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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 August 24th, 2007, 11:38 AM   #16
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No, the BRIGHTNESS image adjustment is definitely not the same as exposure. It's like adjusting brightness on your TV. You probably want to leave it at -1 and never touch it.

There are several ways to lose your exposure lock, but I don't think that there is any way to avoid it. Dialing it back in is just something you have to get used to as a trade-off for bullying this little consumer camcorder into doing things it was never intended to do! ;-)
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Old September 25th, 2007, 10:15 AM   #17
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Quote:
Originally Posted by Sam DeWitt View Post
I have been experimenting with the HV 20 for a couple of days and have been using the exposure lock/miniSD card trick to get the shutter locked to 1/48.
My question, and I know I must be missing something obvious, so apologies in advance, how do I control exposure once I have locked the exposure setting? I know I do not want to increase gain, and if I unlock the expousre and adjust f-stops then I quickly lose the 1/48 shutter.
I have read many posts on this, includiong the excellent one here -

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

but I still feel like I am missing something quite basic.

I hope that this is at least somewhat clear, I know I was not incredibly articualte, but hopefully this will at least point someone in the direction of my basic question.
Try my article, maybe you like it better: http://www.elurauser.com/articles/manual_mode.jsp I discovered the "press photo button halfway" trick by myself when playing with my Elura 100, but principles are identical for the Elura 100, DC50, DC2XX and HVXX.

The Cinemode on HVXX is useless, because you cannot use it together with other shooting modes, like all-important shutter priority. Therefore you cannot have both fixed shutter speed and cine gamma. I hope Canon fixes this in next model, as well as will provide honest manual mode like on GL2.

Well, of course you can set Cinemode and then adjust Exposure slider and verify current shutter/aperture, but after playing with HV20 it seems that the camera does not try to stay at 1/48 or 1/60, it favors keeping aperture to keeping shutter speed, therefore you need too much tinkering, pointing the camera to different light sources and then adjusting exposure slider to obtain some usable exposure setting with 1/48 or 1/60 shutter. Not worth it.
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Old September 25th, 2007, 12:04 PM   #18
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"Locking" is a misnomer. When you push the joystick up, what you're really doing is entering manual mode, and setting a baseline for the exposure based on how bright the current scene is. From there you can nudge it side to side to adjust.
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Old September 25th, 2007, 12:23 PM   #19
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Quote:
Originally Posted by Joseph H. Moore View Post
"Locking" is a misnomer. When you push the joystick up, what you're really doing is entering manual mode, and setting a baseline for the exposure based on how bright the current scene is. From there you can nudge it side to side to adjust.
Why is it a misnomer? You lock exposure based on current light meter reading, then you can adjust it and it will stay locked. If you have shutter speed locked by selecting Shutter Priority mode, then exposure control will affect only aperture and gain. Seems pretty logical to me.

There is no explicit manual mode on HVxx or any other Canon consumer camcorders. The "P" mode allows to gradually gain manual control over different functions. Exposure is just one of the controls that can be locked and adjusted manually.
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Old September 25th, 2007, 12:29 PM   #20
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LOCK: To make or become rigidly fixed or immovable.

If it were truly "locked" then you could not adjust it, no? ;-) Using the term that way is obviously confusing some people.
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Old October 8th, 2007, 01:02 AM   #21
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Locking HV20 aperture to known values

Here is how I do it:

Shine a light into the center of the HV20 while pressing down the photo button half-way. Repeat this until you are able to get the aperture to read 4.8. Lock ing the exposure at 4.8ensures that +11 on the exposure scale is equivalent to f1.8 with no electronic gain. You can sweep the majority of the shutter in the 23 settings from +11 to -11.
-Robert
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Old October 8th, 2007, 01:26 AM   #22
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Quote:
Originally Posted by Robert Kennedy View Post
Here is how I do it:

Shine a light into the center of the HV20 while pressing down the photo button half-way. Repeat this until you are able to get the aperture to read 4.8. Lock ing the exposure at 4.8ensures that +11 on the exposure scale is equivalent to f1.8 with no electronic gain. You can sweep the majority of the shutter in the 23 settings from +11 to -11.
-Robert
Could you explain the point of the light? You can verify whether gain is elevated or not simply by increasing exposure one step, checking aperture, and then decreasing exposure back.
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Old October 8th, 2007, 03:00 PM   #23
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I don't like gain which equals grain any more than the next person but I would rather have grain than nothing at all in some circumstances.

So you're saying shining a light at the camcorders sensor fools the camera into thinking there is plenty of light and allows you to get to the plus side of the exposure scale (0 to +11) when you sometimes can't. Is this correct?

I always thought that it was rediculous that the plus side was killed just when want it the most. Maybe any small LCD light might do the trick? I guess sometimes the reverse comes into play on a very bright day or brightly lit subject where you can't get to the negative side of the exposer (0 to -11).

