Cameracraft magazine – Taking your practical photography further

Tag: SLR

  • Smoke and Mirrors – an idea for Sony

    With the latest Alpha 77, Sony has introduced SLT version II, the new upgraded ‘Translucent’ mirror. This is in an attempt to reduce the ghosting effects created by having an angled mirror between the lens and sensor, the image forming rays passing through a semi-silvered (pellicle) surface, through a thickness of polymer film, and then to the sensor. Having tried it out (update, September 8th) we can confirm that it works. You honestly would never know there was anything between the lens and the sensor.

    But Sony, like all makers, has continued to think in terms of SLR design and the old world of film negatives and slides, where the image always had to be a certain way up on the film, or it would end up being printed and projected reversed left to right.

    In the past a simple reflex mirror for a TLR viewing screen – like the Rolleiflex – did a useful job of turning an inverted image the right way up for viewing. On film at the back of the camera, the image was both inverted and left-to-right. But that did not matter, as the film was viewed through its reverse (back) side to see or print the image.

    Somehow, this old design has been continued to new cameras – but today we use digital sensors. The upside-down or left-to-rightness of the image does not matter as we view the image on a screen or using an EVF. No matter how the image ends up on the sensor, it can always be the right way up and the right way round for us to view.

    So, Sony, when you make you that full-frame Alpha 99 camera change the entire approach. Position the SLT mirror so it reflects the image sideways, upways or downways! And put the SENSOR where it receives the image from the REFLECTED lightpath. Make the mirror reflect 70% of the light and transmit 30%, instead of the other way round.

    There will be no double imaging, no flare patches, no ghosting and not even an extra substrate or layer for the image forming rays to pass through, if the sensor receives the reflected image not the transmitted one. The AF sensor, in the meantime, can be positioned in direct line to the lens where the imaging sensor has been in the past, measuring the image through the SLT mirror.

    This arrangement (©David Kilpatrick, Friday morning, August 26th 2011, scrambled eggs with smoked salmon for breakfast) will in a single stroke remove all the complaints about image degradation as the mirror will provide a perfect image.

    But – would it? Slight lack of plane perfection in the SLT mirror used to transmit the image-forming light, and reflect the AF-measuring light, does not have much effect on the image. Anything less than an optically perfect mirror would fail to create a quality image. It would be like sticking a cheap filter on your lens, or worse. And of course it would never fit into a normally shaped camera body with a full frame sensor and shutter.

    Solid solution

    Ah – the AF sensor, unlike the imaging sensor, does not need cleaning to remove dust spots. So the mirror would not have to be movable. Actually, it would not have to be a pellicle mirror. It could be a lovely big lump of pure glass prism moulded straight on to the AF module itself, even including the condensor-collimator lenses of the AF system. It could be solid glass all the way from mirror surface to AF receptor, and the 45° front face could be to the same optical perfection as the best Sony G lens. Or even the best Carl Zeiss lens. Hell, it could be a Carl Zeiss prism and then the camera could have the CZ logo!

    Diagram above: light blue = solid glass optical prism with 45 degree semisilvered front face; the two white indents at the right hand side indicate AF modules set into the prism rear face. Pink = shutter (optional, ideal system would have electronic shutter only). Dark blue = sensor. Green = top mounted waist level viewing screen, also articulated. A secondary eye-level EVF would or could be used. Design ©DK with a bit of nicked Sony lens cross-section.

    Design? Rollei 6000 all the way! A professional, Hasselbox-shaped thingy to cradle in your hand. With a rotating 24 x 36mm sensor too, so that you change the format aspect by pressing a button not maneouvring the camera body. A 3 inch square OLED on the top like a giant waist-level finder, showing the image vertically or horizontally as you turn the sensor. A waist-level viewing hood for a giant magnified view. Maybe even a monster top prism for the biggest EVF you could imagine!

    Mor realistically, an eye-level EVF in addition to a top plate OLED or LCD panel designed to be hinged up/rotated/twisted – rather like the LCD of the Sony Cyber-Shot DCS R-1, one of the best ever ‘waist level finder’ options fitted to a digital camera to date. In fact something like s giant updated R-1 full framer might do well.

    As for the image sensor, that could be in the well of the camera (mirror aiming down) but maybe having it in the top of the camera, below the viewing screen (mirror facing up) would help gravity reduce the dust issue.

