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The Alpha 580 – a three-way view

Add glass and mix

I’m almost ready to provide a list of how the three finder modes work, and to add this a reference to the Sony Alpha NEX E-mount system and its LA-EA1 lens adaptor. First you need to know about different lens types.

The basic Alpha lensmount, from 1985 onwards, is in-body motor driven focus. Everyone calls this ‘screw drive’ and who am I to argue with such an inaccurate term? We all understand it, so ‘screw drive’ is what I’ll call these lenses.

The Alpha system jumped in early 2000s to a supersonic motor drive, built in to the lens, controlled electronically and supplied with battery power from the body. Only two Minolta lenses ever had this, the 300mm f/2.8 G SSM and the 70-200mm f/2.8 G SSM, by the time Sony took over in 2006. SSM was introduced to compete with the speed and silent operation of Canon’s USM and Nikon’s new AF-S, and the lens choice reveals why – it made a big difference in sports and action photography with large telephotos and zooms which were difficult to drive from the in-body motor.

The SAL 70-200mm f/2.8 G SSM – inherited from Minolta – offers the best type of focus compatibility with the A580, SSM supersonic motor drive

It was never a matter of the body motor being too weak; sometimes, it was too powerful or too fast. The first generation of screw drive lenses needed a lot of power. Later ‘HS’ high speed variants were easier to drive. Then Minolta made the in-body motors even more powerful to help handle the increased demand for closer focusing, fewer ‘screw’ rotations, and even more complex zooms… upon which some of the HS lenses ended up overdriven, focusing too fast for accuracy or even hitting the end-stop with gear train crash results. So SSM was actually a body independent solution with the motor precisely matched to the focus action required, sometimes slower than older screw-drive but always smoother and finer in adjustment.

Sony overlooked the need to convert all lenses to SSM as soon as possible. Their new Carl Zeiss 16-80mm, their own 16-105mm, even the CZ 85mm replacement were still screw drive. They obviously did not foresee the HD video revolution in DSLRs, despite a long history of both the Sony and Minolta teams being almost prescient in their innovations from the 1980s on. Catch-up demanded a solution and their found this by going back to Canon’s early days and putting ordinary micro motors into lenses – the SAM (Smooth Auto Focus) range of ‘easy choice’ budget optics.

These Chinese made plastic bodied lenses are optical surprises, far better than their feel indicates. Mechanically, the SAM motor is anything but ‘smooth’; it can be damaged if you use the body switch to change from AF and MF and then try to turn the focus ring, it is vital to move the AF/M switch on the lens instead. They make noises ranging from little buzzes to prolonged grinding. But Sony did not mean ‘silent’ or ‘silky’ when they said smooth. They just meant capable of very fine adjustments under full control, like the SSM lenses without the same cost. And that is needed for the A580/560 with contrast detect autofocus in live view mode, and hopefully for real-time AF during video shooting in future cameras.

The same function also enables use of the SSM/SAM lenses on the NEX with LA-AE1 adaptor.

Beyond the Sony range, there are third party lenses which have screw drive, and some which have ultrasonic motors (Sigma HSM, Tamron just beginning to roll out) or micromotors (Tamron, including models rebranded as Sony). While the motors may be similar the protocols within the lenses don’t appear to match. I have been unable to get reliable CDAF with third party lense; it is best to select Phase Detect focus in Focus Check LV mode via Camera Menu 2. This then has to be switched back on the same way if you want to use it with genuine SAM/SSM lenses.

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19 comments to The Alpha 580 – a three-way view

  • OldNoob

    David,
    Thank you for the review and helping me understand my camera better.
    I do have many questions,, but i will only ask one.
    Which Auto-focus mode do you feel is most accurate when using Minolta Primes such as the 50mm f/1.7?
    The reason i ask is from experience with terrible back-focusing when using a a560 with my Minolta lenses ,, which are tack sharp on my a100.
    After reading your review i see it may have just been a matter of me not understanding the camera and the different focus modes.
    To be honest ,, i dont really care about the Live view, i use the optical viewfinder for everything. Yeah, im that old.
    Anyway, thanks again.

