HD100 ASA rating? at DVinfo.net

Jay Kavi · February 1st, 2007, 02:10 AM

Has anyone done a test to find the ASA rating of the HD100? The rating or the process to find it would be great! or is it even worth doing?

Stephan Ahonen · February 1st, 2007, 07:19 AM

I've never had to bother figuring out the ASA of a camera, because of the feedback you get in the viewfinder for exposure. Just turn the iris ring till the picture looks good. A light meter can still be useful for ensuring even lighting in your scene, though.

David Parks · February 1st, 2007, 08:56 AM

On these boards I have read that most people are rating it at ISO 320. However, I talked with Robert Yarosh, a JVC Sales Engineer just last week here and he said it actually can rate faster at a baseline ISO 400. Of course I imagine it depends on if you're using stock lense, relay lense etc. And what sort of look you're going for.

Joshua Clarke · February 1st, 2007, 09:23 AM

Jay, in my opinion David and Stephan both have it right. I've set my meter to 320 ASA to get a "general" reading, but I use it mostly for ratios. What I also do is set my Zebra to 60%-70%, and adjust the iris until the zebra starts creeping in on the key side of a face. Of course that's all dependent on what you're shooting, but it's a good place to start to combine a lightmeter and the Zone System.

Jay Kavi · February 1st, 2007, 04:53 PM

Sweet! thanks ya'll. I shot a music video over the weekend and the DP was rating the camera at 200asa (stock lens w/ the color reversal setting). I only saw the LCD and it looked blown out, but the images look correctly exposed on my CRT and SD TV. I'll do some tests with that zebra setting and asa.

Matt Setnes · February 1st, 2007, 05:21 PM

I did a test and I get anywhere from 250 to 320. I never gotten anything as high as 400. That seems to be a little high

Stephan Ahonen · February 1st, 2007, 10:36 PM

Probably the best way to judge is to set your zebras for 50% and expose an 18% grey card so it's just barely getting zebras. Assuming a flat gamma curve (you would need a chip chart and waveform monitor to verify this, and unfortunately full chip charts can be pricy) you should end up with a fairly accurate idea of what your ASA rating is.

Of course the lattitude of a video camera is small enough that you can't really depend on a light meter to tell you exactly how you should expose unless you've figured out how you can apply the zone system to this camera. Otherwise, you really have to just eyeball it on a scene-by-scene basis.

John Vincent · February 2nd, 2007, 09:51 AM

Quote:

Originally Posted by Matt Setnes

I did a test and I get anywhere from 250 to 320. I never gotten anything as high as 400. That seems to be a little high

I agree, too high...

john
evilgeniusentertainment.com

Tim Dashwood · February 2nd, 2007, 10:45 AM

Quote:

Originally Posted by Matt Setnes

I did a test and I get anywhere from 250 to 320. I never gotten anything as high as 400. That seems to be a little high

It really all depends on how the gamma controls are configured. It can range anywhere from 100ASA with the gamma turned down to as high as 640ASA with the gamma cranked all the way to max.

Typically though, I would rate NORMAL gamma (cine) at around 250ASA.

Cecil Searcy · February 3rd, 2007, 10:42 AM

At a flat gamma (non-cine) at 30p I got an ASA of just under 400...but that was on my 110

Jemore Santos · February 21st, 2007, 03:00 AM

Are there any official ASA Ratings from JVC?

Amos Kim · March 4th, 2007, 09:43 PM

how would one measure the asa for a given scene file?

February 1st, 2007, 02:10 AM	#1
Jay Kavi Major Player Join Date: Aug 2005 Location: San Francisco, CA Posts: 243	HD100 ASA rating? Has anyone done a test to find the ASA rating of the HD100? The rating or the process to find it would be great! or is it even worth doing?

February 1st, 2007, 08:56 AM	#3
David Parks Major Player Join Date: Feb 2006 Location: Houston Posts: 789	On these boards I have read that most people are rating it at ISO 320. However, I talked with Robert Yarosh, a JVC Sales Engineer just last week here and he said it actually can rate faster at a baseline ISO 400. Of course I imagine it depends on if you're using stock lense, relay lense etc. And what sort of look you're going for. __________________ David Parks: DP/Editor: Jacobs Aerospace at NASA Johnson Space Center https://www.youtube.com/user/JacobsESCG

February 1st, 2007, 09:23 AM	#4
Joshua Clarke Regular Crew Join Date: Jul 2006 Location: Philadelphia, PA Posts: 88	Jay, in my opinion David and Stephan both have it right. I've set my meter to 320 ASA to get a "general" reading, but I use it mostly for ratios. What I also do is set my Zebra to 60%-70%, and adjust the iris until the zebra starts creeping in on the key side of a face. Of course that's all dependent on what you're shooting, but it's a good place to start to combine a lightmeter and the Zone System. __________________ Section 1 Films

February 3rd, 2007, 10:42 AM	#10
Cecil Searcy New Boot Join Date: Nov 2006 Location: Kansas City, MO Posts: 14	30p ASA At a flat gamma (non-cine) at 30p I got an ASA of just under 400...but that was on my 110

February 21st, 2007, 03:00 AM	#11
Jemore Santos Major Player Join Date: Oct 2005 Location: Tokyo/Sydney Posts: 297	Are there any official ASA Ratings from JVC? __________________ "eyes through a digital world"

February 1st, 2007, 07:19 AM	#2
Stephan Ahonen Major Player Join Date: Apr 2005 Posts: 512	I've never had to bother figuring out the ASA of a camera, because of the feedback you get in the viewfinder for exposure. Just turn the iris ring till the picture looks good. A light meter can still be useful for ensuring even lighting in your scene, though.

February 1st, 2007, 04:53 PM	#5
Jay Kavi Major Player Join Date: Aug 2005 Location: San Francisco, CA Posts: 243	Sweet! thanks ya'll. I shot a music video over the weekend and the DP was rating the camera at 200asa (stock lens w/ the color reversal setting). I only saw the LCD and it looked blown out, but the images look correctly exposed on my CRT and SD TV. I'll do some tests with that zebra setting and asa.

February 1st, 2007, 05:21 PM	#6
Matt Setnes Regular Crew Join Date: May 2006 Location: Chicago, IL Posts: 114	I did a test and I get anywhere from 250 to 320. I never gotten anything as high as 400. That seems to be a little high

February 1st, 2007, 10:36 PM	#7
Stephan Ahonen Major Player Join Date: Apr 2005 Posts: 512	Probably the best way to judge is to set your zebras for 50% and expose an 18% grey card so it's just barely getting zebras. Assuming a flat gamma curve (you would need a chip chart and waveform monitor to verify this, and unfortunately full chip charts can be pricy) you should end up with a fairly accurate idea of what your ASA rating is. Of course the lattitude of a video camera is small enough that you can't really depend on a light meter to tell you exactly how you should expose unless you've figured out how you can apply the zone system to this camera. Otherwise, you really have to just eyeball it on a scene-by-scene basis.

March 4th, 2007, 09:43 PM	#12
Amos Kim Major Player Join Date: May 2006 Location: San Francisco, CA Posts: 335	how would one measure the asa for a given scene file?