Examination using a non-aware raw converter like Raw Photo Processor or Capture One Pro shows the full 3:2 raw. If you shoot RAW and set 16:9 image ratio (HDTV format) you will discover that not only your JPEG is cropped – your. What is the difference? If you own an Alpha later than the 100, you can try it out. The Alpha 350 does not feature it for the 1.5X and 2X crops when in Live View mode, but the 16:9 mode results in a visually cropped raw file in correctly aware raw processors (as on the 700/200/300). Windowed readout allows different crops or aspect ratios to be selected. The Alpha 900 sensor is said to feature ‘windowed’ readout, a function also found on the Nikon D2X and D700, and on the Nikon D2X models. The earlier beta release cropped A700 files but did not crop the latest model files. The final release of ACR 4.5 treats 16:9 raws from 700, 200, 300, and 350 identically – locking out the full raw file size which is actualy present. This section has been amended – the Alpha 700 doesn’t window 16:9 ratio files. My view is that this is good for marketing, but we can expect some reports of sensor misalignment those have happened with all the KM/Sony DSLRs so far, and every other make I know of except Olympus.) (Update Aug 22 – several sources insist that the Alpha 900 finder is not only the largest and brightest of any DSLR now on the market, but definitely 100%. But a 95% finder would be safer for the user and Sony alike.
They might print a small warning in the user manual to state that for accurate use of the 100% viewfinder, SSS should be turned off. Would Sony dare put a 100% viewfinder in a camera with SSS? It’s just possible they might do so. The 95% view provides a good margin of safety. So on the whole, we get in our image what we composed in the finder. In practice, the movement of the SSS mechanism is tiny – measured in a few pixels at the most, and as each pixel is only around 1/100th-200th of a millimetre, displacements of 2.5mm or 5mm are very rare. (See comments to this post – ‘in theory’ you should always get what you composed! – I have now run tests and the variations in sensor position or parking are very small, between 10 and 20 pixels, with just the occasional shift big enough to be noticed). In theory it is possible to have SSS shift the sensor so far, at the moment of exposure, that you might fail to get exactly what you saw through the finder on your final shot.
The subjects are offset to the left in the image, but were centered in the finder however, all of what could be seen through the finder is present in the overall image (the crop shown would be moved to the left to restore the composition). It also makes it less likely that a displacement of the sensor, with SSS on or not precisely parked, could produce a composition significantly different from the viewfinder view.Ī carefully composed Alpha 700 shot with AS enabled, showing the theoretical 95 per cent viewfinder coverage and the actual frame. 95% is not a big trim round the edges of the field of view, but it’s enough to ensure that the sensor more than covers everything when SSS is turned off. Therefore, a 95% view through the large prism seems far more likely. SSS would have to park the sensor assembly dead centre to make it match a 100% viewfinder. It’s difficult enough to make a 100% viewfinder match up perfectly to a static sensor, as Canon and Nikon have both found. Why should this affect the viewfinder? If the finder was a 100% view, it would only be accurate when the sensor was parked – SSS turned off.
Mechanical happens if the sensor moves beyond the rectangular frame created by the shutter opening. Optical vignetting happens if the sensor moves to the edge of the lens image circle. There is some possibility that optical vignetting may occur when strong SSS correction happens during an exposure, but I would hope no mechanical vignetting is allowed. Photographs of the inside mechanisms indicate that it does have an oversize ‘film gate’ and shutter assembly, to allow for the movement of the 24 x 36mm sensor. The Alpha 900 has full-frame SSS, in-body image stabilisation. Well, I’m going to risk being shot down and say that I think it will be 95% coverage, like the Nikon D700, but could even be slightly less than 95%. (Note: this post was written in early August – it is now 100% certain that the finder is 100%, and at 0.74X magnification will be – as had been hinted – the largest of all current DSLR finders in apparent visual terms except the EOS 1Ds Mk III which is 0.76X. I am not one, so rest assured, this is not a leak! What can you expect from the Alpha 900’s full-frame prism finder?
It’s not going to be long before we see the Alpha 900, and some cameras are known to be out there on trial in the hands of Sony staff and pre-release testers.