Ultimate Guide For Long Exposures – Part 3

Tutorials | 6 Oct 2009 | 46 Comments

Joel Tjintjelaar

How to calculate the exposure time?

Choosing the right exposure time when using ND filters can be quite confusing.

First of all, do a light metering without the ND filter. Most DSLR’s have a built-in light metering function. Just set your camera to aperture priority (AV for Canon, A for Nikon), select the aperture you want to use and press your shooter about half way in. The proper exposure time will appear on your LCD. If you camera can’t do this, use a light meter.

Remember the shutter speed on the LCD and go down the number of stops that your ND filter filters. Let’s say your camera calculates an exposure time of 1/500s without your ND8 filter. What shutter speed do you need to use with the ND8 on your camera? Easy. Remember, ND8 is equal to 3 F-stops. So, just go down 3 full stops of shutter speed. 1/500s: 1/250s – 1/125s – 1/60s. Now you put on your ND filter, set your camera to manual with the aperture you’ve chosen earlier and a shutter speed of 1/60s.

Now, calculating the exposure time can be easy if you just need to go down 2 or 3 stops. But going down 10 stops might be difficult without a calculator… So, for your ease (and mine), I created this chart seen below (click to view it large).

chart 2

I think it might use a little explanation. The first line resembles the shutter speed given by your camera without a ND filter (the line that starts with 0, 0, 0, 1/8000s, 1/4000s, 1/2000s etc). That is your reference point. Imagine you’d want to use a 6 stops ND filter. First you meter the light with your camera without the filter. Your camera might say you’ll need a shutter speed of 1/500s. What shutter speed do you need to use with the ND filter? Go to the top row (row’s are horizontal, column’s are vertical), this is your reference point. At this row, go to 1/500s. Go down in that column until you see a 6 on your far left in the F-stop reduction column. I highlighted this example in purple. You’ll see that you are going to need a shutter speed of 1/8s.

chart3 smaller

So once again to be perfectly clear: if the camera meters the light at 1/500s without the 6 stops ND filter, than you’ll need to use a shutter speed of 1/8s with the ND filter.

One more example: the camera meters the light at 1/30s without the ND filter. You want to use a 10 stops ND filter. What shutter speed do you need with the ND filter? If you follow the chart correct, you’ll see that you’ll need to use a shutter speed of 30 seconds.

A quick note about the chart

In theory this chart should be perfect. However it has its flaws…

The darker the ND filter, the less reliable this chart gets. For example, if my camera calculates an exposure of 1/30s without my 10 stops ND filter, I would need to use an exposure of 30 seconds with the 10 stops filter. This is true in theory, but doesn’t always quite work out right in real life. I recommend going 2 or even 3 stops further, so using 2 or 4 minutes of exposure time.

For the lighter ND filters (until about 6 stops) this chart holds up pretty nicely.

And a tip: always take notes while shooting. Make it as detailed as possible. What type of light (hard sunlight, moon shine, strobe, cloudy), what time of day, the subject, what did the sky looked like, what shutter speed did your camera calculate, what shutter speed did you end up using, etc, etc. These notes will prove their use in the future.

In short: when using heavy ND filters, go down 2 or 3 stops further than the chart says. When using light ND filters, the chart is mostly correct.

An overview of ND filters

There are many ND filter manufacturers, some produce only light ND filters, some produce a whole range of them. The filters come in different price ranges and in different sizes. For your and my comfort I created this chart that has all of this information on just one page (click to view larger)

chart4

A work in progress

“The ultimate filter guide for your long exposures” may sound a bit pretentious. And it is. I want to cover everything related to long exposure photography. However, this guide can only be really ultimate if all of your questions have been answered. Although I strongly believe that I’ve covered a large area, I can’t imagine every single question of you has been answered.
If you have any questions, comments, remarks or critiques, let me know. I will add your questions or comments to this guide. Only with your help, this guide can become really ultimate.

46 Comments

  • Holly Marlin on 7 Oct ’09 at 1:40 pm says:

    Hi Joel,

    Thank you so much for preparing and sharing these guides! Your work has really inspired me. I have done some experiments with my new 10 stop ND filter, which arrived just last week, and found that the + 2-3 stop addition to exposure to be pretty accurate (apparently reciprocity failure is alive and well in digital cameras).