    The point is – it does not matter where the image sensor is placed, it does not have be where the film once was. It does not matter whether the image reaching it is inverted or reflected, as unlike film it does not have an emulsion side or a film-base side, the electronic viewfinder is independent of the orientation of the optical image.

    Future ‘SLT’ EVF cameras – especially a future Alpha 900 replacement – do not need even to resemble today’s DSLRs and can be made better by abandoning ideas fixed in designers’ minds since the era of film cameras.

    – DK

    Technical note: angled partial mirrors, whether prism surface or semi silvered, create polarisation effects, colour shifts and a varying efficiency of reflection depending on the angle of incidence of the ray. This is one barrier to the use of pellicle mirror design for a full-frame model, as the back focus or telecentricity of lenses relative to the format would mean a greater range of incident angles across the mirror surface. Sony appears to have overcome any such problems in the existing APS-C SLT design, and the slightly forward tilt of the mirror (not a true 45°) helps in this respect. I propose the above design in full awareness of related optical and technical issues. I’m not assuming they do not exist – they would need solving.

  • Four new Alphas – and two 'translucent'

    It’s a funny word to use, because the mirrors involved are transparent and not translucent (which implies passing light but not in an image-forming manner). Translucent means semi-opaque, letting light through in the way that an opal perspex sheet or Kodatrace foil does. Transparent means something you can see through.
    But now, thanks to the wonder of changing language, translucent is also going to have to mean transparent, or semi-transparent. Pellicle, semi-silvered, whatever term you wish to use.

    Unfortunately, for this writer the misuse of the word translucent stands as one of the biggest schoolboy howlers ever imposed on the entire world by the ignorance of a corporation. It’s such a glaring error I can hardly bring myself to use the term – others, like Dave Etchells, have happily assimilated the new meaning into their technical lexicon. And as the video above shows, they’ve made it into a trademark, a permanent part of the future of this technology.
    Wiki, and pretty well every dictionary ever published, disagree with Sony’s imaginative use of a word from which they have now removed its exact meaning:
    Wikipedia: “Transparent materials are clear, while translucent ones cannot be seen through clearly.”
    Merriam-Webster:

    trans·lu·cent/transˈlo͞osnt/

    Adjective: (of a substance) Allowing light, but not detailed images, to pass through; semitransparent.
    (the semi bit of semitransparent cited here seems to mean semi-detailed, vaguely delineated – not slightly darker; otherwise the primary definition of the word is diluted).
    There has been some heated argument on dPreview forums about this post of mine (my view is shared by many). No-one has made the point that words evolve to have useful exact meanings. Transparent and translucent are words which may once have shared a common poetic meaning in 18th century descriptive writing, but whose meanings were refined with the progress of science and technology. This process in the course of over 200 years resulted in a useful distinction between the meanings of transparent and translucent. Sony’s commercial misuse of the word Translucent is damaging to the English language and to the scientific and technical lexicon; it predisposes future confusion about the meaning of the words.
    It is also a fait accompli; there is no turning back, since Sony’s corporate stance is much like that of Mrs Thatcher; no u-turns and never admit to be being wrong. They have also no doubt invested hundreds of thousands of dollars in the consultancy involved, and the registration of the term as a trademark, the creation of branding artwork.
    They could have branded the mirror TransLumina® or, more usefully, just called it a transflecting mirror – transmitting-reflecting. That term is already used to describe the sort of mirrors used in ‘Big Brother’ with cameras behind them.



    As to whether it’s a true pellicle mirror (a thin stretched film of vacuum coated Mylar or a similar polymer) no-one seems to be clear. It moves out of the way to allow sensor cleaning but could be relatively fragile. It certainly does not need to move to allow 10fps (Alpha 55) or 7fps (Alpha 33) continuous shooting. Sensor dust is often created within the camera by wear and tear on the shutter mechanism, so access for cleaning is essential and the mirror can not be designed to seal the sensor chamber. The Alpha models still have a shutter, that’s the next thing we shall see eliminated. That old rumour of the 15fps silent shooting Alpha DSLR seems to be more than a rumour; we are almost there.


