The Laowa 15mm f/4 wide angle has got me thinking…

For a couple of months I have used the Laowa 15mm f/4 wide angle macro from Venus Optics Company and have just penned a very detailed review and sent it off to Keith Wilson editor of WildPlanet photo-magazine with a large selection of images. I have posted some interim images and comments as my relationship with this lens has deepened. It has also set me thinking (not unusual) in what I want out of wide angle lenses. Have written a great deal on this already in both blogs, articles and the book Wide Angle Macro | The Essential Guide which Clay Bolt and I wrote together and are currently revising with LOTS of new material for we have not stopped experimenting and probably never will.

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A hornet with attitude (Vespa crabro) photographed here using the RayFlash unit and a desperate attempt to focus which almost came off…

Along the way, I have thought a great deal about possibilities and expectations bearing in mind that many people using lenses might have studied sciences at school that never contained even the most elementary material on geometrical optics – the stuff to do with how lenses and lens arrangements behave. It is not riveting stuff and very dry unless you have a reason for ploughing through it (like it forms part of your finals in a theoretical physics degree for example!). I have condensed a few ideas in what follows.

First:  just how close do you want to get with that wide view and what are you after?

Here, in one conveniently sized package, is a lens that allows you to get much closer than any other ultra-wide angle and thus produce some really stunning wide-angle images with impact. Whether the life-size (1:1) capability it offers is usable (and when and how) is an important question because one of the advertised features that will attract many is the ability to go to this reproduction ratio.

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This elephant hawkmoth (Deilephila elpenor) shows that, with larger insects the Laowa lens offers a frame-filling capability with superb detail and the background still retained – aperture about f/16 and RayFlash unit illumination. Camera handheld.

There are practical problems for, at the closest focus, the subject is slightly less than 5 mm (0.47 cm to be exact) from the front lens element. In the field this makes it ‘challenging’ , to say the very least, to get close to agile insect subjects. Even if you detach the lens hood, the lens front will cast a shadow and the small space you have at your disposal between the front lens element and the subject makes it tricky to light that subject and to use fill-in flash.

I have had good, if somewhat erratic results just by holding a small flashgun together with the camera and feel that this is a possibility worth exploring. I will suggest some other ideas towards the end of this review.

The possibility of getting very small subjects set in the context of their background is, a very attractive one for many. For those of us schooled on David Attenborough’s innumerable series, the sight of the maestro in sharp focus in the background, watching some ant or other tiny creature, has become a BBC trademark. I happen to count as an old friend and fellow obsessive naturalist, Peter Parks, the man who developed these techniques (also in 3-D) and I know that Peter, the genius and Oscar winner behind much of the work of Oxford scientific films (and many sequences on BBC series), did not do it with one lens. He used the technique of aerial image projection where a lens (called a relay lens) brings the background into the focal plane of the macro lens you are using on the subject. In the new edition of the e-book: Wide-angle macro | The Essential Guide that Clay Bolt we shall cover this in enough detail to get experimenters working. However, because of the accurate alignment problems with lenses it is easier to do in a studio – even if that is a table outdoors.

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A small emerald moth photographed using a small handheld flash (SB200) as a fill-in. The backlight was created by the rising sun – note that the camera is so close with this small that the background is blurred even at f/16. Even with a wide-angled lens the background detail falls of as you get closer to the lens and you lose that appeal of wide-angle macro where the subject is set in context of its surroundings.

In practice, I have not found this proximity to the lens surface too much of a problem because I get results that please me more at life-size and higher reproduction ratios by using longer focal length lenses.

Depth of field with different lenses

 When you use any macro lens at 1:1, the depth of field is very small even at apertures smaller than f/16.

It is a fact of life (and one that seems counter-intuitive) that in the close-up range, the depth of field at a given aperture and reproduction ratio is very nearly THE SAME WHATEVER THE FOCAL LENGTH OF MACRO LENS YOU USE.

This is a pretty startling statement but, in practice with wide-angle lenses, it means that any background you would like to include becomes extremely blurred when you are very close to your subject, even at the smallest apertures. In essence you lose that special appeal of setting your subject in that background that might have drawn you (like me) to the wide approach.

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This image pair using a Houseleek (Sempervivum) as subject shows the changes in stopping down the lens. The stamens are the centre of sharp focus and the lens renders them superbly…note how the background appears as you stop down from f/5.6 in the upper image to f/16 in the lower one. There is obviously room for creative photographers to explore the visual impact of the depth of field at close-quarters where detail is not well-defined.

