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Bolex 16mm - Slow Motion...


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#1 Joey Dee

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Posted 19 December 2006 - 10:38 PM

Hey folks,

Here's a quick question and let me know if I screw up. When you shoot slow motion on the Bolex 16mm is it better to have it run @ 60fps or 32fps and slow it down in post? Cause what I did was I left it @ 24fps and I will slow it down in post - Im not trying to achieve a SUPER crazy SLOW MO SHOT but I still want a nice "normal" slow mo shot, so Let me know if I'm good or It was better to shoot higher. But I think im fine however I'd still appreciate your opinions.

My best,
Joey Dee
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#2 adam berk

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Posted 19 December 2006 - 11:36 PM

One of the greatest things about film versus the very fine bunch of video flavors available now is the ability to shoot at higher framerates for slowmo easily. I realize there are quite a few superb slomo softwares available now, like shake's inbuilt optical flow retiming, kronos from The Foundry, etc..but nothing beats true high-speed cinematography. The only time I EVER resort to using a software slowmo solution is if it's an afterthought. I never actually shoot with plans for a software slowmo. No matter what, no matter how good your source material is for the purpose of slowing down in post, these softwares just won't quite reach the look of true in-camera slowmo without introducing strange artifacts, especially if you're not using a highend software and instead the inbuilt slowmo in avid or FCP, etc. Avid does have optical flow slowmo inbuilt now with the latest versions, but it is extremely slow and never looks good (in my experience). You should absolutely shoot at higher framerates on your camera, unless you're short on film or you don't have enough light. And in either of those two situations, I would first look at solving the problem so you CAN do a high framerate shot before considering doing a software slowmo.

I would shoot some tests if I were you so see what each of the different framerates looks like. If you're on a spring bolex, I think the highest you can go is 64....which believe it or not, isn't really all that slow. Don't under or overestimate the camera speeds, go out and shoot some tests....it's worth more than the price of 100' of film.

Hey folks,

Here's a quick question and let me know if I screw up. When you shoot slow motion on the Bolex 16mm is it better to have it run @ 60fps or 32fps and slow it down in post? Cause what I did was I left it @ 24fps and I will slow it down in post - Im not trying to achieve a SUPER crazy SLOW MO SHOT but I still want a nice "normal" slow mo shot, so Let me know if I'm good or It was better to shoot higher. But I think im fine however I'd still appreciate your opinions.

My best,
Joey Dee


Edited by adam berk, 19 December 2006 - 11:39 PM.

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#3 Joey Dee

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Posted 20 December 2006 - 12:05 AM

Hey Adam,

Thanks for the tips, really appreciate it mate! I have allready shot all my footage now the film is being processed to a digital format for me to edit in post next week. I have Twixtor: http://www.revisionf...m/rstwixtor.htm and I have tried on many digital footage that I shot (obviously on a digital format) and it looked great to be honest - I generally don't use too much slow mo but I should of thought of testing before shooting :(

So do you think since I shot on 24fps on my 16mm and I'll try to slow it down by 20-30% in post it would kill the quality? I personally don't think so, but of course I haven't done it yet hahah so your experiences with it is more valid then mine as I need to find out next week but I guess that question can be objective as it depends on what each person is trying to achieve no?

my best,
Joey Dee
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#4 adam berk

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Posted 20 December 2006 - 12:24 AM

Twixtor is definitely one of the best optical flow based slowmo kits. I actually think that the optical flow slowmo that's inbuilt with Flame and Inferno is based on that code. You've definitely got one of the best tools there is for artificial slowmo.

About losing image quality.... Optical flow slowmo doesn't really ruin "quality" but rather changes it. The way it works is the software looks at and tracks each pixel of the image over time, then creates new frames based on where it "thinks" each pixel "would" be if the shot were taken at a higher framerate. You can absolutely get fantastic results using a tool such as Twixtor or Kronos, but it really depends on the source material you are feeding it. Keep in mind that you are depending on the artificial intelligence of the software to figure out what is what in the picture, and how everything is moving. With all this said, due to the more grainy nature of 16, versus a formats like HD or 35, the software may have a more difficult time figuring out exactly how to calculate the new frames. Sometimes you can get weird morphing, etc.. that is very visible. But it can be cool sometimes too.

Optical flow has been a great tool for me, as a flame/smoke artist working mainly on television commercials and music videos (if i'm lucky). Scripts are CONSTANTLY changed, all the way up to 5min before tapes are supposed to be going out the door. Ha, half the time producers will show up with no script at all. It's all great fun. Those jobs are usually pretty cool because things open up for me to get extra creative. So, the ability to create good looking slowmo in post is extremely valuable in these types of situations.

