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image stabiliser
- see also:
- Bob Atkin's - sensor vs optical IS - even Bob is coming around to the win-win fact of having sensor IS in the camera
with the amazing Olympus 5-axis image stabiliser, you don't really need to resort to the chook mounted stabilising system:
Introduction:
- image stabiliser (IS) technologies reduce camera shake blurring photos but are not of use in reducing blur due to a moving subject or focus issues, nor are they of much use when the camera is mounted securely on a tripod, in which case they can even make the image worse.
- image stabilization is not a replacement for high ISO - it can combat camera shake, but it doesn't allow you to increase the shutter speed and therefore cannot do anything about blur due to movement of the subject in low light.
- BUT IS has a potential BIG advantage over high ISO in that it allows a slow shutter speed for when you want motion blur but no camera shake blur which is useful for moving water, etc. (of course using a tripod would be better but you don't always have your tripod with you and even if you do, you can't always position your camera in the spot you want when using a tripod).
- image stabilisation was 1st released for 35mm photography in 1995 with the Canon EF 75-300mm f/4-5.6 IS USM lens.
- image stabilisers come in one of two main types:
- traditional optical IS embedded in the lens:
- Canon IS lenses - most are about 2-3 stops but the newer models are 3-4 stops
- Nikon VR lenses (VR for vibration reduction) - currently about 2-3 stops but the newer models are 3-4 stops
- Tamron VC lenses (VC for vibration compensation) - mainly for Canon/Nikon - 3-4 stops
- Panasonic Mega O.I.S. / Leica IS for Olympus Four Thirds dSLR system - currently about 2 stops
- CCD sensor shift IS in the camera body and which should work on all lenses:
- Olympus dSLRs and Micro Four Thirds system
- in general, the IS mode can be switched on or off or activated only during shutter activation.
- some IS systems allow panning mode so that IS is not used to reduce horizontal movements but only vertical movements.
- note some manufacturers deceptively call a high ISO mode an image stabiliser and whilst this is true to some extent as high ISO allows faster shutter speeds, all cameras can increase ISO to some extent with variable impact on image noise, lack of detail and sharpness and reduced dynamic range.
- IS is also of great benefit when using super telephotos:
- even when tripod mounted as the high magnification and the often slow 1/60th sec shutter speeds for dawn/dusk means any camera vibrations due to wind, etc needs to be minimised.
- even when shooting birds flying using 1/3000th sec, IS in mode 1 is of some benefit in improving image sharpness
- for maximum resolution the requirements in approx. order of importance are:
- zero camera shake - ie. tripod preferably with mirror lock up +/- image stabilisation
- stationary subject or a sufficient shutter speed to freeze the motion adequately
- accurate focus
- lens resolution (usually maximal stopped down 1-2 stops but diffraction reduced resolution at apertures smaller than f/11)
- reducing image blur using software:
- although not image stabilisation, it's worth discussing here.
- software algorithms can reduce image blur by several methods:
- sharpening
- Photoshop's “unsharp mask” tool and similar tools
- deconvolution
- Lucy-Richardson deconvolution
- tends to cause a ringing artefact of light & dark ripples due to Gibb's phenomena in Fourier analysis at discontinuous points such as image edge points or boundaries.
- Maximum Entropy deconvolution
- multiple image de-blurring and de-noising:
Optical IS:
- pros:
- works during video unlike sensor-based IS
- is more effective when using telephoto lenses as these would need the sensor to move by 10-20% of its size to give the same range of stabilisation as optical
- can visualise it's effect in an optical viewfinder, potentially making manual focus easier in some situations
- nice big buttons on the lens to adjust mode and turn it on/off
- cons:
- expensive as designed in each lens
- means not only your digital camera will depreciate fast but also your lens as new lenses with better performing IS come out.
- older versions not as effective as the newer CCD shake IS such as in the Olympus E3
- Nikon's VR I give 2-3EV while their VR II is said to give 4EV, not quite matching the Olympus E3's 5EV IS.