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Whereas depth of field might be numerically the same with a 15 mm wide-angle and a 150 mm telephoto macro at 1:1 and f/16,let’s say the appearance of that background is not the same and this leads to the erroneous idea that a wide angle lens always has ‘greater depth of field’. Our perception has more to do with the way that background falls off beyond the plane of sharp focus.

With telephoto lenses, background detail falls off very quickly as you move away from that plane,  producing those soft blurs that accentuate the subject in the foreground and characterise tele-macro lenses (150mm – 200mm focal length).

With a wide-angle lens, however, the background can become a series of slightly disconcerting blobs so you have to choose the background carefully, where you can.

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The small elephant hawk illustrated here demonstrates what I like in wide-angle macro shots where the background is not pin-sharp but you know what it is. That slight blurring helps to emphasise the sharpness of the foreground.

My personal choice is always for a background which is not in pin-sharp focus for the image becomes cluttered and your attention is drawn away from the subject. AS hint of what is there – shapes of mountains, trees, hedges, the sea…that is all that is needed to convey the information and the fact it is not sharp accentuates the sharpness of the subject.

You can see it in practice but for those of a mathematical bent (or bent mathematically) you need to find an equation relating to depth of field, focal length and diameter of the circle of least confusion (that again), make the approximation for life at close quarters and then find the rate of change  blur circle diameter with distance from the plane of focus  for different focal length lenses…got it? Sorry, I used to be a mathematical physicist but then saw the light (or rather left its theoretical aspects).

When taking photographs in the field with the Laowa lens, I tend to back off slightly getting my insect or flowers subject no more than half life-size in the frame: the result is aesthetically pleasing, beautifully sharp and scientifically useful because you still see that background with discernible, if blurred, details.

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The size of these corncockle flowers (Agrostemma githago) allowed me to back off slightly and this quickly brings the background into focus setting the plant in the context of its habitat as a cornfield weed of traditional cultivation and as such one of my favourite plants.

Lens defects – aberration and distortion: what can you reasonably expect?

Ever since it was realised that a single converging lens element could not bring all the rays in the visible spectrum to a joint focus there have been ingenious efforts to correct this defect known as chromatic aberration (CA). Lenses bend light (refraction) but also spread out the rays rather like a prism does (dispersion) because light at the red end of the spectrum travels at slightly higher speed through glass than that at the blue end. The first solution was to utilise a converging lens made of two elements having different refractive indices (a measure of light bending power) – a convex one of crown glass and a biconcave one of flint glass (slightly greater ending power to bring the dispersed rays together again). The combination was called an achromatic doublet and is used today as the objective lens in many refracting telescopes. Others tackled the problem of CA and other defects, most notably the genius Gauss who created his triplet design – many modern lenses are a variation on this. The search for optical perfection has continued unabated,but every time another glass element is introduced to correct a defect it imports another…

Many wide angle lenses are well corrected and do not reveal a high degree of CA because their close focus is limited. As soon as you go closer then light rays make oblique angles with the lens elements and the splitting of light that causes the aberration becomes more evident, especially along twigs and other edges outlines by the sky.

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If I had taken a shot of this striped hawkmoth /Hyles livornica) into the sky in the direction (but not provoking flare by including the sun in the frame) then I would have seen chromatic aberration at the edges of the antennae, for example. The best way to cope with CA is to avoid the situations provoking it.

As a matter of course I try to avoid those situations I know exacerbate it. In my own efforts to get close I have made (and written about) adapters that allowed me to focus more closely using a mirrorless camera – my trusty Sigma 15mm f/2.8 wide angle lens and the Sigma 10 – 20mm zoom in particular. With the latter at the short focal length end chromatic aberration becomes obvious when an element of sky is included and with such an angle of coverage that is hard to avoid. In practice I find that the de-fringing algorithms incorporated in Lightroom work well in reducing this.

Another lens defect with wide-angle designs is that of barrel distortion where straight lines away from the centre become curved as you swing the lens upwards or downwards. It is particularly in evidence with rectangular fisheyes and something you can use creatively if you have a mind. I find that, with the Sigma 15mm f/2.8 rectangular fisheye which I use on APS-C format then I am using the central portion of the image circle and the elect is far less pronounced than when used with a  full frame sensor.  With the Laowa 15mm f/4 wide angle lens the effect is very slight – but again I am using APS-C sensors and minimising the effect.

People often have a great deal to say on-line (usually without the experience or knowledge to back up their statements) and I have read some comments on the Laowa lens mentioning CA, almost with surprise.  Having used numerous wide-angles over the years (and various formats from 8mm cine to plate cameras), then my reaction was delight that it was  only evident at  a low level: perhaps I am just more realistic in my expectations and know just how difficult (and expensive) the correction can be and the inevitably in the close-up range. 

