Technique – Stacking photographs for long exposure results

Technique – Stacking photographs for long exposure results

A landscape photographers best friend: long exposures! The traditional technique for this in bright well lit scenes means using a neutral density (ND) filter which can impede on image quality – any piece of ND glass you put in front of your lens will degrade image quality and leave colour casts but thanks to the people at Adobe we have a modern digital fix for this. It can produce results that can better the traditional technique in many circumstances.

What you will need:

  • Camera and Lens
  • Tripod
  • Intervalometer release or Intervalometer in camera
  • Lightroom or post processing software
  • Photoshop

What you are going to do:
You are going to shoot a batch of photographs that will get stacked and blended together using Photoshop. For that part, you are just a monkey clicking buttons and we leave Photoshop to do all the algorithmic magic to produce the final image. Where your expertise is needed is in composing the photograph, nailing the exposure and understanding how time affects your scene.

PHOTOGRAPHING THE SCENE

Setup your camera on your tripod in front of your scene and compose your shot, manually focus or use AF-L (back button focusing) and manage your settings in full manual mode so there is no variations in exposure from frame to frame.

Now to use both sides of the brain – creativity and mathematics! You’re going to want to imagine what your scene will look like during a long exposure, and here’s where the maths comes in – try and figure how many seconds you would like to achieve the effect in your final photograph.

Example- If you are shooting a waterfall and you think a 5 second exposure would look really nice and your shutter settings on your camera are 1/30th of a second then that means that you will need 30 frames to equal 1 second – 30 frames x 5 seconds = 150 photographs! (Your shutter speed is the most important part of this technique, you do not want to have to process thousands of photos to compile into one because of a faster shutter speed, you won’t like the process and your computer will probably implode. So try and keep your shutter speed low, around 1/60 and lower to be in the 10’s to 100’s of photos to process.)

Use your intervalometer cable release or the built in one to program the amount of shots you need to make it work. This reduces camera shake from you pressing the shutter button and also – who wants to press it hundreds of times??

POST PROCESSING

Import your images into Lightroom and enter the develop module.

Select and edit just one from the batch of photographs

With the image you just edited, go to the bottom image preview scroll bar and hold down SHIFT and select the last image of the batch. This will highlight all of the ones in between. With all of them highlighted, hit the SYNC button on your develop module on the right. A pop up will open and make sure you have everything selected, then click Synchronize, all of your images will take on the changes you made to the edited image.

With everything synced and looking the same, keep your images selected.
Head up to your main toolbar and click- Photo -> Edit In -> Open as layers in Photoshop.

This part can take a little time, be patient and you will be rewarded.
Each image comes through into PS on its own layer in the same window. Once they are all loaded Select them all by selecting the top one and scrolling to the bottom, holding SHIFT and select the last image. This will select all of the layers. Head up to- Layers -> Smart Objects -> Convert to Smart Object.

This part too can take a little bit of time. Once your layers have been converted into a single Smart Object/s make sure the layer is selected head back up to Layer -> Smart Objects -> Stack Mode -> Mean. This is where PS does some wizardry.

Once that is completed, you will have a single long exposed photograph!

BEFORE AND AFTER - With this capture, I only blended 25 of 100 images that I shot of this technique in mind, this gave me textures in the falls still. So you can have the full effect or as little as you like and fine tune it to what you require!  BEFORE AND AFTER – With this capture, I only blended 25 of 100 images that I shot of this technique in mind, this gave me textures in the falls still. So you can have the full effect or as little as you like and fine tune it to what you require!

This technique of post processing can be used in all forms of photography, but notably gets the best results with water, clouds, light trails and even improves the visible digital noise produced by ISO’s in modern digital cameras. Hope you enjoy this technique and good luck!