[Hands On] Venus Optics (a.k.a Laowa) Aurogon Macro Lens

[mjkzz]

Fingers crossed to see if I fixed my 50x 0.42 Mitutoyo. I got it from an "honest" seller 5 years ago when he admittedly told me it was built from two damaged ones (and still costed about 839USD), it was working fine since then till it went through 2500km journey and appear somehow less as a sharp shooter. Tweezers and some twist and gentle knock on table and shake seems to get it back in working condition. Still can not believe it was so easy to fix a 50x objective. Waiting for Sunset moth

[mjkzz]

It is rather important to have even lighting with this set of lenses, so I spent some time re-designing the LED strip based cone light, made it a larger and more powerful (now, 6.5W vs 4.5W before). Bad lighting or lighting from sides can lead to some severe CA or all kind of weird stuff going on which I have not observed with Mitutoyo (as severe).

Padded the neck of this cone with some fabric with back glue so it is much better fit with Aurogon front lens without using thin wrapping film. After all of this, I ran out of LED strip!!! So time to wait for them to come. Note, the LED strip must have high rendering index (Ra 97+ or CRI 95+).

New design, much larger in diameter and now has 26 LEDs (about 6.5W)

Padded the neck (even newer version has shorter neck of 20mm vs 30mm as shown).

These are failed attempts -- too loose due to tolerance, too thin and it is easily broken, etc.

[mjkzz]

I want to share the 3D printing file, but tolerance is very different on different 3D printers, so it is not a good idea to share it because people will not get it right out of printer. Another reason is where to share it? But here is what I did in Autodesk Fusion 360, so you can replicate it:

1. Draw with line tool, note, this design is heavily parameterized so I can print different versions. The important parameter is the diameter of neck, it is designed to have a 1mm thick padding fabric. LED strip used is 10mm wide. The 45 degree constraint is important -- my Bambulab P1S can print 45 degree over hang without support, which could be messy and waste a lot of material.
2. Revolve that line segments 360 degrees
3. Thicken the revolved surface OUTWARDS by 1mm (0.5mm is too thin, easily broken)
4. Cut a 6mm wide rectangular window at bottom for LED wires

All units are in millimeters and degrees. Also note, the front element of lens should be positioned at the rim of the cone, not far back, so we do not lose working distance.

There is also a cover, which is easy to do, just make some circles and cut a 6mm wide window for LED wires

Solid model

How this cone light is used, the front element of lens is at the rim of the cone.

[mjkzz]

So, again, it seems Aurogon is very sensitive to lighting conditions. I wish Laowa can make some better lighting tool so that people can use it correctly out of box!!! One design change is to use denser LED strips, currently, it has 3 LEDs per 5cm, there are denser ones, like 3 LEDs per 2.5cm, but none of them (that I can find) have high rendering index.

So till my high rendering index LED comes in, I will re-design it a bit more and start playing with this set of lenses again .

[mjkzz]

They actually listened to me and sent me a denser (6 LEDs per 5cm), high rendering index (CRI > 97) LED strip, but at 24V which is fine. It seems much better in terms of color rendering, somehow a bit over saturated if standard picture profile is used, so I have to use neutral.

Since I am shooting a video, here is how it looks after assembly (video screen capture).

[mjkzz]

I still can not believe how happy I am with Aurogon, it is a little bit "too good to be true", but true No, I am not promoting it, I am just shocked how good it is given some "bad" images I have seen. Here is a corner crop, shot at 35x magnification, 0.3NA and exposure time is 1/4s (see, the LED cone light is pretty powerful).

This is "straight" out of Zerene Stacker except scaling to meet requirement of this forum, so some sharpening due to scaling.

This is "processed" of above

This is the "straight" crop of corner, also scaled, so some sharpening due to scaling.

This is "processed" (just a little bit) crop of above.

[mjkzz]

The LED cone light is really cool, here is a shot at 0.5NA, exposure time is ONLY 1/10s at 35x magnification. I think if you light it from sides (left and right), you would need two 100W led lights, but this is only 5.1W (this LED strip has smaller LED and each is about 0.1W with total of 51 LEDs vs 0.25W for big with total 26 LEDS). The denser LED also make it even more diffused. Thumbs up to the LED seller

35X 0.5NA, processed.

