Sony announces hybrid EVIL/DSLR

Internaut

http://www.dpreview.com/reviews/sonyslta55/

http://www.dpreview.com/news/1008/10082421sonyslta55a33.asp

I have to say, I'm still trying to wrap my head around the advantages and disadvantage of this. It's about the size of an Olympus E-4X0 DSLR accept it's EVF is obviously going to be bigger and brighter than the Olympus OVF (but will also have an EVF's disadvantages.

ziggy53

Since the mirror doesn't have to move during exposure the primary advantage is continuous AF using phase-detect AF. The transmission of the semi-silvered main mirror is actually about the same as a conventional dSLR (with regard to the central section of the main mirror), but it does mean that the sensor is receiving less light, reducing the effective sensitivity of the sensor. Since this is a crop-c sensor that could be significant in low light. Indeed these new Sony cameras are using a very aggressive NR to maintain control over high ISO noise, at the expense of image detail.

In good light the very high frame rate of the a55 should be very nice but the relatively small image buffer seems somewhat limiting. Since it's an electronic viewfinder, tracking moving subjects could be tricky. No live view at highest frame rates makes that mode impractical for many applications.

The slow 1/160th flash shutter sync also implies a low-grade shutter assembly.

Video mode looks very interesting in good light and AF lock with the phase-detect AF during capture should be a welcome improvement in maintaining focus during video acquisition.

Overall it's not a bad design but there are several opportunities for improvements without too much trouble so I suspect there is more to come from this basic premise in camera design.

jdorseydesign

ziggy53 wrote: »

Since the mirror doesn't have to move during exposure the primary advantage is continuous AF using phase-detect AF. The transmission of the semi-silvered main mirror is actually about the same as a conventional dSLR (with regard to the central section of the main mirror), but it does mean that the sensor is receiving less light, reducing the effective sensitivity of the sensor. Since this is a crop-c sensor that could be significant in low light. Indeed these new Sony cameras are using a very aggressive NR to maintain control over high ISO noise, at the expense of image detail.

In good light the very high frame rate of the a55 should be very nice but the relatively small image buffer seems somewhat limiting. Since it's an electronic viewfinder, tracking moving subjects could be tricky. No live view at highest frame rates makes that mode impractical for many applications.

The slow 1/160th flash shutter sync also implies a low-grade shutter assembly.

Video mode looks very interesting in good light and AF lock with the phase-detect AF during capture should be a welcome improvement in maintaining focus during video acquisition.

Overall it's not a bad design but there are several opportunities for improvements without too much trouble so I suspect there is more to come from this basic premise in camera design.

This is really interesting, but it just seems to me that most photographers are all about getting as much light onto the sensor as possible (which is why we buy the fastest glass we can). This seems a bit counter productive to be reducing the amount of light just for the sake of continous autofocus. BTW.. can't the new Nikon D3100 autofocus while shooting video without this translucent mirror tech?

ziggy53

jdorseydesign wrote: »

... BTW.. can't the new Nikon D3100 autofocus while shooting video without this translucent mirror tech?

Most dSLRs with video use Contrast Difference AF in video mode, which is slower and requires moving the lens focus fore and aft until maximum contrast is detected at the point of focus.

With Phase Detect the AF system knows which direction in which to focus and, just as important, when to stop, allowing focus braking to be accounted for. It is a much surer method and generally much faster to use phase detect. The best of all current AF systems is the "Area SIR, Phase Detect" system used in the top tier Canon and Nikon cameras. It is best because it can detect edges at any angle and it has greater sensitivity in low light.

ziggy53

richy wrote: »

didnt canon do this for years with pellicle mirrors?

...

Yes, Canon used pellicle mirrors in at least a couple of models, as I recall. The viewfinder was somewhat darker as a result and exposures did not match external exposure meter readings for film ISOs.

esc2476

I ready about these mini-SLRs in the August issue of Outdoor Photographer which seemed to heartily endorse them (starting with the editor's column). I love that magazine, but I was disappointed to then see all of the advertisements for mini-SLR cameras.

AlbertZeroK

I have a Sony NEX 3 and have been VERY happy with it, although, the adapter to use Sony/Minolta lenses for the NEX cameras is manual focus (someone should be fired over that one). But to me, it's a high end point and shoot solution. I took it to the zoo a few weeks ago, and I was pretty impressed with it's capabilities, it's fast focusing and more importantly, I think the focusing system for video our performed my T2i.

But I do think the Sony lines are comming around!