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100 asa VS 200 with 1 stop overexposure


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#1 Edgar Dubrovskiy

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Posted 14 May 2009 - 06:40 PM

Hi guys!

What will, in your opinion and experience, give a finer grain on 16mm?
shooting 100 asa, rating 100 asa.
shooting 200 asa, overexposing it a stop and bringing it down in telecine.

The stocks used, most probably will be: Vision2 7212 100T and Vision2 7217 200T.
The final project will be going straight to 2K scan, no print.

I will do tests hopefully next week, and post the results.
But just out of curiosity - is there even a point doing this?
Will I get a finer grain out of overexposing and then pulling back, than simply shooting 100?
What else will I get by overexposing a stop? More info in shadows? Even comparing to 100asa?

Thanks a lot in advance!
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#2 Tom Jensen

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Posted 14 May 2009 - 06:48 PM

I've always had good results getting finer grain overexposing by 2/3 of a stop on negative. 100 ASA has or should have a finer grain structure.
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#3 Dominic Case

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Posted 14 May 2009 - 06:51 PM

Higher speed stocks have bigger grains. Simple. That's how they work.

Your suggestion is that a 200EI stock will give you tighter grain than a 100EI stock if you expose it the same (i.e. rate it at 100EI).

It won't.

It MIGHT be the case that the 200 stock rated at 100EI would give a better result than the same 200 stock rated at 200EI.

I suspect that if the faster stock could be tricked into giving tighter grain than the slower stock, then Kodak would simply stick 7212 labels on it and market it as a new, finer-grained 100EI stock.
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#4 Brian Pritchard

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Posted 15 May 2009 - 02:09 AM

I suspect it won't be a very popular view, but after nearly 50 years in the film industry I still maintain that you get the best result by exposing at the recommended exposure index. Under or over exposure, pushing and pulling will result in some loss of quality; what you gain in change of saturation, grain and speed involves a loss somewhere else.

I have been wanting to say this for a long time, now I've done it I will quietly retire back into obscurity!


Brian
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#5 Tom Jensen

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Posted 15 May 2009 - 10:26 AM

I suspect it won't be a very popular view, but after nearly 50 years in the film industry I still maintain that you get the best result by exposing at the recommended exposure index. Under or over exposure, pushing and pulling will result in some loss of quality; what you gain in change of saturation, grain and speed involves a loss somewhere else.

I have been wanting to say this for a long time, now I've done it I will quietly retire back into obscurity!


Brian


Any guy with 50 years experience has to be somewhat popular. In the 80's Steven Burum wrote an article for American Cinematographer about shooting film tests, called something like, "Making Film Stocks Your Own." He explained the importance of shooting tests to see exactly where you could overexpose and underexpose your film stock and still get a good print. Film might have more latitude now but the tests showed that film had a one stop latitude. The brightness range is something different than latitude. If you expose your negative in the middle of the characteristic curve, you have about an 8 stop range, meaning you can have areas on the negative that are 4 stops under and not turn to mush and you can have areas of brightness of about 4 stops over before the highlights blow out. I think Kodak uses the one stop of latitude as a marketing ploy. If you have a one stop latitude of underexposure, you can safely call your film 100 ASA when it really is 64. Why 64? When I first started shooting tests, I used Steve Burum's article religiously. This article was what taught me about exposing negative. That and the Ansel Adams book on the negative. What I learned was that overexposing the negative by 2/3 stop gave me the best reproduction on the print and negative of a gray scale and color chart. You can expose the negative at the manufacturers recommended ASA and get a perfectly acceptable image and reproduction. What I have found and what the article found was that a negative overexposed by 2/3 stop gives you the highest quality exposure on your negative thus giving you the highest quality of print.

A lot of what I said was geared towards the student and I'm sure most of what I said, you already knew. In no way did I mean to sound condescending. I'm just giving you my experience as I know it.
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#6 Saul Rodgar

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Posted 15 May 2009 - 12:08 PM

Kodak '12 is very likely the finest tight grain film stock available today. I would shoot it rated normal or with a slight overexposure (1/3 or 1/2 stop) over any 200 ASA stock rated 100 ASA.

