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#1 Ashim

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Posted 17 October 2006 - 01:25 AM

Why do cinematographers generally prefer to overexpose their stock by a stop???
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#2 David Sweetman

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Posted 17 October 2006 - 01:30 AM

Why do cinematographers generally prefer to overexpose their stock by a stop???

giving more light to a negative exposes more of the grain, which makes it appear less grainy. I'm not sure you could say that is generally practiced, but it is a useful tactic for decreasing grain and also influencing the image in other ways...I think it affects contrast and saturation? I'm not really sure of all the side-effects, maybe someone else can fill it in...
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#3 David Mullen ASC

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Posted 17 October 2006 - 01:31 AM

Why do cinematographers generally prefer to overexpose their stock by a stop???


A full stop is not common -- most will likely overexpose by 1/3 or 2/3's of a stop. And this only applies to color negative.

There are a couple of reasons. You end up with a denser-than-normal negative which requires higher printing light numbers to print "down" to normal brightness. This has the effect of making the blacks blacker in the print, which naturally makes the colors and contrast look snappier, richer (conversely, weak blacks will make colors look more pastel and contrast look lower).

It also gives the effect of less graininess because you are exposing the smaller (slower) grains inbetween the larger (faster) grains that always get exposed first. You also record more shadow information on the negative, although at the expense of some overexposure information, but since film handles bright areas well, this is usually not a problem unless you heavily overexpose, like by two stops or more.

Another reason for rating the film slightly slower is a hedge against underexposure, which can look worse than overexposure, or more visible (weaker blacks and more grain.)

One reason though why people don't overexpose by a full stop or more is that if the point is to reduce graininess, then they might as well use the next slower-speed stock instead.
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#4 David Sweetman

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Posted 17 October 2006 - 01:45 AM

A full stop is not common -- most will likely overexpose by 1/3 or 2/3's of a stop.

When overexposing by a fraction of a stop, when is the image pulled back? Won't the labs only pull by full-stop increments? Your post indicates the exposure is corrected by the printer lights - does this mean the final print of the film, and if so - say if the film were finishing on HD - could it be corrected there, perhaps in telecine?
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#5 Michael J. Schilling

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Posted 17 October 2006 - 02:43 AM

When overexposing by a fraction of a stop, when is the image pulled back? Won't the labs only pull by full-stop increments? Your post indicates the exposure is corrected by the printer lights - does this mean the final print of the film, and if so - say if the film were finishing on HD - could it be corrected there, perhaps in telecine?


Well an overage of 1/3 to 2/3 if left uncorrected in tranfer will come back down with a print to film. If you're printing out to film you can lose 1/3 to a 2/3 exposure in the process. Now in telecine you know you're going out to a hd format you can correct this, however most tv's not hd or ntsc can project the image anywhere from a 1/2 to 2 stops under based on its age and calibration so take this into consideration if you're doing an hd out. I too am a student and since most of my work ends up going to hd I usually leave an overage of about a 1/3. Most people who will view my work will probly just watch on a regular tv and not notice a 1/2 or 1stop difference and anyone who views it on a calibrated monitor or tv just might not notice a 1/3 overage or wont say anything. I'd rather show an image a little over than under, and in truth 1/3 isn't noticable to the eye unless they are well trained to it. This is just my experience thus far, and am more than welcome to any further infomation or corrections if I've been misled. I hope this helps you with your future endeavors.
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#6 David Mullen ASC

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Posted 17 October 2006 - 10:04 AM

You overexpose by 1/3 or 2/3's of a stop and develop normally, not pull-process to compensate, so that the resulting negative keeps the overexposure, i.e. it becomes slightly denser (darker) than normal and the image is brighter than normal. So the brightness is corrected either in the printing or in the video transfer.

If you overexpose by one-stop and pull-process by one-stop, the resulting negative would be normal in density and print at normal lights. It would still be less grainy from the overexposure, but it would also be lower in contrast and more pastel, as opposed to printing down a denser-than-normal negative where you would get deeper blacks, stronger colors, and a little more contrast. So it's a different look, overexposing and compensating in processing versus overexposing and printing down. For video transfers only, there is less advantage to heavier overexposure but a little still helps.

Because your negative is denser, it helps to shoot a grey scale at the head of the roll with this overexposure so that they know it's supposed to be timed to normal in brightness.
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#7 Nor Domingo

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Posted 17 October 2006 - 10:31 AM

So it's a different look, overexposing and compensating in processing versus overexposing and printing down. For video transfers only, there is less advantage to heavier overexposure but a little still helps.

