By Paul Harcourt Davies © 2014 The saga continues with further thoughts, ramblings and homilies on a great 105mm macro lens in particular… and macro lenses in general. This lens makes a great companion for the Nikon Macro speedlight R1C1 that will be covered in detail in a forthcoming post. Part 1 can be read here. What about using autofocus at close distances? In general, I have found it better to dispense with AF altogether when working at the closest limits of a macro lens — an AF mechanism can tend to ‘hunt’ slightly then, if you get too close, it can suddenly whizz off (together with your startled subject) looking for focus. By choosing to work at a little bit more than the closest distance you give a range over which the autofocus can function and it does. Only in strong breezes do I ever feel the need to switch it off when efforts to secure focus becomes distracting. As for speed, the autofocus mechanism in this lens is reasonably fast but, in the seven years since I bought it, other lenses have got faster. However, it is positive and accurate: would that all lenses met the same standards.
Hidden changes: a 105mm f/2.8 lens doesn’t always stay that way focal length: as already mentioned, the convenience of internal focusing comes at a cost — the focal length of the lens changes. No manufacturer trumpets the fact that at its closest focus on the 105mm focal length, a macro lens has effectively been reduced to an 80mm optic. This means that if you had an older manual focus macro (with its extension tube) side by side with an autofocus lens and set them at 1:1 on the same subject, you would have a greater working distance with the manual lens.
apertures: It is not only the focal length that varies with increasing image magnification. Maximum and minimum apertures do, too. This is well-known with extension tubes and bellows and you can find tables of factors for modifying exposure, etc. It also happens with internal focusing too. These are figures read off the information display within the camera for the scale of reproduction given in the left hand column.
|Scale of Reproduction||Maximum Aperture||Minimum aperture|
|Infinity to 3m (10’)||f/2.8||f/32|
|1:5 – 1:3||f/3.2||f/36|
How OK is the Bokeh? I must admit I preferred those days when no one used the word ‘bokeh’. You see it dropped with such pretension in reviews it seems to be the photographic equivalent of the language of wine snobs (who, in reality, could not tell a Chardonnay from a Sangiovese — unless they saw the colour). So, here goes: this lens boasts a nine-bladed (rounded) diaphragm and does have very decent bokeh, indeed. Think of the image on a sensor (or film) made from tiny images — whose edges assume the shape of aperture in the iris diaphragm. If the aperture is a perfect circle, then overlapping images are precise circles that blend beautifully and backgrounds look smooth — ‘good bokeh’. If the diaphragm is not circular, then the angular edges do not produce perfect circles and the bokeh is slightly ‘harsh’. The more diaphragm blades (7-9), then the closer to circular (rather than polygonal) the aperture and, if these blades are slightly curved as well, then you get what Nikon gives you here…’Luvverly Bokeh’. The longer the focal length the better the bokeh because of the way the lens relates objects in foreground and background. Sorry if my tone sounds dismissive, but ‘bokeh’ is subjective and yet people talk about it as if there are absolutes: one person’s ‘good bokeh’ is another’s poison… to mangle a metaphor.
And finally… image softening at small apertures: a worry? You quickly learn when starting photography that the size of the hole in the iris diaphragm is related to some entities called f numbers and that the larger the value the smaller the aperture, which is a bit counter intuitive. Moving from one f-number to the next in the series changes the area of the hole by a factor of 2 (i.e. doubles or halves). When we close a diaphragm (stop down) to get greater depth of field, then diffraction, an inescapable wave property of light, becomes obvious: it creates a definite softening of an image. Light wave-fronts are affected by the edges of apertures they pass through and tend to spread. With wide apertures it is not obvious, but reduce aperture size and it becomes noticeable. In the first books I wrote on macro I mentioned that you had to weigh up the gain from increased depth of field against the slight softening when you used f/16 and smaller. Now, I often use f/22 with modern macro lenses because you can counteract that softening with a bit of judicious post-production sharpening in Photoshop or Lightroom. Unsharp Mask and more sophisticated processes such as Smart Sharpen work wonders. The diffraction process is countered – it is not reversed for you are doing just what looks good… the sharpening algorithms change the tone of pixels at edges — a bit like drawing a line in harder pencil to accentuate a boundary… yes, I know that’s simplistic. But, let’s face it, the result is great: at a rough guess and with subtle use you get the apparent ‘undoing’ of one- two stops worth of diffraction softening. That’s my impression. Optimum aperture work – the ‘sweet spot’ All lenses have an optimum aperture the ‘sweet spot’, where an image will be as sharp as any assessment criteria used will allow, typically it’s f/8 – f/11. But you would have to have impeccable technique and use special targets to notice. Reviews full of “seems to be’s” beg questions as to who was using the lens and just how precise they were. If you wanted to get the very best quality it is tempting to create an image stack at f/8 and merge them with Helicon Focus or similar…amazing depth of field, background bokeh and so on. Increasingly, I create daylight stacks with this macro at about f/5.6, especially on the Nikon F3S where the shutter speed can be 1/400th on ISO 800 and more.
So is it worth the price ? Personally, I think that for Nikon users this lens is a veritable classic. I would suggest that if it disappoints then it owes more to the photographer than the equipment. It is not cheap, but then this kind of solidity and quality costs. You can get independent lenses from Sigma and Tamron that are both optically excellent (I have used both), but of a slightly different build quality. Maybe that doesn’t matter too much, but boy is it great to work with a lens where precision-engineering is faultless. “Yer pays yer money and takes yer choice” Many photographers have their favorite focal lengths for macro lenses and will offer you advice accordingly. Whereas I used 50-60 mm focal length macros in my early days working in the close-up realm I now do less frequently — but the possibility is still there. If I want to work really close it is either to get wide-angle shots (see my series of posts on wide-angle macro) or in the extreme macro realm which I shall be posting about soon with a whole bunch of DIY ideas.
Just a word on behalf of the subject With animal subjects I try to avoid getting so close that I impinge directly upon the subject I’m trying to photograph. It’s an approach ingrained in me from endless days of watching and filming wildlife of all sorts: I am the observer and ergo, must try at all costs not to perturb any behavior I am trying to record. What I have seen at times watching groups of photographers and their leaders often concerns me greatly. The shot is all…it is an attitude that we cannot condone on this blog The advent of HD video in many SLR’s will mean former stills photographers will have to think about this one carefully. It is one thing to record single images, but when running together as a moving sequence, any displacement behavior (or panic, as we call it) becomes extremely obvious. So, my choice, where the subject dominates, lies in the mid-range (90-105mm) and longer focal length (150-200mm) macro lenses. They work for me and I am a great believer in leaving each to his or her own… your choice, that’s what’s important. For instance, whether to use extreme depth of field or shallow depth of field is up to you. I often go for both and choose later. A PLEA… avoid slavishly following fashions — consider what others have to say and take what YOU want, make it your own. The macro world can take it… something for everybody My great delight is when people come up to me after a talk and say “I read your book and then I went and did so and so…” It’s progress and, for me, its enough to play a small part…
© Paul Harcourt Davies 2014
NB No part of this blog may be used in any way without the express permission of the author concerned: all commercial use of images must be accompanied by a fee (rates on request)
© Paul Harcourt Davies 2014 NB No part of this blog may be used in any way without the express permission of the author concerned: all commercial use of images must be accompanied by a fee (rates on request)