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Filed under: Cameras •

PMW-EX1: Update on lens issues

When I looked at a prototype Sony PMW-EX1 camcorder I noted that the lens had some problems. Sony told me that the prototype had a lens element misaligned due to a bug in the firmware, so I didn’t make a big deal about it.

Since then, others have received production EX1s, and ‘Net discussion lists are filled with reports of lens problems, mostly off-center vignetting.  I sat down with Sony’s Juan Martinez at DV Expo last week in Los Angeles, and we had a chat about the issue.

First, some background: The prototype camera I had for review showed excessive “port-holing” (a very soft vignetting, with picture edges up to a stop darker than the center), and the optical stabilization caused motion-specific vignetting, both problems occurring only at certain focal lengths, and only with the lens iris wide open.

When the EX1 shipped, some recipients reported one or both of two problems: focal-length-dependent port-holing, and sharp-edged corner vignetting, often in one corner only. Other EX1 users found nothing of the sort: their lenses showed no defects of these sorts whatsoever.

At DV Expo, Samy’s DV & Edit had a captive EX1 chained to their booth. I aimed it at a blank wall and ran through the zoom range, with the iris wide open. I saw no excessive port-holing, but at full telephoto, the lower-right corner of the image showed a sharp vignette, as from the edge of a round lens shade that wasn’t wide enough, and it wiggled when I shook the camera, as if the optical stabilizer were steering the image around.

When I returned from the show, I had another EX1 waiting for review, this time a nearly-final pre-production model (I’ll be studying it in some detail over the next ten days). This EX1 shows no abnormal port-holing: there is some at full telephoto, full wide iris, and if I shake the camera with Steadyshot on, it steers around in response. However, at rest the vignetting is barely noticeable, and it’s pretty much evenly centered, with no corner favored over another, and if I shoot a real scene instead of a blank wall, it’s virtually impossible to see, as the scene’s own detail and variation in tone overwhelms the visibility of the port-holing.

Note that almost every wide-range zoom lens shows some port-holing to some degree or another, but, as on my current EX1, unless you shoot a featureless, blank wall, you’ll never notice it. Part of the problem is that once you know it exists, or is at least a possibility, you become sensitized to it—and if you’ve never noticed it before, it’s a bit of a shocker. I think that’s a large part of the problem on the discussion lists: people test their new EX1s for a defect they’ve never noticed before on their previous cameras—even though it has always been there; it’s certainly there on my Z1, and on the 15x Canon zoom on the DSR-500 I sometimes use, and on the stock Fujinon zoom on the JVC HD100—and suddenly It’s The End Of The World.

So first of all, relax: I’d be surprised if a lens this ambitious in terms of performance, compactness, and low price didn’t show any port-holing. Second, I apologize: now you know this sort of thing happens, you’ll find it happening on most of the zooms you use, and you’ll be upset—and it’ll be my fault. Sorry!

Anyway, back to our story… port-holing aside, some of the EX1s are reported to have asymmetrical vignetting. Juan Martinez, a “Senior Manager, Technology” for Sony, confirms that there are issues with some of the cameras. This is the first one-piece, fixed-lens camera that Sony has done where the lens comes pre-built and pre-tested as a unit from Fujinon, and is then integrated with the camcorder body at Sony. While the lenses arrive bench-tested and approved, it appears not all of them are being mounted on the camera bodies in perfect alignment (having worked on several engineering projects involving third-party components, I can attest that it’s easy for something to go seriously askew at the final integration stage without anyone noticing until it’s too late).  Juan said, “we go over these things with a fine-toothed comb, rejecting cameras even for almost invisible cosmetic defects. So, yes, we’re taking this very seriously.” Sony is reworking its internal processes to ensure that these problems won’t happen in the future. The good news is that the camera is heavily backordered, so there isn’t a lot of faulty stock sitting in warehouses waiting to be sold. The stuff currently being airshipped to dealers should be the last batch that ships with potential issues.

As to the cameras in the field, It looks at this time (early December) like Sony will have a procedure to set them right. Juan spoke off the record regarding the details of the procedure, so I can’t be more specific; have patience, I’ll spread the news (as will every other reporter concerned with the EX1!) as soon as it’s announced. It may take a while—remember the audio fix for the PD150?—but if you have an EX1 with obvious, excessive and/or asymmetrical vignetting (no, not the normal port-holing, unless I’m very much mistaken), there will be a remedy coming.

More about the EX1 in days to come.

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