Long Exposure Tutorial

First and foremost, let me apologize for completely falling off of the map.  As some of you know last March I moved from Dubai to South Korea.  Since then I've fallen behind on my website...a lot.  Lets not even start talking about emails.  So here's my first picture taken out in Seoul last week.


In the past I've gotten quite a few emails regarding my processing and process in general.  Recently I had a discussion on Facebook with a photographer in Seoul and she was asking about long exposure photography.  I figured why the hell not just make a blog post about it.  Maybe this will put me back on track from being the slacker ass I've been.  (I also have a loaner Sony A7Rii I'm going to be doing a review of).

What exactly is Long Exposure photography?

You know, this question is actually a bit more debatable than I thought.  Initially without putting much thought into it, I thought anything that has a shutter speed long enough that requires a tripod (or some other means of stabilizing camera).  And for the vast majority and a simple generalization, I think this is very true and accurate.  However, one can argue that panning shots and dragging the shutter can be considered long exposure. Then of course, photography is art...so that expands the definition a bit more perhaps?  What exactly is art though?  Why are we here?  What came first, the chicken or the egg?

Types of Long Exposure photography

So the "what" is probably better explained with some examples.  There are many reasons as to WHY one would want to do a long exposure.  So lets start with the most basic and hopefully obvious:

It's really dark

So as we hopefully know, there are three factors involved when it comes to exposing a photo (film or digital).  Aperture (aka f-stop), shutter speed and ISO.  The point of this tutorial is long exposures, so for the most part we're going to stick with the lowest ISO possible on your camera which will be ISO 100 for the majority of folks.  So for now that will remain a constant.  Next we have aperture.  This is a physical limitation of your lens.  It can only open up so much right?  You might have a 2.8 max aperture, or 5.6 or slower or faster.  Even a 2.8 aperture shooting a night scene at iso100 is going to require a shutter speed of probably 1-5 seconds depending on the amount of ambient light.

Of course this could be shot at a higher ISO to allow for a handheld shot.  But as ISO increases, so does image noise.  Ever notice how grainy those camera pictures are when taken indoors with poor lighting?  That's what high ISO does.

Light trails (of any kind)

Any light source that moves during your exposure is going to create a light trail.  Cars, stars, flashlights (there's a whole art to light painting), moon, sparklers, fire....I think you get the picture. (haha...puns)  Sometimes this can be used to show movement within a photo.  Sometimes it just looks cool.  Below are two examples, left was a .6 second exposure and the other was a 6 second exposure.

Another light trail example

Composite of multiple 20-30 second exposures

2 second exposure

Getting rid of moving objects

Most often this technique is used during daylight hours to eliminate people or cars from an image.  In the below example a 10-stop Neutral Density (ND) filter was used to allow for a 15 second exposure.  To the left was without the ND filter at 1/60th.

Here is a 15 second exposure also.  If cars have headlights on you will still end up with streaks (think exposure here and how bright headlights are).  The point here was to portray movement in the shot.

Streaky clouds and milky water

Often used by landscape photographers you see photos will streaky clouds or very milky smooth looking water.  If shot at night, no problem as you'll probably need a long exposure anyway.

But during the day...here enter ND filters again.

Half second exposure at the crack of dawn

50 second exposure with Lee Big Stopper (10 Stop ND filter)

Showing movement and just being......artsy

I most often see this kind of stuff in street photography and motorsports (panning shots), but you're only limited with your imagination.

So now that we've covered some of the why's and hopefully painted a picture for you as to the why.  Now lets dive into the how, after all I did call this a tutorial.

The exposure trinity

There are tons and tons and tons of articles out there on exposure.  Maybe one day if there's a need, I'll write one as well (who doesn't like web traffic right?  Plus my endless witty banter about what seems like nothing sometimes....ugh..I really need to learn how to write like an adult) (note: After proof reading the below, I pretty much have got into writing a mini article on exposure, sorry....or you're welcome....which ever)

So what makes a picture?  As in physically....what needs to happen?  Light....has to hit a photosensitive medium.  Whether a digital sensor, film or photosensitive paper thru a pinhole camera.  The more light hits this medium....the greater the....wait for it......exposure.  Things are starting to come together huh?  

