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.

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.

Thanks

Sam DeWitt

The short answer is that there is no perfect thing that you can do. You can try to avoid using gain, though:

- If you've properly "exposed" the sensor using the light trick, then you should be able to bump the exposure a couple of stops without introducing gain.
- If you use Tv mode, the cam is gonna stay at 1/48th no matter what.
- If you use CINE mode the cam seems to try to stay at a 1/48th shutter, and it also tries to avoid using gain, and has a gamma curve more amiable to low light.
- If too much light is the issue, then ND filters are your friend.

I am trying to stay with Cine mode (to get the flattest gamma curve I can).

It seems to me that in cine mode I lose the 1/48th rather quickly, and unless I am missing something from this video -

http://www.dvinfo.net/conf/showpost.php?p=673130&postcount=20


- I am going to introduce gain if I increase exposure (that is open up the lens, or decrease the f-stop).

Are you saying to add external ND's, or let the cameras kick in? ( I am acting like I know that the camera has a built in ND. although that is another thing I am not clear on yet either).

Thanks very much for your reply.

Sam DeWitt

http://www.obtuse-ny.com




The short answer is that there is no perfect thing that you can do. You can try to avoid using gain, though:

- If you've properly "exposed" the sensor using the light trick, then you should be able to bump the exposure a couple of stops without introducing gain.
- If you use Tv mode, the cam is gonna stay at 1/48th no matter what.
- If you use CINE mode the cam seems to try to stay at a 1/48th shutter, and it also tries to avoid using gain, and has a gamma curve more amiable to low light.
- If too much light is the issue, then ND filters are your friend.

- You need to experiment with how bright of a light source you lock your exposure against, relative to the overall brightness of the scene you are shooting. I wish I could explain this better, but I confuse myself when I try to explain it! What I've ended-up doing is loading-up my iPhone with a handful of different images from 100% white down to 50% grey. The brighter the scene I'm shooting, the brighter the image I use for locking my exposure.

- I'm talking about external ND filters, since the camera's aren't directly accessible.

- Yes, CINE will drop out of 1/48th, but it seems to only do so when it can no longer adjust the aperture, and at that point, your image would be incorrectly exposed, so you probably need to try to do something else anyhow (adding or subtracting light from the scene.)

PS. I'm approaching this from a narrative filmmaking standpoint. If your goal is run'n'gun or ENG shooting, there's not much you can do to control lighting ... you're gonna get into situations where gain is unavoidable.

OK - this is actually helping me understand.

So say I am in a controlled environment (interioir), I point at a bright light source, get my 1/48th and I lock my exposure.
Now when I frame up to the actual scene I am underexposed and if I unlock exposure and get a decent exposure that puts me out of 1/48th shutter, what is the recommended "fix".

PS - I am also approaching from a more or less narrative viewpoint, but more to get backplates to enhance with VFX work and extensive color correction, hence the desire for the flat gamma.

PPS - I am not using the "cell phone trick", or in your case the "iphone trick" (that sounds quite clever BTW), but am simply using the ability you get with a miniSD card installed that lets you check exposure and shutter speed at any time.

Sam,
In that case, you locked the exposure to something too bright. You'd be stuck pushing the camera into gain because it had already closed down the aperture to try to control the overexposure of the bright light. You need to lock it to something that more closely matches the overall brightness of your scene. That's why the cellphone, iPod, iPhone, whatever hack works so well ... the brightness of those devices is much more inline with natural highlights within a scene.

OK - with this knowledge is it safe to say that once the exposure has been locked, there is no other way to manipulate the camera without increasing gain (or adding ND in the case of overexposure, or adding more light if that is an option)?

Thanks

Sam

No. The aperture should have some room to open before gain needs to be added.

If you see the f-stops going down (using the photo button) then you're not peobably not using gain.

right, but you can not see the f-stops going down if the exposure is locked, correct?

Sam

I don't have it in front of me, but I think you can see it as long as you're not actually recording. The exposure isn't so much "locked" as it is "manual from a baseline."

I simply mean that once you have locked the exposure, you would have to unlock it to manually change it again, up or down.
The main thing I am trying to confirm is that there is not another way to adjust exposure, since you want to keep the shutter at 1/48.

Thanks again for all you replies.

Sam

I'm not sure what you mean by "locked."

Once you're in manual exposure mode you can adjust from -11 to +11. The baseline "0" (shutter, aperture and gain) comes from what you exposed against when you went into manual mode.

You don't have exact control over what the camera does when you step-up and down, but if you're in Tv or CINE mode, you can probably get a few steps in each direction without ruining the shutter speed or engaging gain.

By locked, I mean you push the joystick up to get to the manual exposure mode, find the exposure you want, then click the joystick "in" to lock it.

Yes, that's the only way to manually adjust exposure.

Yes, that's the only way to manually adjust exposure.

I noticed the exposure setting is not remembered when you turn off the camcorder. Is there a way to do this? I know there's brightness setting in custom mode. Would that be the same as exposure?

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! ;-)

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.

"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.

"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.

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.

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

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.

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.

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.

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.

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?

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