Laowa 25mm f/2.8 Lens Review: 2.5-5x Macro Magnification

There is a brand new addition to the Venus / Laowa macro lens line up: a 25mm f/2.8 with 2.5x – 5x magnification on full frame. That opens up really exciting possibilities by taking you into the realm of extreme (or ultra) macro photography at very high quality, but this time round it is much less costly than what other competitors offer.

This lens completely opens up previously hidden worlds. Here the Venus lens is pushed to its limits at 5x magnification to show tiny fruiting bodies on a lichen. With an aperture f/5.6 with an image stack of 40 images combined in Helicon Soft software to get a greatly extended depth of field.

Specification

• Focal length: 25 mm
• Shooting magnification: 2.5 times to 5 times
• Minimum aperture: f/16
• Maximum aperture: f/2.8
• Field of View: 10.3 degrees
• Lens construction: 8 elements in 6 groups

• Number of diaphragm blades: 8
• Minimum photographing distance: 173 mm to 223.5 mm from sensor plane
• Minimal focus distance: 40 mm (5 times) to 45 mm (2.5 times) from front lens element
• Ultra low dispersion lens element to suppress chromatic aberration and promote high sharpness with high color fidelity.
• Lens elements have multilayer coating to minimise ghosting and flare
• Weight: 400 grams

Background

Venus Optics (a.k.a The Anhui ChangGeng Optics Technology Co., Ltd)  was established in 2013 by a group of optical engineers and  enthusiastic photographers who had previously designed lenses for Japanese and German manufacturers.

Their intention is to create unique, high-quality (yet still affordable) photographic lenses and the current line up already boasts two specialist macro lenses. The first is the 15mm f/4 (1:1) ultra-wide macro – a superb, if occasionally demanding, lens. Then there is a 60mm f/2.8 2x macro that is extremely sharp and very well made.

Now comes a third ‘niche’ lens for those who want to work in what is now known as the ‘extreme’ or ‘ultra’ macro region. In the past, this was embraced as Photomacrography.

All the Venus / Laowa macro lenses are manual (focus and diaphragm) which might put some people off, but with practice this matters less and less and exceptional results more than compensate.

The lens itself

This lens is small, neat and, being precision machined in an aluminium alloy, as with the other Venus macro lenses,  there is a feel of old-fashion quality and solidity.

The focusing thread is extremely smooth and well damped (no chance of focus slip) which makes for a piece of high quality equipment that is a pleasure to use  and it snaps into and out of focus.

Internally the lens has 8 elements (multicoated to minimise ghosting and flare), arranged in 6 groups with one of ultra low dispersion glass, to promote a high level of sharpness and colour fidelity as well as suppress chromatic aberration.

The distance from subject to front lens element does not change greatly (at 2.5x it is 45mm; at 5x it is 40mm). This is reasonable for a lens of this sort and allows room to get light onto your subject from small flash guns or LED lamps, especially since the front element is not recessed and the lens barrel is slightly tapered.

Moving from 2.5x to 5x times scale of reproduction the lens barrel, extends in length by approximately 5.5 cm. In practice, it is easier to focus by moving the camera. You can see the scale of reproduction by extending the lens barrel (there is a clear scale engraved on the side). Fine focus can also be achieved by using the focus ring over a limited range close to the position of sharp focus.

The iris diaphragm is at the front of the lens with marked F-stops at 2.8, 4.0, 5.6, 8.0 and 16, with a click stop at f/11 between f/8.0 and f/16.

Diffraction softening is often the major problem experienced with extreme macro lenses: as you stop down to get greater depth of field diffraction becomes more evident in the softening of details at their edges. You would usually expect to see this from about f/16 – f/22 but this lens is remarkable in that the image does not seem significantly degraded even at 5x magnification and at f/16 the smallest marked aperture. It is often a trade off…greater depth of field for slight softening.

Note: When working with magnified images (involving extension) we need to think of an effective aperture, rather than the marked lens aperture. If M is the magnification then (M+1)  is the number of f stops smaller the effective aperture is, For instance, working at f/8 (marked) and 4x magnification this would mean the working aperture is effectively 5 stops smaller…f/45. Many people forget this and wonder why they get soft images.

