Sony Alpha a33 and Alpha a55 DSLR's


After two-plus years of claiming they're not going to incorporate video capture into their DSLR product line until they can overcome the limitations of DSLR capture—i.e, no autofocus and viewfinder blackout during video capture—Sony has introduced two compact DSLRs that address both issues.

The Sony Alpha a33 and Sony Alpha a55 are a pair of interchangeable-lens DSLRs that make good use of a couple of interesting camera technologies, including one not seen for a couple of decades, to solve a couple of modern-day DSLR video-capture roadblocks.

The Sony Alpha a33 and Alpha a55 both make full use of Sony Alpha a-Series optics, and the differences between them are the resolving power of their respective APS-C format Exmor HD CMOS imaging sensors and the quality of their video capture—a 16.2Mp sensor and 1080p video in the Alpha a55, and a 14.2Mp sensor and 720p in the Alpha a33.

The first part of Sony's solution to the present day "DSLR-video dilemma" has to do with the mirror assembly, which in the case of the Sony Alpha a33 and Sony Alpha a55 are fixed, translucent mirrors that allow light to pass through them, rather than the mirrors lifting up and out of the way each time a picture is taken. By incorporating what Sony is calling Translucent Mirror Technology into the new cameras, Sony's engineers were able pull off a trifecta of technical goals—continuous autofocus while shooting video, uninterrupted image viewing through the viewfinder when shooting stills (JPEGs and/or RAW) and video and still capture burst rates of up to 7 frames per second in the Alpha a33 and up to 10 frames per second in the Alpha a55, making it the fastest frame-banger to date among current video-enabled DSLRs.

The concept of using a pellicle mirror as a method of increasing frames-per-second burst rates is not a new one. It was used originally in the Canon Pellix SLR in 1965 and last used in Canon's EOS RT film SLR back in 1989, which was capable of firing up to 10 frames per second, which was even more impressive back then, although it's mighty impressive today.

Sony's solution to the autofocus and blackout quandary has been addressed by replacing the pentaprism/pentamirror housings used on traditional DSLRs with a high-res (1,440,000-dot) Tru-Finder electronic viewfinder (EVF), which under bright viewing conditions replicates the viewing experience of an optical viewing system remarkably well. Once the sun goes down, though, the Tru-Finder EVF becomes as noisy as the rest of the lot, at least on the pre-production camera we tooled around with for a few days prior to the official announcement. Nonetheless, the EVFs on the new Sonys, which feature a 60 fps refresh rate, are a huge step forward in terms of clarity than comparable EVF offerings. 

A plus side of the Tru-Finder EVF is that it makes it possible to view the same exposure and scene mode data you'd normally only be able to view on the camera's variable-angle tilt 3" Xtra Fine Live View (921,600-dot) LCD, which can be swiveled 270° horizontally and 180° vertically. It should also be noted that you can view 100% of the total image area on both the LCD and Tru-View eye-level finder.

One particularly handy visual aid you can bring up onto both the Xtra Line Live View LCD and Tru-Finder is a Digital Level Gauge, which while some may find distracting (and they can always turn it off if they do), this user found mighty handy especially when shooting in video mode.

Both the Tru-Finder EVF and Live View Xtra Fine LCD enable you to display histograms and gridlines as well as preview the look of all Scene modes and/or color settings, i.e. exposure compensation, white balance and creative styles in true WYSIWYG fashion when shooting stills or video. The Tru-Finder EVF also allows you to zoom in for critical eyeballing of your pictures, just as you would with the LCD, without having to fend off glare when shooting under bright lighting conditions.

The lack of image blackout made possible by the pellicle mirror system also aids in boosting what is already a very responsive 15-point TTL Phase Detection autofocus system, which performed equally well on our pre-production test camera indoors and out, and that's using the camera's Sony DT 18-55mm/3.5-5.6 SAM kit lens. We would imagine the AF system will prove to be even more responsive when used with any of the faster Sony  AF optics. And like all other Sony Alpha DSLRs, the new cameras work equally well with any older Minolta AF lens you might have knocking around.

