Are my expectations too high?

[Ryley Grunenwald]

Hi,

 

I would really appreciate any help on this matter.

 

In 5 days will be shooting my graduation road trip film (predominantly day exterior) on Kodak Vision 250D that was bought by my film school. the emulsion number of the stock I tested was traced by the stockist and it is apparently new. I did some crude film tests where I disovered the latitude was about 5 stops (2.5 stops on each side of 18% grey). While some people I have spoken to, including the stockist, say that 5 stops is great - others say I shoud expect more. Not having any experience on this stock I'm not sure what to believe.

 

I basically shot the test on an Arri SR2 S16mm camera with a 9mm Kowa lens. I pin pointed the exposure between f8 and f11 as this was the incident reading. I then closed the aperture stop by stop until f22 and then opened it until f1.2. the acceptable range (if that's what one calls it) was from f4 to f22. the stock seemed to favour underexposure to overexposure. I did this on a grey scale card as well as a Macbeth Colour Chart.

 

Seeing that it was my first test, perhaps I made some critical errors?

Please could some one tell me if this latitude is perfectly normal or if I should make plans to buy new stock?

 

In some ways a smaller lattitude may be helpful as I can get more contrast more easily? But on the other hand, the huge stop differences of car interior and exterior may need a more forgiving latitude since I won't have much light aside from refletors to boost the interior readings.

 

Thank you so much.

 

Ryley Olivier

student

[Sam Wells]

I think the previous thread - Film/Camera tests - and note what Dominic Case says -

pretty much answers yor questions.

 

I'm not surprised at your results; typically the negative will appear a bit better on the overexposure side.

 

Or you may have a slightly pessimistic meter.

 

I think you'd find quite a bit of recoverable highlight information in a real world situation.

 

You might look at the grain in the even area of the grey card to see which in exposure condition it seems least apparent.

 

-Sam

[David Mullen ASC]

I'm not sure how you got the overexposure range as only being 2.5 stops, nor the underexposure range being that short. I find with color negative that there is detail from almost 4 stops under to nearly five stops over -- about a PRACTICAL nine stop range. There may be information in an even broader range, about eleven stops worth.

 

Certainly if you underexposed an image by three stops, there would still be detail recorded so I don't know where you got 2.5 stops as the range. Same with overexposure. But the issue is whether you are talking about the range of detail that is visible or the range in which you can accidentally expose your key and still have an acceptable image after correction. But then I'd be even more conservative and say only two stops in either direction.

 

As for "favouring" under- or overexposure, color negative favors overexposure simply because a mistake in mild overexposure and printing down looks better than a mistake in underexposure and printing up. A denser negative printed down produces tighter grain, better blacks, and snappier contrast. A thinner negative printed up produces a grainier image with weaker blacks and lower contrast.

 

You didn't say how you evaluated the test. Was it a print that was projected? A telecine transfer of the negative? Simply viewing the negative with a magnifier & light box?

[Bob Hayes]

In my experience you can underexpose or overexpose KODAK stock by 2 stops and reprint it so it looks like it was properly exposed. Is that what you mean by latitude?

[Ryley Grunenwald]

Thank you all for your help.

 

It think it all boils down to my definition of latitude.

 

There definitely was some inforation beyond 2.5 stops either side. On the underexposure side most of the image was there but obviously very very grainy and dark - espeially in the dark tones. at 2.5 stops overexposure the image was already washed out; at 3.5 very milky; at 4.5 stop I could just make out the edges of the clapper board; at 5.5 stops it was completely white.

 

(The film was processed at The Filmlab; viewed a Telecine; then dumped onto miniDV tape for further viewing).

 

If latitude includes ANY detail whatsoever (like the edge of the clapper), then the latitude is probably more like 8 stops. If it is purely the boundaries that one can expose the key and correct acceptably - then it is more like 1.5 stops either way.

 

Does this sound more normal. Should I shoot with this?

 

By the way, what are the official definitions of range and latitude.

 

Thank you again.

[Dominic Case]

Latitude is really how muchyou can vary the exposure and still reproduce the full range of tones that you want to see. In a scene with average brightness range, you could expect latitude of a couple of stops each way, with the underexposed tests falling off much more dramatically once you reach the limit.

 

Sometimes the terms is used (misleadingly in my view) to refer to the entire response range of the emulsion - in other words if you do spot readings of shadows and highlights, what is the darkest shadow that just registers as density on the negative: what is the brightest highlight that isn't totally burnt out? On the new V2 stocks you could expect up to 11 stops. Obviously, if your scene has less range than this, you can vary the exposure (MY definiton of latitude, above) and still have good reproduction of the entire tonal range.

[John Pytlak RIP]

If you underexpose, the shadow areas of the scene start to fall more on the "toe" of the film's characteristic (sensitometric) curve. Even when timed/graded, the underexposed shadows will tend to be lower in density (less black) in the print, and graininess will increase because you are using more of the fast emulsions to form the image.

 

Overexposure will generally give "richer" shadow detail and blacker blacks, with less graininess, with a bit more color saturation. But once you overexpose by more than a few stops, you will start to see a loss of highlight detail, and may start so see contrast mismatch (slight coloration) in the highlights. The other issue with a really overexposed negative is that the high density may require a change in printer setup or increased noise on telecine.

 

The Kodak website has a good discussion of tone reproduction and exposure:

 

http://www.kodak.com/US/en/motion/support/h1/structure.shtml