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Lazy Lens May 10, 2009 2:53 PM

FZ28 lens flaw
Upon inspection of my new camera, I noticed a single bubble in the lens. It appears to be in the element directly behind the foremost (objective). It's located at upper left and is about .26mm diameter and about 7.43mm from the lens periphery (close as I could make out using a digital caliper). Close examination under magnification reveals no other perceptible flaws.

I don't know if it will make much difference in an image, as I haven't taken test pics and pixel-peeped them. In any case it's rather annoying just knowing that an otherwise flawless lens has this bubble in it that lights up like a flashlight when light hits it from certain angles.

I've read that where there's one lens with a bubble, there are usually a lot more in a given batch with a similar flaw. I'm disappointed in Leica/Pan quality control, especially after having read so much praise of this lens. I wonder if today's lenses are allowed a certain percentage and severity grade of flaws (like dead pixels in an LCD screen).

Is this a common flaw in modern Leica/Pan lenses, in particular the FZ28's, or would this be grounds for shipping back for an exchange?
If bubbles are common, I'd risk getting a different unit with possibly more than one bubble or a larger singular bubble, or some other flaw. And I may have to pay return shipping and maybe even a restocking fee (will have to check policy).

rfdandrea May 10, 2009 2:57 PM

Whether it degrades the image or not, you will probably never be 100 percent happy just knowing it's there.

I think it's probably reason for an exchange.

P.S. I'm not going to check *my* lens for bubbles because if I find one, then *I* won't be 100% happy.

rfdandrea May 10, 2009 9:08 PM

OK, I lied
I just checked my lens.

No bubbles.

Lazy Lens May 12, 2009 5:20 PM

Thanks. How did you examine yours (naked eye, magnification level, lamp or sun, etc.)?

I initially spotted this bubble under a 3x magnifier lamp. Additional examination using a 5x OptiVisor (combined with the lamp and independently) revealed a second possible bubble. It's smaller and much deeper in the assembly and much more difficult to spot, as the light must hit it just so. The foremost one is readily apparent with the lens out for zoom, and now that I know where it is, I can easily find it with the naked eye.

I've tried some solid white test shots (108+ inkjet paper) and couldn't find any anomalies at 100%. However, I haven't tested for microflares in outdoor/sunny scenes or used darker/color papers. Nor have I tested with zoom.

I know many people consider bubbles a sign of high quality in older lenses. And I have old film SLR lenses with bubbles. However, I've read that bubbles are quite rare in modern, quality lenses. I'm not sure how picky/retentive a person should be with these modern lenses.

Unfortunately, demo FZ28's aren't readily available for me to examine in person, so I'm hoping several (numerous?) additional FZ28 owners will be willing to check their lenses.
My decision will be determined by either the majority or by time (the time allotted for returns). If I'm about out of time before I get more reports in, well, I don't know what I'll do frankly.

ol'skool May 12, 2009 8:50 PM

Hi: New here, just ordered for Mothers Day an fz28 for SWMBO. Haven't recieved it yet so no report on bubbles.

Here's a link to a Schott pdf about bubbles in optical glass:

A bubble or two theoretically can reduce constrast, but have never been able to detect it in the final product.

In telescopes, arguably the most demanding use of optics, a few bubbles are generally not an issue as long as the surface is figured accurately.

The real issue is if the bubbles breech the surface or there are solid inclusions which WILL damage the final image.

Honestly I would not be afraid of that camera at all. Some of my old Nikkor lenses have bubbles, wouldn't trade them for anything...

Take Care,

Lazy Lens Aug 7, 2009 3:16 AM

Sorry for the late response. I've been pretty busy with other things.

I doubt anyone's still interested in this thread, but just in case:

After doing some legwork to gather my own empirical data on the incidence of lens inclusions/bubbles (because I couldn't find such reports online), I ended up returning my first Z28. Anyone champing at the bit to point out to me that the REASON that info isn't readily available is because the majority feels said bubbles are generally insignificant should consider that I am fully aware of the majority view on the subject, and that was not the point of my research. I simply wanted to know.

I had used Paintshop Pro create a diagram of the first Z's bubbles.
I don't know if that's the reason or if it's just their normal M.O., but exchanged it w/o delay -- their site said it could take 2 weeks, but they shipped the replacement out the SAME DAY they received mine! I was favorably impressed. :cool2:

What didn't favorably impress me, unfortunately, is that the replacement also has bubbles.
This one has a super-tiny bubble ON THE SURFACE (yes, breached), and another very very small one deeper in the assembly.
At first, I thought the surface imperfection was a speck of adhesive used in production and that I might some day be able to remove it, but high magnification revealed the truth.

