Problem with manual Exposure (iris)

[mike9399]

Hi,
i am not sure if this subject was discussed already, didn't find any entry about it.

When i am using the AF with the Lumix Zoom lense and i am zooming out quickly i noticed that the exposure "jumps" resp. it "pumps". It gets some more light for less than a second and then it jumps back on the normal condition. When i zoom in quickly the effect does not appear. Iris was setted on manual.

Furthermore, few days ago i had to film roads and roadworks and in a few shots, when cars passed by fast, the same effect appears without doing any zoom - but here it's almost not to notice.

Anyone made the same experience, knows what this is about or have a solution for me?!?

 

[hendosan]

It's because the lens does not have a fixed aperture throughout it's zoom range.

 

[mike9399]

So i get it right, even if the iris is set on manual, so locked... when zooming, the value changes because of the lens, and the cam is compensating that and that's why i see this "pumping effect". In other words... no zooms possible?!

 

[Barry_Green]

The 14-140 does vary the iris and the focus somewhat during a zoom, and then corrects when you've stopped zooming.