NX200 test shots - lenses, focus, and ISO 400

Started Nov 9, 2011 | Discussions thread
Billx08 Forum Pro • Posts: 11,373
Re: NX200 test shots - lenses, focus, and ISO 400, part 2 of 2

(continued)

With the new round of shots taken with the NX 60mm macro, we're confident the aperture setting is now correct (F8), and shutter speeds consequently match other cameras to within 1/3 stop at any given ISO. However the longer focal length and larger aperture inevitably combine to reduce DOF compared to the previous set. Most obviously, the Queen of Hearts and corner checkerboards are now just beyond the depth of field, and look slightly soft as a result. There's little we can do about this given the 3D-nature of our test scene.

Thanks for pointing this out. I didn't see cues (or clues) that would have made it obvious that the Queen of Hearts is positioned so far in the background, and to my eyes (the same ones that are more sensitive to brightness differences) it appeared not to be "slightly soft" but grossly soft.

The ISO 400 shots have been withdrawn because we've identified slight motion blur at the shutter speed used (1/80 sec). The pattern is highly consistent between all of the duplicate shots we took, despite the fact that the camera is (as always) on a heavy studio tripod, with OIS turned off and using the self-timer for release. Note that the blur is so slight you'd never notice it in real-world shots - you can only see it when you place the ISO 200, 400 and 800 shots side-by-side and pixel-peep intensely. It's important to understand that it's unlikely to have any real impact in practical use. However it was clear from comments that it was immediately being massively over-analysed, so we withdrew the shot to avoid confusion.

I never saw these motion blurred photos and think that it would be useful if DPR would make these available somewhere (with an appropriate disclaimer) so that the "pixel-peepers" might be able to judge for themselves whether the blur is so noticeable that it causes massive over-analysis (which I also haven't seen) or so unnoticeable that it would never be noticed in real-world shots.

As for what's causing this blur, our current working theory is that it may be shutter-induced vibration. This would explain why it affects only a narrow range of shutter speeds, and appears pretty consistent in both amplitude and direction from shot to shot. The relatively light bodies and double shutter action (close then open) makes this type of camera theoretically more prone to this effect than either SLRs or compacts (which use in-lens rather than focal plane shutters).

It's not just theory, either; we've seen essentially the same effect previously with the Olympus E-PL3 and E-PM1. However on these cameras it can be mitigated using Olympus's 'Anti-shock' setting, which closes the shutter, waits a specified time, then opens the shutter again to make the exposure. The NX200 has no analogous setting.

If your theory is correct, and I assume that it is, then do you think that the only practical way to fix or minimize it would be for a firmware upgrade to add a similar "Anti-shock" setting, assuming that a firmware fix could work? Also, how wide is the range of the affected shutter speeds? DPR didn't pull the ISO 200 or ISO 800 comparison images, so either the increased blurring didn't extend to 1/40th or 1/160th, or if it did, the blur was sufficiently attenuated to be much less noticeable. The NX100 has five shutter speeds that lie between 1/40 and 1/160 so I'd guess that the NX200 also can use these shutter speeds. If so, it would be nice if current NX200 users (there are a few) know whether they should try to avoid 1/50 - 1/125, 1/60 - 1/100, or just 1/80.

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