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Advice on clip test densitometry results

35mm Negative Expired Old Lab

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#1 Alex Reid

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Posted 29 July 2016 - 06:19 PM

I am shooting a small project on Monday with old 35mm stock that I have saved since I was a loader. I just got the densitometry results back from the lab and as expected, the faster stocks have come back quite heavy, e.g. some Vision 500T came back +0.43 + 0.52 + 0.52 above the AIM RGB Densitometry numbers.

 

Unfortunately I don't have time to shoot some tests with it, so any advice would be hugely appreciated.

 

Should I treat each +0.10 off AIM roughly as 1 stop? Therefore if its averaging +0.50 above AIM, then I should overexpose it by 5 stops?

 

Gratefully,

 

Alex Reid.


Edited by Alex Reid, 29 July 2016 - 06:20 PM.

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#2 Tyler Purcell

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Posted 30 July 2016 - 03:30 AM

Ouch! Them's some way off numbers eh?

Honestly, I've got a lot of old stock I've shot with, but my test results weren't quite that off. I was more like +22, +28, +30 and I over-exposed by a stop and it came out ok. In fact, some of my tests were underexposed and sure it was grainy/noisy, but not crazy by any means.

I know my lab says anything over +40 should be "discarded", whatever that means.

Over exposing by 5 stops would not be smart as the stocks sensitivity hasn't really changed, it's the "fog" level that's gotten worse. It's slightly different then exposure and I fear over-exposing by huge numbers, would probably generate issues in the highlights and brighten up the midtones too much. Worth testing for sure, but I'd not go that far.
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#3 Alex Reid

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Posted 30 July 2016 - 06:43 AM

Thanks Tyler, that was really helpful. I will keep my exposure compensation to around +2 stops over rather than the +5 I was considering! (I did think that was a bit drastic)

 

What I didn't mention in my original post is that we are going for a 'look' with the old stock, we welcome any aberrations as we want a period & degraded quality.

 

Gratefully,

 

Alex


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#4 Michael Rodin

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Posted 12 August 2016 - 04:15 AM

Ouch! Them's some way off numbers eh?

Honestly, I've got a lot of old stock I've shot with, but my test results weren't quite that off. I was more like +22, +28, +30 and I over-exposed by a stop and it came out ok. In fact, some of my tests were underexposed and sure it was grainy/noisy, but not crazy by any means.

Alex is talking about densities not printer lights! In terms of negative density 0.15 roughly equals one stop of exposure, given that your stock's gamma is 0.5. The general formula is, (Density) = gamma * (log exposure) + base + fog

 

Yes, Alex, you're gonna be safe with 2 stops overexposure. Even 5 stops over is not a disaster, Vision 3 can tolerate it. It will be near impossible to print though, since the lab will have to use "trim" settings on the printer.


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#5 Michael Rodin

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Posted 12 August 2016 - 04:18 AM

I know my lab says anything over +40 should be "discarded", whatever that means.

They're doing their best to make their life easier. I would say everything printing below 10 is garbage, but there's also something to the way a thin negative looks.


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#6 Alex Reid

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Posted 12 August 2016 - 07:23 AM

Alex is talking about densities not printer lights! In terms of negative density 0.15 roughly equals one stop of exposure, given that your stock's gamma is 0.5. The general formula is, (Density) = gamma * (log exposure) + base + fog

 

Yes, Alex, you're gonna be safe with 2 stops overexposure. Even 5 stops over is not a disaster, Vision 3 can tolerate it. It will be near impossible to print though, since the lab will have to use "trim" settings on the printer.

 

Thanks Michael, that was very informative.

 

I have the 2K scan of the negative back and we are happy with the results. Its a little early to comment as I am viewing it in Log, but the footage all looks really nice to me, as expected, the 500 ASA is grainier than I remember it, I tried to rate it at 125 ASA (where possible), but this stock clip tested an average +0.50 denser than the AIM density, therefore it had 4 stops of base fog due to its age. We are shooting the second half of the film on the 27th of August and I'll be using some older 500T which is on average +0.60 denser than AIM density, looking forward to seeing the results!


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