In addition to "normal" still shooting, both cameras feature Sony-centric shooting modes that have been incorporated into many of Sony's digicams including Handheld Twilight mode, which enables you to shoot sans tripod in near darkness by capturing six rapidly-captured, ISO-boosted exposures, sampling them and editing the sharpest, best-exposed portions of each into a single, optimized (and surprisingly noise-free) image. Low-light shooters can also take advantage of the camera's Night Portrait and Night View modes, as well as the ability to boost the ISO ratings from a native ISO 100 up to an extended ISO equivalent of 25600.

Even in brighter lighting conditions, Multi Frame NR enables you to go beyond single-frame capture by allowing you to capture six rapid-capture frames and synthesize them into a single optimized image at any ISO rating in order to squeeze every last bit of detail from the shadows and highlight areas.

Additional tone-expanding shooting options include Auto HDR and D-Range Optimizer, and as with all Sony DSLRs, both cameras feature SteadyShot INSIDE image stabilization, which enables sharper imagery with all Sony and Minolta AF lenses.

Sweep Panorama mode is another Sony shooting mode that's been incorporated into the new cameras. This mode captures up to 65 individual images and combines them into a single ultra-wide (12416 x 1856) panoramic image for incredibly dramatic landscapes, architectural and interior imagery.

Switching from stills to video and back is also easy with the new Sonys and is accomplished by simply pressing the One-Touch Movie button, which is located on the top deck, just to the right of the EVF eyepiece. Both cameras also feature built-in stereo mics, which are located on the right and left side of the EVF housing. You have the additional option of using more advanced shoe-mounted mics, which are available from Sony as well as third-party manufacturers. There's also a built-in GPS device in the a55 that automatically tags your photos and videos with coordinates in the EXIF data


Shooting videos in stereo is One-Touch away,
and you have the option of using third-party stereo
mics as well as a built-in GPS receiver in the a55.

Both cameras record images in a choice of sRGB or Adobe RGB, and you can expect to shoot about 330 exposures per charge (of its 7.2V, 1020mAh InfoLITHIUM battery pack, part number NP-FW50), which can be recorded onto Memory Stick PRO, Memory Stick PRO-HG, SD, SDHC, or SDXC memory cards.

Discussion 18

Add new comment

Add comment Cancel

There was some chatter that multiple flash triggering might not work with this model.. 

I wonder about that. 

Im pretty new to all this and I used a Nikon but Im not  a Canon, Nikon, Sony or who ever less they are paying me to shoot with there cameras, I dont understand how people can be so Loyal to a consumer product like they give a crap about you there job is to make money off of who ever. Just do your home work people and find out what works best for what you want to do be it shoot vidio or take pictures. but if your a photograher complaining about video ur in the wrong line of work.

Nice camera! Too bad about the video codec. No native 24p. ;(

No true slomo.

After the hacked GH1 firmware came out earlier this year I would have hoped later offerings would have taken this development into account. This is not quite enough for me to switch from my 7D. Nice to see some competition nonetheless, perhaps someone will hack the firmware and give us the options that will truely let this camera fly. 

Important correction - the a33 has full 1080 AVCHD video, not 720. That was a speculation by the rumour mill that was wrong but has fallen over the threshold in many places.

The differences are the 2mp in the sensor, speed and a smaller buffer - the a33 slows down after a second or so at full speed. The a33 does 7fps only (!), not 10x.

I have had a pre-production a55 unit for a week or so now. The translucent mirror is used to divert vision to a phase detect focus sensor and it is fast. There is no blackout shooting at 10x but there is a short blackout when it writes to buffer. This makes it tricky to shoot football - well Australian football anyway as it doesn't keep stopping like the strange American version. It's hard to shoot a series of short 4-5 shot bursts. Otherwise the shutter is quiet and scary fast.

Most interesting feature - multi-shot noise reduction. Shoot at any speed but at 1600 or 3200 it works well. Takes a burst of 4-5 shots and then blends them to reduce noise. It works well and I left it enabled for indoor work. At lower ISO it seems to improve dynamic range, reducing noise in shadows.

This sensor will receive 30% less light than a traditional DSLR. So, the image engine would adjust the brightness? Any example posted? Which implys we lose 30% ISO speed/quality.

I did have an NEX5 on order. I'm glad Sony were out of stock. Now I've cancelled the Nex in favour of this option.

