The Light Slide

fun with photography

Sigma System Focusing macro lenses: secret soft focus

Surprise! It's a soft focus lens.

Late one night, trawling eBay for cheap lenses — as one does — I stumbled across an oddity: a 100mm f/2.8 1:1 macro lens, from Sigma, for $30.

Now I've done a lot of research into vintage macro lenses and this one had never come up, and that's weird, right? There aren't that many 1:1 lenses out there, much less vintage ones. And for $30? With a changeable mount? Unheard of!

Zooming into the listing photos for clues — as one does — I noticed it had a whole lot of labels in white and green. "System Focusing," it said on the side. An enigma.

Thus armed, a little googling led me to the reason for its obscurity… and the reason I bought it with a rush of glee.

Sampling the secret soft focus

This is the Sigma YS 100mm f/2.8 System Focusing Macro lens without the "macro" function engaged.

NB: I had to use a little focusing helicoid to get close enough for this framing

And this is the Sigma YS 100mm f/2.8 System Focusing Macro lens in "macro" mode:


Here's how it works:

  • To use normally, you just… use normally. Focus with the big grip in the middle of the lens. The regular minimum focusing distance is quite long, close to a meter. It's pretty sharp!
  • To engage soft focus (cough "macro" cough), turn the big grip to the closest possible focus marker, then grab the front ring and start turning. It will resist at first; it has a magnet or something that holds it in place until you really want to move it.

Turning the big, center focus grip away from the minimum focal distance will engage some mechanism that snaps the front element back to its "home" position automatically.

That means you can only get this effect on close-up shots… the only downside. You can turn the outer ring at regular focal distances, but all you'll get is an out-of-focus image.

A dreamy pictorialist landscape lens this is not.

But then again, those lenses aren't for macro!

I can't wait til I can pick up some flowers and really test it out. Because, realistically, that's the only thing this "macro" function is good for: Moody flower portraits.

Soft focus… really?

I'm no soft-focus expert, but what I can tell you is that there's a big difference between soft focus and out of focus.

Even when you're focusing with this hazy monster in "macro" mode, you can see the focus snap. It's just that there's also tons of fuzzy bloom on top.

From what I understand, that's because a soft focus lens like this works by increasing spherical abberation rather than actually changing the focal point.

Now I imagine anyone who bought one of the Sigma System Focusing lenses for their stated purpose would have been more than a little put-off by the fact that they're actually defocus control lenses, but I'm delighted.

I have a thing for soft focus lenses. And bad lenses. And really old lenses; even, sometimes, dirty lenses. It's not only that perfect, clinical drawing leaves me cold… there's something about the whacky and wild that I just can't quit.

And this lens is certainly that.

Sample images in normal use

It's also plenty sharp enough to be worth purchasing to play around with and use as a normal 100mm f/2.8 lens. I don't know exactly what it is, but I like this lens a lot.

wide open: dare I say it? this baby has the vintage "pop"
good colors and easy to focus manually
it's just got a very pleasing drawing
sharp but not too sharp… and notice the bokeh in the bottom left

Shopping tips

  • These lenses are not worth much
  • There are a bunch of identical or near-identical Sigma lenses with System Focusing, all with different badges like YS, XQ, Telemax, etc etc., and sellers will often not mention System Focusing in the listing at all
  • Search for the main specs (length, aperture, maybe YS/XQ mount) only and then check all the photos, you're likely to find one for $25-40

I paid $100 for this one, out of frustration after the $30 one got away — a late night splurge I don't regret exactly but which didn't have to be so much. I found my next one, the 135mm, for $35 using the tips above.

Further reading