High-Magnification Rig

The previous page includes extreme close-up photos of a PCB taken with an Intel QX3 microscope and a Panasonic GH4. I experimented with various lenses, extension tubes, lighting, fixture hardware, and stacking software to obtain the best results.

Magnification

The QX-3 microscope has a 352 x 288 pixel sensor (<0.1 megapixel), but only 320 x 240 pixels are used by the software. The software then interpolates the image to 512x384. The Panasonic GH4 has a 4608 x 3456 (16 megapixel) sensor, which is a 170× advantage.

The QX-3 has up to 200× optical magnification. The Leica 45mm micro four-thirds lens which is officially capable of 1:1 focus (object size scales exactly onto camera sensor). The Panasonic 17.3 mm x 13 mm sensor with 4608 x 3456 pixels is 4608 pixels/(17.3 mm/25.4 mm per inch) = 6765 dpi. On a 96 dpi monitor, the magnification should be 6765 / 96 = 70 times.

Swapping in a Yasuhara Nanoha x5 lens provides 5:1 optical magnification. Meaning the small Panasonic lens and modern monitor should display an effective magnification of 70x5 = 350x magnification.

For my target, I used a 0.01 inch wide line from a 1200 dpi printer. The line should be 1200*0.01 = 12 printer pixels in width. It should be seen by 6765/1200*12 = 67.65 pixels in the image at 1:1 to the Panasonic sensor on a 96 dpi monitor.

Magnification target 10 thou

Magnification target 10 thou (Leica, w/extension, Nanoha, Nanoha w/extension)

Here is the approximate magnification based on a 0.01 inch line whose pixels were measured in the photo using a paint program:

My measurements might be slightly off or the hardware may be exceeding specifications. In any case, this proves that the camera and Nanoha lens is capable of magnification greater than the old toy microscope.

Extension Tubes

The extension tubes, mentioned above, move the lens away from the camera sensor to increase magnification (think of an old-school optical telescope or extra long zoom lens).

Fotasy extension tubes for increased magnification

Fotasy extension tubes for increased magnification

The inside of an extension tube is empty; there isn’t any glass. Higher quality extension tubes do include metal pins to make electrical connections between the camera body and the lens to support lens recognition, power, and other functionality.

Camera Mount and Fixture

Clearly a tripod is needed for macro photography. However, at such magnification, even shifting my weight on the wood floor is enough to move the shot noticeably. Below is the setup that keeps the camera and target synchronized:

Macro photograph setup

Macro photograph setup

SLIK PRO 700DX tripod to hold the entire setup.

StackShot Automated Macro Rail Package to take multiple images at varying distances to be combined in software for increased depth of field.

③ Cable that controls the stepper motor on the StackShot.

④ Cable that triggers the camera from the StackShot.

Panasonic LUMIX DMC-GH4 micro four-thirds mirrorless camera.

Fotasy Auto Focus Macro Extension Tubes 10/16/26 mm to increase zoom. These extension tubes include pin connectors to allow the autofocus and other features of the lens to continue to operate.

Yasuhara NANOHAx5 Micro Lens

⑧ Custom machined aluminum mounting bracket to attach the target base.

⑨ Custom machined clear acrylic plate to hold the target subject and permit backlighting.

Bracket

The StackShot does not come with any front mounting holes. I wrapped the StackShot carefully to avoid metal chips from getting into the lead screw. Then, I drilled two unthreaded holes.

StackShot protected during drilling

StackShot protected during drilling

The mounting bracket is solid 9.5 mm aircraft aluminum for stiffness. The mounting bracket has space in the middle to avoid contact with the lead screw or bearing.

Target bracket spacer machined from aluminum

Target bracket spacer machined from aluminum

The bracket attaches with the bolt heads on the inside. An L-shaped hex key tightens and loosens the bolts on the rare occasion that the bracket needs to be removed.

Mounting bracket with notch attached with screws

Mounting bracket with notch attached with screws

It can be challenging to line up a shot when using extreme magnification. Just barely touching the subject can cause it slide out of frame. So, I purchased a linear stage from an auction site. Turning the dials slowly moves the subject up/down/left/right and rotates it.

3 axis XY linear rotary stage

3 axis XY linear rotary stage

I was honestly surprised by how well the stage works. I assumed that the pressure or vibrations from my fingers would jiggle the image. But, no, it was amazingly stable. Of course, the XY stage is securely attached to the camera using a thick plate of aluminum.

Camera with XY Delta table

Camera with XY Delta table

The linear stage doesn’t move very far in any direction. So, it is a good idea to place the subject as well-centered as possible. The stage works by having spring loaded plates pressing against the spindle of a micrometer.

Shutter Jitter

This camera setup dramatically improved the quality of the microscopic images. I no longer had to leave the room while the StackShot was automatically taking photos, for fear that my movement or breathing would misalign or defocus the shot. Yet, there still seemed to be some smearing or fuzziness in the most extreme shots. The StackShot pauses after movement before taking a photo, so it was not to blame.

It turns out that vibration from the shutter or speaker noise affects clarity in extreme close ups. On the Panasonic, switching to silent mode prevented the issue. (Some people advocate turning off automatic image stabilization as well, although I haven’t noticed a difference.)

Panasonic Lumix silent mode

Panasonic Lumix silent mode

Speaking of clarity, there is another factor that greatly affects image detail, which is addressed on the next page.