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Canon VIXIA Series AVCHD and HDV Camcorders
For VIXIA / LEGRIA Series (HF G, HF S, HF and HV) consumer camcorders.


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Old October 21st, 2007, 07:25 AM   #1
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HV20 Gain?

Hi,

Is there a way to control the gain on a HV20 like you can on the XH-A1? If not when does the gain kick in or is there a way to tell if wain is on?

Also what is the best wide angel lens for the HV20, preferably wider than 0.7.

Thanks in advance,

Simon
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Old October 21st, 2007, 09:04 AM   #2
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1. Some links that have helped/taught me:

http://www.dvinfo.net/media/canon/hv...urecontrol.mov (great video tutorial).

http://www.dvxuser.com/jason/hv20/

2. Do a search for the many discussions on this, but the Canon WD-H43 0.7x appears to net out as the best option (I own it; I'm happy).
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Old December 5th, 2007, 12:28 AM   #3
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I seem to be missing something. With exposure locked and a miniSD card in place, if I press down the Photo button, I get a blinking red camera icon that says "OFF" and no display of shutter and aperture.

What am I doing wrong?
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Old December 5th, 2007, 01:43 AM   #4
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You probably have still image recording off in the video menu. Hit function button, toggle down to next to last item on the list of option, then toggle right to the level of image you want. It should now work.
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Old December 5th, 2007, 04:20 AM   #5
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That was it. Thanks, Chris!
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Old December 5th, 2007, 01:35 PM   #6
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Quote:
Originally Posted by Simon Frances View Post
Hi, Is there a way to control the gain on a HV20 like you can on the XH-A1? If not when does the gain kick in or is there a way to tell if gain is on?
There is a workaround, but it is complicated by built-in ND filters. These filters are undocumented but it appears that the camera has them. They are automatic. On a simpler camera like the Elura, one can lock the shutter speed, then lock exposure, check aperture, then increase exposure, then check aperture value again. If it increased then you are ok, if it didn't then it means that the gain kicked in.

With the HV20 you cannot be 100% sure because instead of turning gain on the camera might just remove one of the ND filters, reporting the same aperture value.

On the other hand, it SEEMS that the ND filters are used in f/4.0 - f/5.6 range only, so when you get to wider apertures the filter does not come into play anymore and the exposure is adjusted by gain only. YMMV ;-)
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Old December 6th, 2007, 12:18 AM   #7
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What i do is this:

Put the camera in Cinemode or Shutter Priority mode. (For shooting in 1/48th)

Point the camera at a light bright enough to make the aperture drop to around 4.4 (or something close to it, don't have the camera on hand so i can't check what the ideal number is). Half press photo button with sd card in and photo option on to check the aperture.

Once you get the light at the correct brightness to achieve 4.4/8 lock the exposure. (press in joystick, click down, click up, press again) Now you can move the camera way from the light and start knocking the exposure up or down to correctly expose the image if you can. You should be able to go all the way up or down without gain kicking in at all.

Reason is, at 4.8, the most the exposure slider will let you go is 11 clicks (i believe) and that happens to be 1.8, it's lowest aperture. If you were to set it at 3 for example and lock it. And starting opening the aperture, once you got past 1.8 it would start adding gain.

So it's really as simple as that. Point at light, lock at 4.8, open back up to 1.8 (if need be) and shoot.

Hope this helps
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Old December 6th, 2007, 11:19 AM   #8
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Originally Posted by Dale Backus View Post
Point the camera at a light bright enough to make the aperture drop to around 4.4 (or something close to it, don't have the camera on hand so i can't check what the ideal number is). Half press photo button with sd card in and photo option on to check the aperture.

