ASA rating for the DVX 100

Re: ASA rating for the DVX 100

This is the method I learned in Electronic Cinematography at the Maine Photographic Workshop. The course was taught by Peter Fasciano. You might recognize his name from the ASC article reviewing the DVX. The following is from the course book.

Step 1
Set up a standard chip chart. Make sure the chart is evenly illuminated across the entire frame. The chart, lens and lights should all be at the same level.

Step 2
Verify the incident illumination level across the surface of the chart.

Step 3
The camera should be white balanced, the focal length set to fill the frame with the chip chart, and its aperture set manually to provide a video level of 90 to 100 IRE units on the waveform from the brightest chip.

If you don’t have a waveform I set the iris until there is no 100 zebra pattern on the white chips.

Step 4
The shutter speed on the light meter should be set to 1/30 of a second. Video cameras take 30 frames per second. Since they normally have no shutters like film cameras, the exposure time and frame rate are the same. Read the aperture setting on the camera. The ISO dial on your meter should be set so the aperture reading of the meter matches the lens.

This is the method I have always used to get an ASA setting for non 24p cameras. Give it a try. I will be soon and I will let everyone know my results. When this was written, video cameras did not have variable speed shutters. So, that may change things a bit.
 
Re: ASA rating for the DVX 100

We checked it tonight with my Minolta spot meter. sure enough....640ASA. Cool.
 
Re: ASA rating for the DVX 100

The one thing I love about this site is how a simple question of ASA can get everyone involved. It is great to have a combined source of knowledge like this. One question, how is everyone doing this test. Everything I have read says use a grey scale chip chart. Using a white piece of paper does not give you an average. I am doing a test tonight with a chip chart and an incident and spot meter. I also saw this article:

http://www.kenstone.net/fcp_homepage/over_under_expose_video.html

See what you think.
 
Re: ASA rating for the DVX 100

We shot gray, we shot colors, we shot indoors and outdoors, bright light and dim light, raw sky, walls, tungsten, daylight, fluorescent, high shutter speeds, slow shutter speeds, anything and everything I could think of.

It always came back as 640.
 
Re: ASA rating for the DVX 100

Actually, I'm not so surprised.

Over the years, I've shot lots of 35mm stills of sets during video shoots for behind-the-scenes pics.

In particular, our news desk anchor positions would average 120 to 130 footcandles of light.

When photographing the set (complete with anchors), I would usually push the film to 800 or 1600 ASA.

Sometimes, however, I would expose it at 400 ASA. Whenever I did, I had the camera on tripod and used 1/30th sec. shutter speed (to approximate video frame rate) and would be wide open @ 2.8 and the images would usually be a bit underexposed.

My point? It seems even the old tube cameras (RCA TK-47) we used yielded a slightly better f-stop with no gain than did 400 ASA Tri-X.

Of course, I didn't break down and do all the tests on those TK-47s like BG & FM58 did with the DVX. So, I don't know the exact ASA of those cameras.

Anyhow, I had always assumed any DV camera since the VX1000 was capable of better than 400 ASA (without gain).

This has me wondering what the ASA rating is for the "Low Light Champion" PD150?
 
Re: ASA rating for the DVX 100

It should be better than 800. In my tests with the DVX, I found that you get about a stop better sensitivity in interlaced mode, which put it (verified with similar, though much less extensive testing) at somewhere between 800 and 1280. Since the PD150 doesn't have a usable progressive mode, it will have the benefit of line-pair summation in interlaced, and should therefore deliver 640-800.

Hey Pat, how 'bout running the test on Bart's VX2000?
 
Re: ASA rating for the DVX 100

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...
 
Re: ASA rating for the DVX 100

This is the first day that I have looked at this site... and I have to say that it's great... I just love this ASA debate... Kodos to Barry and all... you guys all sound really great... except for the guy who started the whole mind-bender... The grey card, spot meter sounds like the best bet... I have been shooting for over 10 years now mostly film and I just love this website and everyones style... I own an XL and just recently saw some stuff shot on the DVX and I was amazed... thinking about dumping it and getting a DVX???...
thanks guys for all the great debates and good luck in all of your shooting... :)
 
Re: ASA rating for the DVX 100

welcome Natykas.. and we will see you on the dark side soon :)
 
Re: ASA rating for the DVX 100

You guys are awesome, It just so happends that this past weekend I was filmimg at a high power model rocket launch sponsored by our group (Buffalo Rocket society.org). There was a writter and photographer from Popular Science magazine covering the event as well.