I wouldn't have bothered returning it had I not personally examined other Z28 lenses under magnification and found them to be bubble-free -- as best I could tell given the available lighting and condition of the lenses (e.g., dust specks); those ceiling floodlights cause lots of false positives which must be ruled out. Now that I've seen the surface bubble on my Z28, I can't be certain some of those dust specks were not actually bubbles. For various reasons, I didn't clean each lens prior to examination and I didn't feel for surface imperfections with my fingernail (for OBVIOUS reasons).

Panasonic certainly isn't the only brand who passes flawed lenses thru their QC chain. I discovered that, statistically, Canon is a worse offender than Panasonic, Sony, Nikon and Kodak.

As it turns out, it's basically a crap shoot when it comes to getting a bubble-free lens, even though production techniques have supposedly improved by leaps and bounds over previous generations. I discovered bubbles are absolutely not a "rare" occurrence, as some have suggested (on other sites).

I'd post my findings in detail, but I doubt there is sufficient interest in the forums for it -- and few people appreciate reading negatives about their personal property they've come to admire so.

As to my replacement Z28, I performed numerous test shots under various lighting conditions and camera settings, and, despite my best efforts, was unable to find any deleterious effects on images from its bubbles -- I looked for things like micro flares, distortion and contrast dips. I did "pixel peep" each shot very carefully.

I'm not sorry I did the research, and I'm not sorry I returned the first camera. Nor do I have severe regret for having landed this one in its place. The ordeal did cost me an extra $15 in return shipping. However, as I now find that the few (couple?) etailers who actually have an FZ28 in stock have it priced at $475-$500, I feel lucky to have ended up with one when I did!

sdromel Aug 10, 2009 7:14 PM

Since you've done all that, you might as well test for hot & dead pixels (which are more annoying).

In my experience, you need to have a pretty big flaw (or chunk of debis) on the lens to create a noticeable effect.

I would consider existence of hot or dead pixels to be a more serious/annoying issue.

Lazy Lens Aug 13, 2009 12:55 AM

Since the Z28 can't be powered on in record mode with the lens cap on -- for those who don't know, the hood ring doesn't extend far enough, either -- and since I don't have an adapter tube, I couldn't perform the dead pixel test with the lens cap on as recommended. So, I covered the lens with a black, leather, insulated glove that has an elastic wrist band. This made for a nice seal.

I ran the test on camera-generated JPG, SilkyPix-generated JPG (100% quality), and SilkyPix-generated TIF. The reason I bothered with these 3 is because they were reported (by Irfanview) to have different numbers of unique colors, which I thought might affect the test.
All 3 blank images returned 0 dead and 0 hot pixels.
I'll be glad to post these in an album if anyone wants to examine them.

I also ran the test on a solid blue sky fill image I had shot earlier when testing for unusual micro flares due to lens bubbles, just to verify the test utility was functional. In case anyone's wondering, the flare test pics themselves were shot with the sun at varying angles entering the the lens periphery. Yes, I also took numerous flare shots at low light levels (nighttime, street lamp, fluorescent bench lamp, etc.).
At any rate, the fill image resulted in 0 dead pixels and millions of hot pixels.

So, it appears that Panasonic is more concerned with sensors than with lenses when it comes to QC. That, or I was just lucky enough to get one with a "perfect" CCD sensor -- assuming the test was accurate. I suspect the former is more likely.

sdromel Aug 13, 2009 3:27 PM

Glad that your pixel tests went well. (My FZ7 tests outstandingly well, but my old Olympus C2100 would begin to show hot pixels after 6 sec & that got a bit worse with age/use.)

Checked my FZ7 lens for flaws & some of the Pany cameras on Demo at Fry's & there were no discernable bubbles in any of the lenses. It is disturbing though that you encountered two units each with such artifacts. Let's hope that this is not the beginning of a new trend.

In the final analysis though, being a better photographer is more important than the camera being used, so proceed to enjoy your photography effort.

Pixmate700 Aug 13, 2009 6:12 PM

Do any people on this forum actually use their cameras or do they spend all their time moaning about them?. In the past 60 year of using a large selection of camera from 5x4 plate to the latest digital I have had only camera with an actual fault and this was from the first chinese manufacturer to produce a slr camera ( a Seagull). The the main fault/problem with modern cameras is the person who operates them not the camera itself . I have had bubbles in several lenses in the past and they haven't caused any problems that I have noticed. I used to develop and print my own film and have done some very large enlargements so would have noticed it they had.You can find bubbles in lenses of even the hightest most expensive cameras produced and in 99.99% of cases no reduction in quality occurs. Forget the bubbles and simple use the camera for what it was designed for, taking pictures.

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