- limited availability:
- wide angle, standard, short telephoto and macro lenses tend not to have IS
- none of Canon's or Nikon's prime lenses under 300mm have IS except Nikon's AF-S VR Micro-Nikkor 105mm and AF-S VR Nikkor 200mm f/2
- none of Canon's L series zoom lenses under 70mm have IS except for 28-300mm f/3.5-5.6 L IS USM which is a bit long and slow for my liking
- none of Nikon's zoom lenses under 70mm have IS (VR) except for AF-S VR 16-85mm f/3.5-5.6, AF-S VR 18-200mm f/3.5-5.6, AF-S VR 24-120mm f/3.5-5.6 and AF-S VR 55-200mm f4-5.6, all of which are a bit slow compared to Olympus' f/2.0 zoom lenses.
- adds weight to the lens
- adds extra optical elements to lens which increase aberrations and lens flare whether you have it turned on or not
- astrophotographers generally avoid optical IS lenses as they cause aberrations on the shapes of stars.
- most optical IS only give 2-4 stops, while potentially newer sensor shift and dual IS technology is giving 3-5 stops.
- more to go wrong with your lens
- the arrogance and marketing economics may prevent Canon or Nikon adding CCD-shift into their camera bodies so they can keep selling IS lenses but this may be to their detriment, at least in the prosumer market who will be more interested in CCD IS, lighter, smaller, cheaper cameras and lenses than lugging around big, heavy, expensive lenses. If they don't provide CCD-shift, then I can foresee Olympus and Pentax gradually taking over in the prosumer market place, and as sensor noise technology improves this will potentially provide an impetus into the professional marketplace.
Canon EF image stabilised lenses:
- 1st generation IS:
- lenses with mode 1 & 2 (ie: panning) 100-400mm and 300mm f/4L IS for example… as well as ones that did not have Mode 2. These were the first 75-300mm IS and the 28-135mm IS.
- lenses had to have the IS manually turned off when mounted on a tripod or solid arrangement, as the IS could introduce image anomalies and otherwise unwanted behavior if left on while tripod mounted.
- 2nd generation IS:
- all second generation IS lenses have Mode 1 & 2, but recently some of the newer models at the wide ends also lack the Mode 2 function.
- In addition to faster start up times, and improvements that Canon claims add more “stops” to your hand-hold-ability, the current 2nd generation of IS only adds one set of features in addition to those already found in 1st gen multi mode IS. That feature is Tripod detection and tripod vibration mode.
- basic 2nd generation IS will disable IS when it detects that the lens is mounted solidly such as on a tripod.
- SuperTelephoto lenses with 2nd Gen IS also detect tripod mounting. Rather than disable the IS, 2nd gen Superteles will use IS to counter subtle vibrations that are present and magnified by super teles even when on a tripod. This includes mirror slap vibration. Lenses include:
- most fast primes in range 300mm, 400mm, 500mm, & 600mm
- 70-200mm f/2.8L IS
- 70-300mm f/4.5-5.6 DO IS
- 28-300mm f/3.5-5.6L IS
Sensor shift IS:
- pros:
- it's a no-brainer really, assuming it only adds $50-100 to the cost of the camera, you would be crazy to forego it if you had the choice - whatever you believe about which is better, unless you have optical IS on ALL your lenses, then sensor based IS makes very good sense.
- for legacy MF lenses on Olympus bodies, you just dial in the actual focal length that is on the lens, not the 2x crop value, and it works for all lenses 8mm-1000mm even mirror lenses, macros, fisheyes and tilt-shift.
- more versatile and cost-effective
- can automatically activate it in mirrorless cameras during magnified view to make manual focus much easier
- can still use an optical IS lens if you wish and there is one available, and with newer cameras and lenses can utilise both at same time for even more effectiveness “dual IS”
- cheaper
- it is much cheaper to replace a IS camera body than a whole kit of IS lenses in order to upgrade the performance as new technology is introduced.
- most optical IS give 2 - 4 stops reduction in camera shake while newer sensor shift IS technology is giving 3-5 stops.
- Olympus and Pentax allow IS to work on ANY lens - if it is not a digital lens, user can select a focal length manually
- can be utilised for a range of other functions if camera allows it such as:
- automatic horizon rotation
- star trail eradication for short exposures
- anti-alias effect without needing a filter
- cons:
- not as effective for telephoto as can only shift the sensor by 1% or so, hence Olympus has added OIS to its Olympus mZD 300mm f/4 PRO lens so both can be used
- cannot visualise it's effect in an optical viewfinder but only in a live preview LCD image.
- when using dSLRs, without it being available to the AF sensors, AF may not be quite as effective for hand held telephoto shots
photo/is.txt · Last modified: 2016/03/03 13:35 by gary1
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