Wednesday, 26 August 2015

So ... what does it actually LOOK like when you wear a pair of EnChroma sunglasses?

That's a tricky question to answer, because when you think about it, you don't know what the world actually looks like through my eye's (or anyone else's), and I don't know how you perceive all the colours around you. The world looks "normal" to me, even though I perceive it differently to you.

I've been wearing the EnChroma sunglasses for a couple of days now, and the best overall description I can provide is to imagine turning the colour down on your TV or computer screen until it's black and white, and then bring it back up to 6/10 or 7/10 - that's sort of what the world looks to my unaided eye - the colours are all there, but they're all a bit muted and subdued.

(Actually, that's NOT how the world looks to me, but it's the best simulation I can think of!)

Now turn the colour back up to "normal" viewing (10/10), and then take it up to 11:

THAT'S roughly what the world looks like to me through EnChroma - everything becomes more saturated, and just "pops".

The effect is most noticeable on pastels and other unsaturated colours - they all become richer, denser and more saturated. If a particular shade has just a touch of red, or green or yellow, it will seemingly "boost" the colour to make it several shades "richer". You know how an external painted masonry wall will fade over time, and all your favourite shirts fade with multiple washes? It's like giving the wall a fresh coat of paint, or buying a new Hawaiian shirt.

Bright, saturated primary colours aren't affected nearly as much - but I can see most of them clearly anyway. Fire engines and mail boxes are still "signal red", the sky is still sky blue, Hi-Vis Safety Shirts are still canary yellow. But when you think about it, most of the colours in the world around us are a bit more subtle and muted than that, and it's these unsaturated colours which seem to get the strongest boost.

There were a few surprises as well:

Green traffic lights have always looked almost white to my eye, with only the slightest hint of colour - a bit like how "warm white" compact fluorescent bulbs look compared to the "cool white" ones - but now they are bright green. Also, for the first time ever, red traffic lights are brighter than amber traffic lights, whereas the amber has always been quite a bit brighter than the red to my eye.

The EnChroma lenses can give a strong green cast to some (but not all) digital displays – my SmartWatch and tablet are now green when they should be white (both have OLED screens), and there's an LED display board near my work which is now green, but my TV and phone look pretty normal (but a bit dark!), and as I sit at my computer typing this reply, the white is just white.

Interestingly, the blue LED status lights that you often see on electrical equipment seems to be a colour that my unaided eye sees very brightly, but the EnChroma lenses seem to block very strongly. I noticed it first on our TV Set-Top Box and a computer monitor at home, and also on the lift buttons at work. Even though the lift is well illuminated and I can see fine with the glasses on, the floor button back-lights almost disappear completely when I put the glasses on. I guess it depends on the exact colour spectrum of the RGB pixels - it would be interesting to see if this effect persists with the Cx-65 lenses, which are apparently optimised for digital screens and the like.

Drab greens and browns (I'm thinking of colours that you would probably describe as faded olive green or mission brown) become a LOT more dense, and therefore get quite a bit darker - again, it's a bit like over-painting a faded fence with new paint which is a couple of shades darker. I think these colours must lie pretty well in the red-green "notch" in the EnChroma transmission spectrum.

I suspect things like army camouflage would be pretty strongly affected by this - but I haven't seen any army vehicles or personnel since I got the EnChromas. (Or maybe I did, but they disappeared totally against a dark background?)

Anyway, that's enough of a report for now - I've got to get back outside to look at some more flower beds. (And look for that Jeep that I misplaced somewhere.)

Tuesday, 25 August 2015

Spectroscopy of EnChroma Cx 15 lenses

I have taken a few spectroscopy images of the white light of a halogen bulb as viewed directly, and through a pair of normal (polarised) brown-tinted sunglasses,  and through the EnChroma Cx 15 lenses.

Here's the direct halogen spectrum,  unfiltered:

(Ignore the streak on the left-hand side -  the interesting bit is the rainbow on the right.) 

