Cameracraft magazine – Taking your practical photography further

Tag: GM

  • Sony A7RVI and 100-400mm f/4.5 GM lens

    Sony A7RVI and 100-400mm f/4.5 GM lens

    • 66.7 megapixel back illuminated partially stacked full frame sensor
    • Bionz XRII processor with AI subject recognition and tracking over 94% of the frame
    • 3X brighter OLED viewfinder with better than sRGB colour
    • New battery for 15% more stamina
    • Dual SDII/CFExpress Type A card slots
    • Illuminated buttons for low light operation
    • 8.5 stops sensor-based image stabilisation
    • New 100-400mm constant f/4.5 optically stabilised zoom with 3X faster AF
    • £4,400 launch price already on pre-order from dealers such as Clifton Cameras and WEX

    Sony’s new A7RVI hit the news desk – though the UK company no longer appears to issue press information and relies on a website little different from anything they provide for dealers – on the same day we ordered a replacement deep eyecup for our A7RV. Evening sunshine had made the otherwise superb EVF hard to see, and the silicon surround of the original eye-pad had split at one corner.

    Sony doesn’t make a deeper eyecup but others such as JJC and Smallrig do, alongside regular replacements. But for those buying the A7RVI in June, its EVF has a boost to make it three times as bright as the V, while the otherwise similar near-10-million dot OLED gets better than sRGB colour and increased dynamic range.

    If you do not need the other improvements such as 30fps blackout-free continuous shooting, up to 5 seconds of pre-capture frames, four times faster readout from the new stacked 66.7 megapixel sensor greatly reducing silent shutter action/pan distortion and video rolling, the EVF enhancement might well be your main reason to upgrade to this £4,400 body.

    It also has a new mode dial with 1-2-* instead of 1-2-3 for Memory recall of complete setups – the * opens rapid access to many saved setups previously needing menu diving. And when you need buttons, there’s another button to light them. Give me one which instantly puts on my reading specs and it would have more use!

    The additional pixels in the image are of little importance. Mark Galer (one of the better ambassador/influencers) states repeatedly in his blog post that it’s ‘twice the resolution’ of the A7V. Well, 66MP is not twice the resolution of 33MP because resolution is and always has been a linear not area measurement. It’s actually 1.41X the resolution, twice the megapixels.

    The increase from 9504 x 6336 pixels to 9984 x 6656 is not insignificant but not game-changing. For astro and wildlife or any kind of tele photography where the pixels capturing a subject with a specific lens are what counts, the OM-Systems 20MP MicroFourThirds sensor is like a crop from an 80MP full frame, Fujifilm’s X-Trans 40MP matches 94MP on the same basis. The APS-C crop on the A7RVI is 28MP, compared to 26MP on the V.

    Relative to the A7RIV/V the VI has a 5% increase in resolution and does become the highest resolution 24 x 36mm sensor camera, and to this Sony add marginally better in-body stabilisation, improved dynamic range to 16 stops depending on capture format and hopefully some improvements to noise levels across the entire low to high ISO range. 

    As with other recent R series models having no low pass filter, the A7RVI offers 4-shot (true RGB for every pixel) or 16-shot (2X pixel dimensions) multi-shot high resolution. There is no upgrade to in-camera processing (as used by OM-Systems) and it’s a strictly static subject tripod mounted option. This isn’t surprising as creating a 240MP image from 16 70MB raw captures demands much more than OM’s 50 or 80MP generated from 16 20MB raws.

    Extending the AF point grid to cover 94% of the full frame as feasible will help deal with lenses that have curvature of focus field when used for action photography with a subject relatively small in the frame.

    Sony’s colour has always been good but Auto White Balance far too variable. The Bionz XR2 processor (introduced with the A7V) adds AI-derived image analysis which can give much more consistent skin tones in changing light and settings. It’s a something wedding, portrait and fashion/lifestyle photographers need. 

    A new XLR digital microphone module with four channels has also been announced, fitting the multi function accessory shoe as for previous mics and preamps. The second USB C socket has a screw thread beside it to accept new lockable cables without needing a clunky tether-anchor assembly.

    Battery with more ammo

    The one change most likely to frustrate existing owners of A7*III and later bodies, including even A9III, is that a new larger battery priced at £99/$120 is used to solve the problem of the poor performance of the NP-FZ100 with its 2280maH rating. The NP-SA100 (already listed by dealers – see Clifton Cameras) offers 2670maH at the same nominal 7.2V with an expectation of 600 shots. While Sony has never attempted to improve the FZ100 third parties like Mathorn (sold by WEX) offer 2600maH already and it might have been reasonable to think Sony could have improved their now ageing battery to at least this spec without having to change to a brand new shape and fitting.

    Here’s an interesting 2600maH third party – Llano brand from Amazon with a neat power level display which lights up at a touch. It is not biometric as they claim, just plain old touch-sensitive inductance. But it’s half the price of some third party cells.

    However, if the NP-SA100 battery after moderate use doesn’t do the now familiar FZ100 trick of showing over 30% charge in the finder display then dying completely after half an hour taking just a couple of dozen frames, it may save newcomers to the system experiencing an urgent need to buy two more.

    Twin USB 3 connections do make it possible to chargenot only while shooting, but also while using a tethered display or video SSD recorder. Power banks work well – here’s a very good Ugreen deal which is also a magnetic wireless charger for iPhone. There is also a new battery grip accepting the usual two to double everyday stamina, £399 on pre-order.

