ND FILTERS: how to use them

[anda_m]

<p>Hi all<br>

I am in the long and painful process of learning photography. I start to know my camera and lenses, but I would like to be able to make water+beach+rocks images, where the water would look...unreal, mostly blurred. I am not able to do that , not even at dusk with my minimal shutter speed. I decreased the ISO and the aperture, still not enough. It seems I need a ND filter. My question is: what shutter speed would give me the best dreamy look for the water? What filter factor would I need?</p>

<p>thanks for your help</p>

[peter_leibowitz]

<p>Take a look at a website called bwvision.com . It has a great tutorial about using ND filters. Good luck.</p>

[peter_leibowitz]

<p>The tutorial's called, "The Ultimate Guide to Long Exposures", and is broken into three parts. It should have a lot of the info your looking for.</p>

<p> </p>

[leighb]

<p>Hi Anda,</p>

<p>Neutral density filters are rated by fiter factor, a number that's printed on the filter and shown in the advertising. A factor of 0.3x means one stop; 0.6x is two stops, 0.9x is three stops, and so forth. The highest I've seen recently is 10 stops. The most common filter is the 0.6x (two-stop) type.</p>

<p>You can change any combination of slower shutter speed and larger aperture to increase your exposure by this amount.</p>

<p>The actual shutter speed required will vary with the subject. I would think 1/8th of a second would be a good starting value, then try one or trwo steps either side of that and evaluate the results.</p>

<p>Although I've seen this technique used on countless images, I haven't tried it myself, so the suggestions are just that.</p>

<p>Good luck.</p>

<p>- Leigh</p>

 

[anda_m]

<p>thanks so much!<br>

It's funny, the pier on this web site (http://www.bwvision.com/wp-content/uploads/2009/09/Scheveningen-Pier-II.jpg) is in my current town, near my home :-) and it would be nice to try out his techniques exactly at the same spot (not copy it, just test the filters:-)). Thanks to you both!</p>

[Alan Marcus]

<p>Filter factors (FF) help us compensate for the loss of light that comes about when we mount a filter.<br />The FF value and how to apply can be confusing. Let us see if I can help you.<br />Filters allow some light energy to pass while blocking some energy by absorption.<br />Keep in mind that a modern camera will likely sport a built-in light meter that reads and calculates the exposure "thru-the-lens". This being the case, when a filter is mounted, the absorption of filter will be taken into account by the camera's automation. In other words, the photographer need not worry about filter factors.<br />If a filter is mounted, the photographer can manually compensate. The compensation is based on the known exposure information before the filter is mounted. There are several ways to apply a FF.</p>

<p>1. Multiply the shutter speed (without filter) by the filter factor. The result is the revised shutter speed. Example a filter is mounted with a FF of 4. The uncompensated exposure is 1/200 sec. @ f/11. Multiply 1/200 x 4 = 4/200 which reduces to 1/50. Difficult - these days as most of us are unfamiliar with the math of factions.</p>

<p>2. Divide the ISO by the filter factor. The ISO setting can be used to apply a FF. Assume the FF is 4 and the initial ISO setting is 100. Before mounting the filter divide ISO by FF thus 100 ÷ 4 = 25. Dial in a revised ISO 25 and take your reading. Return the camera to 100 ISO and manually set aperture and shutter speed to the values obtained with the revised ISO applied.</p>

<p>3. Best way for me: Count on your fingers in powers of 2 thus 2 - 4 - 8 - 16 - 32. If the filter factor is 4 then two fingers, compensation is 2 f/stops. If the filter factor is 16, then 4 fingers, compensation is 4 f/stops.</p>

<p>4. Memorize this sequence of shutter speeds listed in one f/stop increments. 8 - 4 - 2 - 1 - 1/2 - 1/4 - 1/8 - 1/15 - 1/30 - 1/60 - 1/125 - 1/250 - 1/500 - 1/1000. Say the exposure without filter is 1/125 @ f/11 - to apply a filter factor is 8, count on your fingers 2 - 4 - 8 this is three fingerer = 3 f/stops. The revised shutter speed will be three increments left of 1/125 thus mount the filter and set the shutter at 1/15 sec.</p>

