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Technical Question Re: FPS and Exposure


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#1 Anne Winter

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Posted 09 March 2009 - 07:46 PM

Hello Everyone,

I am fairly new to the art of Cinematography and have been asked at short notice to shoot on S16mm this weekend. I have used the camera before and have assisted on a few student productions but I have a couple of areas I am not clear on.

1. The film is ideally to be screened from a 16mm print however it will also be put on to DVD in order to be sent out to festivals etc. I am unsure whether to shoot at 24fps or 25fps. I think that the 24fps would work out best for the film print and make it easier to sync up the sound but perhaps if it will be seen on DVD initially it might be best to shoot at 25fps?

2. I have the use of a L-608 Cine for the duration of the shoot. I know that for the most part F Stops and T stops are interchangable however the light meter I have only allows me to measure in F stops. If I wanted to work out the difference or loss of exposure should I for example go from a prime lens to a Zoom lens while in the same set up and wanted to keep the same exposure how would I work out the diffrence between the T Stop and the F Stop?


I do apologise if my questions seem ignorant. I have a few books with me on the subject and cannot find a definitive answer. I really appreciate any imput anyone has into these questions.

Thank you in advance.

Anne.
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#2 Michael Collier

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Posted 09 March 2009 - 07:53 PM

I would shoot 24 fps. Assuming your in NTSC land, or more importantly the festivals you want to submit to are in NTSC parts of the world. Also with 24fps, it can be dealt with to make it work in 25fps pal, so don't choose based on DVD submissions.

It says f-stops on your meter, but trust me it really means T-stops. F-stops on your meter is assuming you have 0 light loss through your lenses-a practical impossibility. T-stops are the calibrated F-stop, so basically meter your light, set your T-stop and if they are all set up correctly you should get the same exposure between all your lenses on that T-stop. F-stop markings on lenses is the mathematical F-stop and are used for DOF calculations that are not affected by light loss.
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#3 Anne Winter

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Posted 09 March 2009 - 08:03 PM

Hi Michael,

Thank you for your swift answer. I think I am okay with the F Stop V's T Stop thing now. I thought they were more or less the same these days but just wanted to be sure. So thanks for that.

I am actually UK based (yes I'm up a bit late!) and so would that affect your advice regarding what fps to shoot at as the film will be more likely to be shown here in the UK or in continental Europe rather than the US. So that is also where the DVD's would go. Will this make a difference?

Thanks again!
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#4 Michael Collier

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Posted 09 March 2009 - 08:12 PM

It wouldn't affect my advice to shoot 24fps, since I know it should still be workable; but you should get some post options from someone who has dealt with PAL. I have only worked with pal once, and I wasn't editing, so I don't know the endgame of that, just that it works.

I mean obviously it works since every major picture is shot 24fps, and I am sure they make it to DVDs that play on Pal TVs. I am just unclear exactly how they do that. I heard once they just speed the footage up to 25fps.

But if your printing for festival you'd be best served by shooting 24fps and figuring out the DVD option. I am sure in PAL its quite simple, its easy as pie here in NTSC.
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#5 Jim Carlile

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Posted 18 March 2009 - 03:21 AM

I believe your question might have been answered in another thread, but if you are in PAL land then by all means shoot in 25 fps if you are doing any kind of digital work there.
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