Did not quite understand how that related to filming speeches though?
You mentioned using different focal lengths at different distances. I wanted to point out that this changes your perspective just like a "dolly zoom" does.
So ND filters is the only way if you have a bright lens shooting outdoor? I thought some manual settings would help
You can compensate to a certain extent. But:
1) Shutter speed affects motion blur. So, similar to how it's better to add lights instead of changing aperture, it's better to add ND filters instead of adjusting shutter speed.
2) the G6's base ISO is 160. So, per the Sunny 16 Rule, to shoot at f2.0, you'd need six stops of compensation. So even if you did try to compensate with shutter speed (which, again, you shouldn't), you'd exceed the G6's fastest shutter speed after only four stops. i.e. you'd be overexposed by two stops. (And for the sake of completeness, just in case someone is jumping into this discussion late, we're specifically talking about achieving proper exposure without
adjusting aperture because aperture also affects DoF. i.e. the goal is to achieve proper exposure outside in daylight with a large/fast aperture (for shallow DoF).)
I could perhaps get away with a 25mm ... do you have one in mind?
No, I just picked 25mm because the math worked out. (Although, I do own a Panasonic 25mm f1.4 but I was not necessarily recommending you get one for yourself.)
What I found playing around with the G6 and 14-42mm was that I get best shallow DoF with fully zooming into the object, and the object having some distance from the background. I found that strange though as the aperture value goes up the more you zoom (whereas lower aperture is supposed to provide the most shallow DoF as you said?).
Well, I also said, "everything affects everything else (which is why I would again recommend a DP whose job it would be to deal with all this stuff for you)
But yes, focal length and distance to subject also affect DoF. But remember from above that focal length also affects perspective. (i.e. the wider/shorter the lens, the more background is visible.) So you generally want to pick your focal length based on how much of the background you want to see. And, as mentioned in previous posts, the focal length and the framing you want (head/shoulders, waist up, head-to-toe) will then dictate how far away you place the camera. Now, with those two factors determined, the only means you have left to control DoF is aperture.
The G6 in intelligent auto mode actually has an option to increase the blurriness of the background and it works well. ... I'm not why they don't just call it "increase the shallow depth of field"?
I have no idea, either. You'd probably have to ask someone at Panasonic that question.
Question I have is ... how can I get that with a fast prime lens that does not zoom, as the best shallow depth I got was with zoom?
Key word there is "fast" prime lens. Basically, see two paragraphs up. At the same focal length and distance to subject, to shorten/shallow DoF, you use a larger/faster aperture (and add ND filters if this results in overexposure). More specifically, the 14-42mm lens you're using now has a max aperture of f5.6 at 42mm. Whereas the upcoming 42.5mm f1.2 prime lens will be more than four stops faster, and therefor give you much shallower DoF (assuming, again, the same distance to subject).
Actually, even less theoretical, go back to the "bokeh test" pics I linked to on Flickr a few posts back and note how much more bokeh there is with the 20mm f1.7 prime vs the 14-140mm zoom lens at a similar 19mm focal length (but much slower f4.4 aperture).
And bokeh is another name for the blurriness?
Basically, yes. But "bokeh" refers specifically to the blurriness of the background
, as opposed to blurriness caused by the subject being out of focus, for example.