It is always important to test your stocks _but if that can't happen, you ask questions, as you did. ;)
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#7 David Mullen ASC

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Posted 15 May 2009 - 01:04 PM

Going thru a D.I. right now, I can tell you that I'm glad I rated 500T stock at 320 ASA most of the time, because it's a safety net against accidental underexposure plus it provides more information in the grade, plus it protects you when the director wants to brighten areas in the frame, or the whole frame. It's the times I rated the stock at 500 ASA as recommended by the manufacturer or when I had to push it that I'm most sorry.

We shoot in real world situations, not test charts, and with negative film, there is more latitude in the highlights and less in the shadows, so when you can, you're generally better off biasing the exposure for more shadow detail because the stock has so much overexposure latitude.

Rating 500 ASA stock at 500 ASA is fine in high-key lighting and when you absolutely are sure you will never try to brighten any area of the frame in post... but since that never happens, and often you are shooting more low-key scenes, well, I've never had a colorist complain about too much information to pull up in the grade, almost all the problems come with underexposed material.

Now with slow film, you have a little extra latitude for corrections because grain is less of an issue.

100 ASA film naturally has less grain than 200 ASA film, so overexposing 200T won't make it as fine-grained as 100T, though it will tighten the grain and give you more low-end information compared to normally exposed 100T.
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#8 Tom Jensen

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Posted 15 May 2009 - 02:20 PM

We shoot in real world situations, not test charts, and with negative film, there is more latitude in the highlights and less in the shadows, so when you can, you're generally better off biasing the exposure for more shadow detail because the stock has so much overexposure latitude.


True, it's a very good point that I failed to mention. It's a good idea to put a face in the test. Shooting test charts is a good idea if you've never shot tests before. Students particularly can learn a lot from shooting a color chart and a gray scale. It serves as a logical progression from light to dark that remains consistent throughout the tests. I wouldn't dismiss it entirely. By now, you know what you want and like but shooting charts gave me an understanding of the characteristic curve that had eluded me somewhat before I had shot any tests. Once you've done it, you understand what it you were trying to do and why it is important. How do you shoot your tests now and what do you look for?
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#9 Saul Rodgar

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Posted 15 May 2009 - 03:29 PM

How do you shoot your tests now and what do you look for?


By testing I mean testing the stock in as close a situation as you will encounter during the shoot you are considering the stock for, whatever it may be. Otherwise the test will be as inconclusive as it can be, as far as I am concerned, and it will likely be a waste of time and money.

I have never been partial to testing lenses and stock at the camera rental shop, unless the upcoming shoot's conditions can be closely recreated there. Registration and (technical) lens and camera tests may be adequately held at the camera shop. Conversely though, it may be impossible to have access to an entire grip & electric package at a hero location to perform a stock / lens test. Still, sometimes being creative to choose time of day and locations that share a similar look to the scenes that one is testing the film for can save the day / test.

A couple of years ago, I worked on pre-prod on a feature where the DP, Shane Hurlbut, ASC, took the camera package out and about to shoot 2nd unit footage as a camera and stock test, potentially killing two birds with one stone.

Edited by Saul Rodgar, 15 May 2009 - 03:30 PM.

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#10 Tom Jensen

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Posted 15 May 2009 - 04:36 PM

Film testing is extremely important in my opinion. Especially on features. If you are shooting a day here or a day there, no big deal. Most stuff goes to telecine anyway. If you are shooting second unit, you just get notes from the DP. Exposure tests let you decide what your effective or base ASA is going to be. On a big feature, I think lens testing is a must, especially if the feature is on location out of the state and especially out of the country. You don't want to be in the middle of nowhere and find out a lens doesn't match, it's soft or if it has an aberration, or if the zooms breathe too much. And if you are shooting a period piece or something make-up intensive, you'll want to shoot those tests as well. It's not always safe to assume but if you rate your film 2/3 of a stop over, you'll be OK. Testing can get expensive. Saul were you saying that Shane was shooting 2nd unit on a test day. I know that trick too. ;)