[mjkzz]

Forgot to mention, there are vignettings around corners at 35x magnification on my Sony A7R5 (full frame), it looks like they are "hard" vignetting instead of graduating ones, suggesting it is caused/limited by tubes instead of smaller image circle (a limitation of optics). Maybe using larger tubes or something can correct this.

Sunset moth is finally coming!

Vignetting at 35x magnification on Sony A7R5 (full frame)

Here is an inside shot of the front lens looking from back (screen capture from my video), it seems it does not have glasses after iris.

[mjkzz]

While waiting for Sunset moth and lunch, stacked this one to kill some time

The "straight" out of Zerene Stacker image was scaled to fit this forum (and obviously marked with red rect). It was stacked from 101 images at 35x magnification and 0.3NA, and step size of 1.25um (probably too short), 0.8s exposure. It looks fuzzy and very little details, but just "cropping in" to about 2/3, so the FOV is about 50 to 52x magnification. After "processing" it a bit with Paint.net, so nothing fancy, a lot of details are revealed, take a look at the black scale. The last image is the butterfly/moth, the coin is similar to the size of US quarter.

"Straight" out of Zerene Stacker

"Cropped and Processed"

A lot of images shown posted were from this butterfly/moth, some are from the other side of it.

The other side of the butterfly/moth

[mjkzz]

Sunset moth . . . 35x 0.3NA 91 images at 1.25um step size, exposure 1/5s

"Straight" from Zerene Stacker

"Processed" -- increased brightness, saturation, clairty, no sharpening, using Paint.net (v5.11), "stamped" to remove some dusts.

[mjkzz]

I used to have "low grade" Sunset moth, very dirty and broken, did not want to explore more, but this one is rated at A1/A-, and of course, much expensive, but much cleaner . So, I found this multi-colored part.

35x 0.3NA exposure 1/4s (to get the darker part), 91 images at 1.25um step. Increased exposure, saturation, clarity in Paint.net. No sharpening at all.

[mjkzz]

35x 0.3NA 1/5s exposure, 181 images, 1.25um step size. This part is not as "flat", so the increased number of images, even that, I missed one part -- one scale at lower right Again, some exposure, clarity adjustment, a little S curve, no saturation, a little bit - minimum amount allowed by Paint.net, of sharpening.

[FotoChris]

Fantastic images, waiting for that sunset moth hat definitely paid off

I'm still wondering whether there's basically empty magnification happening beyond 20x (or even 10x)... could you perhaps post a full resolution 10x and 35x (or 50x?) of the same area of the wing, with the same adjustments etc?
You wouldn't have to do fine retouching, or anything of the sort, I'd just like to know whether there's more to be gained by higher magnifications.

I know it's a lot to ask for and if you don't have the time for such a comparison it's completely understandable!

[mjkzz]

Before moving on to 50x, here is how I do specimen slice -- using a small LED light (CRI > 97) to back light it. Note the LED light is not on, it is too bright to see other stuff in the setup. This is to show how to use this set of lenses in education(/even research) environment.

Spinal cord cross section

Onion skin -- it seems one shot is not enough, so I stacked it with 10 images at 1.25um, even that I am not sure is enough as I last time I did this kind of thing was LONG time ago.

[mjkzz]

Fantastic images, waiting for that sunset moth hat definitely paid off

I'm still wondering whether there's basically empty magnification happening beyond 20x (or even 10x)... could you perhaps post a full resolution 10x and 35x (or 50x?) of the same area of the wing, with the same adjustments etc?
You wouldn't have to do fine retouching, or anything of the sort, I'd just like to know whether there's more to be gained by higher magnifications.

I know it's a lot to ask for and if you don't have the time for such a comparison it's completely understandable!

Come to think of it, I think empty magnification is happening (with my Sony A7R5), as you can see from my repeated FOV comparisons in previous posts. I do not remember exact formula as I do not learn by rote, so no quantitative analysis, but here is a HUNCH (could be wrong, that is ) based on those FOV comparisons: the pixel size of Sony A7R5 is smaller enough to resolve NA 0.3 at 10x, maybe barely at NA 0.5 at 10x, a little "over sampling" at 20x would capture enough details. Any higher magnification would result in the same amount of detail, just bigger, hence empty magnification.

But for those cameras with larger pixel size, like the 24MP Sony A7M3 or even larger ones for A7S3, higher magnification is a must to capture details the Aurogon can offer, so 35x and 50x magnification sets are necessary for those camera.

So, there is your answer