Tutorial Section:

[Duke]

Many, many thanks to Patrick for his video tutorial http://hv20.info/yopu/hv20aperturecontrol.mov, and to Jason for his article http://dvxuser.com/jason/hv20/.

I’m sorry, but I just couldn’t follow the UK accent in the video tutorial on my non-amplified speakers. The article was very helpful, but left out the preliminary steps and gave two ways to not do it first. I figured we needed a step by step guide for people in the same boat as me.

CONTROLLING EXPOSURE ON THE HV20:
[Cell phone trick and SD Card trick included.]

First, make sure you install a medium sized mini-SD memory card by opening your LCD screen, then opening the little door at the bottom. This step gives you a way to check your settings, later on, that you won’t have without the card.

Push in the dummy card and it should pop part way out. With the camera turned OFF, pull the dummy card out and replace it with a real SD card. It goes in with the SD logo on top. Push in until it clicks and stays in. Close the door.

INITIALIZE THE CARD per page 65 of the manual. (Slider to card, rotary switch to Player, press function, select menu, select initialize.) Wait for it to finish formating the card.

Second, make sure the slide switches on the right side are then set as follows: Top switch to P and bottom switch to tape (not to card) even though you just installed an SD card.

CHECKING THE F-STOP AND SHUTTER SPEED:
Next you have to enable the photo mode so you can check the f-stop and shutter speed while in tape mode. (Do not do it with the sliding switch on the right side that switches it from Tape to Card.) Instead:

Push FUNC
Down Joystick to Still Image rec off (the one above menu)
Joystick right to LW (1920x1080)
Push FUNC to close the menu.

Now when you push of the PHOTO button on the top of the camera half way in it will display the f-stop and shutter speed in bottom right corner of the LCD.

SETTING THE SHUTTER SPEED:
Fully zoom out.

Press FUNC and at the top left of the menu it will say what mode the camera is in. When the top icon on the menu is highlighted, move the joystick left or right to select a mode.

There are two main modes to control what we want to control.

1) Tv mode (shutter priority), which allows you to manually control the shutter speed, but doesn’t allow you to directly control the gain or f-stop. Once the mode is selected you and joystick down.

Or

2) Cine mode. Cine mode tries to be fully automatic but has a gamma curve that tries not to blow out highlights or crush blacks, overall it seems darker though. CINE mode will ‘try’ to go to 1/48 at 24p. Once the mode is selected you and joystick down.

Why chose one or the other? Personal preference. Some people swear by one or the other. Others say use Tv mode outdoors and Cine mode indoors.

NOTE: This menu system is less intuitive that it could be. Even though you can manually control the shutter speed there is no menu item marked shutter or speed. It’s marked Tv. [How did they get Tv for shutter? Tv mode = Time value = fraction of a second.] In the manual they talk about Shutter prio. Maybe in the menu the limited space stops them from saying Shutter priority or shutter control, but there’s no reason to not say it in the manual.

SETTING THE F-STOP with ZERO GAIN:
What you do have control of is the Exposure control, which is really the camera balancing the shutter, f-stop and gain, but it can be locked when you get it where you want it.

Point the camera at a mild light source. No gain will be on when it is pointed at a light source. (Gain turns on when it's too dark.) Your LCD computer screen or LCD cell phone screen work fine. (Don’t worry that it looks bluish on the camera screen.)

One suggestion is loading a white picture in your cell phone. Another option is note pad in your cell phone. Make a document with only one period on it, then save it. Either way a fairly blank area to point the camera at is what you want.

Hold it pointed at the screen and press the joystick in. The joystick menu will pop up. If it’s not in EXP, move your joystick down until EXP is shown. Keeping it pointing at the screen, Press up ONE TIME and the exposure adjustment bar will appear in the upper left corner. (If you press up a second time the exposure lock will turn off.)

Note the adjustment bar is set to zero db, and was done when pointing at a light source. No gain is on and as long as the adjustment bar is on the gain is locked off!

Now you can aim the camera at what you’re really going to shoot and adjust the EXP left or right until you get the right light level you want. If you have the 70% zebra turned on make sure there are no zebra stripes.

You can now check the f-stop and shutter speed by partially depressing the photo button, even when the EXP menu is visible.

When you have it where you want it press the joystick in ONE TIME. The exposure bar will stay at the top left, but the joystick will no longer move it left or right. It is locked.

If the light changes or you move locations slightly you can press the joystick ONE TIME and make adjustments left or right. DON’T MOVE IT UP or you will release the lock and have to do it over again.

