Introduction

Cloud-to-ground lightning out of virga fallstreak.

Lightning photography is both one of the most tricky and one of the most rewarding types of photography. Some reasons which come to my mind for saying this are: 1) You get only one chance for the particular situation - it is not like portrait photography where you can go back in the studio if the photos didn't come out well; 2) lightning varies so much in brightness, intensity and location that guessing the proper exposure requires a lot of experience, as well as luck; 3) you are always at some risk when photographing worthwhile lightning; and 4) lightning is a point (line) source, and demands the most of the optical quality of your camera system.

Equipment

For lightning photography to be successful at all, you will need:

• SLR camera with B-shutter speed (preferably SLR; you might try using your digital camera, if it has B mode, but this is much more difficult)

• lenses ranging from 28mm to 135mm at minimum. Fixed-focal lenses are preferred over zoomlenses. Aperture ranges should be f/2.8 - f/22.

• sturdy tripod (metal or plastic doesn't make any difference whatsoever at all in safety - if lightning is so close by, you are in trouble anyway)

• cable release, which can be locked

• Slow-speed film: 100 or 200 ISO

The SLR should have a quicklink for tripod mounting, so that you can quickly setup the equipment. Thunderstorms can mature and die fast, and every minute usually counts.

Make sure all your lenses are very clean - no scratches, fingerprints or other imperfections. Lightning is so bright and so thin, that any imperfection will show readily on the photo. Also make sure you have lenses which you know don't have too much coma effect at low apertures - for lightning, any coma becomes readily visible.

Location

It is important that you seek proper composition to photograph the lightning.

It is important where you setup the equipment. You can choose to photograph at your own house, if you are lucky enough to have a nice view. Or you can choose to go outside on the street, or on a sidewalk, to practice. When you become more experienced, seek for proper composition in the landscape. It is adviseable to search for a suitable location first, days before the first storm happens. Then you will know where to go, and you don't end up in potentially dangerous locations.

It doesn't matter much where to operate, but I recommend some place which stays dry during rain, under a roof or something, and is not too close to citylights (or cities in general). When you are out late at night in the dark, there may be drunk people driving by, so avoid the roads. Seek a small trail.

Choose a place at which the view to the sky is optimal. But most importantly, choose a location that is safe during lightning. Some situations you shouldn't be in when there are thunderstorms closer than about 10 km or so are:

• being on a dike or hill, or on top of another tall object
• being in the open field
• being at or in a body of water
• being near to trees
• being near fences or powerline poles
• being indoors and very close to a window
• Taking a bath, or washing your hands (you risk an indirect hit)
• Talking on the telephone (unless wireless/cellular)

These are some situations (the list is not exhaustive) in which you risk being hit by lightning either directly or indirectly, and you should avoid them, unless you are well protected (sitting in a car with the windows closed, is considered by many as being very safe, even in a storm). The only safe place to be is in a metal cage, like being in an aircraft or a car. Keep in mind that photographing lightning at a thunderstorm just overhead is extremely dangerous while being out in the open, even if there is no rain falling. It's best to get indoors after pressing and locking the cable release, and look through a window in the same direction as the camera outside does, and after a 'successful' lightning flash go outside to operate the camera.

Suitable thunderstorms

Sheet lightning can be nice when it lights up a cumuliform section of a storm from the inside.

What I'm used to do if a thunderstorm is active and I spot it, is to observe it and wait for the first next lightning bolt I see, rather than immediately getting my camera, because not all thunderstorms are suitable for lightning photography. The following conditions are of little or no use at all to photograph lightning:

• thunderstorms producing just sheet-lightning (although good sheet lightning can be beautiful)
• thunderstorms far away (> 25 km) and embedded in low-level clouds
• very weakly electrified thunderstorms, discharging every 15 minutes or so
• thunderstorms where the lightning is wrapped by rainfall. Rainfall washes out lightning and produces a lot of scattering and low contrast photos

Whereas the next are interesting:

• isolated active thunderstorms
• the line of thunderstorms (squall) which sometimes forms ahead of a cold front or trough. These are very active thunderstorms producing lightning every second or more, with many CGs. Even though there may be torrential rainfall, you can get several very nice pictures
• mesoscale convective systems (MCS) and supercell storms

The technique

This is very simple, even though many people at first don't understand how anyone can be so fast in triggering the shutter release after seeing lightning. The trick is, you don't do that, because you will photograph lightning during the night (indeed daytime lightning photography is quite a challenge). You make use of the B shutter speed mode, which will leave the camera shutter open as long as you want, and you wait for lightning to occur in the frame.

The camera should be on a tripod, with a cable release: it should not move at all during the exposure, or the photo will be blurred.

Lightning sometimes comes as a multiple flash with several channels.

So, lightning photography is nothing more than setting up your equipment at night, setting focus to infinity, selecting the proper film speed and aperture, and open the shutter. Then wait for lightning, and when lightning occurs within your camera's view, you close the shutter (by unlocking the cable release) and advance the film for the next frame.

Complications arise, however, because you also have to deal with ambient light - light pollution, cloud movement and such - which will give your photos a look you may or may not want. The maximal exposure in cities is very limited, sometimes less than 30 seconds or so. If lightning is inactive, you'd spend a lot of film without lightning that way. Also, the correct exposure is still dependent on the film speed and aperture setting - it is the aperture setting which is one of the crucial factors determining the difference between good and mediocre photos. Another factor is composition.

