This is the first of a detailed series of posts for photographers who are thinking of using relatively cheap old manual focus lenses on an APS-C DSLR. In order to do a meaningful evaluation we’ll need some proper test shots – so other than a few examples on 35mm film and a rather nice Dorset mill as a subject there aren’t any photographic masterpieces I’m afraid.
All test shots on an 18MP Canon 60D at ISO 100 and Olympus OM mount lenses using a Fotodiox adaptor. Images were taken in centre weighted metering mode, saved in RAW and converted to JPG with default settings in Canon’s DPP software.
So starting the lens series at the wide end – a 1980’s era Vivitar 17mm f3.5 and quite a special focal length on a 35mm Olympus film camera. Ultrawide on 35mm (I think the angle of view is 92 degrees) it’s capable of some typically dramatic distortion :-
This lens is identical to a Tokina branded lens of the same era, and the edge performance and chromatic aberration always left something to be desired – at least that was the rumour. These lenses were always mid range and weren’t expected to produce top flight results. However, this is ‘only’ an APS-C sensor so the edge of the frame (usually a weakness in cheaper lenses) isn’t in the picture. Maybe this lens could be useful – unfortunately it’s only around a 28mm equivalent when the 1.6 crop factor is taken into account so it’s not that exciting an effective focal length. The minimum focus is 25cm.
The focus mechanism is smooth and even, and focussing is difficult through the viewfinder as the depth of field is huge. For critical results use the LCD and ‘focus magnify’, or stop it down to f8 and use the depth of field scale on the lens and don’t focus at all!
One thing worth pointing out about the lens mount adaptors – they only allow ‘stop down’ metering. Most cameras use ‘open aperture’ metering – keeping the aperture wide open until exposure, keeping the viewfinder nice and bright to allow for easy focussing and composition. The manual focus adaptors use ‘stop down’ metering where the aperture set is the one in use at all times – at f16 the viewfinder gets pretty dark. If this is a problem the LCD image will always remain bright even as the aperture closes.
So – the test subject – used for several posts on film as well as digital :-
The samples are taken from the centre by the dovecotes, and the right where a red car is parked.
First samples at f3.5 and surprisingly good in the centre but the edge is a bit vague. There’s also an overall light ‘sheen’ to the image which is common at max aperture and may be caused by light bouncing around the mirror box onto the sensor – this hasn’t helped the contrast of the image. However these are extremely small samples and this would be perfectly good printed to 10×8 inches.
At f8 (5.6 was almost identical) and a dramatic improvement! Razor sharp in the centre and the edge is pretty good too.
f16 -even more of an improvement at the edge and a slight degradation in the centre – sharp across the frame and certainly showing no signs of diffraction.
Finally – edge chromatic aberration – taken from the very top left of the main frame. Perfectly acceptable at f8 and not too noticeable at f3.5. I’m amazed!
As we’re only using the centre of this lens’s image circle, there isn’t that much barrel distortion either. ‘Bokeh’ is almost impossible to judge as the extreme depth of field means that virtually everything is in focus.
So – is this useable?
Yes – and this is a genuine surprise to me – just one stop down at 5.6 it’s very good, at f8 to f16 the results are excellent.
All good so far but this focal length is already covered by kit zooms at around f3.5 so there’s no speed advantage. However, the resolution, chromatic aberration and contrast at f5.6 to f16 are better than I’d expect from a kit zoom lens.
So if you’re a prime lens shooter, or want something better at the wide end than the standard offering this might be for you.
It’s also pretty useful on an Olympus OM 35mm film camera so can happily live a ‘double life’!
It’s around £100 second hand in the UK, with a lens mount adaptor costing anything between £20 and £150 (which you can use for all lenses of the same mount obviously).
Hope you find this useful – thanks for looking.