ASA rating for the DVX 100

Re: ASA rating for the DVX 100

Hey guys, forgive me for my ignorance.

Ok, I get the procedure to get the ASA reading. But, what do you do with it? What do you do with the ASA value? Are you going to control some lights or what?

What exactly is the point of getting this ASA reading?

All the best

Fidel.
 
Re: ASA rating for the DVX 100

If you're using a light meter, you need to know what the ASA/ISO value is in order to get accurate readings off the meter.

If you don't use a light meter (like 98% of videographers) then there's not really any NEED to know what it is, and no way to really use the info.
 
Re: ASA rating for the DVX 100

[quote author=Barry_Green link=board=news;num=1078944734;start=60#61 date=07/16/04 at 17:59:28]If you're using a light meter, you need to know what the ASA/ISO value is in order to get accurate readings off the meter.
[/quote]

Hi Barry, thanks for taking the time to answer that. Before I could ask you more questions, I went to read about this ASA/ISO stuff. Ok, now I know that it relates to film speed. So, would I be right to say that you take the reading to know what type of film to use? I am, obviously, taking about working with film, and not video.

Thanks in advance

Fidel.
 
Re: ASA rating for the DVX 100

Well, sort of. You either know what film stock you're going to use, in which case you use the meter to determine light levels, or you take the meter on location to check light levels, which can help you choose which film stock to use. That second usage is less common, but would be helpful information if, for example, you would be shooting in a place where you wouldn't be allowed to block the windows or bring in your own lights, etc. Under those circumstances you'd want to know the strength of the available light, which would dictate how fast a film stock you'd need to get satisfactory results.
 
Re: ASA rating for the DVX 100

Once again many thanks Barry. Looks like I am learning something after all.

You guys have been really great, and I am sure that soon I will come up with more questions to ask.

All the best

Fidel.
 
Re: ASA rating for the DVX 100

I thought I understood this thread, but then the ending stumped me.

I am reading two things:

One says 320 ASA at 24p and 640 at 60p
Another says 640 at 24p and 1280 at 60p (Barry's position, right?)

Or did I miss something?

(Which wouldn't be the first time.) I want to buy a light meter, and looked this topic up.

-Jerry
 
Re: ASA rating for the DVX 100

It is my position that it is 640ASA at 24P, and even more sensitive (1280 ASA) when switched to 60i. I know people disagree, which is fine, but I tested it every which way I could and always always always got readings that matched 640, so I don't see where the 320 is coming from...
 
Re: ASA rating for the DVX 100

Barry,

Do you see something inherently wrong in the testing in this earlier post by dpryke:

Here are my results: 640 ASA 60i, 320 ASA 24p. I set up a grey scale chip chart with two 300's cross keying. I got the same result with both my incident and spot meters. 60i f5.6 1/60 shutter 640 ASA. 24p f5.6 1/50 shutter 320 ASA. So what am I doing different than everyone else. I messed around for a couple of hours, same results every time. My next step is to borrow a Waveform to see if that makes a difference. I now have a headache and am going to bed...


-Jerry
 
Re: ASA rating for the DVX 100

This subject is confusing, that's for sure. Your testing methodology sounds fine, the only question I'd have is whether you had the autoexposure compensation set to zero (in 24P modes its default is -3, which is a half-stop underexposure built-in).

I did just what you said, and got readings of 640, which was quite surprising. I then took the camera to about 30 different locations and situations, outdoors, indoors, bright light, low light, sunlight, shade, anything and everything. I referenced every shot by using the spotmeter (since the DVX is a reflected-light meter) and consistently got readings of 640. Then I had someone else double-check me, with his own spotmeter, and he got 640 as well. Then Jarred still questioned whether I was sane, so he set up a test and shot with a 400-ASA digital still camera at a fixed f-stop (f/5.6 I think) and the DVX pointing at the same scene at the same f-stop and shutter speed, so the only difference in exposure would be the speed sensitivity of the DVX... and the DVX picture was noticeably brighter.

So I'm pretty sold on the idea of it being 640, but you and MichaelP have both reported 320. The only thing I can think of is that maybe you guys had the autoexposure bias set to -3, which would cost you half a stop (and put it at an actual 480 ASA) and then the DVX's iris is delineated in half-stops, so maybe there's a half-stop variation between the readout of the spotmeter and the DVX meter...
 
Re: ASA rating for the DVX 100

Barry,

Just to be clear, I pasted the post by:

dpryke.

It was *not* me that did the test. It just sounds very thorough, and I really wonder why you and dpryke are getting different results. I'm pretty surprised to hear of a 1200+ ASA reading in 60i mode, but that is great!

-Jerry
 
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