Vibes Thankyou.....and Other Matters
Some light hearted but hopefully pertinent thoughts
about camera support
By Paul James
The universal prerequisite of having a steady platform, whether handheld or by other means on which to capture the photographic image is as old as the art itself. There were initially few problems in the first flush of large format camera usage, where the heavy equipment spent time on a substantial platform or tripod whilst the shutter was fired. Darius Kinsey's forays into the North American woods to photograph loggers during the late 1800's required a bundle of tripods large and small.....
Of the various shutters that came to prominence during those days, the vibrationless leaf forms were favoured most. Whilst barely audible the mechanism was self balancing so there was only the tiniest vibration on firing. This form is still very much the favoured shutter today in large format photography and with good reason. But as soon as its cousin : the reflex camera emerged in smaller form, it looked like the tripod was on the verge of retirement.
I once owned a Thornton Pickard 'quarter plate' single lens reflex with focal plane curtain shutter and 6" Cooke F4.5 lens, which only behaved properly on a very sturdy platform, yet it could and did capture fair images when hand held. Its significant mass was responsible for the acceptable imagery when used on the fly. But the smaller SLRs like the Hasselblad, Mamiya, Bronica and Pentax medium format cameras behaved in a more muted but nevertheless similar fashion in hand, so the tripod never really faded from the photographic scene. In more recent times the 35mm film SLR's popularity increased dramatically, as much more emphasis was placed through design and manufacture of lighter internal parts such as the mirror assembly to reduce vibration to an absolute minimum. And so the success of the modern SLR centers on a design broadly similar in all manufacturers models where portability, ease of use and importantly the virtual absence of vibration during exposures were prominent.
Yet no sooner than handheld camera photography took off, the buffs in this format were very much aware of camera shake, and the broadly accepted lower shutter speed to avoid this undesirable imaging flaw was to shoot at around 1/50th sec or faster with a standard 50mm lens. At around this time this dictum became an acceptable rule of thumb with variations to allow for different focal lenses, aside those who proclaimed their cameras could be hand steadied for eonic exposures :)
Now we come to the more interesting part : The tripod. Obviously any reading from the light meter that required an exposure of around 1/25th or longer needed the camera supported on a rigid platform. Thus the tripod, now well tried and established from the previous large format era, had to hold the latest equipment steady whilst the cable release mechanism was operated. But these modern beasts with reflex focusing and all were dynamic to boot, packing a small wallop during their exposures. Tripods had rarely ever been subjected to these noisy individuals before, as these average light weight three legged supports trembled visibly at the wrong time.
Frustrations of hand held camera shake employing slowish shutter speeds cannot be entirely eliminated simply by upping the brevity of the shutter's opening, it can only be reduced proportionally : Never disappearing but reduced to insignificance ............whatever that means. So the photographer has to be mindful of this simple principle and decide what the lowest speed needs to be regarding other considerations such as film/ccd speeds etc.. Yet despite this, it seems that myriads of photographers have taken succesful photo's at around 1/125 sec. as a matter of course.......Like me ! I'm not trying to split hairs here, but just establish that tradition can be a tad introspective etc..
Back to the tripod : Another misnomer....that the tripod will hold a camera steady should be taken lightly too. In fact I had a revelationary experience which changed my perspective on things 'steady'............One day long ago I took my Mamiya 645 medium format reflex camera to the coast and chanced upon a harbour scene. The fact that I'd no tripod forced me to find a suitable spot to support it during the inevitably longish exposure which as I vividly remember was 1/5th sec at F5.6. The harbour wall was perfect and having found a suitably level dressed stone along its top I set the camera there carefully to take the shots. After releasing the 'mirror up' mechanism I pressed the camera firmly on the harbour wall and then fired the shutter. I knew intuitively then that this was the steadiest my camera had ever been during any previous exposure. In fact the two images I took there were my first true examples of the Mamiya Sekor 80mm lens's performance yielding its sharpest renderings to date. Clearly then it seemed to me that my former tripods were somewhat inadequate though I'd accepted the results of their use for a number of years. Problem is that you can't carry a harbour wall with you..... :)
The effect of vibration from mirror bounce is a very complex affair, especially with a tripod for it can lead to a worse case scenario, especially if the support is light and prone to a natural oscillation cycle near to that of the camera. So rigidity of the support or tripod mount is vital, so long as its mass and shape does not exacerbate the natural resonant frequencies of the camera body/lens assembly. This translates into the larger mass scenario of the harbour wall but infinitely less in scale where a few kilos would be more than adequate in practice. But as with the case of the hand held camera with the 'slow shutter shake syndrome' the problem is not just one of proportion......ie diminishing image softening with faster shutter speeds, but a possible compounding of camera shake induced by the momentary resonant response of the tripod/ camera/lens combo. An interesting virtue of the hand held camera techniques is that any vibration raised during the firing of the shutter is well absorbed by the palms and fingers................. if only the hands could keep still!
However, any salutory lesson in camera support of course carries over to other fields of photography and is as pertinent to photomicroscopy and macro photography as anywhere else. The simple fact is that any SLR, whether, digital or film, and especially medium format examples, will vibrate during shutter release. It can be minimised dramatically by the use of 'mirror up' facilities, but not all cameras sport this ideal feature. The least troublesome in this respect are those consumer digicams with tiny leaf shutters with infra red release, but the majority suffer from noisier ccd's than most DSLR's. Yet their mounting and compatibility with eyepiece output can be easier than DSLR's, but frankly the ideal photomicroscopy camera isn't available as yet to the money conscious amateur :)
Combining the camera to the microscope potentially raises the greatest problems of all from vibration, simply because the aerial image is amplified many times more than with terrestial or even macro photography. To compound the problem there is also the live specimen to think about. It's an inappropriate setup that frightens a poor water critter into the sidelines away from the condenser's spotlight after the first exposure. Far better to implement more subtle techniques that pass unnoticed by those 'posing on stage'. One particularly successful way of eliminating slide earthquakes is to de-couple the camera from the eyepiece in the first instance. I favour this because it allows any camera to be supported over a 'scope so not relying on specific mounting rings etc.. And being totally detached makes for potentially ultra smooth image making. Having said that there's still virtue in having a smaller digicam with its tiny near silent leaf shutter attached to the trinocular port, where it can be operated ad infinitum if need be by its infra red remote so filling its multi gigabyte card with so many exposures, that one might hopefully please :)
old days !
OR of course the ideal image maker today is a large sensored DSLR camera that comes along with 'live view' and an electronic controlled 'curtain shutter' where exposure vibration is entirely absent, because the mirror is locked up, and Oh I forgot ................... Precision focussing is a breeze too........... Wonderful stuff. Maybe I'll get one after the recession ??
|All comments welcome by the author Paul James|
Microscopy UK Front Page
Published in the November 2009 edition of Micscape.
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