Dpreview studio test for 6D is up!

Started Jan 8, 2013 | Discussions thread
Minasgr
New MemberPosts: 21
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Re: Is the 6d images underexposed... ?
In reply to Mikael Risedal, Jan 9, 2013

It is not so simple. There are various parameters that could make exposure different between cameras including slightly movement of the lights in the studio room. I had the same question about this difference between canon and nikon and tried to find the answer in the imaging-resource forum. The answer gave to me the forum administration is below:

"Here's part of the answer, a description of the lights:

http://www.imaging-resource.com/ARTS/TESTS/HMI.HTM

Here's a more specific answer:

We carefully regulate the brightness of the test photos to allow a more meaningful comparison between shots from different cameras. The aperture or shutter speed of a camera is typically adjustable only within increments of 1/3 of an EV. To provide much finer control of brightness, we move the HMI lights on sliders to vary their distance from the test target. We can usually get within a couple of points on the eight-bit 0-255 scale, while a third of a stop is more like 20-30 points at the midrange of the scale.

We shoot in manual exposure mode, and choose an aperture for each camera and target to provide the best case sharpness and avoid diffraction limiting. Therefore, adjusting the lights for each test shot means that the nearest selectable shutter speed may vary to provide the desired brightness of the resulting photo.

Here's the real-world answer:

Your examples, the D4 and 1Dx, are among the most consistent we have ever tested in exposure throughout the shutter speed range. The better Nikon and Canon lenses are also very consistent. But none of them are perfect, especially at wider apertures. Besides aperture and shutter speed, there is also a substantial variation in sensitivity at what should be precise ISO steps, as well as variations due to sensor noise. It makes our job very tedious and time consuming with anything other than the very best cameras and lenses.

And another contributing factor:

We use four samples of a very sharp lens for most of our test shots, the Sigma 70mm macro lens with mounts for Nikon, Canon, Pentax, and Sony. The sharpness is nearly identical between samples, but the brightness varies somewhat when used on bodies from different manufacturers. This may lead to different shutter speeds necessary to produce equal brightness in test photos.

Fun, eh?

-Luke

__

Hope this helps.

Forum Admin"

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