I was a bit iffy about the EVF factor but the reviews are putting my mind at ease.

On reflection I don't think I could have coped with having to rely on the LCD screen and the inevitable poor lcd readability on a sunny day and trying to overcome it with  the expensive optical viewfinder option of the NEX especially as I have to wear reading spectacles.

The 15% evf magnification and no mirror slap is going to be a great boon, especially after coping with the A350.

The HD Video mode is the icing on the cake.

Can't wait !!!

Mr Weitz, you really need to get a handle on the products you are reviewing.  I nearly fell off my chair when you described the Canon 60D as a radically new camera (ooooh, a windbreak for the microphone)  but dismissed the revolutionary nature of these cameras as saying they had 'a couple of interesting techniqies'. Heck, they aren't even DSLRs, because the mirror doesn't move.  They are DSLTs.  This allows them to be smaller, lighter, and radically better performing in a number of respects.  Here's just a few:

 - 10fps shooting in a $750 camera - you need to drop 5 grand on a competing product to get that. 

- Because the mirror doesn't move, the viewfinder doesn't black out when taking a shot.

- The pellicle mirror splits 30% of the light beam to a dedicated AF sensor.  This means that you get constant  phase-detect (ie fast) autofocus during both still and video shooting.

- The first liveview screen that is fully visible in direct sunlight

-The EVF has had a terrific writeup from everybody who has used it, and in fact most reviewers have admitted to disappointment when going back to OVFs on any crop factor camera

Hopefully the above has at least inspired people to google the a55 and have a look at reviews from people who have actually used the thing, rather than just go on the biased and rather underwhelming B&H review.

Here's where I am confused...

If the viewfinder is now an EVF viewfinder, why is it necessary to have a mirror at all? Wouldn't the EVF show the same image as the LCD panel on the back which comes from the cameras sensor?

This is a camera for girls unless they add an accessory battery grip, so a grown man can hold it properly. Sony just never seems to be able to get it quite right. Shame!

 Very interesting development, the camera is a very different concept from whats available today, with the combination of a fixed mirror and an EVF it should be very appealing, my only doubt is about how much light does reach the sensor, and how this affects the sensibility of it

Cool, but...

Bummer your stuck with sony alpha and minolta lenses.  It's not that those lenses aren't good... you can still do some amazing shallow dof and really good cinematic stuff I'm sure.  But I still think I'm sold on Canon simply for the fact that you can buy/rent lenses that open up to f1.2 which has saved me countless of times in low light.  I wish Sony could have made their cameras compatible with Nikon lenses.  

I think Canon and Nikon still have a corner on most of the market for dslr's because of the quality of their lenses and availability. You can go just about anywhere in the country and find a camera store that will rent you a plethora of lenses, but they're all Canon or Nikon lenses. 

If Sony could get their alpha and Minolta lenses into the hands of the same stores that rent Canon and Nikon then I'd be much more interested in what they've got or at least trying it out.  I'm still excited to see what other people are going to do, just not interested in it for myself for the time being.

Too little, too late.

Just yesterday I switched up from Sony to Nikon and do not intend to look back.

I had read about the new Sony DSLRs on Photography Bay and made up my mind that, if true, I was going over to Nikon.  I do not make movies and do not want to spend money on a camera intended to make movies as the raison d'etre for its technology.  Besides, my son and my brother have been making much better images on their Nikon gear than I have been able to capture on my Sony Alpha.

They have wlecomed me into the Nikon family and congratulated me on getting a 'real camera'!

is it available now on display at B&H so we can get our hands on it? 

I have been struggling with the lack of mirror lock-up in Sony DSLR's for a long time now.  Does this new pellicle mirror make this a moot point?  Please, oh please say yes.

 Cant seem to find it but is there a crop factor with these cameras?

I always thought the pellicle mirror was a great idea, but as I recall it didn't go over too well because the mirror deflected too much light from the film surface, lowering the effective ASA (ISO) of the film.  Hopefully, Sony has solved this problem, which I guess is easier to do digitally. 

I'm confused a bit here - what is the difference between these two cameras and the Sony A560 and A580?

Why no OVF? There is a mirror!