[david_henderson]

<p>Don't worry too much about the maths. If you want milky -looking water, buy a 10 stop ND filter to fit your lens and each time you want to use it, take a series of exposures at different shutter speeds checking each on the LCD screen till you a comfortable with the effect you've got. Then set the camera to shutter priority and keep working at that speed. You'll often find that one or two steps faster or slower doesn't make a big difference.</p>

<p>The reason for this is that the exposure needed to create a certain effect in water varies with how fast the water is moving- you need a different speed for a torrent than for a river ambling slowly by; a different speed for waves crashing onto rocks than you do if the sea's lapping gently onto sand and so on. Years ago, shooting film with no ability to review, we had to learn rules of thumb for this sort of thing. We can do much better than that now.</p>

<p>There is another alternative which is much cheaper albeit that otherwise it might not be to your liking. Get up early. The photograph attached is a 4 second exposure taken at f16, ISO 200. No filters, just being out and in place a good half hour before dawn. </p><div></div>

[James G. Dainis]

Alan's advice is very good. If you use auto exposure you don't have to adjust anything, the camera will automatically adjust for the filter. Let me emphasize that his four methods following that advice are for a camera set to <U>manual</U> . For instance, if you are using <U>auto exposure </U>you would not want to set the ISO from 100 to 25 as in method 2.

[lilly_w]

<p>The appropriate shutter speed would be dictated by the light value (i.e. brightness), rate at which the water is moving, and your desired effect. If you currently have a polarizing filter you could experiment with that. Pols generally have a 2-stop (or thereabouts) loss. Try early morning or late evening when light values are low.</p>

<p>Not all ND's are created equal as some (cheaper) introduce a color shift, i.e. <em>not </em>neutral...close but not exactly neutral. While more expensive than others, I find the color-rendering of B+W ND filters to be very good.</p>

[dbcooper]

<p>Sent email (reply too lengthy to post).</p>

[anda_m]

<p>thanks to you all! I have printed the tutorial and <a href="../photodb/user?user_id=2109369">D.B. Cooper</a> 's email and I will get back! thanks again for your time and have a good weekend<br>

Anda</p>

 

[mart_e]

<p>Not sure where you are, but 10 stop ND filters are like gold dust. I ordered mine recently from Lee Filters (UK) - it is going to take 9 months (they only manufacture to order). <a href="http://www.leefilters.com/camera/news/ref:N4B8F96517C324/">Lee Filters The Big Stopper</a>. Also quite expensive. I experimented with ND filters some time ago, and always found unwanted colour shifts (tending towards magenta).</p>

[david_henderson]

<p>Mart E. Then why did you buy a Lee filter? I ordered a B+W from Amazon late last year and whilst they were initially speaking of a 3 month delay I had it in two weeks.</p>

[Palouse]

<p>I'm sorry this is a long painful process. For me the 40+ year journey has been fun. You do have my sympathy. Maybe another hobby is in order.</p>

[anda_m]

<p>I did buy a BW 10 stop filter from a local (online) shop here in The Netherlands and it arrived in 3 days, I had no idea it's such a rare thing. It arrived yesterday and I didn't use it yet, first I am reading your comments, thanks to you all.. It's painful and frustrating because I've had some nice opportunities and my pics are bad due to lack of knowledge and experience, I realised photography is like a foreign language: you need practice, can't learn it over night, no matter how good your books are! And, with other constraints, the time I have to practice is also minimal...Sorry, now it's philosophy :-).</p>

[mart_e]

<p>David, I will hopefully get mine sooner than the 9 weeks too (realised I had a typo in my original response meant weeks not months - too late to edit now). I rang round a few people and looked through Amazon - that was the quickest that I was quoted, and most people said it would most likely take longer (this was for either B+W or Lee) - it was also after the VAT hike, and I was told that there was a real spike in orders prior to then that would contribute to delays.</p>

[dbcooper]