Exposure

Sorry, I can't give you the correct exposure for lightning. But, since the duration of exposure is independent of lightning brightness (namely, you photograph at night using B shutter speed), and you will want to use 100 speed film for high resolution, your only concern is the correct aperture. Here are a few guidelines:

Lightning brightness	Film ISO	Aperture
Very close blinding CG lightning (< 100 m/yards)	100 ISO	f/16-f/22
Relatively close, blinding CG lightning (~ 1 km)	100 ISO	f/11
Distant CG lightning (5-10 km)	100 ISO	f/5.6
Distant CC lightning (5-10 km)	100 ISO	f/4
Distant CG/CC lightning (10-20 km)	200 ISO	f/4-f/5.6
Remote CG/CC lightning (20-50 km)	200 ISO	f/2.8

[Exposure guide for lightning photography. CG = cloud-to-ground, CC = cloud-to-cloud, IC = intracloud]

If lightning is very far away, say > 50 km, you will have to use a fast film, such as 400 ISO. Such lightning is in general not very spectacular to photograph, but you can practice anyway.

If you have lenses which show coma at low apertures, you will have to use a faster film and higher aperture. Coma can really ruin a photo.

Any coma of the lens (at lowest apertures) will readily show up if you photograph something as high-contrast as lightning. The lightning will be washed out and unsharp, while the foreground may still look properly focused.

Exposure depends also on the power and type of the lightning discharges. Some lightning discharges may be close but not so bright; other (especially the very large bolt-from-the-blue) lightning will still be blinding at 10 km distance or so. The experience you have to develop is to guess the right aperture to within 1 stop or so, by looking at the brightness of the lightning.

If there is a lot of haze or rainfall, the lightning light will be scattered, reducing the contrast of the lightning with the background. There is not much you can do to optimize this using aperture settings - except perhaps close the aperture more, but you will loose the branching of the lightning on the photo easily that way.

One thing is very important to understand in lightning photography: you are essentially exposing two different subjects at the same time. Since you use B mode to capture the lightning, the foreground and background is continuously exposing your film, also when lightning is not happening. Your choice of film speed is fixed by resolution, and the aperture is fixed by the the brightness of the lightning. The exposure time is determined by the ambient light. Good lightning photos show properly exposed lightning as well as a properly exposed background/foreground. If lightning is close, the lightning will expose the foreground and you're done - but if not, you will have to stick also to a certain exposure time, disregarding the lightning flashes, in order to get the foreground exposed properly.

Daytime lightning photography

This is usually very tricky. You obviously can't use B-mode; you will have to expose according to what the light meter of the camera says, minus one stop (minus two stops if you expect the lightning to be close). Use the same equipment and film as for nighttime lightning photography, and wait for a lightning discharge to occur within your camera's view. Then immediately react by pressing the shutter release. For this method to be successful, you should have a reaction time not over 0.2 second. If you have a longer reaction time, you have to train your reaction time with some game, if you want to do daytime photography.

This only works if your camera is not too new - in other words, if the camera is mechanical and opens the shutter immediately after you press the release. You will have a fair chance to catch a subsequent stroke part of the same flash (if you notice the lightning flickering, you will usually have a short enough reaction time to photograph a discharge this way).

Daytime lightning photography can be quite a challenge.

However, you will in general not photograph any branches - because branches on CGs only happen during the first stepping-leader process and hence the first return stroke. Any subsequent leaders (dart-leaders) will follow only the main channel to ground, because this has a much shorter resistance to ground. So no subsequent strokes of a flash will show branches. If you are very lucky and very fast, you can still photograph the branches if you happen to react on a flash within the cloud, and while the camera is open, a CG occurs out of that flash, a fraction of a second later.

If you expect such a thing to happen, you can close down the aperture and choose a longer exposure time - such as 1/2 second at f/22 or so (if the light level permits anyway). But keep in mind that with longer exposures during the day, you will reduce the contrast the lightning will have on the photo - because you expose over a longer time window the ambient daytime light, and the lightning would take just the same time to expose.

Optimal exposure times are 1/15 to 1/30 second. For any much shorter than that, there's a fair chance that the shutter will open just in between two return strokes of a CG and thus miss the discharge (even though you would be reacting in time). Any much longer will cause a drop in contrast with the ambient light so much that the lightning may not turn out to be much discernible on the photo.

Note: dusk and sunset allows for stunning lightning photos, because it is dark enough to have the shutter open for a few seconds, yet light enough to capture the daytime light on a time-exposure. Also, the colors of the sky at dusk can be very nice.

Lightning triggers

There exist lightning trigger circuits for your camera, both as a cheap, homebuild unit, and as commercial units. They react by sudden changes in light level. A trigger on your camera will catch most lightning, if it is multistroked - but again, no branches, since the trigger will generally be too late for those. Also, since it reacts to light changes, it will trigger even if lightning is not in your camera's view - and you may run out of film very fast.

My experience is that personal reaction (at daytime) is more efficient in both saving film and success ratio than is a lightning trigger. At night, you won't need a trigger anyway.