Manual Iris changes automatically with zooming.

T

tangierc

Member
Can someone explain why the iris still changes when i have it set to manual when I'm zooming in or out? Perhaps it's not the iris, but whatever it is it's annoying and I'd like to know what's going on and how to turn it off.

Thanks.
 
Does that lens have a consistent f-stop all the way through the zoom, or does it ramp? If it ramps, it's going to change.
 
digitalgecko said:
Does that lens have a consistent f-stop all the way through the zoom, or does it ramp? If it ramps, it's going to change.
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Bingo. If a lens has a different maximum aperture through the zoom range, you may see an exposure change if you are wide open on the wide end and move to the other.
 
tangierc said:
Lumix 14-140 HD lens.
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of course it does change iris as soon as u zoom! the iris is not constant!

there is a new lens that is not for sale yet Pany 12-35 HD f/2.8 - has a constant iris, AF , IS and around 1300usd.... will be available with in a month or so....!
 
anatusa said:
of course it does change iris as soon as u zoom! the iris is not constant!

there is a new lens that is not for sale yet Pany 12-35 HD f/2.8 - has a constant iris, AF , IS and around 1300usd.... will be available with in a month or so....!
Click to expand...


No, that is not the issue with this lens. The aperture fluctuates even if you are manually set to say f11. When you zoom in, it momentarily gets darker then settles back at f11, if you zoom out, it gets brighter during the zoom, then settles back at 11. It's inherent in the design of the lens and for me was a deal breaker. I ended up selling mine for that reason. The focus on that lens does the same thing, it fluctuates during the zoom and then settles back at where you have it manually set.
 
But that doesn't seem to happen when I put it on the GH1 (custom movie mode) or if it does it's so slight I haven't noticed it. So is it really the lens and based on the replies it seems there's not setting to gets round that?
 
As tacotim says... when you zoom the Iris action is approx 0.5 sec behind it so you may have stopped zooming and the Iris is still moving which makes it very noticeable..I guess it the lens
 
Just one reason you can't zoom "live" with that lens. That's they way they are made, not made for shooting video and doing zooms as you record.
 
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