This is the spectrum as seen through the normal sunglasses - you can see that they suppress all wavelengths more or less uniformly:

And here's the view through the EnChroma lenses - you can see that they have two very distinct bands where virtually all light is blocked out,  while other wavelengths pass with very little attenuation :

I've also shot a short video showing the effect -  you should have no trouble working out when the normal sunglasses and the EnChroma lenses come between the light and the spectroscope:

"Color for the Color Blind" - A quick review of EnChroma Sunglasses

I'm severely Red-Green Colour Blind (technically, I have Deuteranomaly, a genetically transmitted condistion). 

I’ve just acquired a pair of EnChroma Cx Explorer sunglasses, which are designed to boost colour perception for many people who suffer from colour blindness. (See

The theory is that for people with normal vision, the Red receptors in the eye respond strongly to red, but only moderately to red-green colours, while the Green receptors respond strongly to green, but only moderately to red-green colours. For people with Red-Green colour blindness (which is my problem), the red and green receptors in the eye overlap in their colour reception, and both respond strongly to similar wavelengths in the red-green range, so they don't differentiate between red and green as well as a normal eye.

The EnChroma lenses effectively transmit red and green, but largely block the intermediate red-green colours, so the red receptors will be triggered strongly by red but not by red-green (which are blocked by the lenses), while the green receptors will be triggered by green but not red-green. 

Where these glasses differ from other products that I have seen advertised before is that these use narrow band-pass "notch" filters to cut out a very tightly defined band of red-green, whereas the more common type use pigmented dye filters, which filter out a wider and less clearly defined band of colours. 

(The EnChroma lenses also have a "notch" for blue-green, which could be beneficial for some forms of colour-blindness, but is probably not so important for me - although maybe it helps with the overall effect as well?) 

My pair arrived yesterday.

So - do they work? In a word:


They're quite dark (just 14% overall light transmission), so they're intended for full daylight use, not really suited for indoor use. If you're wondering - 14% transmission is pretty typical for a sunglass lens designed for full sunlight. E.g. Oakley provide a range of tints from 9% to 11% for "Extremely bright light", while 13% to 22% are rated for "Medium to bright light".

EnChroma offers three lens shades: 14% for "strong daylight", 25% for "medium-to-low light outdoor conditions" and brightly-lit indoor use, and 65% for general indoor / computer use. The 14% has the strongest colour-correcting effect, which is why I chose it.

In muted light this morning (7:30 am, a bit of light cloud / mist), the effect outdoors was obvious - a lot more contrast and definition between various shades of green and red in the garden.

But as the sun broke through - WOW!

Colours became quite eye-popping - our dry winter lawn became a vivid green, pastel flowers that always faded into the background suddenly stood out ...

The most dramatic difference was driving in to work - so, green traffic lights are actually green? Who knew?! J

(Green traffic lights have always looked almost white to my eye, with only the slightest hint of colour, but now they are bright green. Also, for the first time ever, red traffic lights are brighter than amber traffic lights, whereas the amber has always been quite a bit brighter than the red to my eye.)

Some unexpected effects - they can give a strong green cast to some (but not all) digital displays - my Android tablet is now green when it should be white, but my phone looks normal. There's an LED display board outside the Convention Centre which is now green, but as I sit at my computer typing this, the white background is just white. I guess it depends on the exact colour spectrum of the pixels.

I'll by trying to catch a spectrum tonight using my Public Lab Spectrometer - I'm expecting to pick up a couple of strong "notches" in the white light spectrum. I'll post here when I've captured a useful spectrum.

(For the sceptics: There is some “real science” behind these glasses, which differentiates them from other tinted sunglasses which have been promoted as "cures" for colour blindness – e.g. see: 

Friday, 14 August 2015

Affordable (Free!) 3D Modelling Software - A 5-Minute Review

When I started my adventures in the 3D printing world, I was using Alibre Design as my main 3D modelling software. While I still have a valid Alibre licence, they have been taken over by 3D Systems (as you will see straight away if you click on the Alibre link above), and the software has morphed into "Geomagic Design", which has different features and licensing terms, and it has been increasingly difficult to migrate my Alibre licences onto new computers, running new operating systems. I thought it was time to look for a new CAD modelling software system to generate designs to feed my 3D printer.

