Lumix 20mm Pancake Lens Problem

[Corey Graham]

I shot a wedding yesterday, and was excited because I knew the reception location is notoriously dark and I'm using the 20mm pancake lens on my GH1. However, the lens suddenly decided to stop focusing. I couldn't even focus manually -- I would turn the ring and nothing would happen. It's like it was stuck on infinity. I could change aperture with no problem.

I turned the camera on and off, swapped lenses, and eventually it began focusing again. But if I'd turn the camera off and back on again, the problem came back. I'd have to take the lens on and off, turn the power on and off repeatedly before it would work again.

This happened on both my GH1's, so it's not a camera issue.

I've searched around for someone who has had similar issues, but have found nothing. Has anyone ever heard of this happening? The only thing I can think of is maybe temperature/humidity changes. I went from very humid 90-degree outdoors shooting to air-conditioned indoors. That's doubtful though, IMO.

[Corey Graham]

I'm still troubleshooting this. I've spoken with some photographers, and visited my local camera shop to talk to the boys about this issue. None of them seem to have any idea about what is going on, except that it may be a temp/humidity change issue. Since the lens uses electrical means (as opposed to mechanical) for any sort of focusing, this could make sense -- moisture inside the lens could be condensing on some important electrical thing that's shorting something out.

But now I'm beginning to think otherwise. I was ready to ship the lens to Panasonic to be repaired, but read a post on another very respectable forum about third party filters and hoods causing problems with this lens. The threads are constructed in such a way that they obstruct the focusing mechanism at the end of the lens that goes in and out.

I've been using a third party lens hood that screws into the lens (I bought it used, and the seller threw it in), and it seems to be the culprit. If I screw the hood in tightly, the lens will not focus. If the hood is loose or not on at all (or if I screw on the UV filter first), then I can focus as normal.

The true test of this theory will be at this weekend's wedding. Keeping my fingers crossed.

[Jeff Harper]

The 20mm has no practical need for a lens hood anyway, because of the nature of the lens itself, at least according to what a couple of pretty knowledgable guys have said. It may look better, but yes it would be too close to the camera and block the thingy, that makes sense.

[Ed Roo]

I don't have direct knowledge of the problem you describe, but it sounds similar to a problem exhibited by another 4/3 lense.
What was the charge state of each camera's battery?
The Olympus 70-300 exhibits the symptoms you describe when the battery in the E-500/510 and E-1 series camera bodies gets low.
You might want to check the 4/3 forum on dpreview.com and ask your question there.

[Corey Graham]

Originally Posted by Ed Roo

What was the charge state of each camera's battery?

Most of the time the batteries were full, although the lens would behave erratically during all levels of charge.

[Jeff Harper]

Yes, Corey, you already know the problem. That would've been very disconcerting, but at least you understand what is happening!

If your goal in using the lens hood is to appear more "substantial" the best solution might be to acquire the new Leica coming out, which is not a pancake (I don't beleive) and will likely accept a lens hood just fine. If your goal was functional, as I mentioned before, it has been said that because of the nature of a pancake lens, a lens hood is not necessary for the most part, and I have to agree.

Despite that, I think it would be much nicer to have a lens hood for the lens, it would so much better. It looks like a real nothing without, but if our end prouct is good enough, customers won't care anyway.

[Corey Graham]

Originally Posted by Jeff Harper

If your goal in using the lens hood is to appear more "substantial" the best solution might be to acquire the new Leica coming out, which is not a pancake (I don't beleive) and will likely accept a lens hood just fine. If your goal was functional, as I mentioned before, it has been said that because of the nature of a pancake lens, a lens hood is not necessary for the most part, and I have to agree.

I've been using the hood for both look and theoretical function. It definitely gives a "bigger" look to the already small camera body and the ridiculously small lens; it also theoretically will reduce flare and protect the lens to an extent. I was using a UV filter on it, but it caused some very bad glare.

I've been salivating over that Leica ever since I found out about it! I do constant page refreshes at B&H to see if it's available yet :)

The funny thing about that is that I ordered a new 20mm lens from B&H for this weekend's wedding, just to have it in case this lens acted up again. If I'm right in thinking that the lens hood caused the problem, then I'll send the new one back, and already have a nice chunk of cash taken out of the price of the Leica . . . although it's definitely not a "need" right now, it's a "want."

[Jeff Harper]

I already have a 30mm F/1.4 but want the Leica very much anyway. I'm sure it's fantastic.