Focus Stacking Tests (by Terry Mann)
“Focus stacking (also known as focal plane merging and z-stacking or focus blending) is a digital image processing technique which combines multiple images taken at different focus distances to give a resulting image with a greater depth of field (DOF) than any of the individual source images. Focus stacking can be used in any situation where individual images have a very shallow depth of field; close-up & macro photography and optical microscopy are two typical examples. Focus stacking can also be useful in landscape photography” (Wikipedia).
Suitable image processing software is an important tool in combining focus stacked images. The software needs to do the job of determining which parts of each image represent the best focus and then combining these as seamlessly as possible. In this respect not all focus stacking software implementations are equal.
For the purposes of comparison I recently carried out some tests using three different programs.
The three programs tested:
Combine ZP https://alan-hadley.software.informer.com/ This is free but has not been updated since 2010
Zerene Stacker https://zerenesystems.com/cms/home Costs $89, 30-day trial available
Affinity Photo https://affinity.serif.com/en-gb/photo/ Costs £49 and is a fully featured photo editor (cf. LR), 10 day free trial.
I took a number of sets of photos, close-up and macro, using different camera supports and focussing methods.
- Tripod and focussing slide, change the focus plane by moving camera in small increments.
- Tripod and changes the focus plane using the focus ring on the lens in small increments.
- Monopod and change focus plane by tilting the monopod in small increments.
- Monopod and change focus plane using the focus ring on the lens in small increments.
Methods 1 and 2 were the best of course but if you don’t have a focussing slide, method 2 is fine.
I tried using a monopod because in some situations (e.g. insect macro), there would be no room for a tripod and it would be too slow to set up. I found I could get reasonable results but have not had a chance to try this “in the wild”.
All the stacked images I made can be seen below.
The brown dried “leaves” were all taken using a focussing slide and processed by all 3 programs.
The flowers did not use a focussing slide; only Affinity was used to process the images – this was testing the camera support method.
Some landscape image sets were checked too but the images are not shown.
Affinity – Close-up. Best Result
CombineZP – Close-up. Poorest result but probably still usable with edits
Zerene – Close-up. Good result
Affinity – Macro 1:1 Best result
Affinity (crop) – Macro 1:1 Best result
CombineZP – Macro 1:1 Worst but usable result
CombineZP (crop) – Macro 1:1 Worst but usable result
Zerene – Macro 1:1 Good result
Zerene (crop) – Macro 1:1 Good result
Macro Affinity Stack30 – change lens focus distance (Using tripod)
Affinity Stack9 – change lens focus distance (Using tripod)
Affinity Stack24 – change lens focus distance (Using tripod)
Affinity Stitch6 – Adjust lens to focus (Using Monopod)
Affinity Stack11 – Tilt Monopod to focus (Using Monopod)
Affinity Stack8 – Tilt monopod to focus (Using Monopod)
A summary of the results are tabulated below.
|Combine ZP||Useable results, some misalignment at corners.||Average results, a little misalignment at the corners. Ghosting is visible in some cases||No updates since 2010. It has a 2-stage process: align and then stack with a choice of different methods. This program is worth a try before buying better software|
|Zerene Stacker||Good results. LHS of image was fuzzy and had to be cropped but all the was expected was in the cropped image||Good results||This a single purpose program so not good value. There are 2 methods to choose from, one produces a flat looking image; the other processes to get good contrast.|
|Affinity Photo||Good results. RHS of image was fuzzy and had to be cropped but all the was expected was in the cropped image||Good results – favourite||Cheap and you get a multi-purpose program. Easy to use and the fastest.|