Hv20 Ei/asa/iso at DVinfo.net

Rob Robinson · May 10th, 2007, 06:41 PM

Does anyone know what the EI/ASA/ISO is for the HV20? Or how you would determine it?

Bonus round - and once you do know it how do you effectively use it when lighting a scene?

Thanks!

Rob Robinson

Rob Robinson · May 10th, 2007, 07:00 PM

I found this...

1. Frame up a gray card.
2. Activate the camera's auto iris. It will adjust the iris to provide an exposure that's equivalent to middle gray. Some cameras allow you to add over or under exposure compensation to this function so make sure you normalize this setting first.
3. Set the appropriate shutter speed on your light meter. Hold the meter against the gray card and face the white sphere towards the camera. Read the light level.
4. Adjust the ASA setting on the meter until the iris reading on the meter matches the iris reading on the camera. This is your ASA.

So can someone (who has a gray card) do this?

Brian Tori · May 10th, 2007, 07:35 PM

The problem with the HV 20 and finding a ISO level is that the camera in TV or locked shutter mode, does not display F-stops. This makes it difficult to find the measurement in conjunction with a meter.

Brandon Svec · May 10th, 2007, 07:47 PM

Quote:

Originally Posted by Brian Tori

The problem with the HV 20 and finding a ISO level is that the camera in TV or locked shutter mode, does not display F-stops. This makes it difficult to find the measurement in conjunction with a meter.

Try half pressing the photo button. It should show on the display.

Rob Robinson · May 11th, 2007, 05:04 AM

Quote:

Originally Posted by Brandon Svec

Try half pressing the photo button. It should show on the display.

Yes this will work for sure (I think I was the one who first discovered this):

http://www.dvxuser.com/V6/showpost.p...&postcount=139

I would expect to lock the shutter for this test (TV mode) to 1/48 and then use the PHOTO button and joystick to toggle the various iris settings to get the F-stop of the camera.

Brian Tori · May 11th, 2007, 04:48 PM

Thanks for the tip. I will try this soon.

Barry Green · May 11th, 2007, 09:06 PM

That does work, but ONLY if you have a mini-SD card installed. With no card present, you get no shutter/iris display, it only shows a red "no card" icon. But if you have a mini-SD card in, half-pressing the photo button will show you the current shutter and iris. And yes, it does work after locking the EXP, so you can adjust the dial and check and re-check your current shutter & iris by doing this.

Brian Tori · May 12th, 2007, 07:46 AM

I have a miniSD card on the way. So did anyone find the EI of the cam yet?

Rob Robinson · May 12th, 2007, 08:54 AM

Quote:

Originally Posted by Brian Tori

I have a miniSD card on the way. So did anyone find the EI of the cam yet?

Thanks Brian, btw what light meter do you plan to use? I'm looking to get one. Also what "gray card" will you use (who makes it - product #, etc..?)

Thanks!

Rob Robinson

Rob Robinson · May 15th, 2007, 11:03 AM

I purchased a Gossen DigiPro F light meter and created an 8.5" x 11" 18% gray card (from my printer with RGB of 119,119,119) and then lit a scene such that the aperture on the HV20 ( in TV mode and EXP at +0 ) read 2.8 with a shutter of 1/48. Then I adjusted the ISO setting on the light meter until it matched the iris/shutter of 2.8 and 1/48. The ISO setting that matched was 1600. Does this sound right?

Noah Yuan-Vogel · May 15th, 2007, 02:05 PM

No, that is definitely not right. I did a quick test with my Nikon D50 as a light meter and it looked like the number should be more like iso 200 for cine 24p at 1/48 f2.8. thats really really estimated though. My guess is somewhere between 100 and 300. Probably closer to 100. I've been meaning to do a real test but i havent had time nor do I have all the items I need to do an accurate test. I might be able to do it a bit more carefully but itll probably still just be in relation to my DSLR's iso ratings.

Rob Robinson · May 15th, 2007, 03:14 PM

I'm clearly no expert on these matters, but wouldn't it be reasonable that the D50 has a different light sensitivity than the HV20? One of the claims of the HV20 is that it performs well in low-light situations. Why wouldn't 1600 be acceptable?

I may go and buy a "real" gray card tommorrow and try the test again. Although I can't imagine it making that much of a difference - but maybe...

