Response to Anders W and a few comments re E-M1 and A7

Started Dec 23, 2013 | Discussions thread
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seachicken2000
seachicken2000 Veteran Member • Posts: 3,171
Re: Whose humbug?

Anders W wrote:

I did a quick analyses of the jpeg and found the amount of vignetting to be in the vicinity of the value reported by photozone (1.9 EV at 10 mm and f/8 on the NEX-7) provided that you used the standard tone curve shown here

I believe you more-or-less nailed it. I shot a sequence of images .3EV apart, and compared the center of the correctly exposed shot to the extreme corner pixels of the progressively over-exposed images.

At about +1.7EV the corners exceeded the center. So the vignetting must be somewhere between 1.3 and 1.7EV (I am assuming it's typically measured as the worst possible case, the difference between the center and the average of the four very furthest corner pixels - I have no idea; if it's a weighted average using other points in the frame, it's going to be very a different figure).

I will send you a PM with links to a couple of RAWS (DNGs) for your perusal. One from the NEX-F3 and one from the NEX-7 both (hopefully) shot with the same settings under the same conditions. The NEX-7 image looks considerably more vignetted. Assuming the NEX-F3 is ~1.5EV, I'd be shocked if the NEX-7 is only 1.9EV.

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