    The information you have provided to date has been really helpful, and I think comprehensively covers exposure issues. I would personally also love to know whether you have any particular tips for focusing (other than obviously locking the focus before adding the ND filter) – do the standard focusing rules apply in your experience? I’m sure many others just starting out with long exposures would be interested to know as well.

    Thank you again for sharing your knowledge and experience with the world.

    Warm regards,
    Holly.

  • Patrick Goossens on 7 Oct ’09 at 10:45 pm says:

    Thanks for this very good and very readable guide on long exposure photography.
    I wasn’t aware of this technique at all. But seeing your photos I want to give it a try. I will go out to a shop, buy myself such a ND filter and start working with it. I’m looking forward to my first results …
    Thanks again.

  • admin on 7 Oct ’09 at 11:40 pm says:

    Thank you for your comments!

    Holly,

    Regarding the focusing, yes I often have trouble getting the focus where I want it to be or to even focus at all. I’m going to write a bit about this problem and add it to the guide this week.

    In short: I usually bring an external light source, like a flashlight or a laserpointer and aim with it at the spot I want the camera to focus on. That usually does the trick, especially at low light situations. Other tips are to slightly move the camera or zoom in/out untill it gets the focus right.

  • Birgit on 25 Oct ’09 at 9:50 pm says:

    Thanks for the work, pal. I really learnt a lot.

    How would you calculate he exposure time for a GND filter? Just halfway down the chart compared to the equivalent ND?

  • paul langereis on 26 Oct ’09 at 4:44 am says:

    Thank you so much for the series on long exposures. You have helped me understand what needs to be done in a very straight forward fashion. Love the photos that came along with the articles as well!

  • Vadim Gordin on 28 Oct ’09 at 5:01 pm says:

    When stacking filters, does one multiply or add the effect of the two filters? For instance, if I have a hoya hmc nd4 and nd8, what would be the resultant effect? Thanks.

    -Vadim

  • admin on 28 Oct ’09 at 5:14 pm says:

    Vadim,
    In that case you just need to add the effects. Stacking a 4 and a 6 stops for example would result in a 10 stops effect.
    Joel T.

  • Imca on 30 Oct ’09 at 9:53 pm says:

    What a fine website you have, beside your beautiful images there’s a lot of interesting information to be found. Your guides are a really good help in discovering the long exposure photography. Thanks a lot for sharing this.

    I agree with Holly Marlin about the focusing. How does it work right? It’s difficult to screw the filter without changing the focus, I’m looking forward to the article about this subject, I really can use some tips and trics about focusing.

    Thanks again for sharing all this information and keep up with your beautiful work.

  • Neezhom Photographic on 8 Nov ’09 at 8:29 am says:

    Thank God, what a great tips my friend. You are really master in B&W long exposure technique

    keep it up :)

  • admin on 10 Nov ’09 at 11:24 pm says:

    Thank you! Hope you’re doing well. Will take a look at your website too.

    Joel

  • Jerry Ipsen on 20 Nov ’09 at 8:29 am says:

    After seeing your work and also that of Nathan Wirth’s I’ve wanted to shoot some nice LE’s. So after reading this piece several times I finally went out and purchased my first ND. Can’t wait to get down to the ocean. Great article and a very informative piece on how to use them.

    Jerry

  • David Johnson on 3 Dec ’09 at 7:43 pm says:

    Thanks for the chart Joel. Ive just received my BW 110 so will be out this weekend with it. All this exposure calculation stuff takes me back to shooting with Sinars on sheet film using reciprocity factor failures…….golden days!

  • Sergio Maclean on 22 Dec ’09 at 6:48 pm says:

    Thank you SO much for the work and effort. I love long exposures and I love B&W. I also like overexposing which is why I have lived without the use of ND filters this long…but after seeing your pictures I realize how far I have to go and how much more complete the effect is on a properly exposed shot. Thank you.

  • Peter Leibowitz on 4 Feb ’10 at 7:12 pm says:

    Hi Joel, I just came across your website. Thanks for generously sharing your knowledge. Do the adjustments in exposure which you provide in the chart take into account reciprocity failure? Or have they been solely calculated for digital photography?