Unless it's a day exterior, you are not likely to recreate the conditions on shoot days unless you have a big budget. Exposure tests are pretty common on features. Once you know your ASA, and that your camera runs, you pretty much know where to set your lights and where the image will fall. I've worked on big budget commercials where we would light and entire day, shoot tests and then shoot the next day or two. That's not always the norm.
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#11 Brian Pritchard

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Posted 16 May 2009 - 03:28 AM

It is important to remember that there are many factors affecting your exposure rating.

The method you use to measure exposure.
The accuracy of your meter.
The accuracy of the stops on the lens you are using.
The accuracy of the speed of the camera.
The accuracy of the shutter.
The accuracy of filters, different makes of W85's for example.
In rare cases, the accuracy of the lab's process.

If you are shooting negative to be printed onto print stock (not via digital intermediate) it is important that your shadows are placed on the toe of the curve so that when it is printed, the shoulder of the print stock will 'straighten out' the shadows. Over-exposing will place the shadows on the straight line porion of the curve and distort the shadow reproduction; under-exposure will cause loss of shadow detail.

Once we get into the realm of digital intermediate a whole load of other factors enter the equation and it might well be necessary to change your exposure to achieve what you want on the screen.


Having said that if you are happy exposing at an exposure level different to the manufacturer's rating go right ahead; it's your film!


Brian
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#12 Tom Jensen

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Posted 16 May 2009 - 09:51 AM

It is important to remember that there are many factors affecting your exposure rating.

The method you use to measure exposure.
The accuracy of your meter.
The accuracy of the stops on the lens you are using.
The accuracy of the speed of the camera.
The accuracy of the shutter.
The accuracy of filters, different makes of W85's for example.
In rare cases, the accuracy of the lab's process.

If you are shooting negative to be printed onto print stock (not via digital intermediate) it is important that your shadows are placed on the toe of the curve so that when it is printed, the shoulder of the print stock will 'straighten out' the shadows. Over-exposing will place the shadows on the straight line porion of the curve and distort the shadow reproduction; under-exposure will cause loss of shadow detail.

Once we get into the realm of digital intermediate a whole load of other factors enter the equation and it might well be necessary to change your exposure to achieve what you want on the screen.


Having said that if you are happy exposing at an exposure level different to the manufacturer's rating go right ahead; it's your film!


Brian


I agree with you Brian. What I feel is the manufacturers setting is a variable as well. What you are doing is setting the ASA to compensate for all the variables. The meter the DP uses is the one the gaffer sets his to. The tests that you shoot for a feature get printed. It's always the best print that establishes the ASA and it's usually from the negative where the shadows fall on the toe. That's the negative that that was usually overexposed by 2/3 stop. Whenever I shot tests, I always picked the print that looked the best. That's the one you want. It's pretty easy to read it on a densitometer as well. I don't think that when you overexpose a stock that you are really overexposing. I think you are establishing the true or more accurately, the effective ASA of the stock combined with any other vaiables. After you test, set your ASA in accordance to your results, your shadows should fall on the toe of the characteristic curve and the highlights should fall on the shoulder.

Come to think of it, Chris Probst also did a series of exposure tests that was in American Cinematographer. I can't remember what his results were so I might have to dig that out of the garage. Does anybody else have that article?
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#13 Saul Rodgar

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Posted 16 May 2009 - 12:32 PM

Having said that if you are happy exposing at an exposure level different to the manufacturer's rating go right ahead; it's your film!


Test, test, test!

A film manufacturer can recommend the exposure index (EI) of their stocks. But that doesn't mean that that recommendation will be the best choice in all situations. It is up to the DP to choose (based on experience with and careful testing of the stocks) what EI (among many other things) will work best for the situations encountered in real life. When one is out in the field, say, light is running out and one has to get the shot, then the recommended EI be damned, one has to get the shot!

