disadvantages of a translucent mirror:
Loss of light. Sony claims 1/3 stop of light. In reality, testing the
A99 vs the D600 in the same controlled environment the A99 exposures
were about 2/3 of a stop darker.
Battery life. As the camera is constantly looking through the sensor,
it's using more battery. The Sony A99 certainly does use more battery,
I found myself getting around 400 shots a charge vs 1,500 on the D600.
It was kind of like owning a D200 again.
Start up time. I'm not really sure start up time with a translucent
mirror needs to be slower than a DSLR, but the A99 is slow to turn on.
Holding it at waist level I could turn the camera on, bring it up to my
eye, and still be waiting for it to turn on. This is bad in combination
with low battery life, because battery consumption dictates turning the
camera off, while start up time demands leaving the camera on, a true
Theoretical advantages of not
Having a histogram in the viewfinder and seeing exposure through the
sensor. That's right, no more "chimping". I hate chimping, but it's a
fact of life when acquiring optimal exposure on a standard DSLR.
Unfortunately, in use I found the histogram in the A99's viewfinder to be center
making it inaccurate for the whole scene,
rendering it useless as I found myself chimping to check exposures on
playback rgb histogram. On landscape shots the sky was often
overexposed but didn't register in the live histogram.
A moving mirror is one of the most complicated, expensive parts of an
SLR. Just look at this
video to see the magic in slow motion. With a translucent,
stationary mirror the Sony A99 should be cheaper to build than a
with an expensive moving mirror yet the A99 is $700 more expensive than
what I'd consider its direct competition; the Nikon D600 and Canon 6D.
Some may feel the A99 is targeted at Nikon's D800 and Canon's 5D, but
they are both too far ahead in build quality for the Sony to compete.
Just look at the consumer oriented mode dial on the A99/6D/D600 models.
Without a mirror to move, it should be easy for the A99 to blow the
competitors out of the water for frame rates, yet the Sony A99 is right
on par with the D600 and 6D at 6fps. That is unless for some reason you
like cropped jpgs, then the A99 can do at 12fps. Heavily cropped 10mp
raw files and the A99 can do 10fps. Of course in either of these modes
give up all hope of shooting wide. Perhaps these would be acceptable
compromises to a soccer mom, but for a camera targeted at working
professionals, shame on Sony for wasting time programming these options.
No moving mirror, no mirror blackout? Because a traditional SLR uses an
optical viewfinder and mirror, every time the mirror is lifted to
reveal the sensor, there is a blind moment known as mirror blackout.
Many reviews state that the A99 has no mirror blackout. They need to do
some real world testing. Although it's not possible to have no blackout
at all, theoretically the A99 should have less mirror blackout because
there is no mirror moving out of the way. In the real world, when
shooting 14bit raw files, the Sony A99 has considerably more mirror
blackout time than the Nikon D600. In fact it's really, really bad.
Think hard to keep a face framed as a person walks towards you.
I'm not talking
about running here, let alone action sports.
Better auto-focus performance. Traditional SLRs rely on that good old
mirror for auto-focus too, so when the mirror is up the camera
basically does some complicated mathematics to predict the rate of
movement of the object until it gets a glimpse through the mirror
again. With light going to the auto-focus sensors at all times the A99
able focus much better than any SLR. Sony must be behind on their
auto-focus technology, because it has the worst focus tracking
performance of any SLR I've
ever used. Period. Outside of object tracking performance, the A99 just
likes to back
focus behind static subjects too.
There is a lot more that could be said about Sony's A99. Unfortunately,
the inaccurate live histogram, mirror blackout and focus
performance are big enough problems to make saying anything else
pointless, as I sold my A99.
Slightly larger than the D600,
still not a hulking beast.
Sony A99, Sony Zeiss 135mm f/1.8 @ 1/50 f/2.8 ISO 400
I will miss that Zeiss though....
Sony A99, Sony Zeiss 135mm
f/1.8 @ 1/60
f/1.8 ISO 400
Sony A99, Sony Zeiss 135mm
f/1.8 @ 1/30
f/1.8 ISO 1600