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December 4, 2009 at 11:24 PM #45793ProducerLindaParticipant
Hello all.I have called Canon support for this question,but my questions have not been answered.I have a Canon XH-A1s.What is -3 video gain?Does it take away from video gain?When do you use 0 video gain?Why is there no way to turn manual video gain off?Why are you stuck with low,medium,and high video gain specs in manual and there is no way to turn off video gain and not use video gain at all?Thank you.
December 5, 2009 at 4:11 AM #189664EarlCMember
Well, I’m not familiar with that particular Canon model, but many of the Canons in that performance arena are similar. Odd that there’s no automatic setting for gain – most do offer the choice between autogain settings and manual, some with a broader range of settings, others like what you describe with high, medium & low.
There is, however, an advantage to manual gain settings. One such example being in a situation where the general subject area is OK, but a guy in a white shirt shifts into or out of frame, or part of the frame: If your camera was on autogain then you would see this constant shifting of the lighting as the sensors bounce off the shirt, then back on, then off…
…the same would occur if the setting were relatively well-lighted and a guy (or gal) in a black or dark outfit moved a bit in the edge or one side or the other of the frame – a constant shifting of the lightness/darkness of the scene due to the sensors reflecting off the darker element, back to normal…
Auto iris would create a similar situation – gain/iris work in tandem to a general degree. I’m attempting to oversimplify things here, sorry.
With a manual setting that won’t happen. So, based on your overall lighting situation you might be happier to settle for one of the three gain settings.
I personally prefer to set manual gain to 0, I rarely want to use a higher setting in darker lighting situations because that can or will often introduce grain and poor coloration, depending on the camera’s overall sensitivities/capabilities. I would use a negative gain setting, maybe, if I were in a bright or over-lighted situation that I could not control.
There are other approaches, methods and determinations that come into play regarding depth of field needs, lighting, lack of lighting, etc. Learning how to work these various controls in tandem, or individually to get the kind of exposure or image quality you desire comes from practicing.
Use a variety of situations: bright overlighted, good general lighting, dim to dark, and shoot some stuff using all the possible settings on your camera. As you’re recording, make a voice statement regarding the situation and setting for each event. Then, watch this series of recordings and listen to your audio notes and determine/learn what might work best for you in most general situations. Make a cheat sheet, if necessary, something you can refer to when out on a gig and can quickly go for what works.
It might help you also to determine how much the camera adjusts for white balance as well – test and see what the results are indoor/outdoor using the presets like incandescent and sunlight, or other. And testing for various colors/shades of cards, from white, to light blue, to gray.
You will soon enough become familiar with what goes WHAT for you in any given situation and then more than likely be delighted over the control you now have, as opposed to automatic or wondering.
Hope some of this helps and does not further confuse the issue. If not, sorry, maybe somebody else will pipe in.
December 5, 2009 at 8:04 PM #189665BruceMolParticipant
I have a previous version of the XHA1. You can assign values (between -3 and +36, zero if you like) to those switches L,M,H or take the preset values. I’m not sure what the preset values are. I usually leave my AGC off and operate the camera in Manual mode giving me full control over the exposure. The AGC is a great feature in low light but it does add noise.
So, think of video gain as an amplifier.
Q1. What is -3 video gain? A1. Less than what your camera is currently sensing.
Q2. Does it take away from video gain? A2. Yes it reduces the current signal coming to your camera.
Q3. When do you use
0 video gain? A3. As Earl says, most of the time. BTW, Earl has some great advice.
Q4. Why is there no way to turn manual video gain off? A4. When you turn of the AGC you are in manual mode, when you turn in on you are in manual mode with the switches represent values either factory preset or with values you have set.
Q5. Why are
you stuck with low,medium,and high video gain specs in manual and there
is no way to turn off video gain and not use video gain at all? A5. Hopefully you now understand that is not the case at all, you have complete control over the gain.
Please see page 63 of your user manual to learn how to set the values of those settings.
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