30 seconds on a beach in Cannes, France

Aperture

You remember as a kid when you would make binoculars out of your hands?  Do that now but with only one hand.  Close and open your hand making the hole bigger and smaller.  This is exactly what your camera aperture does.  The thing to remember however is that the smaller the aperture number, the bigger than opening.  For example, f/2.8 is a bigger opening (thus more light) than f/5.6.  These numbers are called f-stops (Reason is because f-stop is a ratio, but we won't get into that...google that shit if you're interested).  An increase of one f-stop, is a doubling of the amount of light.  But we'll get more into that later.  For now just remember what the aperture is and smaller number means more light.
So why not just always shoot "wide open" (lowest f-stop)?  Couple of reasons:
1. Your lens is not it's sharpest at the widest or narrowest (just physics here folks)
2. The lower the aperture number the lesser the depth of field.  I'll do a whole article on DOF one day with numbers and shit.  You know those portraits where the face is in focus but the background is out of focus?  That's a shallow depth of field, this requires a opened up aperture (low aperture number and also depends on your focal length).  The higher your aperture number (opening gets smaller) the more of your photo is in focus.
3. Too much light.  At some point (even without flashes and strobes) it can get too bright outside and your camera can't shoot at a high enough shutter speed (length of time your shutter opens to expose your medium to the light)

Aperture numbers can get confusing too.  In one stop increments they go; 2.8, 4, 5.6, 8, 11, 16, 22.  Don't worry about memorizing these numbers right now...it'll just happen one day the more you do this shit.  Plus you end up relying a lot on the amount of clicks when adjusting aperture or shutter speed...I'll touch on that later.

So what's next? 

ISO

So next thing we're going to discuss if ISO.  Eye-Ehs-Oh.  Very simple for our intended purposes.  It's the above mentioned medium's sensitivity to light.  It's not an exact science, but it's pretty close.  There's a somewhat agreed upon standard but it gets a little loose.  You'll generally see ISO values of 100, 200, 400, 800, 1600, 3200 and so on.  Notice the numbers double.  Remember what else doubles?  That's right...one f-stop is a doubling of light.  Each doubling of the ISO value is an increase of one f-stop, or double the light.  
The higher the ISO, the brighter the photo, only drawback is the higher the ISO the greater the noise.  (yes yes...I know...some folks like noise in the their photos as it gives them soul or feeling or some shit....you'll know when you want noise and when you don't, I'm not a fan, but I do agree with it's use at times, additionally as technology advances, higher ISO values are getting higher and higher and doing so with less and less noise, but I digress)

Shutter speed

The last part of the trinity is shutter speed.  How long your medium is exposed to the light.  Normally the value here is based off of a second and majority of photos are some fraction of a second.  A doubling of that time, doubles the light, aka, increases the exposure one stop or one f-stop (just call it a "stop", nobody really says "one f-stop" and you know how pretentious photographers can get, so use the right lingo!).  So if I'm shooting at 1/200th (of a second) and the only thing I change is the shutter speed to 1/100th, I've increased the exposure 1 stop.  Had I changed it to 1/50th, that would be an increase of two stops from 1/200th.  I've doubled the amount of light (via time) by two.

So....now you've literally learned everything you need to know to shoot fully manual (assuming your camera allows it).  Some combination of these THREE things makes for an exposure.  So lets run thru an exercise example:
So class, lets say we take a photo at ISO 100, F/5.6, 1/60th.
Now we take the exact same photo at ISO 100, F/8, 1/30th.  Which of these photos will be darker?
Neither of course.  While we closed the aperture "one stop" making the picture one stop darker, we've increased the shutter speed (slowed it down, exposing the sensor longer) twice as long making it one stop lighter.  So the pictures should both be exposed identically.  Try it out for yourself.  There's nothing magical about this stuff

So if you've never shot in manual mode before, you're ready.  You have learned the three things required to shoot manual.  Your fancy digital camera has a built in meter.  As you change ISO, aperture and shutter speed it'll indicate negative numbers (under exposed), 0 (properly exposed, at least to the camera) or positive numbers (over exposed).  It's not rocket science.  If it's too bright, you need to lower the amount of light hitting the sensor by changing the shutter speed or aperture or lower it's sensitivity to light by lowering the ISO.
Does this mean you should always shoot in manual mode?  Not at all, don't be ridiculous!  And don't listen to those pretentious assholes that state "I always shoot in manual" or "Pros only shoot in manual mode".  Now if you're just starting off, I think it's a good idea that you shoot manual as much as possible (but don't miss a good shot because you're dicking around with the knobs/settings) either.  The better you understand exposure, ISO, aperture and shutter speed, the better you will know when you need what.  The only times I ever "always shoot manual" is when I'm shooting any form of landscape/cityscape or when shooting portraits.  With land/cityscapes, it's mainly because I'm in no rush....I'm setup on the tripod or clamp somewhere and am probably sitting there waiting on the light to be exactly how I want it (sometimes for hours....yes HOURS!  It's not glamorous).  In the studio I'm in a controlled environment, usually shooting with strobes so I don't want the camera doing any thinking for me.  When I'm walking around the city, I'm most often in aperture priority and usually auto ISO (especially as it gets darker).  If I don't like the way the exposure turned out a quick turn of the exposure compensation knob tells the camera I want it lighter or darker.
All that being said...don't be scared of manual mode.  Get familiar with the knobs on your camera.  Most cameras default to one-third f-stop adjustments.  Meaning every "click" of the knob/wheel is a third of a stop adjustment.  So three clicks will make it one stop.  It's very easy once you get a feel for it.

