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photo:focus_stacking

focus stacking for greater depth of field

introduction

  • macrophotography of 3D subjects is problematic as the depth of field (DOF) is rarely deep enough to cover the whole subject, even when the aperture is stopped down to f/11-f/16
  • capturing a subject 1cm in length from head to tail in perfect focus is a feat that all insect photographers wish to accomplish but when shooting at 1:1 macro, depth of field may only be 0.5mm
  • stopping the aperture down too much looses image detail due to diffraction issues
  • an option to address this issue is to take a series of photos with slightly different focus points then in post-processing with Photoshop or similar, combine these images and only display the in focus areas from each - this is called focus stacking
  • now this is very tedious for most of use mere mortals so in 2015, Olympus kindly automated this procedure in-camera for their latest OM-D cameras as well as their Stylus TG-3 and TG-4 Tough cameras by including automatic focus bracketing and taking this a step further to automate the post-processing of these images in camera as "focus stacking" mode
  • it can also be used in landscapes with very close foregrounds!

www.ayton.id.au_gary_photo_images_depth_of_field_-_single_exposure_vs._focus_bracketing-1.jpg

www.ayton.id.au_gary_photo_images_focus_bracketing_stacking-1.jpg

The above images were supplied to me for publishing here by Olympus photographer Kim Holst who created these nice explanatory diagrams

manual focus stacking technique

  • decide if the scene really does need focus stacking
    • if nearest object is more than 3m from lens you might be able to get away without stacking
  • decide on how many you need - the minimum is usually 3 (foreground, mid, distant), and where possible aim for at least 4-5
  • use a tripod
  • ensure camera is not moved between shots to minimise alignment issues (this can also occur due to focus breathing of the lens which effectively changes the field of view as focus point changes)
  • ensure the time between your shots are sufficiently short to avoid changes in ambient light between shots which is particularly an issue at sunsets with clouds (this is where automatic in-camera focus stacking functions such as with Olympus cameras really helps)
  • set camera to Manual exposure to ensure each shot has the same exposure

examples

photo/focus_stacking.txt · Last modified: 2020/07/17 22:00 by gary1