Golden-ringed dragonfly...more about the Carl Zeiss 85mm F1.4 Planar

I packed just the D300 and the Carl Zeiss 85mm F1.4 today for a nice walk in the end of summer sun at Moors Valley. I packed the Zeiss as I fully intended to take some portraits of my wife, Gabriela, just before she has our baby, which is due tomorrow! Yay!!

I love this lens, but its certainly a bit quirky and I have found it perhaps the most challenging lens to use of all those that I own. When it comes together its awesome, but at other times I miss focus or get less than ideal bokeh at wide apertures.

Its well known that it doesn't perform well at minimum focus distance, but to be honest many lenses don't. This is 1 metre however, which is quite a long minimum focus distance these days and probably partly due to its rather historic Planar design.

Its other main issue is focus shift which explains the main reason why its a challenge to use...I'm sure many users feel they have a bad copy, when its actually that they are failing to focus accurately on the subject. Of course with wide apertures focus accuracy is critical anyway and focus shift only serves to complicate things.

Lloyd Chambers makes very sound observations on focus shift in his comprehensive guide to Zeiss ZF lenses and I did my own casual tests to satisfy myself after thinking I was hopeless or the lens was somehow defective! Basically the lens focuses normally at F1.4 (hard enough anyway!) but when you stop down to F2.8 and beyond the focal plane shifts rearward quite dramatically. So you focus on an eye and end up with actual focus being beyond that eye, on perhaps a temple or ear.

Why!? This is the result of residual spherical abberations (RSA, non-coinciding planes of focus) where light from the outer part of the lens element focuses on a slightly different plane to that from closer toward the centre of the element.  The large size of the elements in a fast prime makes this much more likely than with slow lenses.   These RSAs also often cause the slight halation and contrast reduction visible in fast lenses shot wide open.  When you focus the lens the aperture opens to F1.4, whatever aperture you have set it to, to enable lots of light in and coverage by all the focus points.  However, the actual shot is taken at the aperture you have set, say F4, when the aperture briefly stops down for the exposure period. So the focal plane is accurate for F1.4, where focus takes place, but becomes inaccurate for F4 where the lens is stopped down to take the photo, because the focal plane of the light from the more central part of the lens element has shifted rearward. Put simply....you have focused at F1.4 but shot at F4. The increasing effect of depth of field only alleviates the issue at F8 on this lens and then only just! There are a few ways to get around it but basically it remains a pain. I have learned to focus just in front of my intended point, (e.g. on a nose to get the eye sharp) and by experience manage to get a passable hit rate. You can also use the DOF preview or live view as work-arounds, but these are not practicable in most hand-held photography.

Previous use of the ZF 85 has taught me not to bother with taking close up images as the traditional Planar design won't go closer than a metre and images are a bit soft, or suffer contrast loss and halation. Today , when this lovely golden-ringed dragonfly landed near us, I initially cursed my luck at having the 85 of all my lenses! I still decided to have a go and took a few frames at F4 and F8, using only the natural light. I was never going to get close, but I was seriously impressed by the image quality I got...detail, sharpness and contrast were top notch for any normal lens. A combination of accurate focus, suitable shutter speed and stopping down appropriately rendered quality I did not remotely expect. Its another example of using the tool correctly, whether by accident or design and learning from it, as well as a realisation that the lens I considered one of my most role-specific, (i.e. portrait) could actually surprise me with its versatility.

The lens went on to take some nice portraits within its usual comfort zone and rendered its usual natural colours with nice contrast on sharp details. I have loved learning about flash and now tend to carefully balance a manual exposure at 0 or -1EV with some very gentle direct TTL BL fill flash using a speed light dialled down a bit. The Nikon system is fabulous for this and today I just used the built-in, pop-up speed light. I hate direct flash with the exception of fill, for which it can work brilliantly. I like the way a pop of light brings more life to the face, puts a catchlight in the eyes and reduces the contrast from shadow areas under the chin, hair and eyes, or balances a bright background. I try to get my subject in diffused light, to reduce harshness and contrast. Here some diffusion was provided by a tree but relatively bright light was still falling on the subject from the left and slightly behind the subject. The flash tamed this contrast quite effectively. I'm sure I still have a way to go before fully mastering creative lighting, but I'm getting good results much of the time.

Redefining what's possible

I recently shot a wedding where the light was really low in both the church and later at the reception and a couple of days ago I went to the Bournemouth Night Air part of the Air Festival 2010.

