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Author Topic: Neutral Density Filters  (Read 7283 times)
Sean Evison
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« on: December 19, 2008, 04:57:22 AM »
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I am trying to find an ND filter that will slow down a shutter speed from (for example) 1/100 to 15+ seconds.


I am not sure what this is in terms of f-stops so not even sure if this is feasible.


Any suggestions?



Kind regards.



Sean Evison.
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Baxter
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« Reply #1 on: December 19, 2008, 05:40:48 AM »
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B+W do a 10 stop ND filter. I've recently bought one and it works well. Not sure if this is sufficient for you?
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B-Ark
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« Reply #2 on: December 19, 2008, 06:05:11 AM »
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Singh Ray make a variable ND filter, adjustable from 2 to 8 stops.

Also, although its low quality, the glass used in welding goggles, is very cheap and very dark.
« Last Edit: December 19, 2008, 06:07:02 AM by B-Ark » Logged
bjanes
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« Reply #3 on: December 19, 2008, 06:14:13 AM »
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Quote from: Baxter
B+W do a 10 stop ND filter. I've recently bought one and it works well. Not sure if this is sufficient for you?

That should be sufficient for the OPs purpose. The difference between 0.01 s and 15 s expressed as a ratio is 0.01/15 = 0.000667. Taking the log base 2 of this ratio gives -10.55 f/stops. Microsoft Excel does such logs.

Bill
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Dave Carter
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« Reply #4 on: December 19, 2008, 08:07:08 AM »
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Push comes to shove.  You could stack two.
Certainly not as good, but - - - -
Dave
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01af
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« Reply #5 on: December 19, 2008, 08:19:13 AM »
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Filter manufacturers like B+W make high-density ND filters. Note that for filters denser than 8 (3 stops), not the factor but the logarithm thereof is specified.

So an ND 1.8 filter, for example, has a filter factor of 10^1.8 = 64 = 6 stops. ND 3.0 is 10^3 = 1,000 = 10 stops. ND 4.0 is 10^4 = 10,000 = 13 stops. That's about the densest you can buy off-the-shelf. These are quite expensive because ultra-high densities are hard to manufacture reliably and consistently, and dealers usually don't have these in stock.

And beware: Do not confuse ND 4.0 (13 stops) with ND 4 (2 stops)!

-- Olaf
« Last Edit: December 19, 2008, 08:22:59 AM by 01af » Logged
Dan Wells
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« Reply #6 on: December 19, 2008, 09:26:19 AM »
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I know a few photographers who stack neutral density gels (rather than the glass filters) when they want a lot of ND... The darkest ND (stacked gels) I've heard of anyone using is a shot taken with 27 stops (if the metered exposure was 1/1000 at f16, after the ND, it would have been a 4 hour exposure at f5.6!) You run out of light in a day to get any denser than that! If you want even more neutral density, using a lens cap is always an option - there is some light penetration on the quantum level, and I'm not sure how much darker than 27 stops an average lens cap is  I wonder how dark astronomers' solar filters are (perhaps in the 10 stop range)?

                                                               -Dan

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Sean Evison
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« Reply #7 on: December 20, 2008, 03:58:17 AM »
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Many thanks to everyone for the replies -  does anyone know of a UK based site where I can purchase a B+W 10D?


Embarrassing confession #1 - I'd seen B+W filters advertised but assumed they were only for black and white photography - oops.


Kind regards.


Sean Evison.

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kikashi
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« Reply #8 on: December 20, 2008, 08:02:11 AM »
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Quote from: Sean Evison
Many thanks to everyone for the replies -  does anyone know of a UK based site where I can purchase a B+W 10D?
Try filterdepot.co.uk. I bought a 67mm B&W 1000x ND filter from them in January for 38 (plus VAT and delivery). The service was good.

Jeremy
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Sean Evison
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« Reply #9 on: January 07, 2009, 11:54:33 AM »
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I have had no success at all in finding a UK supplier of the 3.0 ND filter.


Can anybody recommend a non UK supplier that will mail this item to the UK?



Regards.



Sean Evison

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Mark_Tuttle
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« Reply #10 on: January 07, 2009, 08:11:29 PM »
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I have a B+W ND4, which is 13 stops.  On a sunny day it will accomplish what you want, but keep in mind that you cannot see through it and my experience has been that with a Phase One P45 DB there is an increasing color shift the denser the ND filter is (I have the B+W 2 stop, 3 stop, 6 stop, and 13 stop ND filters).  The only way I was able to neutralize this was to shoot a Gretag Macbeth color chart and take the TIF raw file, convert to Adobe DNG and run through the DNG Profile Editor.  I wrote down all the information that came up and used that as a profile because trying to do it simply by setting the WB with an eyedropper never gave good results.  A DSLR may be a totally different animal but I suspect the filter is the cause.

Mark

Quote from: Sean Evison
I am trying to find an ND filter that will slow down a shutter speed from (for example) 1/100 to 15+ seconds.


I am not sure what this is in terms of f-stops so not even sure if this is feasible.


Any suggestions?



Kind regards.



Sean Evison.
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Mark Tuttle
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« Reply #11 on: January 08, 2009, 05:21:46 AM »
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Quote from: Sean Evison
I have had no success at all in finding a UK supplier of the 3.0 ND filter.

Can anybody recommend a non UK supplier that will mail this item to the UK?
Sean,

Did you try filterdepot.co.uk, as I suggested above? They list 3.0ND filters on their site in a variety of sizes.

Jeremy
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Sean Evison
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« Reply #12 on: January 12, 2009, 03:53:41 PM »
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Jeremy,
I have tried Filterdepot but they don't stock a 72mm version....thanks for the info anyway.


Sean.
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kikashi
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« Reply #13 on: January 15, 2009, 03:36:07 AM »
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Quote from: Sean Evison
Jeremy,
I have tried Filterdepot but they don't stock a 72mm version....thanks for the info anyway.
You're quite right, of course: how odd. You could always buy the 77mm version, which they do have, and a step-up ring. I wish I'd done that instead of buying a 67mm which I now can't use on my newly-acquired 24-105L. Ah, the wisdom of hindsight.

Jeremy
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Baxter
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« Reply #14 on: January 15, 2009, 03:53:49 AM »
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Sean

I bought my 10 stop ND B+W in 77mm from Robert White (my local toyshop..). Daymen International are the UK importer for B+W so they ought to be able to advise of a supplier if RW out of stock.

Image below was from Sunday using the 10 stop full ND with a Lee 1 stop ND grad on the sky. Ended up at 1 minute @ ISO400.
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Dustbak
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« Reply #15 on: January 15, 2009, 03:59:20 AM »
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I have several ND4.0 filters (13stops), these AFAIK, come nowadays only in Kodak gel form (if you need them at 77mm or larger). I also recently bought a 95mm ND3.0 (10 stops) Heliopan filter. Heliopan can deliver the filter you want in that filterthread. You do need to order it via a dealer since Heliopan refuses to answer emails from photographers for some weird reason.
« Last Edit: January 15, 2009, 04:00:47 AM by Dustbak » Logged
Panopeeper
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« Reply #16 on: January 15, 2009, 06:43:58 PM »
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One linear polar filter on top of a linear or circular one gives a variable ND filter, from about 2-3 stops to total blackness.
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Gabor
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