autofocus Archives - Cameracraft

Sony FE Macro 50mm f/2.8 – only $500

Posted on August 30, 2016 By David Kilpatrick

Sony has just announced yet another 50mm, and this time it’s different – a truly affordable 50mm 1:1 macro, only $500 US. We reckon this will become the most popular standard 50mm lens by far, even more so than the budget 50mm f/1.8. Now you can photograph your food properly at last!

It certainly looks neat and the specifications are good.

It features one ED (Extra-low Dispersion) glass to reduce lateral CA (colour fringes) as the image scale increases. The optical and mechanical construction of the lens is claimed to have less glare and ghosting. The lens is also dust and moisture resistant.

Examples shot with the new lens can be found at www.alphauniverse.com, Sony’s new corporate pseudo-community site. We have to say the bokeh looks funky, not good, and this lens probably lacks the classical drawing of the more traditionally designed (and more expensive) SAL 50mm f/2.8 Macro A-mount.

The 6.25″ (16cm) minimum focusing distance is a clue why. The effect of the 7-blade circular aperture design can be studied in the Sony photo examples. It has a focus-mode switch, focus-range limiter and focus-hold button (the mode switch is valuable as you may not want AF for macro shots most of the time, and the focus limiter is similarly good for controlling frantic hunting and missing – all three switches/controls are important on the mirrorless bodies).

The lens is 7cm long, weighs 235g and during focusing it extends in length by only 26mm, not the 50mm required for a typical Tessar-type lens of this focal length. This, and the minimum focusing distance (should be at least 20cm for a 50mm macro at 1:1) indicate that the design relies heavily on internal/rear focusing groups, much like the 30mm f/2.8 DT SAM macro for A-mount. We would reckon the true focal length of the lens at 1:1, which can not be more than 40mm with a 16cm close focus, may be around 35mm as 1:1 is achieved with 76mm of overall focus extension.

The distance from the subject to this lens front rim at 1:1 is only 3.5cm which many will find a little too close for insects and even for plants, as the shadow of the lens and photographer may interfere. Even the SAL 50mm is not perfect, reaching 1:1 at 20cm from the focal plane with a 48mm dual barrel extension and 53mm front element focus travel (the extra 3mm is down to floating element correction which slightly changes the focal length). This places the lens rim 7cm from the subject, twice the working distance relative to this new SEL FE design.

B&H purchase link (Affiliate)

Look – you don’t read Photoclubalpha to get sales blurb. You come here to find stuff out which you won’t read anywhere else and may not previously have been aware of. It may be difficult. But it will help!

– David Kilpatrick

Lenses - E mount, NEX System

Sony 28-75mm f/2.8 SAM on mirrorless FF

Posted on April 15, 2016 By David Kilpatrick

With the 24-70mm f/2.8 new Sony GM FE lens selling for £1799 (UK) and the A-mount version two 24-70mm f/2.8 for a full £100 more, the cost of a basic mid-range zoom to use with a camera like the A7RII remains very high. There are good arguments to be happy with the 24-70mm f/4 FE zoom, or even the 28-70mm f/3.5-5.6 though that is best limited to use on the A7 (24 megapixel) and A7S (12 megapixel) bodies rather than the A7R (36 megapixel) or A7RII (42 megapixel).

Of course there are good lens adaptors out there and 24-70mm f/2.8 lenses from Canon, Tamron or Sigma with ultrasonic focus drive in Canon EF mount offer one solution. The original 24-70mm f/2.8 for A-mount with its SSM motor of this type can also be found for a fair price. But there’s one lens which I sold after my A7R arrived, mostly because I was parting company with my full-frame A-mount body survivors. It’s the Tamron-based but Sony revised SAL 28-75mm f/2.8 SAM.

Although I did have an LA-EA3 adaptor to use SSM and SAM drive A-mount lenses on the E-mount bodies, the 28-75mm didn’t really work very well on the A7R so it remained on my A99 or A900. I made a few tests and saw that it was certainly OK on 36 megapixels, though even on the 24 megapixel A99 where it played nicely with the AF system it had slightly soft corners when used wide open. They were not any softer than the 24-70mm f/2.8 Carl Zeiss of that time and in some ways the lens was better behaved.