There are many, many free and low-cost 3D modelling software options available, so where to start? Well, a good place is to list my must-haves and nice-to-have features:


  • I am looking for something that will design "mechanical" components, rather than "free-form" modelling (i.e. a mechanical CAD system (MCAD), rather than an artistic "clay modeller")
  • Parametric modelling - e.g. the ability to edit a dimension and have the model "rebuild" itself (e.g. change the size and spacing of a group of bolt holes) 
  • True "solid modelling", not "surface modelling" capabilities - e.g. I need to be able to insert a hole or cut-away, and have the internal volume recognised as a solid rather than a void
  • Precision modelling capabilities - I need to be able to model to a fraction of a millimetre (even if my 3D printer's precision / tolerance are not quite up to the task sometimes!)
  • Familiar UI layout / functionality / workflow - I have used various MCAD software such as Alibre, Solidworks, etc for many years, and their UI and general functionality suits me, and I don't see any need to lean a completely new way of working to achieve the same goals; I realise I will need to learn new icons and menus etc, but I am looking for the same overall workflow concepts such as Create a Sketch / Extrude / Fillet / etc
  • Runs on Windows 10 (all of my home Windows machines have now been upgraded to Windows 10)
  • Exports models in STL format
  • 100% legal for personal / hobby use - I've been down the pirate software option, and I've used "extended trials" and "student licences" and so on, but I want to "keep it clean" from now on


  • Import / Export a variety of industry-standard CAD formats (e.g. IGES, STEP, etc)
  • Assembly Modelling (build assembles of multiple parts, to check fit and interference, etc)
  • Runs on other platforms (e.g. Chromebook, Android tablet, etc)
  • Will run without needing to "install" any software (I don't mind "installing" software on my own computers, but work policies prohibit the installation of software on the company's computers)
  • Legal for limited work-related use (I would sometimes like the ability to create simple models for finite element analysis )
Alibre Design still works very well for me, apart from the licensing / migration issues, so it's time for me to move on. SketchUp doesn't quite cut-it - it's a terrific package for what it does, but it falls short on the precision MCAD capabilities. After doing an exhaustive search (i.e. a few quick Googles), here's what I came up with for closer consideration:


Onshape advertises itself as "the first and only full-cloud 3D CAD system that lets everyone
on a design team simultaneously work together using a web browser, phone or tablet" - and it seems to be true. Forget what you might think about Cloud software, and how slow it surely must be - Onshape has a pretty full set of professional modelling tools, and runs really well in a browser on even modest hardware such as a Chromebook, and it has native apps for iPad and Android tablets.

Onshape running in Chrome browser on Windows PC

Native Onshape app on Android tablet 

Capabilities include a wide range of import / export formats, assembly modelling, and so on. It's missing a few high-end features, but it is still undergoing active development (automatic 2D drawing generation is coming soon, for example).

The software designers come from the team that developed SolidWorks, and it shows in the toolset and UI design - if you have previous experience with professional MCAD software, you will feel at home very quickly.

What is truly remarkable, is that all of this capability is available free for hobby / personal use:

You get access to ALL of the modelling tools for free - the only real limitation for the free account is the amount of Cloud storage space (5 GB for free accounts vs 100 GB for paid "Professional" accounts) - being a Cloud-based system, all of your models HAVE to reside on the Onshape cloud-store, but you can export models to your own file storage. 5 GB should be ample for all but the most ardent hobby modellers, though. In addition, you are limited to having 5 concurrent "Active" documents open at a time. For most hobby users, this won't be an issue - there is no limit on the total number of models you can have, but you may need to toggle some of them to be "Inactive" to free-up a new "Active" model. (Note that a "Document" can be a full assembly, with all of its parts, so you can have a lot of "Active" content at any one time!)

My only real reservation is that being proprietary software, there is always a chance that the owners might decide to abandon the free personal licence model at some future date, leaving me without free access to my models. However, their FAQ suggests that there is no intention for this to happen, so I'll give them the benefit of the doubt:

Q:  Will Onshape ever change or restrict the Free plan?
A:  Although we cannot guarantee that there will never be additional differences between the Free and Professional plans, we expect that CAD modeling, drawings, and data management capabilities will continue to be fully available under the Free plan.