The highlight was the display by the swift team towing a glider with a tug and then solo displaying. It was a brilliant idea with sparkling flares burning on the wingtips. With me I had the Nikon D700 and 200-400F4 lens. It was quite overcast and after sunset the light levels fell very low to what most of us would say was darkness. I kept shooting selectively with the D700 which was using ISO 6400, even wide open at F4.

I was really impressed by the image quality when I loaded the images onto the Imac. With a little sharpening smoothing and the very competent noise reduction tool in Lightroom 3, the shots were very usable and retained decent colour and detail.

Full-frame cameras especially are truly amazing now and give us opportunities to shoot we never had even a few years ago. It always amazes me what is now possible, even though I have had the D700 for not far off 2 years now, I can't take it for granted.

Crop frame cameras are also great, but conditions like this would push them too far. I have both full and crop and there is simply no comparison in image quality when things get really tough.

I mustn't forget the focus system either, which nailed the focus spot-on on a moving subject in near darkness.

And the auto ISO feature, which has been excellently implemented. For action work I set manual exposure mode, set the shutter and aperture I want and let the ISO sort itself out. I can then be assured that the shutter will never fall too low and can control depth of field.

The D700 may "only" have 12MP, but this is plenty for almost everyone. The awesome sensor, great autofocus and huge customisation options make it one of the most well-rounded cameras available.

FX full-frame macro: some observations

I rarely use a full frame camera for macro shooting, probably because it offers 1.5x less effective magnification than my D300 with its DX or APS size sensor. This means its easier to fill the frame of a D300 with a subject when working a bit further away, which is good for active and easily spooked bugs like dragonflies.

The D300 is a good APS macro camera with a relatively bright 100% coverage viewfinder, which makes focus reasonably easy. With its performance in low light being very good, but still short of the full-frame camera, I tend to limit my ISO to 400 on almost all shots (a few very successful shots at ISO 800), which for photographing bugs, usually means using flash to get enough light.

For my recent couple of excursions with the full-frame D700 I chose the Carl Zeiss 100 F2 Macro Planar lens, as I was keen to use it for more bug shots and love its optical and mechanical qualities. With the D700 it gives a very different formula to the D300/Sigma 150mm combination.

The D700/ Zeiss combo of course restricts the working distance and magnification very notably, especially as the Zeiss "only" goes to 1:2, so you need stealth and more cooperative subjects if you get close. It tends to inspire more environmental portraits where the animal is a smaller part of the composition. Technically this combo gives greatly enhanced possibilities for working in natural light by using higher ISO values and the big bright viewfinder is a revelation for focus, as its easy to see detail very clearly. I had little trouble focusing at F4 for the demoiselle shot. Even the best APS cameras have viewfinders with the appearance of looking down a tunnel in comparison. As there is no multiplier for effective focal length on full frame, a lower shutter speed is acceptable, making the combo less prone to camera shake. As a result of these factors my "hit-rate" was much improved.

I love macro shooting and its interesting to try different combinations of equipment to add some variety to my style of shooting and hopefully to add a different character to at least some of the shots. Having less magnification but other advantages certainly made me more aware of trying to compose some shots with environmental elements as well as the subject, which can only be good for creativity.

I haven't tried flash yet on the D700 and Zeiss lens...I will report if and when I do!

Mating Damselflies, Macro Exposure and Flash

20100605-_DSC6693 Mating Damselflies
Originally uploaded by ClifB

As usual with photography getting the shot right is about compromising on one factor to gain another and that is certainly true of macro exposures. This post is a brief exploration on my experiences of juggling shutter speed, aperture value, ISO and flash type and level.

Bear in mind I am a Nikon user and some of the detail may be different on other camera systems, though the principles will be the same. I always use manual exposure mode for macro and close-up shooting with flash so I know what shutter speed and aperture are locked into the camera, as any unexpected alteration of them can seriously compromise the shot.

I tend to find that when shooting at 1:1 and greater magnification then I will use TTL flash which meters directly off the subject and lights it, taking no account of the ambient background exposure. This makes sense as the animal will often fill a large area of the frame. I am generally not a fan of fully dark backgrounds caused by massive underexposure of the ambient conditions, so tend to select an aperture and shutter speed combo that allows some ambient light to creep in and give a colour to the background, or I make sure it gets some of the light from the flash. I tend to dial in a varying amount of negative flash compensation to make the light more subtle and reduce harsh reflections. Usually -0.7 to -1.