    • I always use single shot, centre AF point. The A580 has not proved immune to FF/BF issues though and I am afraid it tends to go with that type of AF sensor despite continued improvements. I have only recently started using the 50mm f/1.4 lens after getting the A77, it’s the only camera I have owned so far which focuses it accurately.

      David

  • admin

    The Sigma is a much better lens. Since you have a choice between OS and SSS there really isn’t an issue. The Sigma is so much better at the long end of the range, optically.

    David

  • william9

    Thanks David. Now that I’ve gotten an a55, I’ve been thinking of selling my Tamron 18-250 and getting the Sigma 18-250, for the potential of better IQ and less distortion, as well as the OS for video. Your review comments stopped me for the moment. From your reviews, it sounds like you’d recommend this kind of switch (it’s affordable), so long as the video would be in the 18-100 range or so. Am I correct in that?

    BTW – do you still find that you get better IQ at 200-250mm from the Sigma compared to the Tamron? Are they pretty much equal from 18-150? Thanks again for your advice.

    William

  • admin

    I did not use a tripod; at times, I used a binocular support (a monopod with a sort of Y-shape at the top) because I was so cold I could not hold the camera still at all. The stabilisation on the Sigma 18-250mm seems fine for movies up to a middle setting, maybe 100-150mm. At a certain point (always at 250mm) it becomes impossible to pan or move the camera without the distorted effect. I think this is due to the type of stabilisation used in that lens, and some other Sigma lenses might behave differently. What I do know for sure is that the in-body SSS does not produce the same effect.

  • william9

    David,

    I was struck by your comment about video and the Sigma OS system: “Don’t think that in-lens OS will be your solution to longer clip lengths before overheating shuts the system down. It doesn’t agree with the movie mode, in contrast to SS which works well.”

    Q: Did you use a tripod when making the video on YouTube? If so, could the “ripple” effect due to the OS stabilizer being on and the lens trying to stabilize something that is already still — the same kind of difficulty as leaving the SSS on when using a tripod?

    Is there any reason to get a Sigma OS lens for a55 or a580 video — or is it always best just to go with SSS and a steady hand?

    Thanks, William

  • LEdgars

    In terms of camera handling I would rate Minolta 7D as best camera made by Minolta/Sony. Suppose A700 and A900 also were designed by Minolta, but ‘improved’ by Sony and both are already one step down.

  • gwbuffalo

    The D-lens distance encoder is great for ADI calculations, and in that case focus produces a distance measurement rather than the other way around. But the D encoders are mechanical, and are too coarse to allow the camera to finely control focus motor speed for silky smooth contrast AF.

    I feel sure the encoder in the E-mount lenses is a high resolution encoder (probably optical) for that reason. Since contrast AF doesn’t really care about distance, I’m pretty sure the LA-EA1 and Alpha cams don’t even use the D encoders.

    With much less mechanical backlash (gear slop) than body-driven lenses, the SAM and SSM lenses contrast focus smoother and quieter (and the LA-EA1 with not drive motor can only focus with them anyway). But E-mount lenses will always contrast focus much better than any of them because there is precise feedback of focus group position and speed to the camera.

  • gwbuffalo

    Excellent article! The best ever explanation of the three viewing systems in use on these newest Alphas.

    One thing regarding the suitability of SSM and SAM lenses for contrast detection AF is the lack of a focus group position encoder in the 8-pin A-mount lens system.

    The E-mount lens system is most suitable for contrast detect AF not just because the focus motor is smooth, but because the control system has knowledge of the exact position of the focus group.

    I believe that is the purpose of the extra 2 pins on the E-mount lenses. It is the A and B phase of an electronic position encoder on the focus group.

    Such an encoder allows the control system to move the focus group very precisely in executing the contrast AF scheme. All A-mount lenses lack this encoder (not needed for phase detect AF). A side benefit of the encoder is the camera body can enter manual focus check magnification automatically whenever the focus ring moves the group.

