The Sony A7R and a Zuiko 18mm f3.5

This mini review features a rather rare and exotic wide-angle optic which has a great reputation as a film era lens on digital – the tiny Zuiko 18mm f3.5. However, 36Mp of A7R resolution (without an anti-alias filter over the sensor) will stretch any lens so this will be pushing this classic lens to its limits.

The classic wide angle shot – lots of sky, deep depth of field (but see later in the text!) and a dramatic perspective.

It’s a manual focus lens obviously, and the depth of field scale would suggest you really don’t need autofocus at all – the depth of field is infinity to 1/2 a metre (3 feet) at f16. The catch though is that – as with all the other old lenses tested so far – it’s really a lot less than that for critical focus. High resolution digital sensors mercilessly expose any lack of sharpness and although 35mm film covered the same area as the Sony’s sensor I get the feeling that hardly anyone checked sharpness in the same way with film as we do now with digital images. In other words – you’ll still need to focus using the focus magnify feature on the A7R.

The tiny and exotic looking 18mm from above. A minimal set of controls – a focussing ring and five aperture stops. There’s no room for a front facing cosmetic ring giving the serial number/spec so it’s printed around the edge of the lens (the bit that looks like a filter but isn’t). This one has a serial number 102085 (no 2085?). The serial number on my Zuiko 50mm f1.8 is 1494292 – I think they made more of those!

Physically it’s tiny – around the same size as the Zuiko 50mm f1.8. Weighing in at 267g (around 10 oz) it’s solidly built with a slightly shinier surface than most Zuikos, and feels quite dense. What’s most striking is the bulbous front element which protrudes from the front of the lens by around 2mm at the centre and looks vulnerable to damage (I remove the deep ‘slide on’ lens cap, take the picture and put the cap straight back on). Minimum focus is 25 cm and focus goes from infinity to minimum in around 90 degrees of a turn of the focussing ring.

There is a 49 mm thread fitted and Olympus made a now rare and expensive 49mm to 72mm step up ring for filter use. I’ll be experimenting with how to sort out this problem later but suffice to say standard filters won’t fit and I don’t want to pay £100+ for a step up ring!

 

That amazing front element hides a complex set of internal lens elements and is quite hypnotic to look into!

According to my old Oly lens catalogue (circa 1980) the lens features an automatic correction mechanism to prevent degradation of lens performance at close focussing distances – nearly all wide Zuiko prime lenses do this too.

A 28mm lens has an angle of view of 75 degrees, an 18mm sees 100 degrees so quite a difference, especially in a cramped interior where you can’t step any further back. The cost of using an ultra wide angle is usually strong distortion, flare and soft frame edges – these lenses aren’t easy to design or use and often suffer from poor edge performance.

The Zuiko 28mm f2 75 degree angle of view – note the slight purple internal flare below the altar.

The 100 degree view of the 18mm – quite a difference and no internal reflections but a slight haze around the light source. I’ve been caught out a few times by including the top edge of my finger as it supports the front of the lens – this really is a wide angle lens.

After using the lens for a day vignetting stood out as a ‘feature’ at f3.5 – it’s very noticable in some shots! In trying to correct the darker edges in DXO a reddish colour cast was introduced so you can’t work around it either. It’s pretty much gone by f8 and isn’t that much of a problem as to get the best resolution you’ll need f5.6-f11 anyway, but it’s worth pointing out. You could use it creatively I suppose – I don’t think I will be though!

Hammer House of Horror would be pleased with vignetting at f3.5 (more or less gone by f8). Unless you really like this effect use f5.6 or ideally f8 to f16. Depending on the composition it can be devastatingly obvious or not that obvious at all.

Flare is usually a problem with ultrawides. With so much in the picture the sun often makes an appearance and with all those lens elements internal reflections can become a problem (lens hoods aren’t that much use either as they’re so shallow). Happily I can report that I had to deliberately engineer a shot to see anything significant and other than this example I saw no flare which was distracting.

The worst flare/internal reflections I could manage. Pointing the camera upwards as in this shot produces these converging verticals.

I found only a little purple/green chromatic aberration when looking for it – the example below illustrates it quite well. It can be easily removed in post-processing but honestly, I wouldn’t bother as it’s virtually insignificant in most shots – a few pixels at most (a few in 36Mp isn’t that much!).

The whole shot

Large crop from the top right.

Close up distortion -well distortion in general really – is minimal. I haven’t seen any pincushion distortion or bent horizons which is remarkable in itself. Pointing the lens upwards will obviously produce converging verticals, but with the camera more or less level the images don’t give away that they were taken with an ultra wide at all.

At f8 – still a little vignetting (easily removed at this severity) but good sharpness and colour saturation and very little chromatic aberration – excellent! This doesn’t look like an 18mm shot at all – more like a 28mm.

Close up distortion is pretty minimal too :-

You’re thinking – ‘so what?’ aren’t you! This was taken about two feet away from the window and there’s no distortion at all in an uncorrected image – that is remarkable. The 24mm end of a high quality zoom would have the centre looking like it was bulging out of the picture.

On to the mill for the acid test :-

f3.5

The full frame at f3.5 with vignetting obvious

A large centre crop and OK ish. Not great it must be said.

The edge at f3.5 is so dark, sharpness is difficult to judge. Unless you like strong vignetting it’s irrelevant, but if you do it’s OK – I can just read some of the wording on the sign.

 

f8

f8 centre and looking very good – not amazing but this is a 18mm lens – not a 50mm!

f8 at the edge.

At f3.5 things are fairly good in the centre, but edge definition is completely masked by vignetting (possibly a good thing!) By f5.6 things have sharpened up nicely, f8 is optimal and, as usual, slight softness is created by diffraction at f16 but the differences between f5.6 and f16 aren’t very noticeable. As you might expect, the edges of such a wide-angle lens are slightly softer than the centre at all apertures but the centre is pretty good – maybe an 8/10. These have been processed using DXO Optics 9 with straightforward default RAW conversion. I’ll have a play around to see if I can squeeze a little but more sharpness out of them using micro-contrast and sharpening controls.

At £300 plus this doesn’t fall into the usual ‘cheap and very good’ category of for Zuiko MF lenses (£300 doesn’t buy many modern AF lenses either), it always was an expensive and exotic optic.

It must be said that it isn’t making the most of 36Mp of resolution, but it’s resolution is impressive for an ultra wide-angle lens. I doubt that most modern lenses, especially zoom lenses, would be that much better in terms of sharpness on the A7r at this focal length. Where this lens really shines though is its remarkable lack of distortion and tiny amounts of chromatic aberration in such a small package. It’s in a different league to my cheap and cheerful Tokina 17mm f3.5.

So oddly, and I wasn’t expecting this, I’ll conclude that for such an exotic focal length, this is a well behaved solid lens which is consistently ‘sharp enough’ from f5.6 to f16 and, if used with care, produces images which don’t have most of the giveaway signs of an ultra wide angle lens. It would be an excellent lens for photographing architecture and landscapes. Highly recommended – I must try it on my OM2N next!

Thanks for looking – hope you find this useful.

If you’re interested in using other MF lenses have a look at the other reviews on the film, camera and lens review index tab.