  • Rob on 20 Feb ’10 at 9:31 pm says:

    Thank you this. I was having such a headache over this nd filter issue.
    I came to this site via redbubble and an article by peter hill, and for the added bonus a website about BW photography.

    I nearly considered getting a singh ray variND until i read about issues some people were having with it.

    for me the problem it holder or screw in filter ?( are the holders easy to set up and handle ?) I think your pros and cons didn’t mention that holders are meant for travelling or even street photography as they are too awkward ( in my opinion ) to carry around.

    my big question is what f stop filter do i need since i live in the gulf ( very bright sunlight ) and i want to capture in this sunlight but with the effects i have seen in this article ( soft, silky etc ). would i be better off getting the 10,6,3,2, and 1 ?

    Regards

  • Rob on 21 Feb ’10 at 7:05 pm says:

    Joel
    Thank you very much for your answer, although for me maybe the jury is out on the singh ray. I have one last question if i may? I think this will apply to many newbies.

    I have a cannon rebel with a diameter of 58mm. I could just buy a filter that matches that size and be done with it. But in the future i want to consider moving up to a full frame camera ( and hopefully the sensors will have improved ). this will mean an increase in diameter size for the accompying lenses for the new camera. Given that I would buy several good quality filters i want to consider them as an investment so i want them to be used on a full frame camera in the future and hence bigger lens, so i going to get larger size filters with a step up ring. so what would anyone define as a good diameter to aim for ? 72mm, 77mm etc

    thanks

  • Max Tuta on 6 Mar ’10 at 5:28 pm says:

    Thank you Joe.
    Do you have any info on B+W IR-Filter?
    I shoot with a D200 and D100, on the D200 I cannot get one shot, I think that the sensor filters all the IR lights and I get black screens only.
    I’ll try this with my ND4 this week.
    Thank you for the inspiration.
    You rock.
    See you on Flickr.

  • Peter on 18 Mar ’10 at 9:46 am says:

    In this increasingly selfish and greedy world I think its wonderful that there are so many people who are willing to share their knowledge and experience for no financial reward.
    Your three part guide to long exposure is fantastic and incredibly helpful. Well done and thanks very much.

  • (: Andrzej :) on 23 Mar ’10 at 10:57 am says:

    Hi

    I am fascinated with the results of long exposure photography….your site is very helpful and with amazing artistic photos.
    however before buying my ND filter I tried it late evening or early morning using f.e. polar filter. and faced the problem with calculating the exposure time.
    If I use the lightmeter built in camera and it shows f.e. 30 s exposure by aperture 4 and 1600 ISO. What would be the the calculation chart and what time should I get f.e. for ISO 100 and aperture 11 ?

  • Robbie on 24 Mar ’10 at 1:59 pm says:

    Very good site. I would like to endorse your comments about adding an extra stop or two with the 10 stop filter in respect to calculating exposures. When I first got mine I found that the exposures were longer than the chart suggested and I thought that I had a dud filter or even had a 13 stop by mistake. Yesterday in overcast light I had an exposure time of 90 seconds at f/16 with the filter in place. The metered exposure was 1/30 second without the filter. Thanks for providing good information!

  • Carlos on 7 Apr ’10 at 6:30 am says:

    Joel.

    I am aleady a fan for Long Exp. Photography and your work.
    Great Tutorial.
    I found a FADER Filter (that can give from 500 to 5000 filter factor.)
    Have you seen this filters? do they work as well as the high quality B+W filters?

    That is the darkest one I found. B+W does not makes the 113 or 120 filters.

    Regards,
    Carlos.

  • phil on 23 Apr ’10 at 1:45 pm says:

    hello.

    i just want to ask you one question if you dont mind.

    can you do long exposure photography when its daylight and still get the same effect to look as its been photographed in low light.
    i do low light long exposure photography when its just going dark and im experimenting shooting in daylight and trying to get the same results as my low light shots, but so far its not very good. any ideas or tips will be welcome. im using a b+w 1000 and hoya ndx400 filters. by the way very impressive website and beautiful images.

    thanks

    phil

  • Vassilis on 27 Apr ’10 at 3:01 pm says:

    Hi,

    Your tutorial is quite interesting and informative.. However can you give some info concerning
    a) the noise reduction protocol you follow a) first according to settings of canon dslr (i own a canon eos 7d) for shooting at ISO’s 100
    b) the role of locking the mirror of the dslr
    c)processing the raw file later on (common noise reduction techniques)..

