Sony announced two potentially very exciting and innovative dSLR cropped sensor cameras today, in a setting where the cropped sensor dSLRs have become rather ho hum and boring – evolutionary rather than revolutionary and limited by the constraints imposed by their optical viewfinder.
The two dSLRs – the alpha A33 and A55 introduce a wonderful new potentially revolutionary technology made possible primarily by the advance in electronic viewfinder (EVF) technology which has become so good, it is better than many cropped sensor dSLR pentamirror optical viewfinders.
By introducing an EVF into a dSLR, it allowed Sony to replace the moving Single Lens Reflex (SLR) mirror with a fixed translucent mirror (hence the new term Single Lens Translucent (SLT) cameras).
This fixed mirror deflects approximately 1/3rd of the light upwards to a bank of phase contrast AF sensors and this allows for a number of revolutionary possibilities:
- fast, predictive, full time phase contrast AF potentially better than ANY dSLR AF as there is no mirror blackout time and thus the camera’s computers can keep assessing the scene and subject to continuously compute AF, even in movie mode!
- no need to move the mirror up to achieve Live View magnified view manual focus.
- faster burst rates as there is no mirror to continuously move up and down, and the potentially better AF system should allow more consistently in-focus images at higher burst rates – an issue which plagued the Canon 1D Mark III in particular!
- longer camera life as less moving parts
- quieter shutter release as no mirror slap noise
- no mirror vibrations to blur the image and thus no need to worry about mirror lock up procedures.
- option for use of contrast detect AF concurrently to allow Face Detection, subject tracking and better low light AF
- if the mirror actually sealed the mirror box area, it could help to reduce dust on the sensor where it is more evident in images.
- if every bit of light was important, theoretically, you could move the mirror out of the way and use it as a mirrorless camera.
- the lack of moving mirror makes this a much, much simpler camera to use as there is no need to get confused going into Live View as you are always in Live View!
There is of course, a cost for having a fixed mirror:
- no optical viewfinder – as good as current EVF’s are, they are no match for a full frame pentaprism optical viewfinder.
- 1/3rd light loss means, in effect, you have to increase your ISO to compensate – presumably Sony have “corrected” the ISO calibration to take this light loss into account so that you can use the same settings between different types of cameras still.
- the mirror adds yet another piece of glass to get in the way of your optical path with potential for dust, etc to adversely effect your images
What did Sony give us?
Perhaps they rushed the development to market, perhaps they just don’t care and are cynical about consumers who may be fooled into buying on specs without checking out the gotchas – why couldn’t they fix up these few important issues which would then make this THE most brilliant consumer cropped sensor dSLR-sized camera?
They have given us the A55 with an amazing spec of 10fps with a very reasonable buffer of 19 frames in RAW mode – that’s as fast as the Nikon D3s, Canon 1D Mark III and IV flagship dSLR models, BUT, according to dpreview.com:
- you can’t view anything through the EVF for 20secs and cannot fully use the camera for 50secs after this burst
- the live view is not maintained through the burst, instead you get a prior image view so you have to guess where to aim the camera during a burst – to be fair, this is a problem with all current mirror-less cameras.
- disappointingly, continuous AF is inaccurate – “We have found that when presented with fast moving subjects (we shot a range of subjects, including cyclists on a track), focus accuracy is far from 100%. In 10fps mode it is clear that the A55’s AF system is simply unable to predict subject position accurately when presented with fast-moving subjects at relatively close range, and in a typical sequence of images of cyclists on a track, whilst the zone of focus shifts from frame to frame, it is almost always slightly behind the intended subject.”
- even worse, if you want continuous AF in 10fps mode, you are forced to use auto exposure mode – in tricky lighting such as is found in many sporting events, this is a big compromise.
- thus, while it may have a 10fps spec, the current implementation in this camera is not adequate for most sports photography which is a real pity indeed – perhaps wait for next version once they have ironed out some of these bugs.
Potentially the best movie camera with interchangeable lenses you can get for the money, but then they crippled it:
- AVCHD 1080i HD video but only at 59.94 fps derived from 29.97 fps
- no 24fps filmic mode which is what many videographers demand in a camera these days
- no 720p HD video for when you want to take up less storage space
- a weird 1440×1080 29.97fps or 25fps motionjpeg mode and no 720p motion jpeg mode
- AVCHD is a very ordinary 17Mbps compression rate – same as the Panasonic GH-1 but at least via firmware hack you can now get to much higher quality with the GH-1 – even up to 50Mbps!
