Though some will surely swear on their mother's honor that there are obvious and glaring differences in image quality between versions, I - begrudgingly - must admit that I haven't noticed any. I'm sure there is a difference (Dynar versions are supposed to have slightly better coverage and tonal reproduction), but alas, my eyes were not blessed with the ability to see it.

One thing you can be absolutely certain of, though, is that no matter which version you get your hands on, the character of the glass (gangster slang for "lens," reserved exclusively for the coolest members of the photography underworld) is tailor-made for portraiture. The rendering is sharp even wide open (though not excessively so, like with process lenses) but at the same time, it has a velvety, soft, and gentle quality. The creamy bokeh in the background is just the cherry on top. And write this down on your ground glass - stopping down a Heliar is murdering a Heliar!

Over time, they earned a reputation as the Crème de la Crème of portrait photography - so much so that many prominent figures, from kings and maharajas to movie stars, generals, and common folk alike, refused to be photographed with any other lens. This was especially true for the Universal Heliar. But more on that next time.

My current 360mm version is nothing less than a 2.5kg hunk of glass and blackened brass (or, to put it more academically, a modern iteration of considerable weight and refined materials), which, over its many long years of existence, must have already crushed an entire regiment of big toes. It features an asymmetrical five-element design, with a cemented biconvex rear group, a convex-concave front group, and blah blah blah - for the handful of eccentrics who revel in optical diagrams, I'll simply direct you to Lens Vade Mecum, the ultimate (and hefty) bible that every lens aficionado should own. For the less committed, Wikipedia or Camera-wiki will do just fine.

And that 480mm version in the pictures? Well, there I was on a weekend, minding my own business like a proper café-dwelling layabout, skipping the real work in favor of a decaf soy pumpkin spice venti latte - when BAM! Out of nowhere, an absolute coconut of a lens smacks me in the face. One of the rarest pieces of glass ever to roll across this planet. Just another Sunday. Where am I even supposed to put another one? SIgh.

Anyway, my current 480mm version is nothing less than a 3.6kg behemoth of glass and blackened aluminum, which, over its long existence, must have annihilated entire armies of big toes - I'm honestly surprised we evolutionarily still have them at all. Very few were ever made, and even fewer have survived. The price tag back in the day must have been eye-wateringly high, whether you were a commoner or a noble. Unfortunately, the signature hasn't survived, as it was sometimes engraved on the lens hood - which, in this case, is missing (other versions had the engraving on the barrel and a permanently attached hood, so at least you couldn't lose it).

A distinctive feature are the Heliar knobs for aperture control, which, on standard versions, sometimes appeared only on the 420mm, 480mm, and possibly the 600mm models. Otherwise, they were a signature of the Universal Heliar, where they also controlled the soft-focus mechanism. Their shape and size evolved over time.

Wait, what? A 600mm Heliar? Yep, it existed. Entire generations of big toes have been trying to forget. Very, very few were made. Even fewer survived. So just forget about it too.

• Update: according to Japanese historical optics expert Masayoshi Hayashi, at least 485 pieces of 480mm and 74 pieces of 600mm were produced according to available sources (based mostly on publications by Hartmut Thiele). What's more, there were also custom-made variants not appearing in official catalogues - for example 500mm f3.5 and 700mm f4.5. In the case of the discovery of such a piece, it can be likened to finding the Holy Grail.

The word Heliar is derived from Helios - the Greek god of the Sun. So why not stand alongside the greats and have your portrait taken before the good weather bids us farewell once again? Because, as the late Ned Stark - may he rest in peace - used to say, the Winter is coming!

So drop me a message, and until we get to portrait time, don't despair. See you in the next episode. Resistance is futile.