EDIT: I just re-read your post and I think I understand now what you are saying. A "proper exposure for 1/48 2.8 *is* an ISO of 200 (100-300). So if I had to set the meter to 1600 then something must have been wrong with my setup?

Anybody else have a gray card and a light meter to test this?

Thanks!

Rob Robinson

Barry Green · May 15th, 2007, 04:03 PM

The HV20 certainly doesn't have much sensitivity. When people talk about "low light", the question has to be based around not only sensitivity but also grain/noise. If you lock the HV20 at 0dB of gain, it looks like it's probably three stops darker than a DVX at 0dB of gain, which would put its ISO in the neighborhood of about 100.

If you just point the camera at a dark scene, recognize that the auto gain is going to kick in, and it can kick in ferociously. I've seen it at 27dB.

So, what's the definition of low light performance? Is it "brightness at any cost"? Or is it "brightness level at a rational noise level"? Or is it "brightness with 0dB of gain"? Once you narrow down what definition you are comfortable with, we can get a better answer. The definition I normally use is "brightness at 0dB", and by that measure my eyeball/yardstick guess is about 100.

Rob Robinson · May 15th, 2007, 05:39 PM

Quote:

Originally Posted by Barry Green

So, what's the definition of low light performance? Is it "brightness at any cost"? Or is it "brightness level at a rational noise level"? Or is it "brightness with 0dB of gain"? Once you narrow down what definition you are comfortable with, we can get a better answer. The definition I normally use is "brightness at 0dB", and by that measure my eyeball/yardstick guess is about 100.

I like "brightness at 0db" definition the best - seems more objective. My goal in finding the ISO of the HV20 is so that I can then set the light meter to then check light settings for a scene knowing that I want to use a fixed shutter with an aperture sufficient enough so that I don't need any gain from the camera. For example what EV do I need from the meter in order to have a shutter of 1/48 and an aperture of 2.2 (mid-zoom) and no gain. If I find that the EV on the meter is too low then I'll add more light, etc... But in order to any of this reliably I need to know what the ISO of the camera is first. And finding that seems to be elusive at the moment...

Brian Tori · May 15th, 2007, 06:07 PM

Rob,

The meter I use is a Minolta Autometer III, which has been properly calibrated by a meter company. The gray card I use is made by Kodak and is 18%.

Once my sd card arrives I will do a test with the HV20. Hopefully I can test this weekend.

Your rating does sound a bit high at 1600. It may be that your meter is off a bit.

The last camera I rated was a standard def JVC DV300. This cam has 3 1/3" chips. The rating I found was between 800 and 1000 ASA or EI. I found this cam to be as sensitive or even a bit more than the PD-150 which is known to be a sensitive cam.

I do not expect the HV20 to be this high considering its single chip and high res.

Will keep you posted.

May 10th, 2007, 06:41 PM	#1
Rob Robinson Regular Crew Join Date: Mar 2007 Location: Cape Elizabeth, Maine Posts: 31	Hv20 Ei/asa/iso Does anyone know what the EI/ASA/ISO is for the HV20? Or how you would determine it? Bonus round - and once you do know it how do you effectively use it when lighting a scene? Thanks! Rob Robinson

May 10th, 2007, 07:00 PM	#2
Rob Robinson Regular Crew Join Date: Mar 2007 Location: Cape Elizabeth, Maine Posts: 31	I found this... 1. Frame up a gray card. 2. Activate the camera's auto iris. It will adjust the iris to provide an exposure that's equivalent to middle gray. Some cameras allow you to add over or under exposure compensation to this function so make sure you normalize this setting first. 3. Set the appropriate shutter speed on your light meter. Hold the meter against the gray card and face the white sphere towards the camera. Read the light level. 4. Adjust the ASA setting on the meter until the iris reading on the meter matches the iris reading on the camera. This is your ASA. So can someone (who has a gray card) do this?

May 10th, 2007, 07:35 PM	#3
Brian Tori Major Player Join Date: Nov 2004 Location: Detroit, MI Posts: 408	The problem with the HV 20 and finding a ISO level is that the camera in TV or locked shutter mode, does not display F-stops. This makes it difficult to find the measurement in conjunction with a meter.

