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Kodak 7231 BW stock over-exposed


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#1 amarogp

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Posted 01 April 2009 - 04:53 PM

Hi,

The DP and myself (1AC) have shot a few tests of 7231 16mm BW kodak film and we did not get what we expected... We shot the test with an aaton LTR, with a 12mm lens. We light the set to a f4 and shot at a correct exposure (f4), then we closed one stop to a f5.6 and finally we closed 2 stops to a f8.
We gave instructions to the lab to push the negative one stop, and definetly the most suitable look is a more grainy and contrasted image in between one and two stops under. At f5.6 (pushed one stop) is clearly over-exposed! That was weird already!

BUT, we also shot 3 shots UNDER-EX to 2 shots OVER-EX to see the latitude results and we were very confused when, at the projecting room, we realized that the image at a normal exposure was one to two shots over-exposed!! It was the same with the previous case as well!And we made sure in class, with 2 lightmeters, 80ASA with HMI's etc etc etc that everything went well. What could be the case? Was it the LAB?

Thanks!

Edited by amarogp, 01 April 2009 - 04:56 PM.

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#2 John Sprung

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Posted 01 April 2009 - 05:16 PM

They may have given you a "best light" print -- trying to hit the middle of the range you gave them.




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#3 Brian Pritchard

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Posted 02 April 2009 - 02:22 AM

Hi,

The DP and myself (1AC) have shot a few tests of 7231 16mm BW kodak film and we did not get what we expected... We shot the test with an aaton LTR, with a 12mm lens. We light the set to a f4 and shot at a correct exposure (f4), then we closed one stop to a f5.6 and finally we closed 2 stops to a f8.
We gave instructions to the lab to push the negative one stop, and definetly the most suitable look is a more grainy and contrasted image in between one and two stops under. At f5.6 (pushed one stop) is clearly over-exposed! That was weird already!

BUT, we also shot 3 shots UNDER-EX to 2 shots OVER-EX to see the latitude results and we were very confused when, at the projecting room, we realized that the image at a normal exposure was one to two shots over-exposed!! It was the same with the previous case as well!And we made sure in class, with 2 lightmeters, 80ASA with HMI's etc etc etc that everything went well. What could be the case? Was it the LAB?

Thanks!

If you expose normally and then push one stop your film will be over-exposed by one stop, one stop under will be normal and 1 stop over will be two stops over.

As John says the result on the screen will depend on how the rush print was graded; best light, graded to grayscale or a standard light. If you wanted to compare the various settings you should really have each scene graded.
Brian
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#4 amarogp

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Posted 02 April 2009 - 04:26 AM

If you expose normally and then push one stop your film will be over-exposed by one stop, one stop under will be normal and 1 stop over will be two stops over.

As John says the result on the screen will depend on how the rush print was graded; best light, graded to grayscale or a standard light. If you wanted to compare the various settings you should really have each scene graded.
Brian



Yes but, we gave instructions to the lab to grade to grayscale only in the first shot. Therefore this first shot wich is light correctly at a normal expsure it shoud be fine, not over-exposed right?

Of course if we expose normally and then we push one stop, the result will be OE, but the first shots of the 2 tests we sent (One to be pushed and the other one to be developed normally) are definetely over-exposed... It must have been the lab!!! I have no other explanation to this.... We might have to stick to their development process, so shoot everything 2 stops under, or check again and discover if they misunderstood....
(Teses french labs..... :)

Thank you all!
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#5 Simon Wyss

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Posted 02 April 2009 - 04:48 AM

If you expose normally and then push one stop your film will be over-exposed by one stop, one stop under will be normal and 1 stop over will be two stops over.

Brian

I beg your pardon, but if one pushes the film will be overdeveloped, not overexposed. What a confusion here !
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#6 Brian Pritchard

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Posted 02 April 2009 - 01:29 PM

I beg your pardon, but if one pushes the film will be overdeveloped, not overexposed. What a confusion here !

There is no confusion. The purpose of push processing is to effectively increase the exposure index. If you expose normally and push process you will get a heavier and higher contrast image. If this was printed at the same light as a normally exposed negative the pushed image would appear over exposed, that is thin.
Brian
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#7 amarogp

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Posted 03 April 2009 - 12:41 PM

Hi,

Going back to the over-exposure issue, I have talked to the lab and they told me that "they gave the wrong values to the telecine and thats why it looks over-exposed". I am going to the LAB on monday to try and process the telecine properly. I will also bring a few meters of unexposed stock to verify the gamma curve and therefore double-check the dynamic range of the film.


Thank you all
Amaro
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