Vibration of the A7R shutter compared to D3 and NEX-7 using a seismometer

Started Dec 20, 2013 | Discussions thread
Horshack Veteran Member • Posts: 7,912
Re: Yes it was too harsh

ferrellmc wrote:

Horshack wrote:

ferrellmc wrote:

A possible way to test shutter vibration and eliminate the variables would be to take an image with shutter vibration and then compare it to an image without shutter vibration.

To take the image with NO shutter vibration have the camera set up in a dark studio, open the shutter for say 10-20seconds. While the shutter is open fire a strobe(s) off camera to expose the image. This exposure will have no vibration from a shutter release.

Then take an image normally but don't use the strobes their duration is too short, use hot lights or similar.

If everything is the same: lens, focus, ISO, tripod mount, distance etc. the difference in the two images is shutter vibration. Then do the MTF mapper (I've never worked with it).

This could be done at different shutter speeds.

I actually considered this a while back but then realized it's not a valid test because the duration of the flash strobe is only a handful of milliseconds, so its effective shutter speed is very high.

I did the test here:

I took 30+ sample images, one set with no shutter vibration and one set with normal shutter vibration exposures. Then I compared the results. I used a Nikon 85mm 1.4 and the Sony FE 35mm 2.8.

I am very pleased to find no visible evidence of shutter vibration in images from the A7R when mounted on a good tripod.

Horshack - Could you please elaborate on why shutter speed in the "no shutter vibration" image matters. The idea is to obtain the "purest" form of an image with no vibration. Although I don't think it's relevant, the fast strobe duration works toward that goal. If you thought a fast strobe might bias the image you could always change methods and turn a light on for a split second to expose the image.

If the only goal of using the strobe was to obtain the "control" image that demonstrates no vibration effects then sure, it doesn't matter. But the same control image could be obtained by just adding more ambient light and using a faster shutter speed (or removing the light and using a very long exposure). My point was that a strobe'd image couldn't be used as an experiment to prove the vibration effects go away when dragging the shutter (ie, using say a 5 second exposure in a dark room, manually strobing during that time, and comparing to a non-strobed image).

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