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A first gran shot with the RayFlash fitted using a striped bug (Graphium italic) on sea holly outside my study. The reproduction ratio is just under 0.5: 1. The sharpness is remarkable …this was point and shoot.

Lighting:

If your background is perfectly lit by ambient light and the lens front casts a shadow on the subject then how do you light something that is less than 1 cm from the lens front? If your subject was translucent then this would not matter so much because all the light would be behind the subject but, for a solid insect or flower it does. The subject can become so dark that even correction in Lightroom or Photoshop cannot bridge the contrast gap.

Microscope manufactures have always had ingenious solutions for such things and created epi-illuminators with prisms that send a light beam down on to a subject that through microscope lens from above… but I cannot see this is a practical solution here.

I mentioned that a small handheld flashgun works as a fill and I have used one of the SB 200 units from the Nikon R1C1 macro flash kit (with its diffuser attached). You need to hold it just to the side of the lens front and up against the rim it so that it doesn’t encroach into the field of view. but still throws light obliquely onto the subject. Experiment is needed and, in practice, it is a bit clumsy when you have to adjust focus and close the diaphragm, as well. I have not had time to fabricate any reflectors or join bits of aluminium alloy to make a better mount but can see how it can be done.

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A hand held flash was used as a fill with this mullein moth caterpillar.

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This looks unwieldy but is not at all….it is light and functional and I can see how small reflectors made of card or white plastic could be placed at the rim (care being taken that they do not extend so far that they enter the field of view…about 7cm proud of the rim according to a quick calculation from the dimension (a radius of about 10cm and angle of view 110º

Simplest of all is a sheet of translucent white acrylic or ‘Flyweight’ envelope stiffener with a hole cut in it and lit from behind…there is a variation on this with a white acrylic panel in our eBook.  At least these can be good starting points for your own experiments: inevitably you will find that you get results where the subject is perfectly lit but then with new-found confidence you go that tiny bit closer and the subject is in darkness – back to the drawing board. Every now and again it is good to work for results you want.

My latest solution to the problem of lighting is a RayFlash universal adapter that creates a ring flash by fitting onto the front of a flashgun that sits in the hot shoe of the camera.

This lighting unit surrounds the lens front and the way it is constructed with acrylic light pipes to carry the flash output means that quite a lot of light spills forwards – especially if you tilt the bottom it backwards slightly. I have ideas for improving this by adding a thin collar around the edge of the device to reflect more light into that small, critical space between lens front and subject. In fact given the 110º angle of view you could construct a reflective collar around the rime of  height 7cm above that rim…after that it encroaches into the field of view. This would throw more light into the subject zone.

I have included several images here so that readers can decide whether the nature of the lighting is something that would work for them.

Venus produce their own macro flash unit The Venus KX-800 Twin Flash which looks perfect for the job both with the 15mm f/4 wide angle lens and their remarkably sharp 60mm f/2.8 which will be feautred in a forthcoming blog. There is also a series of accessories such as diffusers and articulating arms to go with it. The more I see of it the more I think I will order one since I will be able to use it both with my Nikon and Sony NEX 7 cameras.

There is one of a number of very well made videos featuring talented US macro photographer Thomas Shahan that details the use of this macroflash.

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Lois’ hands are more elegant than my paws…note that when holding the outfit the fingers can extend to adjust aperture and focus: just a bit of practice and you are up to speed.

Manual Mode – back to the Neolithic era of Photography?

Working with a stopped down diaphragm is something familiar to those of us of certain vintage and salsa those who have experimented with legacy lenses on mirrorless cameras.. The bulk of modern lenses now have an electronic coupling between the lens diaphragm and the metering and autofocus systems of the camera and this is one of those innovations that you take for granted and don’t realise just how much easier it makes things… its very absence slows you down. Those who expect to take wide-angle close ups of active subjects might find this a drawback unless they read my ‘work around’ and get up to speed.

For some time, I have been using these so-called “legacy lenses” on a Sony NEX 7 body (having amassed a few in my time) where you have no choice but to use stop-down metering and then manually adjust the lens.

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The Laowa lens allowed me to do what I have done previously but I can move that bit closer and get enhanced impact. Here the cornflowers and large daisies on the Piano Grande were the subject.

One problem you might initially find when using this 15mm f/4 wide angle lens on a DSLR is that the image darkens when you stop down and are looking through the viewfinder. Your eye gets used to this but the point of sharpest focus becomes a bit more difficult to discern because you have increased the depth of field on stopping down.

It may be that younger users with better contrast vision will not find this but I have to open up the lens to focus sharply and then stop down to f/16 and beyond. This is an extra movement on your part that complicates things with lively subjects.