I thought this was a long exposure tutorial?

You're 100% right, but I figured there's a good chance you might not know how the above stuff works so why not take a bit of time and write about it without going into a full blown article.  I mean really...if you read the above trinity section and are still confused...stop and email me right now (sebastian@sebimagery.com) and I will gladly go into further detail.  Plus I do this shit for free, with zero ads, I don't push any "sponsor" products (just shit I buy myself and like) and I don't get paid a single penny for anything I write.  If I get a loaner product to write about I'm up-front about it and won't hesitate to give it my 100% honest opinion.  Worst case they don't loan me shit anymore, which has only happened once.

So lets have a look at the below three photos.  The exposure times in order are .6, 30 and 145 seconds.  Click on them to view them larger, that goes for any image on this blog by the way.  The three shots are nearly identically exposed (though all have tweaks in Lightroom so the exposure math isn't going to add up and the sun was setting so it was constantly getting darker).  The first was shot at a very small aperture just to make it a slight longer exposure.  The next two were shot with a 10-stop ND filter.

.6 seconds, ISO 100, F/22

30 seconds, ISO 100, F/5

145 seconds, ISO 100, F7.1

Wait....what the hell is an ND filter?

I mentioned ND filters very briefly earlier in this article.  So what happens when your aperture is as small as it can get, your ISO is as low as it goes, BUT, it's still too bright outside to get anything lower than a 1/30th shutter speed and you really want those streaky clouds in your shot.  Neutral density filters are here to save the day.  These filters go in front of your lens and darken up the scene.  (some lenses and adapters, VERY few, allow drop in ND filters, but you'll know if you have this).  Physically, with the exception of the drop-in types there are two kinds of ND filters.  Round screw in filters which screw into the threads on the front of your lens and square/rectangular slide-in filters which require a holder.  Both have their advantages and disadvantages.  I have both types and use both types.  I'll do a separate blog post on the pro's and cons of each and of course a lot is personal preference.  

Here is a picture of my Sony A7R with the FE55mm lens using Lee Filter's Seven5 system.  Alternatively, I could have used a 49mm screw-in filter (or larger with the use of step-up rings).  What you have is an adapter ring (screws onto front of lens), a holder (clips onto adapter ring) and the filter itself (in this case the 10-stop big stopper). Neutral density filters are not supposed to change the color of your image, but they all do to some extent and the darker the filter, the more it changes the color and vignettes.  Usually it takes a good amount of fiddling around in post to get the colors right.  Though recently NiSi Filters has been making some big claims on their lack of color cast.  I hope to pick some up soon and do a little comparing (hit me up NiSi!!!).  The filters can vary in cost quite a bit, do yourself a favor and don't get the cheapest thing you can.  Even if you just want to tinker around.  The super cheap filters scratch super easily, screw in kinds have horrible threads, color cast tends to be worse and some will actually affect your image quality.  The more expensive filters are usually made of glass instead of plastic.  I own filters from B+W, Lee, Formatt-Hitech, Cokin, Tiffen and Hoya.  For land/cityscapes I most often use the Lee Big Stopper (10-stops) or the Formatt-Hitech Firecrest 16 Stop filters.  In studio or out door portraits I tend to stick with screw-in 3-stop filters from various companies.  I probably own about a grand worth of filters I've collected over the years.  I know folks with five times that.  This doesn't mean you need to go out and sell a kidney investing in filters.

A viable option (and these are very popular amongst video shooters) is a variable ND filter.  These are usually just two polarized pieces of glass that vary in darkness when spun around.  Pretty neat though.  I personally don't use them, I think I own one 77mm variable and haven't touched it in about 3 years. 

For landscape type of work I suggest 6-10 stops.  Anything less than that isn't really much (and we're not getting into graduated filters today).  Do keep in mind that stacking filters is a possibility too.  Not all ND filters are rated in f-stops.  So be careful what you're buying.  An ND filter factor of 8 (ND8) for example is not 8 stops, but 3 stops.  A optical density of 3 is not 3 stops but 10 stops.  Know what you want, and know what you're getting.  I'll have more information on this in the upcoming ND filter post.

Lets get started already!