When the photograpgher seen my DVX he says nice camera, I have one too and use it all the time in his line of work. I was like how cool, I hope he is ready to answer a few questions then, because I love to learn about the power of the DVX.

So he was getting ready to take a photo of this 100 lb model rocket and I was along side of him shooting video. He measured the light with a Sekonic meter and right away I was like can I use that for the DVX as well. He says sure and switches it to 24fps and give me a reading. It was too simple I had to ask more ??? but as the days went by I did not get to spend much time with them because I was too busy helping running the launch.

So today I went and bought the Sekonic L-358 wasn't sure what to set the ASA to, Forgot to ask that all important question. So before I bought one I decided to ask here first. I was positive DVXuser.com would have the answer. Sure enough, I did not have to look far down the list of topics. You guys are awesome.

I'm sure I will be asking some questions in the next few days, untill then keep up the great work.

Ray
 
Re: ASA rating for the DVX 100

Whenever I shoot on the Sony F900 24p I do in-house camera tests to check the ASA. Cus every camera's different. You can do the test on Prosumer cameras as well... I think (never tried it, don't see why not). I just set my light meter to 320 for all video. Hopefully someday you guys will get to shoot 100asa 35mm. It is amazing...
 
Re: ASA rating for the DVX 100

Ok all, so I am now an owner of a Sekonic L-358 exposure meter w cine settings for 24 fps. If I read all the posts correctly I believe I would set the ASA to 640 in 24 fps using 1/60th shutter to get a rough exposier estement?

Ray
 
Re: ASA rating for the DVX 100

[quote author=waycooljr link=board=news;num=1078944734;start=45#51 date=07/12/04 at 18:28:52]Ok all, so I am now an owner of a Sekonic L-358 exposure meter w cine settings for 24 fps.  If I read all the posts correctly I believe I would set the ASA to 640 in 24 fps using 1/60th shutter to get a rough exposier estement?

Ray [/quote]


Set the ISO to 640.  Hold down the Mode button and spin the control wheel until you get the Sun (daylight) and the T (shutter speed) selected.  Then spin the control wheel until you get past the fast shutter speeds and stop when you get to 24 fps.  The shutter speed equivalent will be 1/48 of a second--plenty close to the 1/50 default speed of the DVX at 24P.
 
Re: ASA rating for the DVX 100

[quote author=Barry_S link=board=news;num=1078944734;start=45#52 date=07/12/04 at 18:57:39]


Set the ISO to 640.  Hold down the Mode button and spin the control wheel until you get the Sun (daylight) and the T (shutter speed) selected.  Then spin the control wheel until you get past the fast shutter speeds and stop when you get to 24 fps.  The shutter speed equivalent will be 1/48 of a second--plenty close to the 1/50 default speed of the DVX at 24P.[/quote]

Ok I'm set there, now for the lumisphere. Should it be in the in or out position. Not sure the differance between each.

Ray
 
Re: ASA rating for the DVX 100

The lumisphere should be out unless you're trying to measure individual light sources.
 
Re: ASA rating for the DVX 100

OK, one last question, Whats the best way to take th ereading? Do I point it towards the camera from the subject or at the subject from the camera? Almost wondering if I should have got the spot version instead.

Ray
 
Re: ASA rating for the DVX 100

hold it at the talents face bulb pointing to the camera. make sure your not standing/blocking the light source.
 
Re: ASA rating for the DVX 100

The lumisphere will measure the light that is falling on the subject, so you want to put it right basically where the subject is, and as Jarred says, make sure you're not blocking the light!
 
Re: ASA rating for the DVX 100

Thanks Barry and Jarred, I think this will make for a great tool, giving me a starting point from which to work from.

Ray
 
Re: ASA rating for the DVX 100

I am a cinematographer, meaning the majority of what I shoot is on 35mm. I had the same question as you, so I set up an Arri BL III and a DVX 100a. I then meteredon an 18% grey card. The comparison is just about what the guys are telling you. If you want to use a light meter 320 ISO will give you perfectly good results. Now mind you this was in a controlled invironment. Not all scenes are composed of 18% grey objects. If you have any guuestions about the grey scale go to your local book store and pick up a copy of Ansel Adams book on grey scales. Good luck.
 
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