    For many users, the critical advantage of all four new Sony models will be HD Video with sensor-based in body image stabilisation. This will enable all kinds of lenses from macro to ultrawide or soft focus, manual adaptations and Minolta AF legacy glass to be used for video with confidence.
    Welcome back the circular polariser, unlike mirrorless ILC cameras these new models will not allow the use of linear polarisers without AF efficiency reductions, but exposure should be unaffected as the sensor itself provides the metering with 1200 zones.
    This will be one of the tests reviewers need to carry out on the new pellicle mirror Sony Alpha 33 and 55 models – to confront them with not only polarising filters, but conditions in which light is naturally polarised. How will they render sky gradations or reflections off water?
    Two further Alpha models are being released, which are essentially updates for the 500/550 – the Alpha 580 which will hit the shops before the winter buying season, adding 16.2 megapixels and a 15-zone AF module, HD 1080p video and (non-video) Contrast Detect AF with all Alpha mount lenses. The 560 will not arrive until some time in 2011, using a 14.2 megapixel sensor.
    Versatile features
    More of a landmark than a benchmark, the inclusion of 10fps continuous shooting with active phase detect AF and 16.2 megapixel file size in the Alpha 55 is unprecedented and possibly unforeseen by competitors, in this class of sub-$1000 consumer DSLR (let’s continue to use the term, since they are clothed as DSLRs). The dual format card drive supports the 30Mb/s transfer rate of the latest Class 10 SDHC cards and Sony’s fastest MemoryStick Pro Duo generation. The HD video also has a reasonable 17mbps  bitrate.
    The new technology has been well documented before the launch, but the fine detail of the new cameras is now clearer. The Alpha 55 is some markets will incorporate GPS geo-tagging for stills and videos (we wait to see whether raw files are tagged, and how accurate this is – the accessory Sony geo-tagging system available to date has only permitted JPEG tagging, and has not been accurate enough to know which street in a town the picture was taken in).

    Rumours that the 33 and 55 bodies would be SSM/SAM only, with no internal focus drive, were unfounded as Sony states clearly that both are compatible with ‘the full range’ of over 30 Alpha lenses (indeed, the product shots of the 33 and 55 alone show the 18-200mm SAL DT lens fitted). The 55/33 1080i/60p (1080p in AVCHD camera archive format) video claims ‘smooth, precise’ phase detect auto focus during video shooting, but makes no reference to this being limited to in-lens motor lenses. Therefore we can assume it works with in-body AF drive lenses as well, and you just have to edit the soundtrack.
    The new ISO 25,600 mode does not imply a radical sensor change as it is only available using Multi-Shot Noise Reduction, which requires a burst of 6 frames at the 10fps/7fps native maximum speed of the camera, and can not save raw files. The ISO range of the sensors is 100 to 12,800. Is this range quoted as absolute, or after accounting for the semi-silvered mirror light losses? If it’s the range before allowing for the mirror, then the 14.2 megapixel sensor of the Alpha 33 may be more like the Nikon 3100’s sensor than the NEX (ISO 200-12,800) is.
    Thom Hogan has shown pixel dimensions and size data which support Nikon’s claim to have an entirely different sensor fab line of their own, compared to the A550/NEX sensor. But how about compared to the A33/560 sensor?
    The 55’s new 16.2 megapixel CMOS will probably appear in the forthcoming Alpha 700 successor, which it is believed will form the main Sony exhibit at photokina (Cologne, September 21st-27th). Both models have a new 15-zone AF sensor with three cross sensors, but not f/2.8 sensors – all are designed to operate at f/5.6 virtual aperture. However, there is a hidden clue that the cross sensors may be f/3.5 capable, as the high-speed shooting modes with continuous AF set f/3.5 by default on any lens capable of this (if the lens is, say, only f/5.6 then the largest aperture is always set). Setting f/3.5 implies that this confers an advantage in focus sensitivity over f/5.6, f/4 or any other particular aperture – and that f/3.2, f/2.8 or wider would bring no benefit. That points to some of the sensors having an f/3.5 virtual aperture.
    The new cameras are known as SLTs – Single Lens Translucent – instead of SLR. See my intro. Did they have no English speaking staff on their team? I’m sure there is a German word which describes their mirror correctly. I’d rather have the right German word than the wrong English one. Ah well, as the bloke leaning on the pub bar says, durchsprung vor technik…
    Confusing aspects – Auto HDR is said to be available in P/A/S/M modes. I guess in M mode it must leave the aperture alone and change just the shutter speed. Regular bracketing is still limited to a disappointing 3 exposures at 0.7 EV intervals, maximum.
    But you’ll love the direct D-Range button which gives access to D-Range and HDR options directly, and the direct Finder/Screen button which toggles between using the very high resolution EVF with its ‘virtual 1.1X’ 100% view of the subject – effective visual scale, larger than the Alpha 700 and larger than any previous Alpha digital model except the Alpha 900 and 850. That’s one of the benefits of the EVF, a relatively tiny display is viewed through a high magnification ocular and ends up with a ‘window’ on the world which beats the tiny tunnel vision of optical finders. Technically it is very similar to the last EVF produced by Konica Minolta on the Dimage A200, with the benefit of five years’ further development. It has the same 60Hz refresh rate and visually almost raster-free RGB.