<p>To clear things up a little, I'd like to note that the B+W ND 110 (10-stop) filter is a round screw-on type, and the Lee 'Big Stopper' 10-stop ND is 4"/100mm square glass, and is made for the Lee slot-in filter system. The B+W filters are evidently going through production changes, with slim rings (no front threads) and filter coating being variously added to their ND110 lineup.</p>

<p>Some B+W ND110 sizes are hard to get depending on thread size, especially 77mm and 82mm (mostly for Nikon and Canon users respectively). There are uncoated, single-coated and multi-coated filters listed in the 77mm size at B&H, and all are backordered. The standard (with front threads) ring in 82mm size is listed as discontinued. Evidently, going forward, B+W will make their ND110 filter in 82mm slim mount only (no front threads). All other standard filter sizes 72mm and smaller are commonly available at the moment. That could explain some of the wait-time confusion. I got my 77mm ND110 about three years ago. It was normally in stock then - no problem - but that was then and this is now. If you want a 77mm or 82mm ND110, if you hunt around you might find one in stock somewhere.</p>

<p>The Lee 'Big Stopper' has been a backorder item since it was first shipped last year. I waited about 11 weeks for mine. If you want one, you'll just have to order it and join the waiting line. That's just how it is. AFAIK, no one else makes a 10-stop 4"/100mm square filter.</p>

[szrimaging]

<p>Anda, are you using a screw type filter? If so, I highly reccomend tryin the Tiffen 7-stop ND with IR blocking. Since some digital sensors are more sensitive to IR light, if you don't block it out the image will receive a color cast. I currently use one and will vouch for it's effectiveness and construction. I believe B+W also makes one with an IR-cut filter built in.</p>

<p><a href="http://www.bhphotovideo.com/c/product/688437-REG/Tiffen_W77IRND21_77mm_Combination_Neutral_Density.html">http://www.bhphotovideo.com/c/product/688437-REG/Tiffen_W77IRND21_77mm_Combination_Neutral_Density.html</a></p>

[anda_m]

<p>Thanks, Zach and D.B Cooper! I have bought already the BW 10 stop, it says only "coated", in 77 mount so I will not look for something else now. It was definitely not hard to get, it arrived immediately. I ordered it from a local site, herein the Netherlands. Maybe, for once :-), they are harder to find in the US. Here is the link, they probably can arrange delivery in the US. THANKS ALL FOR YOUR TIME!<br>

http://www.kamera-express.nl/Objectieven-en-lenzen/Filters_lensbescherming/Grijs_Filters_ND/B_plus_W_77mm_ND_110_Grijs_Filter_plus_10_Stops_belichting.htm</p>

[bob_bill]

<p>Anda, I have a post on Portraits re using variable nds with a before and after. Excuse the posing, I couldnt see the subject from where I was standing. My object was getting a sub f/2 aperture for bokeh. Take a look at the second shot, I think it looks like a painted background. 8 stops nd. I was shooting at 1/160 sec which barely blurred the water. If water blurring was the goal, could have gone to f/16, 6 stops and taken shutter to 1/2 sec and could have screwed in my polarizer for 2 more stops taking it to a second. Couldnt hand hold my individual nds in front of lens and be photographed. </p>

[jcuknz]

<p>Since you have purchased your x10 ND filter you probably will be happy ... but if you find you cannot handle over-exposure in bright sunlight there is another approach which is to use two polarising filters. Either a circular and a linear or two linears. When rotated against each other they reduce light transmission to near zero. I would suggest one of each would be the better deal becuase you then have a polariser to darken skies when the sun is out and there are fluffy white clouds etc :-) A linear filter may affect your automatic focusing system. From the size of the filter you have purchased it sounds like you have a DSLR with a wider range of f/stops than the P&S user has so the extra control may not, likely will not, be needed by you unless you want to take photos of buildings in a crowded street and need the long exposure to blurr out the people and vehicles. Note linear and circular describe the construction of the filters not their overall shape.<br>

To answer your basic question I suggest you need a shutter speed of 1/10 but preferably longer for the water into milk effect.</p>