The first thing to do was to fix this lens to the LA-EA3 creating an FE lens unit. Imagine the adaptor is just part of the lens (that’s pretty much how Sony makes many lenses for E-mount anyway). The total unit measures up at 115mm long including the adaptor, and 75mm diameter taking 67mm filters. The lens itself weighs only 565g, the combo weighs 683g with adaptor and lens hood. That compares with the new GM lens at 136mm long and 88mm diameter using 82mm filters and weighing 886g. As I already have a 16-35mm f/4 CZ which covers the 24mm requirement well, the 28-75mm range is just as useful to me as 24-70mm.

While the 28-75mm SAM activates PDAF and multiple AF points, it’s not the full works with tracking and Eye-AF. But it’s also not as noisy as some reviews imply. It’s much quieter than the 85mm f/2.8 SAM, and silent compared to the grinding focus of the 30mm DT SAM macro. Startup is fast, with the lens initialising quicker than FE mount stabilised zooms. The aperture actuation is slicker than with body-drive SAL lenses on the LA-EA4, and quieter. Focus is fast and the only downside is the rotating focus ring which does not support DMF or over-ride on the fly, or auto manual focus magnification. Manual focus requires you to set it on the lens and the body, and whatever you are doing, you need to avoid either turning the focus ring when there is any resistance, or blocking it from turning during AF. It’s a bit vulnerable and the direction of focus is the opposite to normal Sony/Minolta design. The zoom ring which locks at 28mm only operates in the normal direction.

So, what you get with the LA-EA3+28-75mm SAM is basic but fully controlled and communicating, EXIF accurate with profile correctly invoked. It will track with continuous focus and during movies, though slightly noisy for in-camera sound recording; it seems to do so when some SSM lenses, like the 24mm f/2 CZ, don’t play.

As for optical quality, it’s still a 14-year-old Tamron in disguise, but it can match up to 42 megapixels centrally across its full range. The performance over the APS-C image area is superb, even wide open at all focal lengths, with just a hint of misty aberrations slightly masking a super-sharp result on axis. On full frame, a marked ‘cap shape’ deviation from flat field towards the extremes causes strong softening on flat subjects and landscapes at 28mm and is not entirely removed at longer lengths. You would not want to use this at 50mm and f/2.8 if you had a faster 50mm you could fit and stop down to f/2.8. On real three-dimensional subjects at typical working apertures between f/4 and f/11 it can be extremely sharp. The respectable 38cm close focus and 0.22X subject scale (not as good as the new Sony GM 24-70mm) reveal microscopic detail on the A7RII at f/5.6. The shot below is at the closest AF on the large water drop in the centre, at 75mm and f/5.6 – you can see the bokeh is very acceptable, not complex or ‘nervous’ which it tends to be when used wide open for more distant subjects with a slightly defocused background.

A 100% crop from th A7RII file (converted from raw ISO 500 14-bit, without any sharpening for web and with minimal NR) gives an idea how good this lens is and also just how little depth of field you’re ever going to see from a 42 megapixel full frame image used this way!

It would hardly be worth buying an LA-EA3 and a new 28-75mm just to save about £1000 over the GM 24-70mm. If you already own an LA-EA3 and you can find a cut price or good used 28-75mm go for it. The way its aperture works means you’ll get very fast low light focus and minimal shutter lag (but you do need a mark II A7 series body to get the best functioning).

The zoom action is a real pleasure to use, very light but positive, and the overall build and feel of the lens will not disappoint. It also seems to get just the right response from the in-body stabilisation of the A7RII. Sure, 67mm filters may be smaller than many midrange zooms require, but I will either have to use a stepping ring or get a couple of new filters – not cheap, for the quality needed to maintain the lens performance. Also, it’s not weatherproofed.