    Is is better to avoid any noise reduction coming from the dslr and leave all the process later on when the raw file is in the “safe hands” of a suitable photoediting program???

    kind regards,

    vassilis

  • Steven on 12 May ’10 at 1:33 pm says:

    Hi again,

    about long exposure times and color shifts: This is actually called the Schwarzschild effect. From http://www.weatherscapes.com/techniques.php?cat=general&page=film
    As you make your exposures longer than about 1 second or so, you may start noticing that the color balance and sensitivity of your film changes. This is called the reciprocity error, or SchwarzSchild effect. It basically means that if you make an exposure on, say, 1 second at f/8, this gives no longer the same exposure as a 2-second exposure on f/11, as it would be when you do short exposures (say, 1/500 sec or so). Film sensitivity drops for longer exposures, so in general you will need to expose the film longer (sometimes up to a factor of 2 or 3, or 1 to 1.6 stop) than what the light meter suggests.

    It is hard to give a rule-of-thumb for the exposure correction, but what I generally find is that for exposures up to a minute on Fuji slide film, overexposing the photo by between 1/2 and 1 stop, depending on how dark you want the photo to be, gives adequate correction. (This is in addition to the 1 stop overexposure I always do with weather photography, since my slides turn out to be very dark if I expose according to the light value.) If you are photographing a night scene, you may want to make a relatively short exposure, so the night scene will look properly dark on the slide.

    The other problem you get is a shift in color balance. For Fuji slide film such as Provia and Sensia, they shift towards the blue, since the Schwarzschild effect is weaker for the cyan & magenta coupling layers than it is for the yellow coupling layer. You will start noticing this blueshift at exposures longer than a few seconds. The Fuji Velvia is (among lightning photographers) infamous for its magenta-shift when used at night, and if you look the sensitivity curves of the Velvia (the datasheet is available at Fuji’s website), you will indeed see that the magenta sensitivity is higher for long exposures.

    You can get around color shifts by using filters, but I generally don’t do this, since the shift in color is generally small. I avoid using Velvia at night (at 50 ISO it is too slow anyway).

    This is about film but i think the same goes for the digital sensor.

  • Canon EOS 7D on 13 May ’10 at 5:14 pm says:

    Very nice information.

  • White Balance Lens Cap on 24 May ’10 at 11:57 pm says:

    I found your blog on google and read a few of your other posts. I just added you to my Google News Reader. Keep up the good work Look forward to reading more from you in the future.

  • Diana Eftaiha on 30 May ’10 at 10:24 am says:

    thanks for the chart. you made my life easier =)

  • Joy Volpa on 31 May ’10 at 4:00 pm says:

    I enjoy reading this site. Could tell me how I could subscribing with it? I feel I should let you know I found this site through MSN.

  • Munira on 10 Jul ’10 at 3:05 pm says:

    What can I say? Valuable source of information, tips and advice. Thanks, Joel!

  • Gabriel Bacca on 11 Jul ’10 at 11:37 pm says:

    That “quick note” was really helpful, I’ve been experiencing this problem and thought it was my camera or that I didn’t do the math well. That chart is a good point of reference for darker NDs. Thanks for this again man.

  • matt on 12 Jul ’10 at 6:50 am says:

    There is a really wonderful Iphone app for those who possess one. It is called ND calculator and in the field, it is priceless. It simply calculates your exposure time for you, just dial in the ND filter you have against the shutter speed you have without it on and presto! Has saved me missing many shots because of time calculating!!!!!! A must for long exposure enthusiast’s

  • Owen on 15 Jul ’10 at 8:47 pm says:

    Thanks for taking the time to write such an informative guide to long exposures.

    Do you have thoughts about Heliopan’s 3.0 10 stop ND filter? There seems to be a shortage of B+W ND 110 filters at the moment and the Heliopan filter seems a reasonable alternative.

  • pixelkeeda on 31 Jul ’10 at 10:09 pm says:

    Very useful guide, I am very grateful that you have taken time to make such a through document.