    Where the A550 and its earlier stablemates vary slightly around a viewfinder with an effective 0.50X scale (relative to a full frame 100% view using a 50mm lens), the A55 and A33 provide an effective 0.73X and that’s impressive. The ocular is set well back (remember the Konica Minolta A2, and the Sony Cybershot DSC R-1?) because it is a telescope design. This also gives it a very narrow range of possible eye positions, a common feature of EVFs. The eyepoint is close, and you must position your eye precisely.
    The rear screen uses the same type of (Schott?) reinforced glass with (3M?) resin gel adhesive as Canon’s 7D – this totally seals to the LCD module itself eliminating air gaps, and improves contrast. It is a technology first seen in the 7D and becoming standard across the industry though the NEX has shown Sony to have the best implementation so far. It is scratch proof, by the way, and it can be cracked by impact like any other screen.
    The tilt-swivel action is borrowed directly from the Nikon D5000. In fact, it’s so identical in articulation it even included the amazingly silly front facing mode where the screen is obscured by your tripod, hanging under the camera and preventing it from being placed on a flat surface for self-portraits or videos. But it has the same benefit as the Nikon, the screen can be flipped to face the camera and protected completely while you use the EVF.
    Functions familiar from the NEX including Sweep Panorama and Sweep 3D Panorama are built-in and accessed from the main mode dial, which also provides physical settings for all the main modes. Depth of field preview is restored – with the usual button – because is can now actually work. It was always useless in real terms on optical viewfinder cameras, as the focusing screen never represented wide apertures correctly.
    Now, with an EVF, for the first time ever an eye-level Alpha gives absolutely perfect and precise previewing of depth of field and bokeh effects whatever aperture you are working at – even at f/1.4, which was never possible and still isn’t with the A850 or A900 for that matter (which is why their Preview mode is useful).
    You can also preview the exact image appearance. By pressing the AE lock button, the auto gain of the EVF or rear screen are turned off and replaced by an exposure-compensated view. So if you dial in -1 EV (using the adjacent dedicated button), and change the WB, and use a different picture style with more saturation and contrast just pressing AE-Lock will immediately preview your image with these adjustments applied. And you can enlarge in the usual two steps to check auto or manual focus.
    The finder and screen also have a Nikon-style two axis spirit level (flight simulator horizon) display to help you get your horizontals straight and your verticals parallel. It can be activated on either, and does not have to appear on both simultaneously.
    For movie makers, the binaural stereo microphones are a great move. Even on the NEX, the two small top aperture mics give excellent stereo. The 33/55 mics are placed either side of the ‘prism’ housing, rather like the ears on your head. This will give the stereo image created by these cameras a really natural quality. Natural, that is, to a pygmy marmoset monkey… but still, I will wager, the best stereo image of any DSLR/HybriD. And Sony provide a stereo 3.5mm mic jack socket, though without any manual control of gain levels.

    I’m sure we will have to buy the A780 to get that. Click the picture above for a big version. Who says Sony does not have a range to match Nikon or Canon, whether or lenses or of cameras? From the left, the cameras show the current range before we even see the magnesium-bodied Alpha 700 replacement arrive. A900, A850, A580, A560, A55, A33, A390, A290.
    – David Kilpatrick
    Read Sony Press releases and full technical data:
    Alpha 33 and 55 Press Release
    Alpha 560 and 580 Press Release

  • Alpha's Silver Jubilee


    The Alpha System celebrates its Silver Jubilee or 25th Anniversary this month.
    We have a full length revision of the article which appears in the latest Photoworld now online as a page here.
    Read our 25th birthday review of the Alpha system’s history now!