I know the disallowance of where I needed to go on the exposer setting has screwed me up more than once.
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Old October 8th, 2007, 03:30 PM   #24
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Quote:
Originally Posted by John Hotze View Post
So you're saying shining a light at the camcorders sensor fools the camera into thinking there is plenty of light and allows you to get to the plus side of the exposure scale (0 to +11) when you sometimes can't. Is this correct?

I always thought that it was rediculous that the plus side was killed just when want it the most.
You will get the plus side, but it will be relative to baseline set with the light. When you point the camcorder to a dark area you won't see a thing even with all +11 steps. So what's the point?

I think that there is difference between Sony and Canon camcorders that many people cannot understand: AFAIU Sony uses fixed EV scale, while Canon uses relative scale based on current lightning conditions.
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Old October 8th, 2007, 04:43 PM   #25
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I use the cell phone trick. I can usually get 1.8 1/48 at around +6 or +7, at least off of my cell phone's brightness level being set down to 3. No gain that I can see.

However, I recently had to get something outside at night and I had to resort to the cell phone trick again to open the iris all the way. I believe it was at 1.8 1/15 shutter, that's the only way I could have seen what I was filming, whether there was gain or not didn't matter.

With the HV20, you get a lot. Remembering to set manual exposure, day or night seemingly, with a cell phone or iPod is a little tedious but it at least works.

Also, you don't lose 1/48 until you start going to extremes. For instance, the cell phone trick at night let me get 1.8 1/48 at +7, but once I started going to anything beyond that, the shutter went from 1/24 all the way to 1/15. If I took it back, I stayed at 1/48 all the way down to -11. If you're not getting anywhere near these kinds of results then you may have to adjust your cell phone or iPod's brightness.
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Old October 8th, 2007, 05:15 PM   #26
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Seems like I am talking to a wall. Guys, please explain, what the cell phone is for? I get it, with a calibrated light source you are able to have the same EV range in different conditions. Great. But WHAT FOR?

If you shoot in the darkness, you need wider aperture + gain, if you shoot in the bright light, you need less aperture. It is very possible that in both cases you will need to get outside your precious EV range. Even if you don't need to, isn't it simpler to lock exposure for CURRENT lightning conditions, which would base "0" EV step according to camera's light meter measurements? Then you can increase/decrease exposure as needed AND you can always VERIFY WHERE ARE YOU AT using Photo button. This way you will get USABLE range of EV steps, which you can use at current conditions instead of superfluos and superficial "calibrated" EV range.

I can understand that you guys are using 24p + Cinemode and are trying to stay within {f/8.0, f/1.8-3.0}. In this range the camera keeps 1/48 shutter speed. But what is the use of f/8.0 aperture in bright light if your image is all blown up, or f/1.8 with no gain in low light if you cannot see a thing?

You may retort that your way of doing things can hint you whether you need to add more ND filters or to add more light to a scene. But you can do the same simply by evaluating current light meter measurements!

If it is gain you are worried about, then until the camera slows down to 1/24 it does not engage gain. Barry's article basically tells the same thing, check out his EV table:

EXP Shutter Iris Gain
+3 1/8 f/1.8 10.5dB
+2 1/15 f/1.8 10.5dB
+1 1/15 f/1.8 9dB
0 1/24 f/1.8 9dB
-1 1/24 f/1.8 7.5dB
-2 1/24 f/1.8 6dB
-3 1/24 f/1.8 4.5dB
-4 1/24 f/1.8 3dB
-5 1/24 f/1.8 1.5dB
-6 1/24 f/1.8 0dB
-7 1/24 f/1.8 0dB
-8 1/30 f/1.8 0dB
-9 1/30 f/1.8 0dB
-10 1/30 f/1.8 0dB
-11 1/48 f/1.8 0dB

There is no gain if shutter is faster than 1/24.

Am I missing something? Or is this all hassle just because people want to save $20 on a miniSD card?

Last edited by Michael Jouravlev; October 8th, 2007 at 06:01 PM.
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Old November 4th, 2007, 10:42 PM   #27
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I don't know if this thread is dead for a reason, or if i will even answer your question, but i thought i'd at least try:

The whole purpose of the light (a 'controlled' light source, NOT like the sun, but an iphone or something) is to give the camera a relative position for the aperture to begin with.

The whole purpose of this technique, and the only reason people talk about it, is to ensure that gain is not being applied to the image, at the same time keeping the shutter at 1/48th.

So if you use Shutter Priority, lock it in at 1/48th, and then shine a light (like Robert says) bright enough to get the camera to adjust ITSELF to an aperture of 4.8, then you're ensuring that no matter what you do to the exposure at that point, the camera will not add grain.

It's really as simple as that. Figure out a consistent way to get your camera to adjust it's own aperture to 4.8, lock the exposure, and adjust from there. IF you still cannot get the desired exposure (either too dark or too bright) this is an indication that you either need to:

Too bright - Add ND filter(s) or Kill the sun :p
Too dark - Add LIGHT or Add GAIN (boo)

The point here is to eliminate gain and use 1/48th shutterspeed.

Otherwise just leave it on auto if gain isn't an issue to you.

Hope this helped
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