Here are a couple of videos and news from the NABshow in Las Vegas. From a mirrorless point of view the most interesting news is the Sony A7s Full Frame 4K camera. Actually it’s the first Full Frame 4K camera with true pixel readout (no pixel binning and line skipping).
Sony explained the camera cannot record 4K internally because of the too much power it would use because of the large FF sensor. And there would be heating issues too.
Interesting: The new A7s has also a new stainless steal mount. Wondering if that has been introduced also to fix the light leak issue on the mount…
First impression review at Imaging Resource. Sony Alpha 7s – Hands on Review by Den Lennie on Fstopacademy. A7s sites in different languages at Sony US, DE, UK, ES, FR, IT, NL, SE, FI, PL.
6 Responses
Stainless steel is very resistent but, what is the material around it, where lens mount is fixed? If plastic, a hard shock could break not only the lens, but the camera. See Roger Cicala opinions about plastic and metal mounts in dpreview.
I agree for 4K shooting, the “low” resolution makes unnecessary pixel binning or line skipping, but for sure there is line skipping to shoot HD (the resolution you can shoot without the external recorder). For HD shooters this is a standard camera.
The concern with mounts is less with breaking and more with warping and smoothness. As you rightly point out, the stuff around it is more critical to its strength. Screws mainly. Stainless will warp more easily, but hopefully will make a smoother and tighter mount to help ward off light leaks. Hopefully the stuff around it will be designed so as to prevent the increased deformation from causing other problems.
“The new A7s has also a new stainless steal mount.”
That is not interesting per se. Not a number.
More interesting would have been a number: how much weigh the mount is certified to support?
Not that I’m in the target market, but recently I have learned that one of the difference between pro and consumer grade (video) cameras, is how much weight the mount can support.
“Sony explained the camera cannot record 4K internally because of the too much power it would use because of the large FF sensor. And there would be heating issues too.”
That is a very weird explanation. As sensor is concerned, 4K processing is not different to 1080p processing. Especially when they openly declare that they do not do anything on the sensor. The data are just being read out from the sensor at fixed frequencies, independent what later is made out of the data: 4K or 1080 or 720. CPU/GPU – yes. But sensor? – that just weird.
OK, so for those who aren’t materials scientists and are wondering about the stainless steel mount, it must be a little confusing. Let me try to explain.
Normal mounts are made out of relatively hard metal due to their resistance to warping and deforming over time. High-carbon steels and the like. The problem with these metals is that, while they’re very strong, over time they tarnish and form a fine layer of oxide. This makes them rougher and introduces tiny gaps between the mount and the lens. With corrosion-resistant metal like stainless steel, the lens can be fitted much tighter to the mount since the stainless steel will retain its smooth, polished and, more importantly, flat texture.
The tradeoff: stainless steel is softer than carbon steel, so while it may wear less due to less abrasive oxides building up, it will be more prone to warping under stress. Warping may be a concern if you want a light-tight mount or perfect lens alignment, even under stress.
If it’s not stainless steel or plastic, the common alternative is brass. I’m not aware of carbon steel used in common modern lens mounts if at all.
Many cameras have stainless steel mounts. This is neither innovative or particularly special.