# Long exposure photography



## Quasimodo (Nov 25, 2013)

I am just getting ready to start my journey into long exposure photography.

Having just dabbled in long exposures with some screw on filters (NDs, and some vari-NDs), I am now taking the leap with the Lee system. From my wife I am getting the Lee starter kit (with a .6 hard grad ND, and a .6 ND, the filter holder) plus a couple of rings (77 wide, and 82 wide), and from my two kids I am getting the Big Stopper; all bought by me 

I have some questions for those of you who have experience and time to answer it.

1. Is the Cokin Z-system (filter rings and filters) compatible with the Lee 100mm system? (same thickness of glass?) 
2. How do you calculate the exposure time? I have looked at several videos and posts concering this. They mention reading the exposure at a certain F-stop, then adding time based on your ND stops. Some further argues that ISO, and exposure compensation can be used to extend the time. All this seem correct, but incomplete.. Given that you shoot on the lowest ISO possible, then use EC (to say -3), F 22. Would you not be able to reduce it even more by switching to a lens that have F32 (like the 70-200 II), then add a 2xIII TC, thus getting a F 64, hence buying more time (here diffraction might play a devestating role?). 

Not sure if my questions are coherent, or that I might have misunderstood.. 

Any input would be much appreciated, and if you even want to illustrate it by adding a picture that would be great.

In advance, thank you,

G.


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## David_in_Seattle (Nov 25, 2013)

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[*]I use the Cokin Z system with 4x6 glass filters from Tiffen and Cokin. I haven't used Lee filters on the z system, but I assume the 100mm filters would slide into the cokin holder with little issues. The thickness of the filters wasn't an issue for my Tiffen filters as the Cokin holder squeezes the edges of the filter in place. If you buy a lee filter, just make sure it meets the width of the z system holder.
[*]To calculate exposure, first take a properly exposed shot without the filters. A .6 filter reduces the incoming light by 2 stops. Leave the aperture and ISO the same and only adjust the shutter speed. So if your shutter speed was 1/500 without a filter, then 1/125 will give you the same exposure with a .6 filter. (1/500-->1/250-->1/125 = 2 stops). If you want to take a longer exposure, then lower your ISO, use a smaller aperture, and repeat the process from the top.
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Aperture in 1 stop increments: each successive aperture allows 1/2 as much light through the lens compared to the aperture setting to the left of it.
most light f2.0 > 2.8 > 4.0 > 5.6 > 8.0 > 11 > 16 >22 least light

ISO in 1 stop increments: each successive ISO setting is 2 times more sensitive to light than the setting to the left of it.
Least sensitive 100 < 200 < 400 < 800 < 1600 < 3200 < 6400 < 12800 most sensitive


Here are a few shots I took of Scripps Pier in San Diego.


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## JustMeOregon (Nov 25, 2013)

I'm not sure, but I believe that you may be "over thinking" the idea of calculating long exposure time... To save myself from the embarrassment of being seen counting-out the exposure time on my fingers, I often use the iPhone app NDTimer. The basic version of NDTimer is free, but for an additional $0.99 the paid version allows you to easily calculate the exposure time of using "stacked" filters also.

Speaking of stacked filters... when I first started using the Big Stopper, I was surprised to quickly find that it often isn't quite enough! In the middle of a bright sunny day, when 1/125 or so would be a typical shutter speed, the Big Stopper will "only" get you an 8-second exposure -- that's plenty for waterfalls & such, but likely not enough for "cotton candy" seascapes, long-soft "smeared clouds," or "ghosting" people out of a crowded scene. So my "long exposure" Lee Filter kit includes a 2-stop, a 3-stop, & a 6-stop ND filters to add to the Big Stopper! Which of course begs the question, what in the world do you do with yourself during an 8-minute exposure...?

Also, don't forget the 105mm Lee polarizer & adapter. It'll give you an additional stop-&-a-half or so, and is vital for any kind of water-scene.

Richard


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## Quasimodo (Nov 26, 2013)

Thank you JustMeOregon. You might be perfectly right in your comment of me overthinking it  But I can´t shake the feeling that I would be able to steal more exposure time by using a lens with the lowest aperture of 32, and stacking on a teleconverter thus getting f 64 (given that you can compose it with the field of view of 400mm  I will just have to wait and try it out. The idea of combining city scapes and architecture while whisking people away, while still adding elements into the picture has intrigued me for a long time  The polarizer is a given, just have to persuade my wife that it is an absolute necessary accessory. 