Once you get the light at the correct brightness to achieve 4.4/8 lock the exposure. (press in joystick, click down, click up, press again) Now you can move the camera way from the light and start knocking the exposure up or down to correctly expose the image if you can.
Why do you lock the aperture pointing at the light, if you are going to shoot in different conditions? I still cannot get the point of this technique. If you are going to shoot in low light, why not locking the exposure in low light? Going all way up to increase exposure locked on the light produces the same effect as simply locking exposure in the low light conditions and going couple of ticks up or down. The only difference is where you start from on the exposure scale. By locking exposure in different conditions than shooting conditions you limit yourself to at most 11 steps of exposure adjustment, which may not be enough for particular shooting conditions. Why are you doing this? No one so far gave me a sensible reason for this approach.
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Old December 6th, 2007, 05:00 PM   #9
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The purpose of pointing the camera at a light is this:

When you lock the exposure, it sets it at a RELATIVE "0". So - the purpose is to find a point that when you lock the exposure, no matter what you do to it from that point on will NOT introduce GAIN.

If you lock it in a low light situation the HV20 will probably turn up some amount of grain - since there is no way of telling how much gain there actually is at any given time, you have to MAKE SURE there isn't any gain being added by pointing the camera at a light.

Chances are, if you're pointing directly into a light of some kind, no gain is being added. You also know there is no gain being added because it's closing the aperture, there would be absolutely no reason to add gain if the conditions are bright enought to be turning down the aperture.

So, what i've found is, if you lock the exposure at 4.8, you can go ALL the way up and all the way down on the exposure dial, without EVER introducing gain. The shutter is locked (in Tv or (mostly) Cinemode) and now you're basically just controlling the aperture directly.

It is a pretty confusing concept at first, it took me a while myself to understand it. There is a tutorial floating around somewhere explaining this method, however he just says simply to "point it at a light", but never goes into how bright it needs to be. So if you point it into a light that is TOO bright, you'll end up locking the exposure at f5.6 or something, and ou won't be able to open the aperture up all the way, because the RELATIVE "0" mark at that point is 5.6.

I hope i'm making some sense. The bottom line is, is to start at a point where the exposure locking/sliding system basically turns into your aperture control without ever having to worry about gain.

Let me know if this helps at all...
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Old December 6th, 2007, 05:03 PM   #10
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Left out two things:

1 - you have to be zoomed out fully for this to work.

2 - try locking the exposure in a "lower light" situation, and try to lock it at around 2.8 or something. Then start opening up the aperture. Go up one notch on the slider, lock it again and press the photo button, and see what the aperture is at. Do that JUST until you get to 1.8. Then, now you know if you're going any further BEYOND 1.8 in the OPEN direction (to the right) every click is adding GAIN to simulate the aperture opening more.
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Old December 6th, 2007, 07:28 PM   #11
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Dale, your second posting completely crosses out what you wrote in the message above it. My question was: why using some sort of constant light to set the exposure. In your first post you answered: to set the "0" of the exposure scale at the same known aperture/gain level despite actual shooting conditions. Well, this is not the answer what I was looking for, I was looking for an answer to a question WHY do you want you "0" of exposure scale to be at the same position? You said this technique ensures that no gain is introduced when you go all the way up the scale. Well, this is some reasonable explanation, but then again, if you can check your current aperture and shutter speed at any time, why limiting yourself to specific constraints?

I might think of a reason. Say, instead of trying to find the best camera settings for current lightning conditions you can look at the scale and see that you are on the "+" edge of your ideal constant-shutter-speed-no-gain scale and you should add more light to the scene. This approach allows controlling the scene lightning based on camera limitations instead of controlling gain based on scene lightning. But this particuar reason has NEVER been mentioned in any thread related to the HV20's exposure settings, neither on this site nor on the other sites. I am not a movie pro, camcorders is just my new hobby, I suppose this is how pros work, they adjust lightning to equipment they have. I guess this is something every movie greenhorn should know. I didn't think of this before. Would be nice if you confirm that this is a reason (or THE reason) for a "fixed EV scale".