May 11th, 2007, 04:48 PM	#6
Brian Tori Major Player Join Date: Nov 2004 Location: Detroit, MI Posts: 408	Thanks for the tip. I will try this soon.

May 11th, 2007, 09:06 PM	#7
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	That does work, but ONLY if you have a mini-SD card installed. With no card present, you get no shutter/iris display, it only shows a red "no card" icon. But if you have a mini-SD card in, half-pressing the photo button will show you the current shutter and iris. And yes, it does work after locking the EXP, so you can adjust the dial and check and re-check your current shutter & iris by doing this.

May 12th, 2007, 07:46 AM	#8
Brian Tori Major Player Join Date: Nov 2004 Location: Detroit, MI Posts: 408	I have a miniSD card on the way. So did anyone find the EI of the cam yet?

May 15th, 2007, 11:03 AM	#10
Rob Robinson Regular Crew Join Date: Mar 2007 Location: Cape Elizabeth, Maine Posts: 31	I purchased a Gossen DigiPro F light meter and created an 8.5" x 11" 18% gray card (from my printer with RGB of 119,119,119) and then lit a scene such that the aperture on the HV20 ( in TV mode and EXP at +0 ) read 2.8 with a shutter of 1/48. Then I adjusted the ISO setting on the light meter until it matched the iris/shutter of 2.8 and 1/48. The ISO setting that matched was 1600. Does this sound right?

May 15th, 2007, 02:05 PM	#11
Noah Yuan-Vogel Major Player Join Date: Dec 2004 Location: New York City Posts: 613	No, that is definitely not right. I did a quick test with my Nikon D50 as a light meter and it looked like the number should be more like iso 200 for cine 24p at 1/48 f2.8. thats really really estimated though. My guess is somewhere between 100 and 300. Probably closer to 100. I've been meaning to do a real test but i havent had time nor do I have all the items I need to do an accurate test. I might be able to do it a bit more carefully but itll probably still just be in relation to my DSLR's iso ratings.

May 15th, 2007, 03:14 PM	#12
Rob Robinson Regular Crew Join Date: Mar 2007 Location: Cape Elizabeth, Maine Posts: 31	I'm clearly no expert on these matters, but wouldn't it be reasonable that the D50 has a different light sensitivity than the HV20? One of the claims of the HV20 is that it performs well in low-light situations. Why wouldn't 1600 be acceptable? I may go and buy a "real" gray card tommorrow and try the test again. Although I can't imagine it making that much of a difference - but maybe... EDIT: I just re-read your post and I think I understand now what you are saying. A "proper exposure for 1/48 2.8 is an ISO of 200 (100-300). So if I had to set the meter to 1600 then something must have been wrong with my setup? Anybody else have a gray card and a light meter to test this? Thanks! Rob Robinson

May 15th, 2007, 04:03 PM	#13
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	The HV20 certainly doesn't have much sensitivity. When people talk about "low light", the question has to be based around not only sensitivity but also grain/noise. If you lock the HV20 at 0dB of gain, it looks like it's probably three stops darker than a DVX at 0dB of gain, which would put its ISO in the neighborhood of about 100. If you just point the camera at a dark scene, recognize that the auto gain is going to kick in, and it can kick in ferociously. I've seen it at 27dB. So, what's the definition of low light performance? Is it "brightness at any cost"? Or is it "brightness level at a rational noise level"? Or is it "brightness with 0dB of gain"? Once you narrow down what definition you are comfortable with, we can get a better answer. The definition I normally use is "brightness at 0dB", and by that measure my eyeball/yardstick guess is about 100.

May 15th, 2007, 06:07 PM	#15
Brian Tori Major Player Join Date: Nov 2004 Location: Detroit, MI Posts: 408	Rob, The meter I use is a Minolta Autometer III, which has been properly calibrated by a meter company. The gray card I use is made by Kodak and is 18%. Once my sd card arrives I will do a test with the HV20. Hopefully I can test this weekend. Your rating does sound a bit high at 1600. It may be that your meter is off a bit. The last camera I rated was a standard def JVC DV300. This cam has 3 1/3" chips. The rating I found was between 800 and 1000 ASA or EI. I found this cam to be as sensitive or even a bit more than the PD-150 which is known to be a sensitive cam. I do not expect the HV20 to be this high considering its single chip and high res. Will keep you posted.