You can't check gain on the HV20, but if you record to tape you can put the tape in a more epensive camera like the FX-1 that can sense the gain on the tape.

SETTING EXPOSURE WITH A DOF ADAPTOR (Thanks to Anx and Dennis at Cinevate / Brevis.)

1. All the basic steps are the same, with the exception that you turn on 70% zebra in the settings section
2. Set to TV mode, 1/48 shutter speed, fully zoomed out
3. Frame something that is basically 50% zebra'd, 50% normal. The trick is finding something fairly brightly lit.
4. Lock exposure - if you do this you'll end up with the full range of -11 to +11, at 1.8F
5. Change the exposure to +9.


Hope that helps.
Duke

[mrob7]

Toward the end you said:

"2. Set to TV mode, 48fps, fully zoomed out"

Don't you mean "Set to TV mode 48 (shutter speed), fully zoomed out"

Just thought i'd mention it...

Otherwise great tut!

[Duke]

RHKFilm was kind enough to provide full frame grabs from HD video frame, an MJPEG frame and a Blackmagic Intensity direct capture frame for comparisons. See the full pictures here:

http://hv20.com/showthread.php?p=187...sons#post18731

This is a follow up to what was previously said about colorspace:
http://hv20.com/showthread.php?p=326...=yuv#post32682

I made it so you can see the difference it would make if your going to project film onto the big screen in the best case scenario, and so we can do a quick comparison. Many, not all, computer displays images as 72 dpi. A 40’ wide theater screen is 1920 dots per 480 inches (4 dpi).

But don’t just blow it up 18 times because the viewer will be 30’-50’ away while you’re sitting 2’ from the computer screen, so it’s going to appear more like 200% bigger. (Matthew at DV Film Transfer also compares at 2 times bigger.)

I selected/enlarged portions of the pictures that are directly comparable and have good detail.

First an HD video grab:


Then an MJPEG grab:


Then a BM Intensity direct capture grab:


You can draw your own conclusions. In my eye the BM intenstiy grab has the most detail, but the detail in some respects highlights the blockiness of the pixels. However, if you are using a DOF adapter you are projecting the light image onto the GG screen, which will vibrate and shift the grain similar to what film grain does.

Also, the MJPEG grab looks brighter to me. I don't know why.

The HDV grab is also a tad flatter in my view and if you use the DOF adapter it will be even more blurred.

It's not a matter of good or bad, it's knowing the difference so you can make an informed choice.

Duke

[lordtangent]

Another advantage of grabbing 4:2:2 is you simply have more to work with in post. The bandwidth of video is narrow enough to begin with there is no reason to cut it down even further with 4:2:0 is it can be avoided. Also, there is the issue of interlaced 4:2:0 with HDV, which depending on how you look at it cuts the chroma in half again, especially on really fine details.

Unfortunately Intensity capture is not very convenient most of the time.

[ocoeeshooter]

Duke, that was a big help, much clearer than the manual. Thanks for taking the time.

[africanmarty]

brilliant though one thing when i do this, at times the lowest fstop i gan get is f2.8 and not f1.8 ! anyone know why ?? is it the the light source i'm pointing it at is too dull/bright ?? it still stops the gain but i would like extra f stop for some more light! (as i would be using it will a 35mm adaptor) any pointers ??? great tut - Marty.

[Ian-T]

Marty, It definately has to be your light source. That has happened to me before...but my new cellphone keeps it at f1.8 now.

[Duke]

I find my LCD computer screen works better, but of course it's not portable. My cell phone is just a little too dim. I'm going to look at making an LED lens cap.

Duke

[africanmarty]

Originally Posted by John (the Duke) Wayne

I find my LCD computer screen works better, but of course it's not portable. My cell phone is just a little too dim. I'm going to look at making an LED lens cap.

Duke

ok sweet thanks. BTW if you do this ( and lock it at f1.8 ) and take it into a dimly lit room in theory it should just be dark without grain right ??

EDIT: answered my own question YES and with GREAT RESULTS !!! thanks this is so simple yet SO0o effectvie !!! thanks all.

