The Alpha 580 – a three-way view
Image quality
The final question about the Alpha 580 (more so than the 560) is whether or not it has identical image quality to the A55, or to rival makes using a Sony-derived sensor of the same basic type – the Nikon D7000 and Pentax K-5. I can make some answer on the A55 front, I can’t comment on the other two makes. When the A580 first arrived, no raw conversion was available through Adobe (Lightroom and ACR) which is my standard workflow. Using a batch processor, the identity of my first A580 files was changed so that Adobe products saw them as A55 raws. Later, an update was issued. Comparing the results, they are identical which probably means Adobe has done much the same thing – simply updated the tables in the converter to treat the A580 the same as the A55.
The strong contrast curve in Adobe Camera Raw 6.3 restored this ISO 200 shot to a crisp look
This leaves the A580 raw images looking slightly softer than the A55. The light-loss in the A55 is not compensated for by just lifting the gain on the sensor, that much is clear from other specifications (including the metering EV range). It’s achieved using a different conversion curve after the data leaves the A to D converters which are part of the sensor itself. ISO speed in digital cameras is not calculated the same way this it is for film, even if DxO in their tests use a noise threshold method which is not far removed from ‘0.1D above fog’. In real life it’s assigned on the basis of midtone density, the light value and exposure settings which produce 128/128/128 RGB from a 12% reflectance grey target.
The conversion curve of the A55 would seem to compensate for the 2/3rds of a stop or so light loss from the Translucent mirror, leaving the deep shadows without much lift but increasing brightness and contrast in the midtones while preserving highlight detail. This is confirmed by raw conversions which have sudden descent into black at the shadow end, and the type of slightly enhanced colour saturation and sharpness given by a steeper midtone section of the characteristic curve. This can also create higher resolution readings, as these are based on contrast.
A580 JPEGs are processed in camera to produce as much the same look as other Sony models as possible. Lens choice is likely to have more real effect on results than body choice, though, especially at such a high sensor resolution. With the A580, our Sigma 18-250mm proves more the good enough at short to medium settings but begins to run out of resolution above 150mm and looks soft by 250mm. The 16-80mm CZ Sony lens really comes into its own, as it does on the A55. One most noticeable thing, shooting with several cameras and lenses, is how much higher the contrast is from the CZ at 16mm on A55 or A580 compared to the contrast of the E-mount 16mm pancake lens on NEX.
The A580 appears to be handled by some raw converters almost as if it was an A55. It doesn’t have the same contrast boost in camera and therefore the results look just a touch flatter and more neutral, and not as ‘crisp’. I speculated in the A55 report that the configuration of the AF module with the simple SLT design might be responsible for improved focus accuracy. Using Phase Detect AF in Focus Check LV mode on the A580, then magnifying the result, tells me the new 15-sensor AF module may be just as much a reason. The A580, like the A55, has a high ‘spot on AF’ success rate with a wide range of lenses.
My conclusion is that the A580 is not ‘less sharp’ than the A55, it just has a different tone curve when processed identically from raw and shows less detail contrast. That can be corrected by changing the raw processing parameters – adjusting Brightness and Contrast, and the selected tone curve, in ACR/Lightroom. The JPEG engine is pretty crude (come back ‘Extra Fine’ KM quality please!) and any reviews judging the camera on JPEGs alone are incomplete.
When I can shoot in extremely low light, hand holding 1/8th at f/9 with the 16-80mm at 16mm, and get great colours and no noise at ISO 1600, I find it hard to fault the performance of the Alpha system (SSS) or the 580. Click the image for our subscriber-only link page, to download and view the original full size JPEG conversion
As for the high ISO issue, Sony’s policy of retaining as much colour information as possible for settings over ISO 1600 contrasts with Nikon’s deliberate reduction of the colour saturation and discrimination. Nikon perhaps has a better understanding of how human vision works, with the monochrome-sending rods taking over from the colour-sensing cones in low light. We perceive dusk and night colours as desaturated, so there’s no need for a camera to try to capture high levels of colour at higher ISOs.
The full picture at ISO 3200 – auto exposure with the 580 has proved very accurate in unusual conditions. 1/80th at f/4 with the 28mm f/2 Minolta RS lens, hand held with stabilisation
Look at this in-camera JPEG and you would perhaps agree that ISO 3200 quality misses the mark. But Sony spend exactly $5 a year on JPEG quality R&D – or so their track record so far suggests. Most likely, they are using fast dirty compression to enable fast fast shooting
Conversion using ACR 6.3 tells a different story, using default sharpness and Luminance NR 25/50detail plus Chroma NR 25/50detail
Sony does not agree. Colour values are not reduced, and that produces more visible colour noise. What you lose in low light is gained in bright conditions when high ISOs are used for action photography, with the Sony image typically looking normal and Nikon’s results muted. Unless Sony follows Nikon’s example, high ISO shots will always look more noisy and coarser than Nikon because retaining colour values means using a larger sample of RGGB sensel values to create each RGB image pixel.
I am happy with either approach, partly because I hardly ever need speeds above ISO 1600 anyway. And, at 1600 or under using Auto ISO, the 580 creates such fine grain and high sharpness I can use it freely for any type of work including stock library submissions. My ISO 1600 shots from the 580 look as good as ISO 200 shots from five years ago.
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
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
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
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.
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
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.
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.
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.
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.
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?
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.
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.
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.
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.
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.