    Since you are trying to make it even more elaborate i have a request. Could you add a paragraph on how to make calculation when stacking multiple filters.
    ex. ND 3.0 + ND 0.9 = ????

  • gwen2010 on 3 Aug ’10 at 5:30 pm says:

    thankyou for articles and link to Michael Levin’s work–have admired Michael Keena’s pictures for years-=have just invested in ND400 Hoya HMC filter ( ? equiv to 10 ND by other makers )and have started experimenting –your guidance is very useful?

  • phil on 1 Oct ’10 at 8:02 pm says:

    hello joel.

    could you help out solve a problem using b+w 1000 filter.
    for some reason im getting half round circles or contour lines on my shots.
    they appear mainly in the corners of the image.
    ive been doing long exposures using the 1000 filter for years without no problem.
    ive been trying to work out the problem but without any soulution.
    any ideas would be appreciated.

    thanks

    phil

  • Gert on 15 Dec ’10 at 11:38 pm says:

    Beste Joel,

    ik was al een fan van je foto’s, nu ben ik het van je tutorials. Heb onlangs door de foto’s van jou en van Michael Levin zelf een ND10 gekocht en ga er zelf ook mee aan de slag. Door jouw leuke uitleg moet dat goedkomen. Dank!!

    groet,

    Gert

  • Joel Tjintjelaar on 25 Jan ’11 at 8:25 pm says:

    I will take a look at it, but actually this website isn’t officially live yet! So please apologies for my late reply.
    I will get back on this.

    Joel

  • Jc on 4 Apr ’11 at 7:01 am says:

    Joel,

    You’re a godsend for all Photography enthusiast. I came across your website and I was amaze by your photos. Thank you for all the tips & techniques you generously shared with us. More power to you and your Photography!

    Cheers,
    JC

  • Jc on 4 Apr ’11 at 7:02 am says:

    Joel,

    You’re a godsend for all Photography enthusiast. I came across your website and I was amaze by your photos. Thank you for all the tips & techniques you generously shared with us. More power to you and your Photography!
    Cheers,
    JC

  • Paul Ghosh on 7 Jun ’11 at 6:24 am says:

    May be this is a stupid question. Is there anyway I can print the three charts in this tutorial?

  • christopher drake on 14 Sep ’11 at 2:43 pm says:

    Thank you so much forJoel for putting together this wonderful website and for the articles and tutorials. It is something I am referring back to more and more often now, both for the inspiration of its art and for the educational value of its content. I have long been a big fan of yours and am excited that you are taking everything to new heights.

  • Will Hammer on 14 Jan ’12 at 5:25 pm says:

    Thank you, Joel, for sharing the results of your labors — and there isn’t a trace of pretentiousness in this or in any of your writing. I’m not sure who it was, maybe Jason Odell, who quoted someone who noted that while magicians never reveal their secrets great photographers go out their way to reveal theirs. Your work has helped me to find a direction, and the information you’ve provided here facilitates following it. I’ve been playing with starting somewhere and successively doubling shutter speed or halving aperture at night with the 3-stop and less nd’s (do you have any recommendations on stacking filters) I have, and the results are at the least surprising (the 8 minute exposure on a cold night) and at best almost okay. Your charts both give some confirmation to the method and orient me to a starting point, thus reducing time with cold finger on cable release.
    Parenthetically, when I read your compliment on one of my pictures in GooglePlus, I was surprised, honored, and gratified as a follower of your work, but until visiting your profile and site had no idea I had already seen you on the Nik promo, wading in the water and memorably saying that color says nothing to you, which provoked lots of rethinking – as well as a purchase of Silver Efex.
    Have a great new year of exploration and best of luck in any competitions.

  • Mario Bentvelsen on 21 Jan ’12 at 11:35 pm says:

    Thank you, Joel for your information and inspiration. I recently discovered a iPhone app, called Perfect Shot, which I think is very handy too for calculating exposure times. I also like to use Compass, DOF master and The Photographer’s Ephemeris. Which apps do you like to use? I am an absolute beginner in ND-photography, so I hope to learn a lot from your website. I was very inspired by your Zeelandbrug picture and tried to photograph it myself (see 500px). Hope you like it. Please feel free to comment.

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