- Motion jpeg is a poor 12Mbps quality
- built-in microphone is only mono, but at least they do give a stereo mic input jack
- cannot disable automatic audio level control – but then you can’t on most other cameras either!
- no manual control over exposure mode – that is inexcusable!
- unlike the beautiful HD video optimised lens supplied by Panasonic, the larger Sony lenses produce noise during AF which will be picked up by the internal microphone – perhaps Sony will address this with future lens releases … or not.
- single AF is not available – either continuous AF or manual focus
- the potentially very shallow depth of field due to the larger sensor means continuous AF may not be as desirable as you think.
- movie image quality suffers from rolling shutter issues
Exciting concept with a LOT of future potential, but as with many Sony products such as the NEX cameras and their latest NEX-compatible camcorder, the current implementation is full of so many compromises that I would rather wait until they come up with a photographer’s camera or a videographers camcorder.
Despite these negative comments, if you do not need 10fps for sports and the movie capabilities are adequate, then, to me, these are perhaps the best consumer level cropped sensor cameras having the best of both dSLR and mirror-less camera qualities with little downside other than size and weight of the camera-lens kit. This is the future of dSLRs!
Many people will also be excited that the a55 has embedded GPS to tag your images – hopefully this does not drain the batteries too much, and I suspect most new dSLRs in 2011 will have this technology incorporated too.
Why haven’t Sony seen the light and made the flip out LCD come out sideways instead of UNDER the camera when you want to do self-portrait style with the camera on a tripod which would obscure the LCD screen?
Why do Sony persist with their proprietary memory cards – even Olympus has seen the light and replaced their proprietary xD cards with SD cards in their Pen cameras.
Why do Sony persist with their proprietary hot shoe which means no other generic flash can be mounted and used even in manual mode without a special adapter? No other camera manufacturer has this limitation!
Now we just have to wait and see what Olympus are up to – they are the main manufacturer likely to produce a similar concept, but I suspect they will take it further to allow both Micro Four Thirds and Four Thirds lenses to be used, and perhaps add an AF adapter to allow AF of legacy Olympus OM lenses.
Panasonic filed a patent for an adapter which does what the Sony camera mirror does but in a slightly different manner – the adapter containing a pellicle mirror which reflects light to phase detect AF sensors and would thus enable phase contrast AF for Micro Four Thirds cameras.
Please Canon, now I want a full frame dSLR with a fixed mirror to make full use of all my expensive tilt-shift Canon lenses! I am sick of having to put the mirror up and down every time I go into Live preview to access magnified manual focus which is critical when using tilt shift lenses. And, Canon, while you are at it, put the image stabilisation into the body (as with the Sony alphas) as well as the lenses so we can choose which to use as needed.
In reality, I doubt that any of the other manufacturers will come close to the ease of use and feature set of the A55 within the next 6 months, although any manufacturer could just replace their optical viewfinder with a Toshiba EVF, fixed the mirror, and then you have a camera approaching the A55 – they would just need to add Auto HDR, GPS, sweep panoroma modes, built-in IS, etc and they will be there.
The Sony VG10 – NEX-based camcorder camera – a similarly crippled compromise:
The recently announced Sony VG-10 interchangeable lens camcorder based on Sony’s new NEX mirror-less camera system had the potential to be ground breaking but instead, Sony chose to offer a camcorder that is severely compromised as a camcorder converged with a severely crippled mirror-less camera.
- nice to hold but poor user interface – must use LCD screen and not the EVF if you wish to adjust any controls
- ability to use almost any lens ever made albeit in manual focus only
- nice dedicated 10x zoom lens the 18-200mm f/3.5-6.3 with optical stabilisation
- nice stereo microphone designed for spatial stereo
- powered mini jack for external microphones but cannot turn off auto gain control and no level meters
- a nice 24Mbps AVCHD 1080i video but no 24fps “film” mode, and the 60fps is really a wrapper around native 29.97fps.
- no over-exposure warning signals AT ALL – no flashing highlights, no Zebras, histogram does not function in exposure compensation
- no focus confirmation – no focus confirmation light, no peaking, and even worse, no magnified view manual focus assist!
- nice 14mp APS-C but why, oh why did they disable RAW capture? RAW mode is critical for many- I would never buy a digital camera without RAW mode – even 5 years ago! You can’t always get white balance right at the scene.
- no magnified view manual focus assist! I would never buy a digital camera without magnified view manual focus assist.
- histogram does not function in exposure compensation
- poor ergomics and user interface
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