[Chuck]

OK, I finally got my SD card and started playing. I have to admit after reading all the tutorials, watching the video, etc, I'm a bit confused. Here are my results from 2 different light sources. I'm really not sure what to look for here since I have no way of viewing the actual gain. I think I do, but not 100%.

palm pilot on a blank memo as light source:
-11 5.2 1/60
-10 4.8 1/60
-9 4.4 1/60
-8 4.0 1/60
-7 3.7 1/60
-6 3.4 1/60
-5 3.2 1/60
-4 2.8 1/60
-3 2.6 1/60
-2 2.4 1/60
-1 2.2 1/60
0 2.0 1/60
+1 1.8 1/60
+2 1.8 1/60
+3 1.8 1/60
+4 1.8 1/60
+5 1.8 1/60
+6 1.8 1/60
+7 1.8 1/60
+8 1.8 1/60
+9 1.8 1/60
+10 1.8 1/60
+11 1.8 1/60

Does this mean the maximim I can use is +1 before gain kicks in?

Next I used the cell phone and got this (not as bright):

-11 5.6 1/60
-10 5.6 1/60
-9 5.6 1/60
-8 5.6 1/60
-7 5.6 1/60
-6 5.6 1/60
-5 5.6 1/60
-4 5.6 1/60
-3 5.6 1/60
-2 5.2 1/60
-1 4.8 1/60
0 4.4 1/60
+1 4.0 1/60
+2 3.7 1/60
+3 3.4 1/60
+4 3.2 1/60
+5 2.8 1/60
+6 2.6 1/60
+7 2.4 1/60
+8 2.2 1/60
+9 2.0 1/60
+10 1.8 1/60
+11 1.8 1/60

Am I doing this right? Which light source is best, the one that gives me almost full range up to +10, or the brighter one? Do you always stop after the 1.8 starts to repeat itself?

Thanks for all the tips!

[Duke]

It depends on what you plan to do, but the palm pilot looks like it will allow you a wider range of options. Don't forget, the trick doesn't give you the correct exposure, it just shut off the gain. You still need to set the exposre within the range you have alotted yourself with the trick.

Have zebra turned to 70%. Do the trick, and then point the camera at the scene you want to shoot. Adjust the EXP + or -.

If there are a lot of zebra areas showing up, the exposure is high enough it'll blow out the highlights. Too little light and it will be too dark overall and blacks are overwhelming.

Also, there are some advantages to using the wider open aperture settins f1.8to 2.8. They give more DOF, better highlights, etc.

Between those two extremes is the art part of filming. What mood do you want? Film noir? or Mary Popins? That's the fun part.

Duke

[Chuck]

Ok, so at what point does the gain start to kick in on the palm range? after the 1st 1.8? Everything after that it goes up 1.5db? That's how I interpreted it from the video tutorial.

[Duke]

Originally Posted by Chuck

Ok, so at what point does the gain start to kick in on the palm range? after the 1st 1.8? Everything after that it goes up 1.5db? That's how I interpreted it from the video tutorial.

I think you're mixing terms and concepts. If you've locked the exposure, gain (electronic signal amplification causing degradation) doesn't kick in. Ever. That's the point of all this.

1.8 is the wide opening aperture setting. DOF and light exposure are controlled in part by the aperture. Turn on your lights and move your EXP + or - as necessary to get enough light but avoid zebra/overexposure.

There's a link to a tutorial on here somewhere on the interaction of DOF, shutter speed, aperture size and exposure.

Hope that helps,
Duke

[pixelvoodoo]

Here's a stupid question. If I am in the middle of a shoot and the camera powers down or is shut off I have to do this all over again?

[Duncan Craig]

[QUOTE= I’m sorry, but I just couldn’t follow the UK accent in the video tutorial on my non-amplified speakers. [/QUOTE]

As far as I can tell he's a Kiwi!

[Banacek]

Ok..

Anyone can upload to vimeo (for example) a video where the rest of non-experienced users can see the real difference between with or without aperture tricks?

Its really noticiable the difference on footage? Its really make a FILM LOOK?

Will be great to see a difference in the same shot, same scene with this differents settings.

Thanks...

[Vennegoor]

Take a look at this movie:

http://www.vimeo.com/404844

It will show the difference in the dark, it is huge!

[Dennis Vogel]

Originally Posted by pixelvoodoo

Here's a stupid question. If I am in the middle of a shoot and the camera powers down or is shut off I have to do this all over again?

I believe I read in another thread that the settings are *not* maintained over power down/up. You will have to redo the whole thing if your power down.

Good luck.

Dennis

[Dennis Vogel]

Originally Posted by mrob7

Toward the end you said:

"2. Set to TV mode, 48fps, fully zoomed out"

Don't you mean "Set to TV mode 48 (shutter speed), fully zoomed out"

Did this get answered? I may have missed it. Will the article be updated?