However, if you are using the Live View of your camera and focusing from the LCD, then its built-in image intensifier will still give you a bright view even as you stop down. Even better, I find that many mirrorless cameras used in manual mode will offer “focus peaking” (and image enlargement) where the sharpest points of the image – edges of small details such as hairs – will sparkle in white as you shift in and out of focus. You can set this in different colours but I find white easier.

The Laowa 15mm f/4 lens anticipates the possible use with smaller sensor cameras for, as well as the fittings mentioned, you can get both Sony and micro 4/3 manual adapters for a modest extra sum.

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An image pair utilising the Orange Lily (Lilium bulbiferum) that shows how a quick change in focus provides very different images. In the first there is the conventional wide angle macro approach setting a group of flowers in the context of the scene…high above a road in the Sibillini national park. The lower image is one using natural light from a direction that did not cause a shadow from the lens front making the stamens the subject of attention. They are pin sharp at f/16 and enough light to ensure accurate focus through the viewfinder.

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And now to the conclusions:

 On the positive side….

 Although I can obtain many results similar to those I have managed to get before using ultra-wides with adapters I can do it so much more conveniently with this lens. Better still, I can get even closer for greater impact, so this lens not only does the job I had in mind but offers a chance to explore pastures new and that is important for those of us who like pushing their boundaries. It has a permanent place in my main camera bag. Optically and mechanically it is a class performer with biting sharpness and aberrations and distortion very well-controlled

It is good to see a manufacturer that does not follow the crowds and I am really delighted with the quality, both optical and mechanical, of the two lenses that I now have from this innovative Chinese company. Long gone are the days when one might moan about lack of optical and mechanical quality from Chinese sources. I buy all the adapters I need from Chinese companies via eBay, for example, and the engineering quality is superb at a realistic.

A section of the body and wings to reveal the detail resolved by this lens at f/16

A section of the body and wings of a striped hawk (Hyles livornica) to demonstrate the detail resolved by this lens at f/16. I used the Sony NEX 7 with the Laowa lens plus adaptor and focused using the focus peaking aid via the camera’s LCD.

Problems – or maybe just ‘challenges’…

The primary disadvantage that some may find using this lens is the absence of features we have become used to and also upon which we depend for ease of use. The first is the lack of any coupling between the diaphragm and the metering system – you must close down the lens to the taking aperture, manually. There is no autofocus and that can slow down attempts to take those ‘point and shoot’ shots with small, agile subjects.

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I had a lot of failures with this tiny crab spider using a handheld SB200 Nikon flash changing the angle of the flash and enticing the spider back out from the wild carrot (Daucus carota) flower head

With a slight change in approach you can cope with these seeming disadvantages and regain that speed and accuracy of use. I had to play with the lens for some days before I figured out how I could make it work for me.

  1. Preset the reproduction ratio you need (it is etched on the lens barrel)– after a short while you get used to assessing a subject and getting this right. It is a question of the proportion of the image frame you want the subject to occupy. Even if you get this wrong and the subject is too small then there is so much detail provided by modern sensors that you can crop although you will lose that exaggerated perspective effect.
  1. You are going to need to focus by moving in on your subject – many macro photographers do this anyway, because cameras often hunt for focus when very close to a subject. In the worst cases the focus shoots to the end of its range. Advances in camera and lens design have made the using of autofocus much more practical.
  1. To avoid the inconvenience of last-minute adjustments you need to stop the lens to the taking aperture – usually f/16 or smaller if you want to retain background detail. This makes it more difficult to perceive sharp focus both because of the dimming of the image and the increased depth of field. I find this becomes much easier if you use “live view” and if there is an associated focus peaking then so much the better.
  1. The biggest improvement to convenience has come from using the reflash adapter and getting light onto the subject. It needs a bit of fiddling with flash compensation to get this right and a balance with the ambient lighting. I find that I have to under expose by at least a stop with the flash compensation and then for very close shots reduce the underexposure because of the oblique angle of the lighting.
  1. Although the combination of the ring flash adapter and camera looks cumbersome it is very comfortable in the hand and with my right hand fingers extended I can adjust both the aperture and the focus if I wish to make corrections. The setup can then be used on a pretty much ‘point and shoot’ basis. I’m sure others can work out solutions that suit them, but the images I get with this are what I set out to create.

Look out for the full version of this in WildPlanet Photomagazine…coming soon.

 

You can see what Venus Optics Company has to offer by clicking on this link:

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And just to show that this novel 15mm f/4 macro lens does a very good job as a wide angle lens that captures the landscape for you…cultivated fields on the Piano Grande in the Sibillini national park where cornflowers and poppies are used as indicators…when they are just going over the tiny lentils are ripe.

 

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