When shooting bigger animals at considerably less than 1:1, or including more of the animal's environment, clearly the ambient light has a much greater effect on exposure, which is a good thing as it adds to the environmental feel of the image. I still like to add some flash in many cases to fill shadows and to use its very short duration to help to freeze camera or subject motion. In this case I find that TTL flash can often overexpose and completely burn out the subject. Therefore for this type of environmental image I tend to select TTL-BL, which is balanced fill flash. This meters the whole frame, including the subject and background and uses the flash to balance the illumination of the subject with the background and therefore the ambient light conditions.

Being limited to a flash sync speed of 1/250th sec influences choice of aperture to achieve an ideal exposure value between 0EV and approximately -1EV relative to ambient light. Clearly if ambient light is very bright you cannot raise the shutter speed to reduce EV, you have to close down the aperture a bit and select a low ISO value instead. If ambient light is weak and you struggle to avoid serious underexposure you can drop the shutter speed a bit to say 1/200th, open the aperture up and raise the ISO. Always bear in mind that opening the aperture will reduce depth of field and raising ISO will reduce image quality...as always its a trade off to get the exposure you want, so alter things within a range you know works.

This shot of the mating damselflies is a good example of the issues and techniques discussed above. I wanted to use a balance of ambient and flash light while retaining a light, colourful and out of focus background. I also needed an aperture that would enable me to get the eyes of both animals in focus...very tricky owing to the small depth of field at close distances. The animals cover a relatively small area of the frame compared to a real close-in image, so it is more of an environmental shot.

As there was a slight but intermittent breeze and I was using a 150mm lens (225mm equiv. on APS sensor camera) I wanted to use the max shutter speed available of 1/250th. I set an aperture of F9 to give me enough DOF, but this combination resulted in a rather low exposure value relative to the ambient light. To get around this I selected ISO 400, which is usually the max I will go to for macro where detail is essential. I therefore gained a stop of exposure without altering shutter or aperture settings. Another benefit of raising ISO is that the flash output is reduced. This makes recycling faster to the next shot and makes the light more subtle, with less chance of nasty reflections on shiny insect cuticles and eyes.

Its all about practising with your kit and finding what works for you. I guess the holy grail of macro shots are those where it isn't obvious that you used flash as they have nice balanced lighting, no harsh shadows and no harsh highlights or reflections. Using a balance of ambient light and flash is one way in which this can be achieved with care.

Chettle House gardens

20100531-DSC_2431 Chettle House gardens
Originally uploaded by ClifB

I found another reason to love the D80 and the little Nikon 35mm F1.8 prime at the weekend.

I recently had a car smash and have a lot of chest and soft tissue strain injuries. I simply can't hold a D700 and F2.8 zoom at the moment. I have been trying to get out for a walk for a few hours here and there to aid getting back to fitness (and avoid boredom insanity!) and found I can manage the lightweight D80 and this little prime as long as I don't reach or have to get into awkward positions....yay!

So as well as a walk-around, travel and low light lens it is now a lens for one with compromised physical ability!

I actually think the sharpness and bokeh is top grade for a lens of this price and the AF is spot-on, even at wide apertures. If you are a DX shooter with a kit zoom, this lens will add a new dimension in creativity with its image quality, depth of field control and low-light capability.

I consider it to be one of Nikon's most important recent lenses because it brings such important creative qualities to the budget-conscious photographer at a sensible price, when so much new kit is priced into the stratosphere and wholly inaccessible.

The 35mm F1.8G DX...don't leave home without it!

Carl Zeiss 100mm F2 Macro Planar

20100318-_DSC6898
Originally uploaded by ClifB

I had been very interested in this lens for a while as it seemed to offer an interesting combination of portrait and close-up capability for larger macro type subjects such as dragonflies and flowers. As a very happy user of the Zeiss 85mm F.4 Planar I had an idea of what to expect.

All reviews I have ever seen give it a huge "thumbs -up" and the excellent Lloyd Chambers gives it stunning reviews in his comprehensive Diglloyd website, dedicated to photographic technique and equipment in real-world use. In fact he clearly sees it as one of the best SLR lenses available at any price for its ability to out-resolve current DSLR sensors from wide open, its bokeh, subject isolation and mechanical quality.

An excellent local photographic dealers (Robert White, Poole) ran a Zeiss day last week and it turned out to be a hugely useful experience, with access to all the Zeiss SLR lenses, great staff on hand to assist, well-known and very personable landscape photographer Jeremy Walker and a mini studio with a pretty model for trying one's hand with the different kit.

What did I think?....I was perhaps more overwhelmed by the performance of this lens overall than any other I have tried and this impression was both immediate and is increasing with use.

