Focus Stacking Protocol for High-Resolution Insect Photography

Summary

The objective is to offer an accessible, standardized focus stacking method for insect photography, using affordable equipment to create sharp, high-resolution images for taxonomy, biodiversity research, ecological studies and public outreach.

Abstract

Here, we present a protocol to acquire high resolution, extended depth of field images of insect specimens by photographic focus stacking using a modular digital imaging system. The method provides a standardized workflow linking equipment assembly, calibration, image acquisition, and post processing. Using a full frame mirrorless camera (61 MP) coupled to microscope objectives and synchronized strobe illumination, the protocol achieves pixel scales from 0.76 m–0.19 m and produces artifact free composites through sub-micron focus increments (0.2 m). The procedure can capture and process approximately 20 final images per week under routine laboratory conditions. Compared with existing stacking solutions, this low-cost hybrid setup (< 30% of the cost of commercial systems) maximizes accessibility while maintaining diffraction limited image quality. Representative applications include the production of color calibrated identification plates for taxonomy, biodiversity digitization, and outreach. The protocol’s standardized structure facilitates reproducibility across laboratories and field stations, supporting large scale insect imaging campaigns in both resource limited and institutional environments.

Introduction

Insects represent the most diverse group of organisms on Earth and play critical roles in ecosystem functioning¹. Yet, global assessments indicate alarming declines in their abundance and diversity worldwide^2,3. Accurate imaging of insect morphology is essential to taxonomy, ecological monitoring, and conservation, particularly in biodiversity-rich tropical regions where many taxa remain undescribed⁴. However, conventional macrophotography remains constrained by limited depth of field, which prevents a single image from encompassing fully sharp three‑dimens....

Protocol

1. Equipment set up

1. Design a modular imaging system that integrates high-end optical components with affordable and widely available equipment (Supplementary File 1)
2. Combine precision mechanics, controlled illumination, and advanced optics to achieve high-resolution focus stacking while maintaining flexibility for different insect sizes and morphologies.
3. Use the following core components.
   1. Camera
      1. Use a high-resolution full-frame digital camera with strong dynamic range to capture fine morphological structures in detail.
      2. Mount the camera on a highly s....

Results

Validation of Image Quality and Resolution

The focus stacking system produced fully sharp, high contrast composites across magnifications from 5×–20×. Calculated pixel scales ranged from 0.76 µm (5×)–0.19 µm (20×) in object space, confirming adequate sampling for sub-micron structural details of insect cuticle and appendages. Representative stacks of 800–2000 frames demonstrated consistent in-plane sharpness without halo artifacts. The protocol-maintained alignment precision w.......

Discussion

Optimal performance of the focus‑stacking procedure depends on (i) complete isolation of the setup from vibration, (ii) precise focus‑rail calibration at sub‑micron increments, and (iii) consistent color calibration. Any deviation from these parameters significantly increases halo formation and color shifts⁹. The combination of mechanical stability and standardized illumination represents the single most critical determinant of image quality.

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Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Support table	Preferentially 3 pods	Stable base for the entire set-up	150
Antivibration table	Custom	Minimizes vibrations during image capture	3,200
Cylindrical black tunnel	Custom	Controls light direction	350
Reduces reflections for small subjects
Novoflex CASTEL-MICRO focusing rack (macro rail)	Stepping motor–controlled, control unit, network cable, Euro AC adapter	Sub-micron precision focusing (0.2 µm steps);	3,000
automates camera movement
XYZ rotary	Adjustable mount	Meticulous subject alignment and positioning	500
Camera	Sony Alpha 7R IV (61 MP full-frame)	High-resolution image capture	3,000
Illumination	2× Godox SK300II	Uniform, shadow-free lighting;	400
Illumination	2× Godox QT600II	high-speed with short flash duration	1400
Flash stands	3 adjustable stands	Flexible positioning of lights	100
Light modifier	Diffuser	Softens light and reduces harsh shadows	50
Background	“Black hole” velvet	Eliminates reflections, provides uniform background	200
Microscope objectives	Mitutoyo Plan Apo Infinity Corrected: 5×	High-quality magnification for microstructures	1,000
Mitutoyo Plan Apo Infinity Corrected: 7.5×	2,000
Mitutoyo Plan Apo Infinity Corrected: 10×	1,400
Mitutoyo Plan Apo Infinity Corrected: 20×	5,000
Lens tube system	Direct camera use of Mitutoyo M-Plan lenses (2x, 5x, 7.5x, 10x, 20x)	Coupling microscope objectives to camera	400
Adapter	Sony E-mount to NOVOFLEX universal bayonet A	Mechanical connection of camera and optical system	300
Macro lens	Venus Optics Laowa 100 mm f/2.8 2× Ultra Macro APO (Sony E-mount)	Imaging larger specimens at high magnification	550
Trigger	Flash trigger	Synchronizes flash with camera shutter	50
Computer	ASUS or Alienware laptop, ≥128 GB RAM, high-performance processor	Image processing and storage	3,000
Storage media	2× SD 256 GB, fast SD card reader	Secure high-volume image storage and transfer	200
Accessories	Gaming mouse	Precision during editing and navigation	50
Accessories	Wacom One (graphic tablet)	Fine control during image cleaning and editing	500
Total cost			26,800