The Sony A7R and a Zuiko 21mm f3.5

It’s been ages since I posted anything here (sorry!), mainly because I haven’t bought any more lenses! This nice 21mm f3.5 was swapped for my Zuiko 18mm earlier in the year as it was a bit too wide for my tastes, and really I always wanted the 21mm. It hasn’t been used that much so far so I thought I’d give it a proper test and share the results. Wandering round with just this lens was an interesting experience for someone who’s current favourite focal length is 50mm – sometimes it seemed just too wide an angle of view.          

Physically it’s tiny and light – about the same size as my 50mm f1.8, 1 1/4 inches long (3cm ish) and it weighs 7 1/2 ounces (212 g) so very portable. The angle of view is 92 degrees and a very close focussing distance of 8 inches (or 20cm) to infinity focus is achieved in around 1/4 of a turn. And of course being a Zuiko it’s very well made too. It matches the A7R very well as do most of the smaller Zuikos. The A7R’s love of a default 1/60th of a second in ‘A’ mode with MF lenses is also nothing to worry about at 21 mm.

Five apertures to choose from – 3.5 to 16 and a focussing ring – can’t get much simpler than that.

The filter thread is the normal 49mm screw in, but even thin filters cause vignetting so I’ve stopped using them on this lens, so no polarizer or NDs unless you’re prepared to do some cropping in PP.

 

At f3.5 and insanely close, this is the best bokeh I could manage. Using a 21mm lens as a macro lens is – er- eccentric to say the least.

Focussing using focus magnify works well, though at smaller apertures it’s more difficult as there’s a lot in focus, and the changes when the focus ring is turned are fairly subtle. The ‘focus peaking’ feature is pretty useless with lenses as wide as this for the same reason. As with the 18mm, the depth of field scale is pretty optimistic and the zone of really sharp focus is narrower than you might expect – in other words, always use ‘focus magnify’!

Starburst at f16 (with a tiny amount of flare)- not bad at all if you like this sort of thing. Shadows pulled up in PP (the A7R is brilliant for this).

I couldn’t provoke much flare on a sunny day – this lens seems excellent in this respect. I did find an odd circular internal reflection in one shot when the sun was pretty much in the centre of the image which I quite like :-

Native vignetting is moderate at f3.5, gone by f5.6 :-

f3.5 – nowhere near as bad as the 18mm but then few things are. I can live with this and even use it occasionally.

 

f5.6 – hardly noticable and it doesn’t reappear at other apertures.

Distortion when pointed upwards is obvious – what you’d expect really from an ultra-wide :-

This was taken with a slim UV filter but its still vignetting!

Close distance distortion is also remarkably low – this was taken very close to the fence and is uncorrected :-

OK – it’s all looking good so far, what about the resolution? All of these are straight RAW conversions so note that the minimal CA and distortion could be cleaned up quite easily. Here’s the test scene (same as earlier in the post), edge crop from the centre left.

f3.5, the edge crop darkened by the natural vignetting of the lens.

f5.6

f8

f11

So – optimal between f5.6 and f8, tailing off slightly at f11 and f16 (not shown). Quite predictable really. However this is a remarkably consistent performance across the aperture range with minimal CA wide open. It’s nice and sharp in the centre at all apertures, but the edges are never really achieve the same resolution.

In conclusion then, apart from the edge performance which I’d call ‘good’ (or ‘good enough’ for my purposes) a very good lens. Small, light, low distortion, low CA, sharp in the centre and can do sun stars as a party trick. I might use this lens ten or twenty times a year and for me the positives easily outweigh the negatives so I’m keeping this one! If you use this focal length all the time and need better edge performance something more expensive might be in order.

Second hand they range in price between £200 and £300 which is pretty cheap. As with all older lenses exposures have to be carefully monitored (they tend towards one to two stops of under exposure so watch the histogram), some PP will be required on all images, mainly contrast enhancement but the clarity slider in CS is remarkably useful too.

Hope you find this useful, thanks for looking!

 

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