A quick look at how to use focus stacking on the Phase One XF system...
Often when shooting still-life, even when stopped down to f16 (you don’t want to go further than that with digi as you start to get diffraction issues) you can’t get front to back focus in one shot.
Before photographers used to use complicated motorised tripod heads and custom software, involving typing in all data including circles or confusion to get the stack to work! This is an issue with food photography, for example, you can imagine the lettuce slowly wilting...
Focus stacking allows you to shoot multiple images and have them rendered into one image with sharpness throughout the desired focus range.
You’ll need a Phase One XF body (along with Phase digi back and lens) no special tripod or head is needed - but something sturdy is essential.
- On the XF body menu scroll through to Tools/Focus stack (alternatively you can swipe the XF top screen to show the focus stack screen).
There are 3 factors to consider 1) Far focus point 2) Near focus point 3) total number of shots
- Use Live View on the digi back (zoom into 100%) to set Far focus (mountain icon) point (make sure the lens is set to AF) - you can scroll the side dial and fine tune by scrolling the front dial. Save the point using the front key (a number will show next to the far focus point when saved)
- Us the same method to find the near focus (flower icon) point - saving the point with the rear key
- Dial in the number of captures you require using the rear dial. (the smaller the subject generally the more frames you will need, sometimes hundreds of frames!)
- Press the rear user button to start the sequence of captures
- The XF will capture the images from the distant focus point to the near focus point - Use the focus map (green overlay) in capture one to get an idea of how much of each capture in focus and make sure there’s at least some overlap. Too few images and no overlap will result in focus banding.
- Once captured you can (by right clicking on thumbnail) create an album from sequence ID folder (capture records sequence ID in metadata so it knows which images to select)
- These images can then be rendered in Helicon focus or Zerene to create a single image with front to back detail.
Single shot f11 (left) stacked 20 shots @f11 (right)
- When using flash lighting for you stack be sure to use a good quality studio pack and heads, moreover if using say the Profoto 10A make sure it’s set to Normal and not freeze, this will ensure the best colour temperature consistency from shot to shot.
- Use the Seismograph feature on the XF body to assess if there’s any movement of the camera, often standing next to the camera on a wood floor can move the camera during the sequence of exposures!
- trigger the camera remotely to cut down on vibrations - this can be done with the new firmware feature on the XF using an air remote.sync trigger
- Set you near and far focus points slightly before and after the respective focus points, that is one you set your close focus exactly, shift the focus slightly closer - this ensures that everything from front to back is in focus if anything shifts during the sequence.
- Be careful using P Max Pyramid method (Zerene) or ([c] method in Helicon) as this method can introduce noise and alter the colour rendering of the image - the alternative is Depth-Map (Zerene) or method [B] in Helicon.