Blah, blah, blah....I writing way too much here, but I guess the moral of the story is to shoot highspeed if you can, if not, don't depend on perfect looking slowmo created in post...it IS doable sometimes, but don't depend on it. And no matter what, it will never look quite as awesome as it would have if it were incamera.


Hey Adam,

Thanks for the tips, really appreciate it mate! I have allready shot all my footage now the film is being processed to a digital format for me to edit in post next week. I have Twixtor: http://www.revisionf...m/rstwixtor.htm and I have tried on many digital footage that I shot (obviously on a digital format) and it looked great to be honest - I generally don't use too much slow mo but I should of thought of testing before shooting :(

So do you think since I shot on 24fps on my 16mm and I'll try to slow it down by 20-30% in post it would kill the quality? I personally don't think so, but of course I haven't done it yet hahah so your experiences with it is more valid then mine as I need to find out next week but I guess that question can be objective as it depends on what each person is trying to achieve no?

my best,
Joey Dee


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#5 Nick Mulder

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Posted 20 December 2006 - 12:42 AM

If you adjust the governers on bolexes you can get them goin pretty fast, depending on the model from about 80 + expect to see some some image 'wigglin' though as there is no registration pin and its jus the friction of the pressure plate... Some of the earlier model claws are better at doing this I've been told

I tested two bolexes with unmodified governers set at 64fps - the RX4 ran at an average of 68fps and the SB ran at an average of 72fps ... I'd suggest those speed dials are up the wall :rolleyes: Also xpect a speed change of -2fps from a full spring wind to the end of the wind on a 'tired' bolex ie. most of them ...

As for your query even though you have already shot the footage since you have twixtor you can get any footage and apply a slowmo factor to see the relative 'slomo-ness' - eg. 64/24 = 2.7 ie. you footage will run for 2.7 times longer than it would at 24fps - I used twixtor once but cant remember what the interface asks for in terms of numbers - either 2.7 or 0.37 (1/2.7)
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#6 Joey Dee

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Posted 20 December 2006 - 12:43 AM

Thanks alot Adam,

I should of shot 64fps :( but I was so limited in film stock but we'll see how it goes I'll post and update when i get the film back as it's being processed now :)

my best,
Joey Dee
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#7 ryan_bennett

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Posted 20 December 2006 - 01:05 AM

Just remember to compensate open up a stop or so when you change the film speed to faster, and slower speeds close down.
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#8 adam berk

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Posted 20 December 2006 - 01:17 AM

yeah, I would think most cine meters will give you readouts based on camera speed, so just make sure you adjust your meter to the proper speed

Just remember to compensate open up a stop or so when you change the film speed to faster, and slower speeds close down.


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#9 Patrick Cooper

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Posted 20 December 2006 - 04:09 AM

Another advantage to achieving slow motion by running the film at a higher speed is that you are utilizing faster shutter speeds. Hence, subjects will appear noticeably sharper. This increase in sharpness certainly comes in handy when analyzing fast moving objects. The shutter duration of a Reflex Bolex running at the normal speed of 24fps is roughly 65th of a second. If you then slowed down this 24fps footage in post, the motion blur present in each frame would be quite evident.

?I think the highest you can go is 64....which believe it or not, isn't really all that slow?

I wouldn?t necessarily agree with that, depending on the subject. 54fps produces amazing, graceful slow motion that seems like poetry in motion. This is particularly suitable for most human sports and horse show jumping. 64fps would produce an even greater degree of slow motion. However, if you were filming subjects that were moving at an exceptionally high speed (the flapping of wings of many birds for example) then neither 54 or 64fps would be adequate.
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#10 adam berk

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Posted 20 December 2006 - 04:13 AM

I wouldn’t necessarily agree with that, depending on the subject. 54fps produces amazing, graceful slow motion that seems like poetry in motion. This is particularly suitable for most human sports and horse show jumping. 64fps would produce an even greater degree of slow motion. However, if you were filming subjects that were moving at an exceptionally high speed (the flapping of wings of many birds for example) then neither 54 or 64fps would be adequate.


You're absolutely right. It completely depends on what you're filming. My point was mainly that I found it important, for myself, to shoot some tests at all the different camera speeds in order to get a feel for what each speed looked like for the type of stuff I normally film.

Edited by adam berk, 20 December 2006 - 04:14 AM.

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