    • admin

      The D-lens specification is supposed to report a fairly accurate focused distance and the initialisation of the A-mount lens, on startup, has always included a ‘focus range check and park’ process. We need to wait and see how things develop. Pentax devised a very good way to get single shot CDAF with any lens, including screw drive – a simple process by which the camera does a ‘big’ focus range check, maps the result; homes in on the approximate position for sharpness, and does a second smaller sweep around around this; then it moves to the detected peak contrast position and if necessary does a tiny final shuffle; and locks. I don’t think the story is over yet.

      There are two obvious options open to camera designers. One is very simple – detect focus from the focusing screen in an SLR design. Optical devices like the split image RF or microprism create phase contrast in a form the eye can see, and what the eye can see can also be detected by a sensor. The second option is go down the Contax N body route, and build a fine focus mechanism into the sensor carriage – have a sensor which can move forward of backward over a small but functional range such as 3mm. Used with a manually focused lens this could allow enough video focus adjustment with shorter focal length (below 100mm) lenses to enable video CDAF.

  • George

    Now that you have reviewed extensively both the Alpha 55 and the Alpha 580 which would you choose if you needed only one camera for family and vacation shots, no studio?

    • admin

      Alpha 55. GPS, eye level video shooting, autofocus during video, quiet operation, smaller, lighter, EVF is great in low light.

  • The 2s timer for MLU would not work for me. So often, I raise the mirror and wait for the right moment, perhaps waiting for the wind to drop or for someone to move into/out of frame.

    Thanks for a couple of really interesting reviews – this one and the A55.

  • admin

    With all the latest Sony models – NEX, SLT, 560, 580 – you do not see image noise in typical shooting conditions until ISO 3200, provided you process the raw file sensibly. That does not mean cranking up to maximum NR either. I am just going to add a link to a full size version of the antiquey furniture shop interior which is at 1600. I’m sorry these large file download links are restricted to subscribers, but I need to limit bandwidth and obtain subscriptions alike. Anyone with an existing YUDU or Payloadz subscription, or a magazine subscription paid up, can email me [email protected] and I will manually upgrade their Free registration on the site to Normal or Premium status as appropriate.

  • jfirneno

    David:

    That report was extremely interesting (and for me timely). Especially enlightening was your discussion of High ISO low light handling by Sony vis-a-vis Nikon’s strategy. This would explain some of the results I’ve seen on various sites and from photos I’ve received from people working with the A580. The statement you made about ISO 1600 being virtually noise-free caught my attention. My A850 has fairly strong noise from ISO 800 and above (raw, right out of the camera). So I was wondering can you quantify the raw file low light ISO advantage of the A580 over the A850 (or A900) in terms of stops? I promise this will be my last low light question.

    Regards
    John

  • I would figure that the 2s timer would be enough to tame most vibrations, even with FCLV’s double-dip of the mirror. Of course, once you nail the focus, you could leave FCLV, wait a few extra seconds, then trip the shutter. Yes, it’s not as good as having the a900’s multi-fire MLU mode, but I’d say it’d get the job done for 99.9% of the people who relied on 2s timer before.

  • admin

    Bingo! It’s only a 2 second respite, but in FCLV mode combined with the 2 second selftimer, the mirror lifts for the 2 seconds and the shutter closes – both optical and screen finders are black. Then the shutter fires and the mirror briefly flips to return to FCLV mode.

    This doesn’t work with the wireless remote release, if set to remote and the 2 sec button used, you just get a rapid-bleep 2 sec delay and normal firing. It does work with the wired cable release.

  • admin

    My error – I was thinking about the lack of it in Focus Check LV mode when testing this. I’ve altered the paragraph involved to state this. For me, not having the mirror drop and rise in FCLV mode would be the most important (probably impossible) change. That’s because FCLV is the focus and viewing mode I would use on telescopes, microscopes, macro bellows and similar setups needing zero vibration. Of course I have also been working with the Alpha 900 for two years, and that has a true mirror lockup mode not just a pre-lift.

    But you have given me an idea. I have not tried combining the FCLV mode with 2 second mirror prelift or 10s self timer. I’ll check this out right away and add something to the review.

  • David,

    The a580/560 does have Mirror Lockup in the 2s self timer. It’s right on the Sony specs pages for the cameras.