  • Nikon D3S video: dark, rain and wind 400mm f/2.8

    As part of my tests of the Nikon D3S (British Journal, report in December, with additional material by Richard Kilpatrick who is shooting with Nikon on November 25th at a press event) I dragged the £6,000 400mm f/2.8 AF-S IF ED G supertele into the rain as darkness gradually forced the ISO up from a mere 10,000 to the maximum 102,400. The object was make a short video showing rising floodwaters, no threat in our town but still dramatic to watch.

    wet400mmcombo-web

    Here’s how it came back from the hour in the rain, a quick wipe down with an oily rag and it was all as good as new. Actually, it needed a thorough drying with the towel then a clean up with a lint free microfibre cloth to remove dust and towelly stuff. The very deep lens shade kept the exposed front element totally dry despite the wind and rain; I just made sure it was never aiming into the wind.

    During the shoot, wind noise was a major problem. I locked the microphone to level 2 manual gain, not automatic which would have been a disaster. Many clips had to be shortened, some discarded due to violent wind noise I could not mask. The sheer weight of this combo made lugging it with a decent Slik tripod (pan and tilt head for video) difficult; I drove to the evening location with the rig laid flat on the back seat of the car, but still had to walk several hundred yards for some shots. I wore a Tog24 parka and found that by pulling the fur-lined hood over the camera body I could cut out nearly all the wind noise. I must have looked like a view camera operator with a dark cloth, or something out of Monty Python with my jacket pulled up and the hood over the Nikon!

    But, this seemed such a good solution to the wind noise I would consider unzipping the hood from the parka and using it as a baffle in finer weather.

    My favourite part of the video is the one with the worst noise, where I was not able to keep the wind away from the direction of shooting – the sequence of the road (flooded by the morning) with headlights, tail lights and cars in rain. This consists of three takes blended with long crossfades. During each take, the manual focus of the 400mm used at near wide open f/3.2 aperture was pulled to bring the moving traffic in and out of focus, and create huge bokeh circles from the lights. This would be impossible with a camcorder and not all that easy with a conventional high-end video kit. The combination of full frame 35mm format and the fast 400mm has enabled a highly effective cinematic technique to succeed on the first time of trying. With some markers on the focus ring, some practice and many more takes the result could have been refined further.

    But I was getting very wet and so was the camera!

    The first part of the video is all on the 400mm with tripod, with High ISO video enabled. The ‘next morning’ stuff is on the 24-70mm, hand held, locked down to ISO 200 at f/8.

    I’m not sure when our final review of the camera will appear in the British Journal, it should be early December.

    The video is encoded to best quality 720p from iMovie09, and can be best be downloaded and viewed without any YouTube jerkiness at full res if your connection is not good.

    – David Kilpatrick

  • Nikon D5000 HD video – May Day evening

    True to promise, the Nikon D5000 did become available on May 1st in the UK, and my review camera turned up mid-day in time to be photographed and have its battery charged. Taking it out on my walk to the post (regrettably, to send in large sums of VAT and tax…) the sun came out though it was a very cold and windy day. With the sun, the breeze dropped to a reasonable level and on the way back I was struck by the motion of the trees, leaves and flowers.

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  • Canon EOS 500D video test

    The clip originally shown here has been replaced by an edited selection, shot in a mixture of 1080 and 720 modes, assembled using iMovie and written as a 720p final project for YouTube. Don’t mean to cause confusion, some visitors may have linked to this post already, and I do not want to add another post. Please feel free to link directly to the YouTube vid or to this page.

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  • Nikon D5000 – HDvid, articulated screen

    Nikon has announced a May 1st launch for a competitor to the Canon EOS 500D, in their D5000. This camera has the first articulated screen (only 230,000 pixels) to be designed by Nikon. See:
    http://www.cameracraft.online/2009/04/14/nikon-d5000-live-view-hdv-articulated-screen/
    (more…)

  • Which Sony Alpha?

    Now that there are five Sony Alpha DSLR bodies in circulation, with many owners of the original 2006 Alpha 100 considering a replacement, the differences between this ur-Alpha and the 2007-8 generation of Alpha 700, 200, 300 and 350 need examining. (more…)

  • Eyepiece magnifiers for the Alpha DSLRs

    The launch of the Alpha 350, with its small 0.74X viewfinder, makes a proper eyepiece magnifier attachment an essential addition to the Sony accessory range. Olympus, Nikon and Pentax all have such magnifiers, which permit a full view of the screen for most wearers and make all the difference to the manual focusing and general comfort in composing shots. We tested two devices, one of them the highly affordable Seagull 1x-2.5x right angle finder, and the other Olympus’s ME-1 1.2X ocular magnifier. (more…)