Because your negative is denser, it helps to shoot a grey scale at the head of the roll with this overexposure so that they know it's supposed to be timed to normal in brightness.


Sorry, but I got a little confused with terminology. Is "Overexposing and printing down" the same as "overexposing and developing normally"?
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#8 Stephen Williams

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Posted 17 October 2006 - 10:39 AM

Sorry, but I got a little confused with terminology. Is "Overexposing and printing down" the same as "overexposing and developing normally"?


Hi,

Overexpose 1/3-2/3 stop, process normally then print down so the final image looks normal.

Stephen
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#9 Nor Domingo

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Posted 17 October 2006 - 10:51 AM

Hi,

Overexpose 1/3-2/3 stop, process normally then print down so the final image looks normal.

Stephen


Ah!!! thank you stephen!
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#10 Timothy David Orme

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Posted 17 October 2006 - 11:03 AM

Okay, total newbie question. What's print down mean? I'm assuming it's a different thing than pull processing.
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#11 Stephen Williams

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Posted 17 October 2006 - 11:12 AM

Okay, total newbie question. What's print down mean? I'm assuming it's a different thing than pull processing.


Hi,

If you over expose 2/3 stop and print normally the print will be too bright. By correcting the printer points (About 5 or 6 points higher) the print will be darker and look normal.

Most labs have a mid point of 25-25-25 or 30-30-30 so a slightly overexposed neg will print in the low to mid 30's

Stephen
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#12 Timothy David Orme

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Posted 17 October 2006 - 11:32 AM

Hi,

If you over expose 2/3 stop and print normally the print will be too bright. By correcting the printer points (About 5 or 6 points higher) the print will be darker and look normal.

Most labs have a mid point of 25-25-25 or 30-30-30 so a slightly overexposed neg will print in the low to mid 30's

Stephen


So, that is to say your final print (from negative to POSITIVE) is changed? How does this relate to going directly to telecine? I.e., what is the best way to shoot (overexposing what amount) and correct if one is planning on going from negative straight to telecine transfer to a digital edit and finished product?
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#13 Stephen Williams

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Posted 17 October 2006 - 12:05 PM

So, that is to say your final print (from negative to POSITIVE) is changed? How does this relate to going directly to telecine? I.e., what is the best way to shoot (overexposing what amount) and correct if one is planning on going from negative straight to telecine transfer to a digital edit and finished product?


Hi,

Slight overexposure for telecine is fine too. However at 1 stop overexposed there will be more noise so again 1/3 -2/3 is fine not more.

Stephen
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#14 Timothy David Orme

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Posted 17 October 2006 - 12:08 PM

Okay, and if you go from that 1/3 or 2/3 overexposure to telecine, do you have the telecine lab compensate for it or do you do it some other way?
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#15 Stephen Williams

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Posted 17 October 2006 - 12:16 PM

Okay, and if you go from that 1/3 or 2/3 overexposure to telecine, do you have the telecine lab compensate for it or do you do it some other way?


Hi,

Overexpose 1/3-2/3 stop, Develope NORMAL then correct in telecine or print.

Stephen
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#16 Timothy David Orme

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Posted 17 October 2006 - 12:29 PM

So it's best to go from a negative to a regularly exposed print and then to telecine, instead of straight from negative to telecine?
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#17 Stephen Williams

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Posted 17 October 2006 - 12:46 PM

So it's best to go from a negative to a regularly exposed print and then to telecine, instead of straight from negative to telecine?


Hi,

If you owned a lab that might be advice you would give! I knew a lab who stated that upto around 3 years ago!

Assuming you are using a high end telecine then a negative is the normal way to go. Labs don't print many dailies today. If you have a 'Home telecine' then you may need a print.

Stephen
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#18 David Mullen ASC

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Posted 17 October 2006 - 09:43 PM

Okay, total newbie question. What's print down mean? I'm assuming it's a different thing than pull processing.


You have to separate the concept of processing of the negative from the technique of printing the negative onto a print stock (which also needs processing then, although it is pretty standardized.)

Print "down" means that you make the print look darker by using higher printing light numbers (a denser, i.e. overexposed, negative is physically darker and needs more light pumped through it to make a print, hence why the numbers are higher.)

You can overexpose a negative and pull-process it to become normal in density.

You can overexpose a negative and process it normally to end up with higher density.

You can expose a negative normally and push-process to end up with higher density.

Exposure and processing both individually affect the final density of the negative.

It's usually best to transfer from the original negative, since it is the first generation. You can adjust the brightness of the electronically reversed (positive) image in the telecine transfer, correcting for the extra density.
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