In your second message you are saying basically what I am saying: lock exposure, then increase it and check aperture. As long as aperture increases, there is room for the iris to open and gain is not introduced. If the aperture stops increasing while you increase exposure, this means that gain kicked in. Thank you, thank you, this is exactly my point. Which brings us again to the original question: why would you set "0" to an absolute position instead of locking exposure for specific shooting conditions and then checking current exposure?

One more thing. The HV20, like most consumer camcorders, has the lens with variable speed, it is f/1.8 at the wide setting and f/3.0 when fully zoomed in. This means, that you can lock exposure at full wide, then increase exposure, and you would not have gain. Then you zoom in, the iris closes, what happens to gain then? I have not tested this, but I suppose that camera will compensate by adding gain. which means, that exposure should be locked and tested not only for current lightning conditions, but for current zoom setting as well. I will test it today. I don't have my own HV20 yet, but my friend has. I am getting by with a simple Elura 100.
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Old December 6th, 2007, 07:48 PM   #12
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Michael,

I i'll try to answer your question the best that i can, forgive me if i didn't quite extract the correct questions from your post.

The point of having a controlled light source to lock the exposure with is only so you can easily set the exposure at the ideal 4.2 (don't know the exact number off hand) every time. This way you assure, no matter what the lighting conditions and no matter how far or low you jack up or down the exposure, you will not introduce gain. That is all. The real B of it all is when the HV20 shuts off or if you knock the dial by accident, you have to reset everything, having a controlled light source to calibrate the exposure at 4.2 just makes things easier.

Now the purpose of not locking it based on your specific shooting conditions is that if you specific lighting conditions are too dim, you might be locking the exposure with GAIN already being induced. Because the camera doesn't tell you how much gain it's adding, pointing at a plenty bright light is the only way to ensure it won't add gain. You just never know. By pointing at a specific light, you guarantee there is no gain when you lock the exposure. That is the difference.

I hope i'm making sense...

As for the zooming thing, i really don't know that answer to that question. I always thought it wouldn't add gain, but have never really confirmed that. Would be interested to learn your findings.

Thanks

Dale
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Old December 6th, 2007, 08:12 PM   #13
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Originally Posted by Dale Backus View Post
Now the purpose of not locking it based on your specific shooting conditions is that if you specific lighting conditions are too dim, you might be locking the exposure with GAIN already being induced. Because the camera doesn't tell you how much gain it's adding, pointing at a plenty bright light is the only way to ensure it won't add gain. You just never know. By pointing at a specific light, you guarantee there is no gain when you lock the exposure. That is the difference.
What is the point of shooting with no gain, but with blacked out image? You either will need to jack up exposure (read: gain), or add more light. Which brings me back to an assertion in my previous message, which you haven't confirmed: instead of adjusting camera for a scene the proper workflow is to adjust scene lightning for camera's capabilities.

Are you saying that the idea is to always stay within the "ideal exposure range", centered around f/4.someting. If there is not enough light, add light. If there is too much light, add an ND filter. Is this so?

In this case this technique is starting making sense to me.
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Old December 6th, 2007, 09:24 PM   #14
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OK, i see where the miscommunication is now.

Yes, the whole reason for the controlled light thing is to guarantee no gain will be induced. Gain sucks, and i avoid it at all costs.

If you're at 1.8 with no gain and the image is too dark you have two choices:

Add Light
Add Gain

Light is always the better option for me. But it totally depends on what's practical for your situation.

THe last thing you said is exactly right. Too much light, (which would be rare) add nd filter or something, too little light (shooting 1.8) add light. This is just to ensure no gain will be added. Gain sucks.
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Old December 7th, 2007, 02:28 AM   #15
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I've been shooting a lot of interior night scenes lately and have found that it's just better to up the gain a couple notches if you can't adjust lighting. Slight noise is better if it means maintaining a dynamic range for post color correction. It's better than no noise and losing your range. Also, I think audiences are used to seeing some noise(within reason) in low light situations, something the human eye adds iteslf anyways.
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