This motive, a 30 million year old ant trapped in Baltic amber, is about 3 by 4 mm. Wit a normal macro lens or extension tubes, it is not possible to get such a small object so detailed captured. Reversing a wide angle (zoom) lens with an adapter (reverse ring or retro adapter) gives high magnifications and it is possible to get a good picture (right two images). I also had the opportunity to use a microscope with camera, the VHX2000 from Keyence, which is specially built for imaging small objects. I found that both are not perfect solutions, which makes a comparison meaningful.
Before I get to the differences, some words on what they have in common. Both work with lenses and a digital sensor. The depth of field is very limited and both require a stack of 10-20 images from bottom to top that are either merged in a stacking program like CombineZP or Photoshop*. They both disappoint in image quality and detail for printing on a A3 format. For more detail you need to zoom in and make a mosaic composite**. The ant image is based on a single stack image.
| VHX2000 | DSLR |
|---|---|
| Stability | |
| Stable platform present | Need to stabilize camera and object carefully |
| Image Quality | |
| 1600 x 1200 (3200 x 2400) pixel resolution | 5184 x 3456 pixel resolution |
| Compressed/filtered data | Raw data |
| Crisp sharpness difficult | Crisp sharpness difficult |
| Details such as hairs visible | Details such as hairs visible |
| Photo stacks by software | Photo stacks manually |
| Optimal stacking |
Non-optimal stacking (movement of camera possible when turning wheel) |
| Light | |
| Artificial light | Natural and artificial light possible |
| Light from all sides (adjustable) | Light from one side (with natural light) |
| Light can work 'flat' | Lighting very flexible in giving depth |
| Clipping of light areas | Fewer clipping areas (with Raw data) |
| Other | |
| Zoom under 1 mm possible | Zoom limited (here to about 2 mm objects) |
| Relatively fast | Time consuming |
| Expensive | Not expensive, when camera and lens are already in possession |
Conclusion:
The pictures with either a VHX2000 or a reverse ring are slightly different, especially concerning color. The reverse ring method is more complicated and time consuming but gives an image quality that can keep up with a microscope image (apart from small lens distortions that are not considered here). For the price and quality, a reverse ring is a very attractive alternative to a microscope, when the object is not smaller than about 2 mm.
* On digital stacking:
1) CombineZP (freeware for stacking) gives nice results with the pyramid weighted average method. The idea is that the software reconstructs the 3d depth of the object. From the bottom layer, the sharpest is considered and build up to the top layer with complex algorithms.
2) Photoshop can also yield nice results with a different method. It just keeps the most sharp part from each layer. Sometimes the result is nicer than CombineZP, sometimes not. To do this, choose File => Scripts => Load files into stack. In the layer palette, select all layers. Then choose: Edit => Auto-Align Layers, followed by Edit => Auto-Blend Layers. Sometimes the result is better without Auto-Align (eventually manual align).
** Mosaic composite:
E.g. a mosaic of 6 image columns by 6 image rows with overlap in area for stitching gives at most 3 times more detail. With 20 stack layers per image, you need to manage 36x20=720 images (which I only did once). First you stack each mosaic part with the favored software, after which the mosaic is stitched together. This is time consuming because it often requires manual adjustments, and is only justified when an image is indeed to be presented at A3 format.
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