    The one full size sample image (above, click for link) provided by Sony on the press site is shot at ISO 400 and is fairly noisy as well as not ultimately sharp – no doubt there will be many more which prove the A7RVI can at least match the V if not all rival brands or models using sensors in the 40-50MP range.

    100-400mm f/4.5 GM OSS

    Alongside the A7RVI Sony have launched an alternative to existing long tele zooms, a new 100-400mm f/4.5 constant aperture GM OSS. The existing GM OSS is 100-400mm f/4.5-5.6, weighs 1395g, is 205mm long and focuses down to just 98cm with a subject scale of 0.35X, takes 77mm filters and costs £2,149. The new model claims 3X faster AF and better optical performance as well as 2/3rds of a stop extra light on to the sensor at 400mm.

    It is however over twice the price at £4,400 and weighs 1840g, is 328mm long (this is a huge difference) taking 95mm filters though with a rear slot-in option, and its minimum focusing distance is variable from 64cm to 1.5m with a maximum image scale of 0.25X. You can buy two or even three Sony G long tele zooms for the price but not one them will give 400mm and f/4.5 – you can get the 400mm f/2.8 for over ten grand, or use a 2X converter on the 70-200mm f/2.8 and get f/5.6. So there’s a definite place for this lens.

    Pre-order now open from most dealers including WEX and Clifton.

  • Sony’s precision aspherics

    In interviews about the new micron-accurate aspheric lens element moulding process used to increase the resolution of the latest Sony G Master lenses, a visual has appeared which shows the ‘onion ring’ effect that coarser mould machining causes in lens elements.

    Working independently, I’ve been aware of this for years – and I have used a point-source photography technique to study lenses. I’m not an optical engineer or scientist, indeed I don’t even have a degree in anything. I came into photography through Victorian books and teenage years experimenting with lenses, developer formulae, building my own equipment and using observation, corollary and deduction to understand how things work. It’s helped me explain difficult technical stuff to many thousands of readers through books and magazines, without using maths or formulae, and very few diagrams.

    In the Cameracraft back in 2013 I published a home-brewed rendering of aspheric moulding visual analysis.

    Here’s Sony’s visual showing the difference between traditional aspheric moulding (pressed glass aspheric, as pioneered by Leica and Sigma) and their new refined pressing with better engineering.

    onion

    And here is my home-brewed visual from Cameracraft when I explained the bokeh and resolution issues created by pressed elements (and also, some other aspects of bokeh, which I’ll refer to below the image):

    onion-ours

    This is the clip from a 2013 article in Cameracraft dealing with broader aspects of bokeh, depth of field, aberrations and how images are rendered. You can download the two-page article here. Nine years after we launched Cameracraft the magazine is going strong, it’s a bit thicker and does have the occasional advert unlike our original, but it is still one of the best ‘never knew that before’ reads a photographer can have drop through the letterbox. You can arrange that easily enough here!

    Here is the full article as a downloadable PDF.

    Sony’s new superlens was not any better than the Sigma 70mm f/2.8 macro which I still use. My reasons for choosing this macro are simple – it is optically excellent and traditionally made without any aspheric or other special elements, and it uses simple focal extension for focusing, not rear or internal group movement. This means it’s a true 70mm lens even when used at 1:1 and gives the maximum lens to subject distance, for its focal length.

    However, it’s MUCH better than the Voigtländer 50mm f/1.4 used for the colour bokeh shift example at the top. Sony’s information makes it clear that the new more precise aspheric moulding allows new surface profiles and the elimination of chromatic aberrations which cause this magenta-green foreground to background shift in so many otherwise excellent lenses. I’ve said that to do so, the new lenses must be what would once have been called Apochromatic, though that term has only ever meant that all wavelengths focused to the same plane and at the same scale. Even past Apo lenses can show poor colour bokeh. It’s interesting that Sigma, after years of plugging the APO (capitals not actually needed, folks!) label chose not to label some new lenses this way even through their performance matched or exceeded earlier APO models. Sony seems to be taking the same view – G Master will be sufficient label to imply very high resolution, elimination of bad colour bokeh shifts, and by implication an apochromatic performance on RGB sensors.

    So will I be buying these amazingly expensive, large, E-mount dedicated lenses? Probably not. My unscientific observations tell me there are smaller, lighter, far less expensive lenses which will serve me better. Mirrorless digital camera bodies with high quality EVF and high magnification focusing allow me to  do things I could never have done over 40 years ago when I took my first position as a Technical Editor (of the UK monthly Photography published by Fountain Press and edited by John Sanders). Geoffrey Crawley, editor of the British Journal of Photography, showed me how to evaluate any lens quickly with the help of a light bulb, a darkened studio, a roll of background paper and a sharp pencil. Back then you had to expose film, now you can just look through the finder. In a photo store, any LED spotlight will do for a quick check. Focus centre, magnified to max, at full aperture. Move to all corners in turn without refocusing, magnify each time. Refocus each corner in turn when magnified, examine change in rendering of point source. Buy the lens which shows symmetrical, balanced results and the best sharpness of the corners when the centre is correctly focused. Do this with a light source at least 3m/10ft away and if you can, even further. Repeat one stop down, two stops down, with zooms repeat at three or four focal lengths across the range. Never do it at close distance (hint: lens test chart results are only good for the distance you photograph the chart from, which is why Imatest, DxO and other labs have test targets the size of a wall and industrial sized space to work in).

    And, if you have a single LED bulb or miniature LED torch, you can examine any of your lenses in a darkened room and produce a ‘bump map’ which will reveal its moulding defects, scratches or fungus, blemishes, and population of dust and microfauna.

    – David Kilpatrick

    dk-cameracraft-bokeh

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