Ok ok...geez.  So lets get out there and start shooting.  For the following example, here's what I have for gear.  Sony A7R2, Canon 17mm TS-E, Lee Big Stopper, Gitzo tripod and Arca-Swiss Monoball Z head.

I went up on my roof a little while before sunset and setup.  I forgot my wireless remote downstairs and was too lazy to go down and get it.  Sooooo I'm limited to 30 second exposures (anything greater than 30 seconds requires bulb mode and you need either a wired or wireless remote as holding the shutter down ain't gonna cut it).  It's not just an automatic "hey lets shoot 30 seconds" thing either.  You have to consider most importantly what's the shot you're looking for and then take some factors into place.  In the below example: amount of clouds and speed of clouds.

10 or so easy steps:
1.  Mount camera to tripod and install adapter ring (filter off at this time)
2. Turn dial to M and turn on camera
3. Set ISO to 100 and make sure I'm shooting RAW (No reason to not shoot landscapes in RAW) and enable 2 second timer (again, no remote which is my preferred route), white balance I just left at auto.
4. Set shutter speed to 1/30th (I knew I wanted to shoot for the full 30 seconds.  Since I'm using the LiveView LCD on the Sony I initially set everything up without the filter in place, 1/30th of a second, plus ten stops of ND filter equals 30 seconds)
5. Frame the shot
6. I hope for a aperture of F/8, but it looks a bit dark...so I bump it up to a F/6.1, no biggie
7. Focus (I pretty much always manual focus a tripod'd shot)
8. Clip on filter holder
9. Adjust shutter speed to 30 seconds
10. Press shutter and wait 32 seconds (if you're not shooting with a remote, always use the timer, you'd be surprised how much the camera can move when you're pressing the shutter button)

With this amount of clouds I would have loved to had a 60 or even 120 second exposure.  That's what laziness gets you.  However, more clouds are coming so I decide to wait and take a few more shots.
I end up taking 7 total pictures and here's my favorite which I ended up shooting at F/8, 30 seconds, ISO 100:
 

Shooting at night the same basic steps are followed with the exception of installing the ND filter and the initial shutter speed will already be set for the longer exposure.  Sometimes manually focusing can be difficult, if possible give autofocus a try.  I found specifically with the Fuji x-series cameras I had great success using AF at night.

For the below shot I was testing out long slow I could shoot handheld with the Sony A7R2's in camera stabilization enabled shooting without a tripod.  I set the ISO for Auto, opened the lens up as much as possible (F/4.5 in the case of the Voigtlander 15) and tried a few shutter speeds starting at 1/15th and got to 1/2 second at only ISO 320.  I was thrilled to be able to shoot this slow hand held.

This was a half second hand held exposure with the Sony A7R2 and CV15 with Sony's in camera stabilization (IBIS) turned on.  Insane!

Things that'll bite you in the ass:

1. Long exposures require a stable platform.  A tripod, clamp, something to set the camera on.  The higher focal length you're shooting at the more vital this is.  Last weekend I was shooting off of a public wooden deck (the first picture on this post) and people walking and kids jumping around ruined a couple shots for me.  I stood with my remote and waited for moments where people were still to take the shot.  Get a remote!

Shooting 20 second exposures at 500mm is no easy task...things have to be absolutely still.  You can see the motion blur on the left side oval platform of the Burj Al Arab.

2. Light leaks.  When you start getting into the VERY long exposures during the day, you risk light leaks.  Especially when using adapters or tilt shift lenses due to their multiple moving parts.  A black scarf/rag/shirt and some gaffer tape come in very handy here.  Some DSLR's get some light leak thru the view finder as well, some have a built-in internal cover/flap.

Light leak from a M to E-Mount adapter (funny enough the cheap $10 adapter had no leaks)

3. Getting in people's way.  Don't be a dick.

4. Weather.  And I don't just mean bad weather.  But sometimes you have too many clouds.  Sometimes none.  Sometimes they just ain't moving fast enough or at all.  

I think that about does it.  
We've learned about the three things that factor into how a photo is exposed (ISO, aperture, shutter speed) and are ready to start shooting in manual mode
We've learned that an f-stop is the doubling or halving of light
We've learned that the smaller the aperture number the MORE light it allows in
We've learned a little bit about ND filters and I'll be doing a separate post on the subject
We've learned how I went about shooting that example picture from my roof
And hopefully we've learned how shoot some long exposures.  Now get out there and shoot!

If you have any specific questions or comments, feel free to leave them below in the comments or shoot me an email.  I'll be more than willing to help out where I can.
 

A long exposure, of a long camera taking a long exposure (shot with Fuji X100s)