It has that amazing Zeiss rendition where the micro-contrast seems to pop and separate the subject from the rest of the image. It has amazing sharpness and contrast across the field on full-frame, from wide open at its very fast max aperture of F2. The depth of field control and bokeh is simply amazing....apparently this lens has an Arri-Zeiss optical design based on that used in motion picture industry lenses, which are very expensive and this design is used to knock backgrounds out of focus. It has the ability to cut an incredibly thin swathe of razor sharp focus right through an image, while rendering the rest as a pleasing blur. Performance both close-up and at infinity is to the same standard.

The focus action is absolutely sublime, with a firm, silky smooth and long action that easily enables precise focus. The build is awesome....a chunk of heavy glass and metal with the density of a black hole but surprisingly compact and manageable.

When Stu at Robert White kindly printed off one of the mono images for me (with virtually no PP) on an Epson 3880 from Lightroom onto Ilford Gold Fibre Silk paper...that final result in print was the ultimate tribute to the lens and I knew I had to have one in my bag.

To be honest you could talk about it all day but the images really speak for themselves. My brother is a very competent and keen photographer and he saw something special in the image quality even when previewing one of these portrait shots as a small Jpeg on Flickr. The quality is a composite of all the qualities mentioned above but I think that more than anything, its the style of depth of field control that really makes this lens unique.

Of all the lenses I have used I would say that this is one that any keen close-up or portrait photographer should get as a priority and even if you don't see yourself as either of those, its the sort of lens you will always find a reason to use and learn to love. I have a baby on the way in September and can't wait to use it for both detail and portrait shots....oh and before then the dragonflies should be out if this winter ever ends!

Simply superb!

Depth of Field versus Diffraction

20100316-_DSC5667 Kingston Lacy House
Originally uploaded by ClifB

After critically examining some landscape images I took a couple of years back I was disappointed with their critical sharpness, specifically on the Tokina 12-24 lens , which I use mainly for landscapes on my D80 & D300.

Initially I thought the lens was less than great, but I did some research into the effects of diffraction and after a bit of experimentation, realised that it was diffraction having its wicked way with the resolution I was getting...not a faulty lens.

What is diffraction? Well my understanding is that its a physical limitation that cannot be stopped and means you have to use your lens in ways that avoid its worst effects. Basically, its the effect of light rays passing through the pupil created by the aperture diaphragm and as the ray contacts the edges of the pupil, it scatters slightly. When this scatter exceeds the dimensions of a pixel its getting destructive, as the light ray is spilling onto adjacent pixels instead of falling on only one. Therefore cameras with very high pixel densities are worse affected. When the aperture diaphragm is wide open the proportion of light rays that contact the edge of the pupil is small compared to those passing undisturbed through the large pupil. When the aperture is stopped down, the proportion of rays contacting the pupil becomes much higher compared to those passing undisturbed...hence a higher proportion are scattered and diffraction gets worse.

When doing landscape shots on a tripod and including some foreground interest, I was routinely stopping down to F14 and even F16 and F20 on my DX (APS) sensor cameras. This was mostly out of "making sure everything would be in focus" by extending the depth of field...playing safe.

If you look at any lens tests on APS sensor cameras its quite obvious from the MTF plots that diffraction starts to creep in and rob images of sharpness as low as F8. Beyond F11 it really starts to get destructive and F16-22 is simply a no-go zone. If you have a 12MP SLR, let alone a 16, 18 or 24MP SLR your lens will nowhere near out-resolve the sensor and will be the limiting factor in sharpness and resolution.

I did some tests with my own 12-24 lens and found that sharpness held up well to F11, then declined. I was keen to see if this limited my depth of field enough to prevent me getting sharp images with close foreground interest, while still retaining sharpness at infinity.

I was surprised to learn that with careful focusing I could easily get objects in focus from around a metre away to infinity at F11. That was more than enough in all but the most close-up of situations. To make sure I nail the focus I often shoot in manual focus and set the distance scale so I'm not wasting DOF by focusing beyond infinity. I often shift the focus point and use the focus indicator on both the close and distant subject to confirm focus, before shooting.

In this image the Lion was under a metre away and even at F9 both it and the house are in focus at 12mm focal length. The image is sharp and has good contrast.

On full frame cameras diffraction effects tend to kick in perhaps a stop or two smaller than on APS cameras and many better lenses hold out to F16, but of course there is less depth of field anyway than on an APS camera.

As a result of this understanding I never stop down unnecessarily now, try to optimise my DOF and get better image quality as a result. Give it a try.