Sony a77 & NEX LA-EA2 Focus speed compared

Started May 14, 2012 | Discussions thread
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dbiela
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Sony a77 & NEX LA-EA2 Focus speed compared
May 14, 2012

Hi I have a LA-EA2 Sony Alpha to NEX emount adapter to use so I thought I would compared and see if there is a real difference with the autofocus speed between the camera systems using the same lens. I shot with the Sony a77, a NEX-5n and used two lenses. The Sony 16-50mm f2.8 SSM (Super Sonic wave Motor) and the Sony Zeiss 16-85mm with the early screw focus. It was not the most scientific of test but will give you an idea of how they do.

My first setup was with the a77 & 16-50mm f2.8 lens I would manually set the lens foot scale to about 2 feet and them touch the shutter release to see how fast to focus at a building about 150ft away. It was less then 1sec for the lens to lock in focus and hear see the confirmation light and beep. I repeated the same steps with the Sony NEX-5n. I feel that the a77 was just slightly faster then the NEX-5n/LA-EA2 but it was not measured just my perception. Both did well and I would have no problem using either one shooting static objects. Next I used the same setup with the Sony Zeiss 16-85mm DT lens. I would say that both cameras focused at equal speed but the surprise to me was how fast the lens would focus, almost the same speed as the Sony 16-50mm f2.8 SSM lens. It was nosier and you cannot override the focus like a SSM lens but you do not lose any real world performance. The next comparison was to shoot moving cars coming toward me at about 25 to 30mph. For this I used the Sony 70-300mm G lens at about 300mm. Again I found both the a77 and LA-EA2 adapter to have no problem with track focusing of moving cars. Both did extremely well, where I did find a difference is with smaller subjects like a single cyclist. The a77 focus

Sensor had no problem with a person on a bike but the LA-EA2 on the NEX-5n did not always keep focus when the bike was far away like the a77 did. What was interesting was the camera image buffer. Using the same SD card I was able to capture more images with the a77. The NEX-5n started out fine but when the image buffer was full the camera needed a lot more time to recover before shooting the next frame. The last test was the most interesting to me, using the Sony a77 & 70-300mm the Sony focus system was exalent with shooting subjects moving away from the camera. It did not lose focus and all the images were sharp I have shot with other camera brands that have issues with this type of shot.

So the recap

The Sony a77 and Sony LA-EA2 Alpha to NEX emount adapter do very well with both autofocus speed and accuracy. If I am shooting more moving subjects with long lenses like a bike race I would use a a77 over the NEX but for normal photography both do well. Remember that the LA-EA2 is camera independent so it should focus the lens at the same speed no matter what NEX camera you use it on. Finally I own 2 screw focus driven lenses and both focus up fast so I would not sell off an older lens if all you are worried about is how fast is the focus speed it may not be worth the expense.
Hope you find this useful Cheers Dennis

Samples
Lens speed test, Image with lens set to about 2 feet

Image when camera looks focus time to focus less the 1 sec.

Tracking focus with car approaching at about 30mph all the images are sharp

Tracking focus with car heading away at about 30mph all the images in focus. The Sony system does a great job

Sony a77 with 16-50mm f2.8 lens

Sony NEX-5n with LA-EA2 adapter and 16-85mm lens

Sony NEX-5n with LA-EA2 adapter and 16-50mm f2.8 lens

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