Just thought i'd mention it...

Otherwise great tut!

Indeed! I intend to print this out and stick it in my cam bag.

Good luck.

Dennis

[Dennis Vogel]

A couple of typos I have questions about.

Originally Posted by Duke

There are two main modes to control what we want to control.

1) Tv mode (shutter priority), which allows you to manually control the shutter speed, but doesn’t allow you to directly control the gain or f-stop. Once the mode is selected you and joystick down.

Is there a word missing in the bold part above?

Or

2) Cine mode. Cine mode tries to be fully automatic but has a gamma curve that tries not to blow out highlights or crush blacks, overall it seems darker though. CINE mode will ‘try’ to go to 1/48 at 24p. Once the mode is selected you and joystick down.

And again here?

Thanks for doing this great tutorial.

Good luck.

Dennis

[robpowers3d]

Dennis,

I think it should read something like this:

"Once the mode is selected you joystick down to select exposure, point the camera at the light source, then joystick up to lock the exposure."

Hope that helps.

Rob Powers

[Dennis Vogel]

That makes sense.

Good luck.

Dennis

[KBLOCK]

How much can I get an SD card for? Where should I get one? Is it really worth it at the end of the day? I'm a bit of a camera noob, what does manually controlling the apature and gain get me out of the HV20?'

thanks

[Dennis Vogel]

Originally Posted by KBLOCK

How much can I get an SD card for? Where should I get one?

Just about any electronics store. I just quickly checked B&H and I see 1 GB cards from $7.95 up. Prices in stores should be close to that.

Is it really worth it at the end of the day? I'm a bit of a camera noob, what does manually controlling the apature and gain get me out of the HV20?'

Better quality video since you can stop the cam from adding gain which results in lower quality video.

Good luck.

Dennis

[Duncan Craig]

I just wanted to chime in here, as I've just got around to testing this exposure lock tonight.
Firstly I've got a 2GB, 3in1 micro/mini/standard SD card from Amazon UK: http://www.amazon.co.uk/exec/obidos/ASIN/B000R9YIFC (which has just come another pound ($2) since I ordered it - bugger!) Anyway, it works well...
So I'm filming in movie mode on the PAL HV20, in shutter priority. With the shutter on 1/25th - I'm monitoring on my new LG 50 inch plasma via HDMI and there's no visual difference (apart from the extra stop of sensitivity) while fast panning/zooming/shaking between 1/50th and 1/25th, which to me seems obvious as the imager is being clocked at 1/25th anyway.

It may have been discussed already elsewhere, but I believe there's a really easy way to get better control over this lock down business, no Zebras, no mobile phone, LEDs nothing. I've just seen that almost the same numbers where listed above, but the significance was missed.

And that is to lock at f4.8. THATS IT. The magic number sweetspot.

As before, put the camera in TV mode, and full wide.

Just hold the camera up to a bright light source, partly depress the photo button and check it's at f4.8 if not move towards or away from the light source until it is. Then lock it. Now if you adjust the exposure up to +10 it will be at f2.0, go to +11 it will be at f1.8, So no gain at full exposure.

(This assumes the camera wasn't adding gain when I locked it at f4.8, which it couldn't have right? I'm happy to be proved wrong here.)

Anyway the numbers are:

+11 f1.8
+10 f2.0
+9 f2.2
+8 f2.4
+7 f2.6
+6 f2.8
+5 f3.2
+4 f3.4
+3 f3.7
+2 f4.0
+1 f4.4
0 f4.8
-1 f5.2
-2 f5.6
-3 f5.6
-4 f5.6
-5 f5.6
-6 f5.6
-7 f5.6
-8 f5.6
-9 f5.6
-10 f5.6
-11 f5.6

Please note: Although the readout is stuck at f5.6 all the way from -2 down to -11 there is still a huge drop in exposure happening over that range. Every single adjustment over the range of +11 to -11 has an affect on the exposure.

Perhaps the camera is applying negative gain (attenuation) like some full size cameras offer.

Basically it's one number off from Chuck's cell phone number sequence above (I only noticed the similarity after writing all this up) I've checked this still works in 50i mode with 1/50 too!

Anyway, it's my first offering here and hopefully it's right for you guys too.

Just to say - I earn a living as a cameraman/editor normally with a Z1 and the pictures from this little camera are amazing. It's late now, must sleeeeppp.