Here’s a quick set of three hand held (with SSI) comparisons at 28mm – f/2.8, f/5.6 and f/9. I’ve loaded these up at full size so they should open the original Level 10 sRGB JPEG when clicked. The focus in on the foreground railing spike and the fine spider web gives the best idea of how the resolution and contrast of the lens improve from wide open. It’s clearly resolved at f/2.8 but with a gentle ‘glow’ at pixel level. First image – f/2.8.

Second image – f/5.6. If you download all three images and load them into Photoshop, it’s interesting to switch between tabs and see the depth of field change.

The third image is at f/9 and here the ISO is high at 2000. The A7RII can produce great results up to 3200 but I might not choose to have this at 2000. Even so, the sharpness can be judged without problems as the noise doesn’t have much effect on fine detail with current Sony sensors and processing. It always shows more in defocused, smooth areas.

Because I use other lenses – such as the 24-105mm f/3.5-4.5 Sony and 50mm f/2.8 Macro Sony on LA-EA4, 40mm f/2.8 Canon STM, Sony FE 28mm f/2, 16-35mm CZ f/4 and also the unrivalled 24-240mm FE zoom I have many choices overlapping the range of this lens. I remember that for landscape work on the A900 it was hard to beat. Here’s one of my images from that combination, using a 6 second exposure at 40mm focal length, f/8 and ISO 100 with a variable ND filter. With the restrictions on tripod position given by the location, the zoom range of 28-75mm proved just right for a range of studies.

With this lens arriving during a period (for my corner of the UK) of sustained white skies and drizzling rain, it’s not been out and about much. One thing it has done is to focus very well in dim room lighting on my sofa companions –

And, for those who don’t think f/4 is wide enough and desperately want 55mm f/1.8 or f/0.95 lenses, this is at 55mm f/2.8 and of course when the iris of the eye is sharp the fur around it is not and Willow’s nose is blurred. Once again, despite correction for tungsten light at the extreme limit of Adobe Camera Raw, and using ISO 3200, it’s pretty amazing what the A7RII can do seen at 100% (below).

But this super-shallow depth of field is what happens at 42 megapixels. Depth of field used to be worked out based on a 10 x 8″ print held in your hand, not a 6 x 4ft image viewed through the ‘window’ of a screen. Of course for social media you do indeed need very wide apertures because when your pictures are mostly viewed on smartphones, it’s like looking at a contact print from a Vest Pocket Kodak…

To support Photoclubalpha, subscribe to f2 Cameracraft (it’s probably the only photo mag edited by two long-standing Sony system users, myself and Gary Friedman).

– David Kilpatrick

You can find deals for the Sony SAL 28-75mm f/2.8 SAM A-mount lens at B&H Photographic, Wex Photographic for the UK, or Amazon Sony SAL2875 Alpha 28-75mm F2.8 Standard Zoom Lens

DK's ramblings, Equipment Reviews, Lenses - Alpha Mount, NEX System

Mixed up market – specced up compacts, dumbed down DSLRs

Posted on June 8, 2012 By David Kilpatrick

Canon has pulled off another change in the direction of DSLR development with the EOS 650D, but in the process seem to have accepted a blurring of the boundaries between consumer cameras and enthusiast gear. Sony has finally bowed to pressure and put raw image processing back into a compact, using a larger than normal sensor, doing the same in reverse.

To explain, neither of these cameras belong within Photoclubalpha – we don’t usually report on Sony Cyber-shot compacts, equally rarely on Canon’s latest competitor to the A57. But these two cameras are waymarkers. They show us where two strands of development are heading, and how they are converging.

Canon EOS 650D

650D with new 18-135mm STM lens, required stepper-motor technology for off-sensor video auto focus

The new points about the 650D (also known as the EOS Rebel T4i for that least rebellious of areas, the USA) are simple enough. It’s yet another 18 megapixel APS-C model in the series 500/550/600 rather than the more professional 50/60/7 body form. Maximum frame rate is 5fps. It has full 1080p HD, but only at 30fps maximum (720/60p) with a 5.5MB/sec data rate. Unlike previous models, this one can focus during video shooting, and may well do it better than a NEX.

