I have this lens just for a short while, but I noticed, that it closes the aperture when on wide end and then continuously (well not so continuously) opens the aperture as you zoom in.
Does anyone has any meaningful explanation why is this done that way? Why do they unnecessary slow down the lens on wide end?
I have noticed the OIS behaving oddly on my 14-140mm lens. I will zoom in and the image will be rock steady - then the image will start twitching as if the OIS is switched off. If I hold very, very still, the image will then settle down again....and then start twitching.
I haven't noticed the same behavior from the 100-300mm or the 12-35mm lenses.
Alfi666, I'm sure that if the lens performed well at f=14 mm with the aperture set wider than f/4.0, Panasonic would have made it do that. It's hard to make a long-range zoom lens that is fast at the wide end and still has good image quality, and it's quite typical of zoom lenses to reduce the aperture at shorter focal lengths. It's typical of lenses that the images look better when the aperture is reduced a bit from its widest setting.
You can test the lens's performance at f=14 with wider apertures yourself. Zoom in to f=140 mm, set the aperture to the maximum, and focus on something. Remove the camera's battery. Remove the lens. Cut a piece of paper to cover the lens's electrical contacts, and re-attach the lens with the contacts covered. Put the battery back in, turn the camera on, zoom out to f=14 mm, and snap some pics for us. The camera will also need to be set to shoot without a lens, if you haven't already done that.
@balazer : Good tip... I'll certainly do it :)
OK, so I did a test, but unfortunately, the electronics is also manipulating the flange-back distance... so without power, lens becomes a little bit "macro". On wide end, there is also a heavy vignette in the left corners - this obviously goes away when lens corrects its flange-back
I'm so sad that while shooting an event 2day, my 14-140mm lens(operated by my fren on gh2) couldn't do manual/auto focus after certain zoom range(which starts from 50+mm till 140mm after i test it further). So, I guess it's time to send it for repair. Just curious what's actually wrong with my lens and how would Panasonic charge me... warranty is over. I didn't see any case like mine after searching internet...
I'm thinking if it's only certain part got loosen that I could go to local camera repair shop to repair for me.... or since it's focus by wire so i must send it back to panasonic?
Got new replacement of my 14-140mm lens after a month to Panasonic repair center...
Use a Cokin P or A series as a mattebox = no problems...
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