Quote from James Warner on January 5, 2022, 7:35 pm

I received a gift a few months back containing the Pentax-F 85mm F2.8 Soft Focus lens. This completed my Pentax-F prime collection I had been obsessing over, and is by far the odd one out of the bunch. I've never used a soft focus lens before and know very little about them, so join me in some of my first experiments and results with the lens.

What is a soft focus lens?

A soft focus lens is a lens designed intentionally to allow for some level of spherical aberration. Spherical aberration is what occurs when light rays passing through a rounded element don't all end up exactly on the same focal point. I'm going to end my attempt at explaining such things, as it really is above my pay grade. But the point is that an ideally sharp lens strives to limit spherical aberration, whereas a soft lens embraces it somewhat for artistic effect.

It's different than being out of focus, however. And the best way I can think to explain this is that an out of focus shot on a normal lens will have all of the light land fairly equally in front of or behind the subject. Nothing is in focus. On a soft focus lens, there will be some landing on the focal plane on your subject making it in-focus, and varying amounts of light bouncing around near that focal point giving it softness.

First impressions of the Pentax-F 85mm F2.8 Soft

My first time using the Pentax-F 85mm F2.8 soft was in my backyard photographing my children on my Pentax K-1. In perfect honesty, reviewing my first picture taken at F2.8 (where the effect is most pronounced) felt like using a really, really cheap vintage lens with a fungal problem. Trust me, I have experience.

In fact, one of the most popular ways to mimic the effect of a soft focus lens is to take a cheap UV filter and smear vaseline on it. I have no inclination to try that, but I think you get the idea.

Stopping down the aperture lessens the effect. Not just getting sharper as do most lenses when stopped down to a point, but actually reducing the spherical aberration by design. This is actually really neat to play with. Each aperture under F8 has it's own rendering, and by using them enough one could be very precise in how they choose the effect for each scene. After F8 the effect virtually disappears, and it's astonishing. All the sudden you're out of dream mode and using a normal lens. It's weird.

Once I got over my initial reaction I noticed how pleasantly the effect rendered highlights. Bokeh highlights bloomed over foreground subjects in a dreamy way. It got me thinking: instead of shooting the lens on subjects under normal lighting conditions, what if I shot them backlit and exaggerated this effect?

The Pentax-F 85mm F2.8 Soft Backlit Test

To test my theory, and start to study the effects on bokeh, I shot the lens at F2.8, F4 and F5.6 on a tree in my front yard. It's an ordinary scene, but I think you will agree the soft effect turned it into a magical forest. The sample shots are below.

I took this idea into the woods behind my house to see what I could get. Here's a gallery of some shots taken at various levels of softness (aperture) mostly F4 and F5.6. Enjoy, and let me know what you think.

Happy snappin'

Sample Gallery

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