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-   -   Does HV20 have true manual exposure? (https://www.dvinfo.net/forum/canon-vixia-series-avchd-hdv-camcorders/94346-does-hv20-have-true-manual-exposure.html)

David Niemeijer May 18th, 2007 07:58 AM

Does HV20 have true manual exposure?
I haven't had a chance to lay my hands on a HV20, but am considering getting one. A key factor for me is how well it handles manual exposure and I read something in the manual that is making me wonder whether the HV20 manual exposure truly fixes exposure (i.e. fixes shutter speed and aperture as in a SLR) or actually is some sort of exposure compensation (where a change in the light conditions leads to a change in the exposure settings).

The manual states on page 49 that "if you operate the zoom while the exposure is locked, the brightness of the image may change." It is fine for me if when zooming out a window comes into view the brightness in that part of the image will be very high. What I do not want is that the exposure on the object I fixed my exposure on changes because of additional light captured by the light meter while zooming out. Like with the Sony cameras (SD and HD) I have worked with so far, I would like to be able to fix exposure on, for example, the interior of a room and then when panning get an overexposed window, but stable exposure for the objects in the room. I do not want the exposure to shift on the objects in the room as would typically happen with either auto exposure or auto-exposure with exposure compensation (as exposure compensation is relative to the light measurement of the camera).

Can any one who has a HV20 confirm whether the manual exposure truly fixes the exposure even when panning or zooming so that the exposure of individual objects in the image does not change.

I hope my explanation is clear :-)



Chris Barcellos May 18th, 2007 08:34 AM

First of all, you can fix the exposure, ie., the aperature and shutter speed, and gain, by activating the exposure control in various modes. Everything locks in place using that feature.

However, with most zooms on most cameras, the widest available aperature does change as the zoom is zoomed in. Thus it might go from f1.8 to f 2.5 as zoom.

Except for that, with pans and zooms the exposure is locked.

Chris Hurd May 18th, 2007 08:46 AM


Originally Posted by David Niemeijer (Post 681555)
The manual states on page 49 that "if you operate the zoom while the exposure is locked, the brightness of the image may change."

Just to reinforce what Chris points out in the post above, what the manual refers to here is a function of the variable-aperture zoom lens, not the way the camcorder actually handles exposure metering.

Like almost all other camcorders in this class and price range, the maximum aperture at full wide angle is greater than the maximum aperture at full telephoto (f/1.8 vs. f/2.5), hence the reason for the change in exposure through the zoom range... unless you've locked the exposure to an aperture value of f/2.5 or smaller to prevent this change from happening.

David Niemeijer May 18th, 2007 09:04 AM

Ah, yes, this all makes a lot of sense to me now. I wish Canon would have provided just that bit of context for their statement that your posts do provide. Luckily, their camera's are better than their documentation (or their Dutch support center, who were unable to clarify that statement in the manual).



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