u/CambridgeandFiji

So I can finally do a true like for like comparison… photos are of the same type of lens (1.67 index Essilor Varilux and Zeiss Smartlife [edit: this is in fact the clearmind but that shouldn’t affect anything] both with AR coatings and with colortouch blue/photofusion x blue, both near-new so a true like for like comparison (I have previously only done comparing different colours)

(1). This is indoors, unactivated. The c25% colortouch can be seen vs the clear Zeiss (tbh in the photo on white paper suggests Zeiss is less than clear - that any photochromic has a tiny (5%-8%) residual tint is well known… all I can say is put next to other lenses they look v similar, and it is only against bright white paper that this can even be seen… at least in my experience, unactivated looks completely clear when wearing in frames).

(2) the comparison: I left them both in the sun for about 2 minutes on a hot day (c32c/90F). The sun was not directly overhead (as I know even when warm Photofusion can go fully dark when directly facing the sun/using a UV torch), but as you can see there was plenty of bright sunlight hitting the lenses.

- the Zeiss did not go/stay nearly as dark once they warmed up. In the photo example I would say Zeiss went to max 50%, colortouch c75% (ie the base 25% of the colortouch did look to add 25%…)

- the difference when wearing each is probably even more noticeable… with colourtouch the fade when moving through shade or turning away from the sun (ie normal use!) seems less dramatic as even in heat the initial photochromic fade which happens quickly is still on top of the 25% base tint.

So personally I would choose colortouch on hot days…. even though I like the Zeiss blue when fully activated, in heat it washes out too much/too quickly.

BTW when fully activated (ie not in heat) the % feels/looks v similar between the lenses. It may just be that once at or above c85% it is difficult to spot any difference, though I suspect the colortouch wash reduces the photochromic effect above a high % (after all, if you had a 25% wash and a 75% photochromic effect then 100% would mean you would see nothing 😎).

As the weather has turned colder I tried an indoors experiment using a UV torch and a basin of warm (40C) water.

The aim was to test how heat affects photochromics when UV activated (and see if colourtouch were any darker even in heat as a secondary test).

For a reference point there are some black masunagas with a straight 62% blue tint in photo1.

Photos 1-3: The champagne TVRs have blue colortouch in them. Removed from frames are some Photofusion blue and burgundy. With unwarmed (room temp) and warmed (the wet ones I just warmed in lukewarm water at the bottom). photos 1-3 are a time lapse of about 10 seconds.

Results: even warm photochromics do go as dark in DIRECT UV (which I was surprised at) but if warm they fade very quickly (guesstimate they fade to 25% within 30 seconds - compare bottom lens photos 1-3 and contrast with the non warmed lenses above). IRL this means unless you are directly facing the sun they will fade/not activate (recall I was using a bright UV torch directly on them to activate in the first place - anything less and they wouldn’t fully activate).

Photo 4 is really just for info to see the torch I was using… one limit was I could only cover one lens at a time so had to move quickly esp for warmed lenses.

Photo 5 is (bottom frames) amber colourtouch with the right lens having been warmed, after about 30-40 seconds of activating both (the top frame is clear just for reference. Photo 5 is similar in that the colourtouch blue in champagne frames has had one lens warmed and left for about 30 seconds (black frame is again Essilor 62% blue for reference).

Results: colourtouch (unsurprisingly) also fade quicker when warm. But with their base 25% I noticed they did not drop off a cliff unlike other photochromics.

Other comments:

- these are just a few photos, I also had xtractive (basically unaffected by heat), other transitions too.
- I will need to try colourtouch on a really hot day to draw any firm conclusions, but my feeling from this is that they will be better than other photochromics in heat, but if you want really dark you’ll want either straight tint or xtractive or sun adaptive. But see photo 6: the warmed colourtouch lens is similar to the same brand (Essilor) 62% blue tint (contrast photos 2-3 where the warmed Zeiss Photofusion blue fades to nearly nothing within seconds of no strong direct UV). So it may well be that if you are happy with a 50-65% tint even in heat colourtouch will be fine.

Finally, everyone’s needs will be different of course. Colourtouch are marketed as having a residual fashion tint indoors etc, and that is surely still the main reason for getting them.

[edit: in photos 1-3 the two pairs of lenses out of any frame are Zeiss Photofusion x (blue and burgundy). The warmed ones fade really quickly. I did the same with other transitions (green and brown) with equivalent results - ie both Photofusion x and transitions fade in the heat - nothing new there…]

A few photos in 24 Celsius sun comparing colourtouch Amber with Photofusionx Burgundy. We are forecast to have 30 degree heat this weekend so the contrast in not just sun but heat may show up more.

For now, my ‘hypothesis’ is that as transitions colourtouch have a c25% base they will remain darker even in heat. These photos compare colourtouch (amber) with transitions (burgundy), both at full activation.

They are pretty similar but to me the amber does seem to go a bit darker - that may just be the difference between the tint colours, but for instance I can face the sun with the colourtouch amber with slightly less glare.

(Edit: both frames are Masunaga One Hundreds… different colourways).

So it is finally out! I think mainly worth it for varifocals, and it costs (at Simplespex, who do not rip you off) £100 more than Smartlife superb…. The Zeiss description of the new tech including research results is really promising.

So I said I would post once I had them, and did so using another account as Reddit was being painful about this one about a comment taken out of context (not sure they get sarcasm… or humour…)

Anyway this should show colortouch sapphire (i shifted from black to champagne TVR 504 crystal frames as in black acetate they just looked washed out) and amber in Masunaga One hundreds (black/demi - the lower brown in the frames picks up the same tint).

Comments:

- 25% wash now certain (had heard rumours of 35%)

- works fine in certain thick acetate (for black I might suggest Ruby) and more will certainly work in most rimless or wired frames

- goes as dark as any transitions (unsurprising). I will only know if they go a tiny bit darker after a more time in the sun when they are fully bedded in, otherwise, 30 seconds to full activation, maybe 90 back to base tint.

- as the gradient is 25% to zero this will be VERY subtle.. rimless or similar may be the frames for such a light gradient?

Happy to answer any questions if I can!

P.s. these are in Essilor Varilux XR varifocals at 1.67. But they seem to be available across the Essilor range, and some of the Essilor licensed companies make cheaper lenses with the same tech, and Goldie has found one which even offers the standard brown, grey and grey/green under a non ‘colortouch’ brand…