I speak for myself, but I know many others here will have similar stories: I have had great results manipulating the EI and processing on stocks for both printing and video finish. I also have had bad results, mostly when testing, which shows me what I can and cannot get away with. And that is the reason why we test.

There is nothing wrong to follow the film manufacturer's EI recommendations, as long as that works for one. Just like there is nothing wrong with finding something else that works for one. But one should not make blanket assumptions either way, nor approach it with a dogmatic or overly rigid outlook.
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#14 Tom Jensen

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Posted 16 May 2009 - 05:46 PM

I heard a story about a Japanese DP who shot for Kurasawa or somebody big like that. He was speaking at a panel seminar and someone asked him his secret how he created such beautiful images. He didn't speak English and had a translator. After conversing with his translator, the translator said, "He said he looked at the film can and put the ASA number in his meter."
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#15 James Compton

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Posted 18 May 2009 - 12:29 PM

There was test of KODAK VISION (generation 1) and FUJI SUPER-F filmstocks in the
APRIL and MAY 2000 issues of American Cinematographer. Christopher Probst did the KODAK tests and Jay Holben did the FUJI tests. Both showing pushing and pulling. Under and overexposure of all those filmstocks. Although none of those filmstocks are made anymore, it gives you a rough idea of what those different variables introudce into the mix.
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#16 David Rakoczy

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Posted 18 May 2009 - 03:04 PM

I (personally) rate 100t at 64iso.
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#17 Adrian Sierkowski

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Posted 18 May 2009 - 04:17 PM

And I keep my 200 @ 125 ;) and 500s tend best @ 320. it's all about controlling how you are essentially "compressing" the range of luminance and chrominance in the real world to fit best onto the negative.
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#18 Dominic Case

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Posted 18 May 2009 - 06:11 PM

I still maintain that you get the best result by exposing at the recommended exposure index.

But Brian, then there wouldn't be any need for forums like this one :rolleyes:

You and I will both remember when there was only one film stock at one speed to choose from, and it was given an ASA rating. That was scientifically measured and calculated, based on a fixed density above d-min: and it placed the exposure range as centrally as possible on the characteristic curve. As someone pointed out, an average scene has less brightness range than the useful exposure range of the film emulsion, giving a stop or so of latitude at either end of the curve: so it was safe to underexpose a little if you chose to (provided you weren't shooting a very contrasty scene with deep shadow detail).

Then manufacturers started making a range of stocks, and outbidding each other with faster emulsions. At the same time, characteristic curve shapes changed and didn't really fit the original model of ASA ratings. The EI (exposure index) was introduced - nominally the same as ASA, but more based on subjective assessments of what was "acceptable".

As a result, I suspect that EI ratings are a bit more aggressive than the traditional ASA rating method. Why market a stock as 100 when you can expose it a stop less without loss? Sell it as a 200 stock, and outrate your competitor.

The result of all this is that there is less margin for error on the underexposure side, and so a lot of DoPs now (wisely) follow the mantra of downrating stocks by half a stop or a stop.

Others (as Tom recounts) simply use the info on the film can. Others again, push the exposure all over the place to get the effect they want. All approaches are good if the results are what you wanted.
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#19 Saul Rodgar

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Posted 18 May 2009 - 06:15 PM

All approaches are good if the results are what you wanted.


Amen!
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#20 David Mullen ASC

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Posted 18 May 2009 - 09:00 PM

Yes, that's all that matters. I remember reading one major DP saying he was shooting with Brand X 500T stock at 500 ASA and his images were printing in the high 30's, where he liked it. And then I remember another DP saying he had to rate Brand X 500T stock at 640 ASA because his printer lights were too high if he didn't. Yet whenever I used that same Brand X stock, I had to rate it at 320 ASA to get those sorts of high printer lights, at more than one lab. I kept wondering how these other guys were using their light meters.
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