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Kodak 50D


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#1 Kamaljeet Negi

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Posted 15 July 2005 - 06:46 AM

Friends,

I just finished shoting test on Kodak '50D' in tungsten light with a clean lens and grey scaled on clear tungsten lamp on '1 second exposure'. I tested shots with 1/2 and full CTO on for Day and used 1/2 and Full Blue for night. I have no human model rather its a subarbia/city model with yellow, green, brown colour in it.

Results - Tests with Full Blue - I see blue in the shadows when the stock is Underexposed. While I am on the normal exposure (the same as on the meter and camera) The stock looks underexposed - with blue shades. Its like flashed with blue light. When the shot is over 1 stop it looks well exposed.

The shots with CTO (full and 1/2) looks Yellow but not orange.

The colourist told me that he has tried to take the blue off the scenes.

Anyone over here who has any idea how to rectify this as I have already bought the stock and unable to replace with Kodak 100T.

Thanks a lot.
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#2 Laurent Andrieux

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Posted 15 July 2005 - 06:59 AM

50 D is a Daylight stock ; No use to filter with an 85 outside.

Full blue absorbs 2 stops, half absorbs one stop
Full ctO absorns 2/3 of a stop, half absorns 1/3

If you are underexposed and need a color correction, typically a scene is too blue and you want to rewarm it as to take this bluish off, it's normal that the highlight being well corrected, the shadows will remain bluish.

It's a Jones diagram problem...

Anyway, if you digitally color time with a good tool (Avid Symphony for instance) you can correct the 3 "channels" : shadows, average, highlights, seperatly.
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#3 David Mullen ASC

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Posted 15 July 2005 - 10:03 AM

If the stock is old, it will also pick up more of a blue cast in the blacks and shadows, which overexposing will help mask.
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#4 Laurent Andrieux

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Posted 15 July 2005 - 10:25 AM

Right, did you ask your lab to make a sensitometric curve of your stock as to see if it's correct ? Is it short ends you got or brand new stock ?

If it's correct, it's the way you work it that has to be thought of,

If it's not, the lab can help you thinking of corrections to make as you shoot it, or tell you if the stock is not usable...
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#5 Kamaljeet Negi

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Posted 15 July 2005 - 01:08 PM

Thanks for your postings.

The Stock is BRAND new (recanned by Deluxe as it was a 1000ft. long) Remained in the Camera for 4 days while I was doing this test - it is setup for an animation. I thought it would be a good idea to get a great image with a fine grain on the slow speed film so decided to check 50D and not 100T.

The Lighting is all indoors and creating day (by CTO) and night (using CTB) within studio (thought I didn't make that clear before). Lot of Scenes I got are night exterior scenes in the model city we have created - therefore I want to get good shadows. But the exposed image has a lot of Blue in it that it still remains in the shadows even when taken away at TK. BUT that defeats the purpose of using the blue gel on the lamps if I don't see blue in highlights with black shadows.

Some of fellow DP's think it is the reciprocity problem and the use of Daylight film with tungsten lamp. Would going to a Tungsten Film be an answer then? oh I remember I can't get it replaced the 50D.

I will try to contact lab if they can help.

Thanks!
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#6 David Mullen ASC

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Posted 15 July 2005 - 01:21 PM

Blue gels aren't always accurate either, but it sounds like the solution is to overexpose the negative. Yes, it could be reciprosity failure. You should shoot one shot at 24 fps just to compare to the stop-motion version to see if the exposures are the same.

Otherwise, try switching to 100T stock.

I read, by the way, that Fuji 125T was chosen for "Chicken Run" because it had the least problem with reciprocity failure and color variations over time spent sitting in the camera. This was before Vision-2 100T though (72/5212).
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#7 Laurent Andrieux

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Posted 15 July 2005 - 05:14 PM

If you have exposure times greater than 1 second, it could be reciprocity failure, sounds accurate.

If you post in the "stock" section, may be someone could help about that. May be John Pytlack ?

Did you try to have informations about that even on the kodak's site ?

Usually, when it comes to long time exposure, you get a underexposition so it could be that. Concerning the color compensation, you could try some CC minus green and make tests, if you still have time and money for that...

If you don't find a guideline I don't see another solution but to make tests, actually...
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#8 Sam Wells

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Posted 15 July 2005 - 07:01 PM

You should not see a serious color shift on this stock with 1 sec exposure.

I haven't.

-Sam
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