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Over exposure or under exposure question


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#1 John Adolfi

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Posted 27 August 2007 - 06:23 PM

Allow me to firmly get in my mind the idea of overexposing your film 1/2-1 stop.
For reversal say the 100D over expose ok? Preferred? Negative stock overexpose 1/2-1 stop ok? Preferred? Never underexpose to make a stock look better? Thanks. Last question, since negative film is well negative, that means to overexpose is the same as overexposing reversal, right, let more light in? Seems like a silly question but double negatives can sometimes confuse people. So to overexpose a negative you then do not underexpose so that the reverse (overexpose) is transfered on tape or reversal film. I believe know the answer but I had to ask the question.
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#2 Toby L Edwards

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Posted 27 August 2007 - 06:40 PM

Reversal and negative film's are exposed the same as far as under and overexposure go.
Toby
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#3 Anthony Schilling

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Posted 27 August 2007 - 06:40 PM

With reversal it's best to expose normal or under 1/3rd. Negative is ok to overexpose about 2/3rds.
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#4 Michael Nash

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Posted 27 August 2007 - 07:45 PM

Overexposing negative film will create more density on the negative. This means more color and contrast information, which can look richer and less grainy when printed down to normal brightness. People often overexpose negative film by about 2/3 stop to get a little more density (more image information), but without exposing too far off the middle "straight line" response of the film.

Reversal film creates a positive image on the camera original, so a darker (underxposed) image has more density. But with reversal film you don't necessarily get that much more picture information or less grain with a more dense image, for a few reasons. For one, reversal film is more contrasty to begin with, so you can't deviate very far from a normal exposure before you start to lose detail in the extreme bright or dark areas. Secondly, since reversal film is designed to be projected as-is, an underexposed reversal image will simply look underexposed (dark) when projected. If you're going to transfer it to video, you can brighten it back up again. And as far as I know grain size works the same way for reversal as it does for negative, where the larger, coarser grains are used to capture and reproduce darker tones. So you don't get any less visible grain with underexposed reversal.
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#5 Alessandro Machi

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Posted 29 August 2007 - 03:38 PM

So you don't get any less visible grain with underexposed reversal.


But you can get less detail in the blacks, and then the less detailed blacks almost seem to suck out some of the detail in the surrounding parts of the scene near the less detailed blacks.
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#6 Gaetano Frangella

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Posted 18 September 2007 - 03:18 PM

I'm trying to figure out my cameras appeture. im shooting on a Agfa movexoom 2000 with a 200 asa black and white film at 24fs. my handheld light meter tells me one thing and the cameras light meter tells me another. whats a perfect exposure? keeping the in camera light meter at 5.6? it seems to be the middle. i come think that if i knew my cameras appeture i could help me decide whats properly exposed and what isnt. am i completely off? help!!

Gaetano - montreal
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#7 Michael Lehnert

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Posted 18 September 2007 - 08:19 PM

I'm trying to figure out my cameras appeture. im shooting on a Agfa movexoom 2000 with a 200 asa black and white film at 24fs. my handheld light meter tells me one thing and the cameras light meter tells me another. whats a perfect exposure? keeping the in camera light meter at 5.6? it seems to be the middle. i come think that if i knew my cameras appeture i could help me decide whats properly exposed and what isnt. am i completely off? help!!

Gaetano - montreal


Hi Gaetano.

Sorry if this might not be that helpful, but please allow me to ask for some info first to fully be able to assist you with your question:

You are shooting with an Agfa Movexoom 2000, the "Star Trek Phaser" design camera manufactured by Minolta for Agfa? I appreciate the stylish design alot, and Agfa is a greatly underrated camera marque in the Super 8 format. However, to my knowledge, the Agfa Movexoom 2000 has only automatic exposure control, i.e. it regulates the aperture itself (symbolised in f-stops in the viewfinder!?) without means from the camera operator to change this.
Could you please confirm if that is the case? If the Agfa Movexoom 2000 truly has manual aperture control as well? If so, please read the next paragraph. If your camera has (as my references list) only automatic exposure control, then trying to figure out anything relating to exposure is of limited help because you will not be really able to control aperture and hence how the cameras exposes your film anyhow :( .

The f-stop of 5.6 you state, is that a read-out from the built-in exposure meter, or is that from your external exposure meter?

If it is from the built-in exposure meter, then your camera seems to have manual aperture control (in form of an f-stop setting ring, or a manual button or wheel on the camera body).
What you hence need to figure out is not so much aperture - that seems to be f/5.6. What I think you want to find out is actually the exposure time of your camera at 24 fps. That would be the missing element to set your external exposure meter right to compare that ones reading with the exposure value your Agfa gives you (namely f/5.6).

If it is from the external exposure meter, then I would like to ask what exposure time you adjusted on your meter? Does your camera manual provide that info (and few do)? If you have that info, then you already have all the data for comparing the two exposure values ;) .

I am truly sorry if this post was totally unhelpful, Gaetano. I am just trying to fully comprehend the problem at hand that you want to solve :unsure: . I am looking forward to hearing from you :) .
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#8 Alessandro Machi

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Posted 18 September 2007 - 09:12 PM

With reversal it's best to expose normal or under 1/3rd. Negative is ok to overexpose about 2/3rds.


If the dominant visual in your shot are blond haired fair skinned actors, sure. But how can your rule stay valid if you are shooting dark haired, darker skinned actors?
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#9 Gaetano Frangella

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Posted 10 October 2007 - 08:26 PM

yes..it is 5.6
but! it is possible for me to over or underexpose my film even if it is an automatic exposer. what i was trying to figure out (and since have) it what was my film speed. through some research i found that there is a way to mathematically figure it out with a light meter. and it is 5.6 fs at 60.
thanks for the help anyway...
all the best

Gaetano
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