On Sharpness, ISO and Shutter Speed

Started 11 months ago | Discussions thread
Jack Hogan
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Re: On Sharpness, ISO and Shutter Speed
In reply to Anders W, 11 months ago

Anders W wrote:

Jack Hogan wrote:

So I have two initial questions, assuming that the data is valid:

1) What are the practical implications for a photographer of the large spatial resolution differences in the V+H directions seen in the newer sensors measured here ? Will it make a difference whether we look at the final image in portrait vs landscape orientation?

Why would it make a difference if we look at it this way or that way? Blur is blur and to my knowledge, the human visual system isn't differently sensitive to blur in one dimension than in the other. Besides, we wouldn't normally want to look at something shot in landscape orientation in portrait mode or vice versa, for pretty obvious reasons.

Yes, I saw that did not come out right but only after having used up my two corrections already.  Let me rephrase the question:

If in the A7 and D610  there is really such a large difference in horizontal vs vertical captured resolution, is that an issue in practice?  Or should we be preferring capturing in landscape vs portrait orientation to maximize, say, vertical detail in the center of an image?  Many of us spend thousands of dollars on better lenses to typically gain less than the 20% difference shown.

2) Are the dips we see in MTF50 around 1/10th of a second to about 1/300th possibly due to shutter shock - or something else? What implications does this have for people choosing a high resolution camera today?

Hard to say without knowing more about what's going on in DPR's studio. But the shutter speed range affected and the fact that the blur is largely vertical makes shutter shock the likely culprit. The problem is known to occur in that range, with a peak at about 1/100 s or slightly higher. The point where the problem disappears at the upper end of the range may be related to the max sync speed of the camera (disappearing later the higher that speed is). At the lower end, it disappears more gradually, without much of a clear cut point.

That said, it surprises me to see the shutter-shock problem (if that's what it is) appear so clearly in the DPR studio scene samples. Presumably, they use a heavy studio tripod and the focal length is not all that long (about 100 mm EFL). Furthermore, one would at least have expected DPR to take the precaution of using anti-shock delay with Oly bodies and the electronic shutter option with Pany bodies. But I certainly wouldn't have expected any clear shutter-shock problems even if they didn't, provided that my assumption about good tripod support is correct.

The A7r and the D610 show signs of dips around there as well, and they are the lighter of the four FF bodies shown.  Possibly some of this is surfacing now exactly because the better technique and smaller sensors are no longer hiding imperfections that before were below the 'noise' floor.  I wonder if anybody ever put a camera through such rigorous scrutiny 30 years ago

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