All in all, if you are looking for a good 3D modelling capability, you HAVE to take a look at Onshape!


FreeCAD is a totally free, open-source 3D parametric modeller. It seems to be the best-developed open-source 3D MCAD modelling software I have come across, and it is still being actively developed and supported. As such, it has a large user community, and it is likely to be around for a long time to meet your needs. It is available on Windows, Linux and Mac, so will work for most PC users (but no Chromebook or mobile app as yet).

It's part-modelling capabilities arr pretty comprehensive (certainly adequate for my needs), and being open-source (with support for Python scripting), it has plug-ins / add-ons / extensions for a range of other software systems, such as Assemblies, 2D drawings, rendering, BIM / IFC, etc.

FreeCAD on Windows PC

In all honesty, I would have been perfectly happy with FreeCAD if it wasn't for the fact that it needs to be "installed" on Windows computers, which my work will not permit. I was looking for something that I could access occasionally at work, which is how I came across the cloud-based browser-accessible Onshape. However, if you're looking for 100% free, open-source 3D MCAD software, FreeCAD seems to be the pick of the bunch for now.

AutoDesk Fusion 360

The AutoDesk brand should need no introduction, but Fusion 360 might not be familiar to you. Basically, Fusion 360 is a professional-quality cloud-based 3D CAD/CAM tool, which supports both Mechanical and Free-form modelling. If you're familiar with Inventor, then you will understand Fusion 360. While it is a cloud-based service, it does require an application to be installed on your PC (Windows and Mac are supported) - it does NOT run in the browser, so other platforms (Linux, Chromebook, mobile, etc) are nor currently available options.

Fusion 360 UI on PC

The licensing model is rather unusual. AutoDesk has long offered free or very low-cost Student Licences, as long as you have a valid student ID, but these would expire after some period, and you would then be "strongly encouraged" to upgrade to a full licence. Fusion 360 is different:

As well as the traditional free 3-year Student licence, AutoDesk offers a free 1-year "start-up license" for "hobbyists, enthusiasts, makers, and emerging businesses that make less than US$100,000 in revenue per year". At the end of the 1-year term, you can reselect the start-up entitlement as often as you want (and as long as AutoDesk continues to support this licensing model). 

If you are familiar with AutoDesk products (especially Inventor), and especially if you want 100% compatibility with an AutoDesk work environment for example, then Fusion 360 is well worth a look. If you don't have a history with Inventor and other AutoDesk products, you might find it a bit more than you need, but then you only need to learn how to use those parts of its comprehensive tool-set that interest you. Going with an AutoDesk product has the advantage that there is a huge global Inventor user-base, and you can pick up any number of "How To" books from your local book-store (most of which should also apply to Fusion 360), so getting training and support is a no-brainer. 

And since it's free and legal (for now, anyway), why not give it a try if your interest is piqued?

And the winner is ......

Well, for now, it's almost a dead-heat. 

I really, really like Onshape - it works well, offers ALL of the features I'm interested in, and is truly multi-platform. My only qualifiers are the fact that it is Cloud-based (so won't work without an Internet connection) if that worries you, and the fact that it is proprietary software, and they might change their personal / hobbyist licensing terms one day. (I'll probably keep using it as long as it's free). In my view, Cloud-based software is probably the way of the future, and I have access to an Internet connection almost all of the time. The ability to view / refine models on any device at any time is a real plus (e.g. put the finishing touches on a design using your tablet while you're on the bus home after work). 

Otherwise, FreeCAD will also stay in my portfolio - partly because it's very good, and partly as a back-up in the event that Onshape is no longer available to me. It does MOST of what I want, but it isn't quite as polished, and it won't run on all of my devices (I can't install it on my work computer or my Chromebook, and I can't access it on my Android tablet, for example).

In third place for me is Fusion 360 - but mainly because it's a bit of a sledgehammer to crack a walnut as far as my needs are concerned - but if you have a track record with AutoDesk software generally (and Inventor in particular), you may well want to take a look.

For now, I'll give a Points Decision to Onshape - I'll post an update after a few months use to let you know if my feelings have changed.