7 Common Questions About Long Exposure Photography Answered

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Long exposure photography offers a who new way of seeing the world around you. Once you get started you may become totally hooked. It isn’t a cheap form of photography, to begin with, but once those initial costs are taken care of, you can photograph as much as you want, providing you take care of your gear.

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If you are new to long exposure photography it can seem like a very confusing process to get your head around. Ultimately it does become much easier, but there are some common questions that most people first ask. You might have some yourself. Over the years I’ve been teaching long exposure photography, here are the seven most common questions that I get.

1 – What is long exposure photography?

Typically, long exposure usually refers to any photography that requires a tripod. For most photos, you can hand hold the camera. However, there will always be places that are too dark and in order to get a good image you will have to sacrifice ISO and turn it up a lot. That will enable you to get a fast enough shutter speed to capture the image.

Increasing your ISO does introduce noise and for many situations, it is not good to do that. This is when you should put your camera on a tripod. When you do that, you are starting to do long exposures.

Typically, you would do long exposures for night photography or if you are using special filters. However, when most people talk about long exposure photography they are usually referring to the use of ND filters that block many stops of light which will allow you to keep the shutter open for a long time.

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2 – What are ND filters?

There are many different types of filters used for photography, especially when people were using film. However, the most common type for digital photography is a Neutral Density filter or ND filter. This filter sits in front of your lens and is used to block out some of the light. They vary in density, and the darker the filter, the longer the exposure you can achieve.

They are called neutral density as they are color neutral (no tint). Many filters do give you a colour cast, the most common being magenta. However, good filters should not affect the color in the final image at all.

The density refers to how dark it is, though this is often called stops. A 10-stop filter is much darker than a 6-stop. A 16-stop ND filter is very dark and you can’t even see through it with your eye.

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3 – What is a stop?

The stops can be an indicator of how dark a filter is, or what its density is, but it usually refers to time. The higher the number of stops a filter has, the longer the exposure will need to be. A stop is a measurement of time. Put simply, it means you are either halving or doubling the amount, depending on whether you are increasing or decreasing the number of stops.

For example, if you are using a 10-stop ND filter and the exposure time is one minute, but you decide you want to go to an 11-stop filter, then you need to double the time, so the exposure would be two minutes. However, if you went down a stop to 9, then the time would be halved and become 30 seconds. If you decreased another to an 8-stop filter, then you would halve it again, 15 seconds.

This is a very simple way of looking at it. If you want more information then take a look at this article written by Jim Hamel on What is a Stop? The Common Currency of Exposure Explained.

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4 – How do you figure out the exposure time needed?

With experience, you do start to get a feeling for which filter to use for specific conditions, and for how long. That doesn’t help you when you are first starting, but thankfully there are apps available that will help you take the guess work out of it.

You can get the apps for both Apple and Android phones. Just look up Long Exposure Calculator and you will find them. They will help you work out how long to expose for, according to the stop number of your filter. The calculator takes into consideration your ISO, your shutter speed, and aperture when the filter is off.

I have an android phone and I use an app called Exposure Calculator. I have been told the app Longtime Exposure Calculator for iPhones is also very good.

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5 – What subjects are good for long exposures?

There are three main subjects that people use long exposures for; water, clouds, and people. Basically, ND filters can be used for anything that moves where you want to get a blurred effect.

Water

Perhaps the most popular subject for long exposure photography is water. Using the filters can give that smooth water look. Though, they can be good for waterfalls and help to get that marshmallow or silky look. The filters are often used to show howwater moves on beaches, capturing the movement of the water as it rolls in and out.

Clouds

The filters can be used to capture the movement of the clouds as they move through the sky. Many people also do long exposures with architecture having blurred clouds behind the buildings. City scenes are very popular as the effect gives the scene a quiet, empty feel.

People

To help get that isolated feeling long exposures can empty the scene of people. It works really well unless people are walking straight towards you or they stop and stand in the same place for a long period. If you give it less time you can get a blurred effect so that people or cars look like ghosts in your images.

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6 – Square or round filters?

There is a big difference of opinion with this one.

Round filters

Round filters screw onto the end of your lens like many traditional others like UV filters. You order the size according to the size of the thread of your lens. It is the same size as your lens cap (look on the back of the cap).

However, if you want to use more than one lens for long exposures then, in theory, you would need to buy filters for all them. You can, however, get step-up rings, so it is best to buy a filter for the biggest thread size lens. For example, my largest is a 77mm, and I then get step-up rings for the smaller ones. So if you also have a 62mm lens, then you can get a ring that will go from 62 to 77mm. You can then use the one filter for both lenses.

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The disadvantage is that every time you recompose your shot, you have to unscrew the filter and then screw it back on. Some people don’t mind this, but others find it too time-consuming.

Square filters

The square filters are more expensive as you have to also buy a holder for them. But you can get different adaptor rings for the different size lenses. The advantage of this system is that you can remove the holder easily each time you want to recompose your image, then put it back on quickly. It is an easier system in that respect, though it is a bit more work when you are setting it up and packing it away.

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There are a lot of companies that make filters for both systems up to 10 stops, but for darker density ones you have to get square. Many of the top filter companies only offer square filters. I use Formatt Hitech and they make round filters up to 10-stops, but their Firecrest 13 and 16 ND filters are square. Whereas, I believe, the Lee Filters are all square.

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7 – Cheap or expensive filters?

There is an easy answer to this question. You get what you pay for and the cheap ones are nearly always a mistake. They often have a really bad color cast, magenta, and can give you a lot more work to do in post-processing. If you are working in black and white, there isn’t a problem, but for color, it is a headache that most regret.

The top quality filters are expensive. But they will last you for years and if you love long exposure photography they are a purchase you won’t regret. The best filter to start with is the 10-stop. It is the most versatile and you can add more filters as your confidence grows and you have more money. I started with the 10-stop, now I have a 16, a 13, a 6, and a 3-stop. I can also stack them which gives me even more choices as well and doesn’t reduce image quality.

Many filter companies also provide packs that will provide you with everything you need. Formatt Hitech, for example, have the Joel Tjintjelaar Signature Edition and it has the 3, 6 and 10-stop ND filters, plus everything else you need to get started.

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The magic of long exposures

There is something quite magical about long exposures and once you start to do them it is hard to look at water or clouds the same way again. A whole new way of expressing yourself is opened up. Many think it is complicated, but it isn’t really. Take a chance and give it a try. Let me know how you go.

Please put your questions in the comments section below and share your long exposure images with us as well.