Vertical stacking rig for set butterflies and moths

[JKT]

Here's my current vertical stacking rig designed for butterflies and moths. Minimum magnification is about 1:3 and maximum so far 50x by changing lenses. It can't go lower as the center hole gets into the picture and it can't go higher as the StackShot vertical resolution becomes limiting around NA=0.75.

Left rear corner has three power bricks Velcroed together; one for RP, 6V for flashes and 12V for StackShot and the LED strips (inside the aluminum L-profiles), so it all works behind single power switch.

The bottom plate could be deeper, but that is what the manufacturer makes. A dual carriage rail fixed directly to the copy stand would help with that too. Well, the dual carriage would just increase stability.

The flashes are DC powered with wires going parallel to battery back. I've sacrificed the PC socket for the DC socket, so I have to use the remote controller. The flashes work with DC or batteries, but I wouldn't try them together.

The power requirements for the the 6V source are a bit tricky. Initially the flashes draw quite a current. If the power source just gave what it can, this wouldn't be a problem. However, current ones seem to cut off when the maximum is exceeded and that doesn't work here. The solution was a bit crude, but it is effective nevertheless - there's a power resistor in series with each flash, which are in parallel to the power source. The resistor is calculated so that it limits the current in single line under the power source maximum (with some margin). I just have remember to start the flashes one-by-one. The power drain is much smaller during the actual shooting and the power levels in flashes are usually 1/64 ... 1/32. Yes, the resistors generate some heat all the time, but with mains power I don't really care. Most of the time the current is pretty low.

 

[Anton Largiader]

Wow, there's just so much to see there. I like gadgets.

I assume the three LEDs are for focusing, and the flashes are E-TTL? Did you fabricate that triple flash hood? That is nice.

 

[JKT]

Yes for the LEDs ... though there are actually two parallel lengths of 90 CRI LED stripe in each of them. They were added later, so the wiring is somewhat ... coarse.

The flashes are manual and controlled from the remote with 1/3 stop steps. With this setup I've created tables, which relate wing span to ISO, aperture, flash power and stacking step. I have those tables in Zerene, so I first measure the object size and then select a row in Zerene. That chooses the step size and at the same time shows me what other settings to choose. It is not quite exact, so I do the final adjustment based on background in RAW.

I designed the hood, the internal reflectors and also the diffuser shape (not visible from above) that acts as curved bottom so it is actually a closed design except for the openings for the flashes. I had it 3D printed at Shapeways. Biggest problem is the diffusor. The material turns yellowish over time and color settings need adjustment. When I find a better material, I likely do the next version.

I wanted enough flash power, so I can keep the flash duration (flash power) short. I surely got that as I usually need 4x neutral density filter. Then again, near the high magnification I need about 1/16 and that increases the flash time a bit too much. Besides, it will also heat up the resistors during a long stack.

 

[Anton Largiader]

Increases the flash time too much for what? Can you post a sample of what you do with this setup?

 

[JKT]

This was taken at about 50x magnification. At that level it doesn't take much vibration to destroy the image. That's why I try to keep the flash power low enough to freeze the movement. There is some ramp-up and ramp-down in flash power, but most of the adjustment is done by increasing the flash duration.

The way I support those genital slides it is a miracle I get ANY decent pictures! The setup was NOT designed for such magnifications. These have come later. Most of the time it is for whole butterflies and Moths, so down to roughly 10mm wing span.

BTW, that is apparently a Taygete sp. from Madeira, which would make it a new Genus for Europe. Too bad that species hasn't been described.

 

[JKT]

However, most of the time I'm doing this: https://focus-on-photography-forum....nite-share-photos-and-discuss.1140/post-27929 with larger and smaller samples. For the ones in normal pins I take both topside and bottom and for those in short pins just the topside. The objective is to get fast throughput with good quality and minimal hassle.

 

[Chrisa]

Although my version is crude compared to the OP it works. The subject is on a 3D printer. Can be moved 0.1mm at a time. This was just me testing it. Someone on Reddit posted the idea.

 

[JKT]

I started with a tripod as well.

.. and a borrowed Nikon Coolpix 4500.

If you ever need to do stitching in addition to stacking, the plate makes that trivial.