Thank you David for your advice and beautiful photos. I especially love the latter one taken in between the pier. Looking forward to try it out. One of the reasons that I would to mix the Lee and the Z system of Cokin is that the latter is way cheaper, thus trying different filters that looks like fun, without breaking the bank.


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## JustMeOregon (Nov 26, 2013)

You're absolutely right of course, any way at all that you can restrict the light from reaching your sensor will necessarily require a slower shutter speed to obtain a given exposure. So cracking-down on your aperture all the way & slapping-on a 2x TC will certainly give you a longer exposure time, but the resulting hit to your image quality will likely be pretty high... To minimize diffraction (& maximize sharpness) I try not to crank down my apertures any smaller than f/16. And I'll only use a TC if the "field of view" demands it.

If you just have to have that extra 3-stops of exposure time (from f/16 to f/64), I'll again urge you to consider stacking an additional filter on top of your Big Stopper. To achive that additional 3-stops I'd use my Lee 3-stop 4x4" glass filter http://www.bhphotovideo.com/c/product/491473-REG/LEE_Filters_9NDG_4x4_Neutral_Density_ND.html; which is a bit expensive, but the resin filters are almost as good and much more reasonably priced.

Of course, if I forgot my extra ND filters (or I'm just too lazy to walk back to the truck) I'll do what ever I have to do to get the long exposure time that I want -- I'll use a polarizer even if I don't really need it, I'll crank-down the aperture to a ridiculously small size, what ever it takes...

Richard


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## Quasimodo (Nov 26, 2013)

JustMeOregon said:


> You're absolutely right of course, any way at all that you can restrict the light from reaching your sensor will necessarily require a slower shutter speed to obtain a given exposure. So cracking-down on your aperture all the way & slapping-on a 2x TC will certainly give you a longer exposure time, but the resulting hit to your image quality will likely be pretty high... To minimize diffraction (& maximize sharpness) I try not to crank down my apertures any smaller than f/16. And I'll only use a TC if the "field of view" demands it.
> 
> If you just have to have that extra 3-stops of exposure time (from f/16 to f/64), I'll again urge you to consider stacking an additional filter on top of your Big Stopper. To achive that additional 3-stops I'd use my Lee 3-stop 4x4" glass filter http://www.bhphotovideo.com/c/product/491473-REG/LEE_Filters_9NDG_4x4_Neutral_Density_ND.html; which is a bit expensive, but the resin filters are almost as good and much more reasonably priced.
> 
> ...



Yeah, diffraction worries me too, but I will get to see how bad it actually is for different scenes. I am getting a .6 ND as well as part of the startup kit, so I´ll get an additional two stops there. I agree that stacking is probably the way to go, and that is probably where I will end up finally. Nevertheless, I will experiment with all kind of stuff (using the EC for instance) and see how my pictures are punished. I have also surmised that there is a limit to how many filters it is wise to stack given its impact on IQ, so I given the need for extra stops will probably have to cough up for some expensive high stop filters (hence the alluring Z system


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## Zv (Nov 28, 2013)

Quasimodo said:


> JustMeOregon said:
> 
> 
> > You're absolutely right of course, any way at all that you can restrict the light from reaching your sensor will necessarily require a slower shutter speed to obtain a given exposure. So cracking-down on your aperture all the way & slapping-on a 2x TC will certainly give you a longer exposure time, but the resulting hit to your image quality will likely be pretty high... To minimize diffraction (& maximize sharpness) I try not to crank down my apertures any smaller than f/16. And I'll only use a TC if the "field of view" demands it.
> ...



With very good filters I'd probably only stack two or three max. Also I'd try and keep the aperture at around f/8 - 16 maybe f/22 if really required. It also helps to shoot on cloudy or slightly dullish days rather than bright sun. Shoot late afternoon and blue hour to get some color in your shots. 

I'm getting into long exposures myself. Just recently bought a ND400 just to experiment a bit. If I like it I might buy into the more expensive stuff.


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## Quasimodo (Nov 28, 2013)

Zv said:


> Quasimodo said:
> 
> 
> > JustMeOregon said:
> ...



I am really looking forward to test this. I just also bought the linear polarizer (the round one) and the holder, hoping that I will be able to catch those beautiful colors. I will not get the chance to experiment before Christmas as they are my gifts


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