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Low-light slow motion?


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#1 Derek Van Gorder

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Posted 30 April 2009 - 09:27 PM

Hi all.

I am shooting a scene for a student short this saturday that takes place in a bar. I've rented a Beaulieu 4008 ZM2 with a Schnieder 6-66mm Zoom Lens (f1.8, if I remember correctly), and have purchased both 200T and 500T color negative stock from Kodak.

The lighting in the bar is very red (which is perfect for the intended look), but fairly dim. Trucking in lights isn't an option since we're shooting during open hours (with permission, of course), all I will have with me is a small reflector.

I really want this scene to be slow-motion. However, I assume that a higher frame rate will require more exposure. Does anyone have any experience shooting slow-mo Super 8 in a situation like this? For reference, here is the bar's website, it has lots of photos of the interior:

http://www.rbarnyc.com/

The rental house tells me the camera shoots up to 80fps. Is it realistic to hope for decent exposure in a bar at that frame rate? I've seen tests of 500T online that get great picture with candlelight alone, but is it a totally different game at high frame rates? How many stops should I expect to lose, and would it be worth shooting slightly lower at 70 or 60 fps?

Any advice would be highly appreciated. This will be my first "serious" shoot with Super 8. I would have loved to perform tests with the 500T in advance, but the schedule won't allow it. Any tips welcome.

Thanks!
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#2 Ian Cooper

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Posted 01 May 2009 - 02:04 AM

I can't give you any direct advice as to whether you'll be 'alright' or not, but working out the difference in light levels between the two speeds is fairly easy.

A quick google shows the Beaulieu 4008 ZM2 has what approximates to a 170 degree shutter angle. This means when filming at 24fps the shutter speed will be 1/50. At 80fps the shutter speed has increased to 1/169.

The difference between the two shutter speeds is about 1-2/3 stops, or in round figures about 2 stops less.

Can you go to the venue in advance with a light meter to check what the levels are?

The lattitude of 500T is such that you'll probably get something, but if the lens is already wide open at f1.8 when you're shooting at 24fps, the slow motion footage being 2 stops underexposed is likely to be noticably more grainy for a start.
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#3 Ian Cooper

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Posted 01 May 2009 - 02:42 AM

Mmm...

I've just come across this manual for the 4008 ZM2. That seems to show the maximum filming speed is 70fps (not 80), and the shutter speeds are 1/87 at 25fps and 1/250 at 70fps. That would tend to imply the shutter angle is actually about 100 degrees - not perhaps the most suited camera for filming in low light conditions, that's about 1 stop less sensitive than a 'normal' 180 degree shutter.

Anyway, for completeness, the difference between 24/25fps and 70fps would still be basically 1-2/3 stops. So long as the shutter angle remains constant, it doesn't alter the relative difference.
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#4 andy oliver

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Posted 01 May 2009 - 01:23 PM

If your hiring in the camera, ask if they have a 4008 fitted with the 6-80 T1.4 angenieux lens, that will give you a bit extra on the exposure, perhaps just crank up to 36fps. As metioned, 4008 at 24 fps shutter is around 1/87th. Is a 6008 or 7008 available for hire?
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#5 andy oliver

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Posted 01 May 2009 - 01:30 PM

A zm2 was available with 80 fps, it was supplied with the 6-80 angenieux lens and i believe only 500 units were made, around 1976-ish....

Edited by andy oliver, 01 May 2009 - 01:33 PM.

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#6 Derek Van Gorder

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Posted 02 May 2009 - 12:16 AM

Thanks for all your replies.

The 4008 was sort of in that sweet-spot between price and desired qualities. Their catalog described it as shooting 80fps, though on receiving it I noticed it was only 70 fps. Which is fine, because I am definitely thinking of toning down the frame-rate, if not just shooting at 24.

I also was able to rent a small handheld light, so if it seems that there is just not enough light, I can hopefully employ that sparingly in the bar. Won't get much time to scout out the location in advance, so I'll just have to play it by ear.

I have a decent amount of extra stock, so I may try shooting just the key shots both in slow-motion and 24fps, for safety.

Thanks again.
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#7 Rafael Rivera

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Posted 03 May 2009 - 03:57 PM

Here's a sample of V2 500T I shot with a ZM2 @ 70 fps with the Schneider 6-66 during a ballet performance. Look at the slow mo scene (~1:30), there're 2 light trees on each side of the stage with 2 lights each, shot wide open. The shutter angle is roughly 100 degrees.
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#8 Jim Carlile

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Posted 03 May 2009 - 10:15 PM

Use 500T and push it two stops.
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#9 Derek Van Gorder

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Posted 12 May 2009 - 06:56 PM

Thanks again for the help and suggestions. I thought I'd post some screengrabs to share the results.

I shot somewhere around 40fps, wide open on the Schnieder lens. I used a 200w Pocket Par, it traveled with the actress for a handheld tracking shot. Background is mostly lost, but the red lights on the bar still add enough of the menacing atmosphere I was hoping for.

I went with the cheapest & quickest miniDV transfer I could find given time constraints, so I don't think the footage is at its best here. The last still shows the footage before color-correction. I hope to pursue a better transfer later.

In the future I will likely try a different camera for low-light conditions, but all things considered I think this came out well given the intended feeling of the scene.

Attached Images

  • club1.jpg
  • club2.jpg
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  • club4.jpg
  • club5.jpg

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#10 Jim Carlile

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Posted 13 May 2009 - 12:57 AM

It looks good. Kind of Rembrandt-y, in fact. Did you push the film, or just process it regular?

That's a hard camera to us, IMO-- it can be tricky-- and it's not a good low-light camera either. It's not XL at all. The focusing was sharp, too-- that's the hardest thing about open aperture shooting at short distances, especially with a Beaulieu. I'd be happy with those results.
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#11 Derek Van Gorder

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Posted 13 May 2009 - 01:21 PM

It looks good. Kind of Rembrandt-y, in fact. Did you push the film, or just process it regular?

That's a hard camera to us, IMO-- it can be tricky-- and it's not a good low-light camera either. It's not XL at all. The focusing was sharp, too-- that's the hardest thing about open aperture shooting at short distances, especially with a Beaulieu. I'd be happy with those results.


Regular processing (by the time I read your post suggesting pushing it I'd already sent the film to the lab).

Thanks, I really am quite happy with the results, especially with the scene in motion, it works perfectly. The flicker is pretty bad, however, and so far I'm having trouble getting a version for web exported that looks decent; somehow the conversion seems to accentuate the grain and flicker a little more than I would like (looks much more tolerable when compressed for DVD, though). I am wondering if I should hold out for a better transfer before releasing it online...

I'll definitely post the finished film in the forum here when it's done.
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