I particularly like working with rectangular fisheye lenses for my wide-angle macro work because they exhibit better good close-focusing capability than normal ultra-wide lenses. I have extolled the virtues of the Sigma 15 mm f/2.8 rectangular fisheye on many occasions when I was using it on APS-C format (with Nikon bodies and with a Sony NEX 7). Using a lens like this, designed for full frame, with formats smaller than that, permits the utilisation of the centre part of the image circle. The images then show remarkably little distortion – just a bit of curvature towards the edges: sharpness is excellent as is contrast and the close focusing capability is remarkable. In fact, this was the main lens that both Clay Bolt and I used when gathering images for our e-book: Wide-Angle Macro | The Essential Guide.
Of course, I can use also this lens with the micro 4/3 (MFT) format and a suitable adapter (Nikon to micro 4/3) but then it behaves as a 30 mm wide-angle compared with 22.5 mm forAPS-C, that is, unless you use the Metabones SpeedBooster. Then with the model I use it behaves as a 19.2mm lens with a maximum aperture 1 1/3 times wider than f/2.8…around f/1.8 – but more about that in the next post.
With a change of format to MFT, I wanted to go that bit wider…
Samyang 7.5 mm f/3 .5 rectangular fisheye
Over 6 years ago, at the same time as I was first trying out the Sigma 15 mm f/2.8 rectangular fisheye, I also borrowed a Sigma 10mm f/2.8 rectangular fisheye and really liked it. The equipment budget would only run to one of them then and so now, with a change of format, I thought that, this time, I would go for a wider rectangular fisheye…
The Sigma 10mm f/2 .8 rectangular fisheye behaved as an equivalent 15 mm lens on APS-C format with its x1.5 sensor factor. Conveniently, the S. Korean manufacturer Samyang offers a 7.5 mm f/3.5 rectangular fisheye on its list specifically designed for the MFT format…the equivalent of a 15mm wide angle on full frame.
I had never previously used a lens from this manufacturer but had heard its praises from people whose views I respect and now, having used it, am extremely impressed with it. A couple of years ago I started using Laowa (Venus) lenses from the relatively new Chinese manufacturer – these are also manual lenses and optically exceptional. In all these manual lenses theuild quality is excellent with an all-metal construction and focusing via a helical thread that has just the right amount of resistance to enable you to focus very precisely.
The Samyang 7.5mm lens is exceptionally sharp and has excellent colour balance. It is tiny, perhaps too small for some hands when it comes to manually adjusting the aperture and focus, however, although my paws are large I manage most of the time. At close quarters, this sort of diagonal fisheye lens offers considerable edge distortion especially if the lens is angled up or down on the camera body. At one stage I would have found it unacceptable but my perception has changed and now I like it and make use of it.
When working at closest focus, I first focus wide open, using the viewfinder focus aid on the Panasonic GH4 where the central rectangle is magnified. If you try to do this when the lens is stopped down it is difficult to tell exactly where the point of sharpest focus is, even when using focus peaking. When subjects are a meter or so away you can be quite cavalier with this lens since the depth of field is incredibly large and focus hardly seems to change as you rotate the focusing ring.
Reproduction ratio at minimum focus
Nowhere, could I find a figure for the reproduction ratio of the Samyang 7.5mm lens at its closest distance of approach (as measured from the sensor) but an estimate, using the lens to photograph a tape measure and comparing the view with the width of the sensor (18mm), gave me a figure of about x 0.15 – 0.16. This makes it very effective for viewing plants in close up set in the landscape: fortunately, I have plenty of other lenses that can cope with close-ups of insects in the landscape and that will allow me to be slightly further away from the subject… the Laowa 15 mm f/4 wide angle macro lens, for example.
The images that I have appended show the capability of this very neat optic. I found one for £239.00 new at ukdigital – a price that represents superb value for a lens of this quality and far less than equivalents (if you could find them…) for full frame and APS-C.
© Paul Harcourt Davies – neither images(s) nor text may be used in whole (or in part) without the express permission of the author.