x) would probably be necessary on really bright days though, even with 100 ISO film, so if you could afford it, I'd invest in both (hope your lenses are small, these filters cost a fortune!).

For my work with 8x10 I focus on the Nude in water, and seldom use more than a 1 stop (2x) filter, just to give the water an extra kick - http://www.ebb.ns.ca/retro/OT1/pages/810-02-118.html and http://www.ebb.ns.ca/retro/OT1/pages/810-03-143.html are examples.

Peter Hruby
13-May-2005, 08:00
What about using two linear polarisers at the same time? Rotation of these two polarisers determines how much light will be passed through the lens...

Mark McCarvill
13-May-2005, 13:07
Hi Eric,

Very nice work! I'm originally from PEI but live in Toronto now. I'll be in Nova Scotia (staying in the Hantsport area and photographing Cape Chignecto, Port Grenville, Five Islands, Blomidon and Peggy’s Cove) and PEI in early August. No plans to visit Moncton at this point but if I do I'll look you up!

With respect to the filter, I picked up a Heliopan 8x ND filter from B&H for US$40. Seemed like a good starting point.