It is very tempting to stack images with such a lens as then you can shoot at a wider aperture e.g. f/ 5.6, changing the focus by a tiny amount between each shot. You’d then combine the images, using software such as Helicon Focus or Zerene Stacker, and get fabulously sharp results with extended depth of field and the soft bokeh associated with a wider aperture.

Who is this lens for?

If you love the world of experimental close-up then a lens like this takes you into new realms. However, just as users of the Venus / Laowa 15mm f/4 ultra-wide angle macro have found, you need to spend a modest amount of time mastering such ‘niche’ lenses after which your success rate improves dramatically. Those used to ‘auto-everything’ might need to learn patience before they can get the best out of the lens.

Optimising the chances of getting great images

To get the best out of this lens you have to keep a few things in mind when using it. These things are dealt with in much greater detail on the website learn macro but a brief summary is given here:

Movement and Vibration of any sort (subject, camera, shutter bounce) must be eliminated since the depth of field is often a fraction of a millimetre and the slightest movement sends things out of focus. Any form of camera shake will soften the image: use a cable release, timer, remote Wi-Fi or infrared signal. If the camera has an in body stabilisation use that. I also tend to use a focus rail of some sort at magnifications of 2.5x and above.

Diffraction – an inescapable property of light when wave fronts are changed as they pass through small apertures – you see it manifest as a softening of the image, particularly at the edges of details. Remember when dealing with magnified images that the aperture marked on the lens s is not the ‘true’ aperture (effective aperture).

Lighting – use small, well diffused flashguns to freeze movement and vibration. and illuminate from the side at about 45° to get ‘relief’ those tiny shadows that accentuate details. LED lights are well worth experimenting with.

Focusing – absolute precision is necessary (easiest with a focusing rail). Many cameras with live view let you magnify a portion of the image for critical focusing. As a devotee of Micro 4/3 the EVF allows me to focus with a bright image at any aperture thanks to its inbuilt image intensifier. Other aids such as focus-peaking are useful, too.

I’ve written another post about this lens on the Learn Macro website, where you can find out more about dealing with vibration and diffraction using this lens.

The competition

Canon users have had the 65mm MP-E to use for some time – a superb lens (scale of reproduction 1x – 5x) but with a high price attached: specialist adapters would allow it to be used with mirrorless cameras, too. Other lenses, all fixed magnification, have recently appeared such as the Yasahura Nanoha  x5 super macro lens and the Mitakon 20mm f2 Super Macro lens with 4.5x magnification.

In the past, this ‘extreme’ macro range has attracted a number of top lens makers (who also happen to be microscope makers): Zeiss had its Luminar lenses and Leitz its Photars, now much sought after with each lens computed for a specific range of magnifications. Olympus, too, produced a range of 4 lenses for its OM series film cameras. Initially, these classic lenses were all ‘lens heads’ with no focus meant to be use on bellows or extension tubes with a fixed arrangement of lens element: later versions of the Olympus lenses did incorporate focusing mounts. The Venus lens has a more complicate structure with movement of elements within the lens tube as it is extended.

Conclusion

This is a superb little lens, much cheaper than the main competition, with no sacrifice whatsoever in quality. It can be used in the field though you need to do all you can to cut movement of camera, subject and shutter bounce. Depth of field is tiny and the slightest movement seems like an earthquake.

Available mounts will include: Canon EF, Nikon F, Pentax K, Sony FE  – with micro 4/3 I use a Metabones speedbooster which couples my Nikon-fit lens to the micro 4/3 mount. It is manual, but I am used to it.

As a final accolade, In my tests at home using a Zeiss 60mm luminar (the ‘Rolls Royce’ of macro optics) and an Olympus Zuiko 38mm f/3.5 macro: the Venus lens more than held its own with wonderfully sharp results. Praise indeed.

You can buy the Laowa 25mm f/2.8 macro lens from the Laowa website.