Sony Nex 6 with 50mm upgrade.

Started Feb 8, 2013 | Discussions thread
EinsteinsGhost
EinsteinsGhost Forum Pro • Posts: 11,977
Re: Sony Nex 6 with 50mm upgrade.

Fredy Ross wrote:

thanks I didn;t think to set the iso instead of auto. I need to ptactise more but still wonder if 35mm updated is worth getting.

As far as focal lengths are concerned, 35mm will be better as a walk around lens with limited use for portraits. And 50mm will be better as a portrait lens with limited use as a walk around. Depending on your priorities, you can have both, or just one (I have both focal lengths).

As far as the issue of motion blur, DoF and Auto ISO is concerned, use of 35mm wouldn't have guaranteed avoidance of blur either. The difference between the 35mm and 50mm will be in terms of metering (the camera will use a wider frame with 35mm and if more of it is darkness, it may slow the shutter speed down, or choose higher ISO). But, 35mm would increase DoF which could reduce softness due to out of focus areas.

But here is another thing to consider. With Auto ISO, the camera is looking to use the minimum shutter speed it assumes "safe" (without having to use stabilization) before it switches to a higher ISO (in Auto ISO, the ISO rises in thirds, a reason you see ISO 250 which you cannot set manually as your choice will be either 200 or 400).

The minimum shutter speed is determined by the focal length. Since you were using 50mm lens (75mm equivalent), the camera assumed you wanted at least 1/75s for shutter speed. It rounded it off to 1/80s and determined the ISO that went with it: ISO 250.

If you had 35mm lens instead, and the metering were identical, the camera would have opted for 1/60s for shutter speed and a corresponding ISO for the brightness value of the scene.

I normally shoot in Aperture Priority mode with manual ISO for this reason. I can control DoF and shutter speed by manipulating ISO. If there is a movement in the frame that I don't want blurred out, I would pick ISO that is at least 1/125s but preferably faster.

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