It has a conventional 9-cross point phase detect AF module much improved over earlier versions, included a central double-cross f/2.8 sensitive point. When shooting video, hybrid AF combines normal wide area contrast-detection with a similar centrally located phase-detect pixel arrangement that offers much faster locking on before the CD takes over to fine tune and track moving subjects or faces.

No visible signs on the CMOS – but that sensor had a phase-detect central zone

So there are two AF systems, one of which remains live for video. To work properly it needs a new type of lens motor, called STM. This stepping motor appears to be not unlike the NEX system lenses, offering the necessary control for AF during video with silent action. Just two lenses initially have it, a pancake EF 40mm f/2.8 STM and a general purpose stabilised EF-S 18-135mm f/3.5-5.6 IS STM. If you know your Canon system terminology, you’ll spot that the 40mm is compatible with full frame DSLRs it’s not just an odd 64mm equivalent for the APS-C models.

With other lenses, the implication from Canon is that AF during movie shooting will not work. That includes the cheapest kit option, the 18-55mm. No matter what type of USM or micromotor AF drive. If you want video with AF, you need the new STM lenses.

The Canon phase-detect on sensor is purely a central patch, not an overall function like Nikon’s 1 system 71-point PD. But, like consumer cameras, Canon adds touch screen functions to the 650D. This is a response to consumer demand. You can still operate the camera with the rear screen completely reversed. I have to admit that the first thing I did with the NEX-5n was to disable the touch screen function, and never use it.

For a Canon, the 650D has a surprisingly limited battery range, as low as 180 shots per charge if live view, flash and image review functions are used in their worst-case scenario.

The Sony Cyber-shot RX100

A neat metal bodied almost Samsung-like compact, the RX100 has an 8.8 x 13.2mm sensor, the 1/1 or one-inch ‘1’ format already used by Nikon. It offers a stabilised Carl Zeiss 28-100mm equivalent lens which is very fast (f/1.8 at the wide end, f/4.9 tele) and may be of enthusiast-pro quality, and a 3″ rear screen where daylight viewing brightness is enhanced using white pixels as well as RGB.

The RX100 offers full HD movies at 28M bitrate – 1080/60p equal to NEX and Alpha. It also seems to get reasonable life from a small battery, 330 shots or 165 minutes of movie, and to have a decent 2.5fps conventional fps plus the popular Sony 10fps speed piority mode.

For most of us, the really big news is that for the first time since classic bridge camera models like the F-828 Sony has decided to provide raw image capture in a pocketable compact. No doubt the success of the Fuji X10, Canon G1X and others has been observed. It is fair to say that Sony could have put raw capture into far more compacts – they all have it hidden away away, an ability carefully locked out by firmware.

To date, we have felt that Sony wanted to protect the NEX and Alpha markets at any cost by omitting raw even from the best Cyber-shot models. The RX100 changes this perception. It leaves the expensive semi-pro hybrid video and still camera, the NEX VG-10, looking a bit sad with its JPEG-only still capture. After all, if compact owners do indeed want raw, surely VG-10 owners would be expected to want no less?

And that sensor is 20 megapixels. It’s twice the pixel count of the Nikon 1. There was a time something like happened in the past. Nikon made a camera called the D1 (then D1X) which had a 5-megapixel sensor, and then a sort of firmware and processing fix to make it halfway like a 10 megapixel sensor. It was revealed that the ‘rectangular pixels’ of the D1 were actually two pixels in a strip. When a different RGB topping and readout was applied to the same exact silicon, it became the Sony 10 megapixel sensor we saw in the Alpha 100 (and the Nikon D200). Nothing like that could possibly have happened with a Sony 20 megapixel sensor to make a Nikon 10 megapixel sensor, even though they both share the same unusual 8.8 x 13.2mm size.

And even though Nikon uses a whole stack of pixels on that sensor to perform phase-detection AF without any apparent loss of those pixels to the image – spread out over 71 points across the entire frame too. There’s no way, is there, they could ever have based that 10 megapixel PD-AF capable sensor on a Sony 20 megapixel original.

– David Kilpatrick

Cameras (DSLR), News