Sony Alpha SLT-A33 review
Design - What Is 'SLT' & How Does It Work?
Sony Alpha SLT-A33 - Design
Without the pentaprism as a fundamental part of the design the A33 is smaller than a usual DSLR - but only ever so slightly in terms of height, to the point it's barely noticeable.
Most of the hand will comfortably fit around the grip, though your little finger may stray
off the bottom of the body and that can be uncomfortable for long periods of use. 
Elsewhere the design is as expected from
a usual DSLR - the mode dial to the top left can be quickly adjusted, while the opposite side has one-touch buttons for each of the Finder/LCD, D-Range, Movie, Exposure Compensation and AEL functions. The rear
has a standard D-Pad and an Fn (Function) button above this for quick access to the
most commonly used settings.
The main menu, accessed for the button behind the main mode dial, is the same as current Sony Alpha DSLR cameras. Divided
into a number of sections with up to seven settings per page it avoids being too cramped and, as there's no scrolling to located options, it's fairly easy to find those more detailed settings. It's really with the quick menu by using the Fn button that most control will be had, however, and this offers a comprehensive and easily navigable list of options.
What Is 'SLT' & How Does It Work?
The best way to explain how a translucent mirror system works is to compare it side by side to a DSLR system's operation.
In a DSLR camera the light enters from the lens and bounces off the camera's mirror into an AF sensor for fast phase-detection autofocus. Simultaneously light also bounces into a pentaprism that in turn feeds a preview image to the eye via an optical viewfinder (the pentaprism is there to flip the image from upside down and back to front to the usual way we see). Once the image is framed and the focus set a full shutter press will flip the mirror upwards and out of the way before the shutter itself fires to expose the image sensor (for the time period the shutter is set at) for the final image capture.
An ‘SLT' camera, as Sony is naming the A33, also has a mirror construction - but, as this is translucent, 70% of light can permanently pass through, thus eradicating the need for the mirror to move at all during an exposure. Without the need for this slow mechanical movement it's only the shutter that fires to make an exposure - and this can happen much more frequently, hence the A33's super-fast 7fps shooting. The 30% if light that bounces off the mirror is still available to reach the AF sensor for continuous phase-detection autofocus during live view mode - the first time this has been possible.
However the construction does not lend itself to an optical viewfinder due to the
lack of available light that could reach a hypothetical optical viewfinder - this is
why the A33 features a built-in electronic viewfinder in its place.
Have your say!
Latest comments
December 26 11:41
Mike
Mark - I'd err on the side of caution for astrophotography, depending on the size of the light-emitting bodies that you'll be shooting. The ghosting issue of this camera could prove problematic from 'small-scale' stars within the frame, as you may end up with a repeat ghost image. As for the 70% light passing design, it's not an issue to the final resulting quality (on the assumption you're shooting long exposures at lower ISO settings (as per any DSLR/SLT)).
January 28 15:30
Caroline Dodds
Thanks for all your comments. Decided on A33, just purchsed for £499 at Jessops. Excellent value.
May 13 00:40
liz tredrea
I've now had my A33 for just on 2 weeks. Before I had a bridge Kodak, (which I loved dearly and thought met my needs fully). Within a day I realised that this camera was an absolute treat. I have small hands and it fits perfectly, all the grips are in the exact place I need them. Mine was bought from Jessops as a bundle with a Tamron lense capable of macro too. I've bought a few accessories - extra battery - I'd say this is essential and a remote control. My absolute favourite feature is the 'panorama'. You just set the button and move the camera from one side of the scene to the other - the camera does everything else. I've photographed just about everything that moves, (and doesn't move) and have had very few that haven't worked. I'm also disabled and the fact that the screen can be angled so I can take pics low down or up high is really useful. Can you tell I love this camera? Probably! Sorry I'm not being more technical but I also love the fact that the screens are really easy to use. They tell you exactly what everything 'does' so no more leafing through instruction books before trying to take a special photo. I was quite scared of moving from bridge upwards when my beloved bridge's sensor failed but there was no reason to be. Hubs is now looking at a higher spec in this range despite having a dslr already.
August 11 23:45
HB KAHN
I JUST NOTICED YOUR RATING ON THE IMAGE OF THE SONY A33...I THINK YOU SHOULD CHANGE YOUR LENS!..YOU WOULD BE SURPRISED WHAT A QUALITY LENS WILL DO FOR THE IMAGE PART. THANK YOU.