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Old January 3rd, 2019, 12:55 PM   #1
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Is it possible to pull focus on a lens while crash zooming?

I have a short film project coming up where I want to do crash zooms in a few shots.

However, when I do crash zooms on my Canon 70-300 lens, the lens goes out of focus during the zoom, and then snaps back into focus, right after the zoom is done.

I was told by others that I need to pull focus during the zoom. But I'm having a lot trouble cause I have to pull focus one way really fast, and then pull it the other way really fast, just as the zoom finishes, and I have to do the push and pull, all within a small fraction of a second, since it's a fast crash zoom.

Does anyone know how to do this exactly for crash zooms?
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Old January 3rd, 2019, 03:35 PM   #2
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Re: Is it possible to pull focus on a lens while crash zooming?

You're running head on into some of the limitations of using a lens designed for still photography for video. AFAIK there is no magic bullet for the challenge you're facing.

A focus pull would need to be done in MF mode. In cinematography, it would be done by the 1st camera assistant (AC). And, with a rehearsal or two and some tape marks an AC could pull your focus. A follow-focus would allow easier repeatability, and a whip for it would get the AC's hands away from yours.

A zoom lens designed for video/film is parfocal, that is, if you accomplish sharp focus fully zoomed in, the design maintains focus throughout the zoom range. Such are a bit more expensive than most still lenses.

Some of Canon's still lenses will do better at this than others. I've not used the 70-300, but it's a USM lens, right? The STM designs I've used (18-135, 24 pancake, 55-250) tend to be more responsive in focus for video use, but I couldn't say how well they'd keep sharp with a crash zoom - never tried.

The 17-55 f2.8 EF-S is a USM, but, it's *almost* parfocal.

Could you do a slower zoom that has the focus characteristics you want, then speed it up in post?

No magic bullets...
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Last edited by Seth Bloombaum; January 3rd, 2019 at 09:33 PM.
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Old January 4th, 2019, 04:13 PM   #3
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Re: Is it possible to pull focus on a lens while crash zooming?

Are you Ryan Wray or Ryan Elder?

There are four different Canon 70-300 lenses:

EF 70-300mm f/4-5.6 IS II USM, appx. $500
EF 70-300mm f/4-5.6L IS USM, appx. $1350
EF 70-300mm f/4.5-5.6 DO IS USM, appx. $1400
EF 70-300mm f/4-5.6 IS USM, discontinued 2016

Not that the circumstances change much from one of these lenses to the other, but it's always helpful to be specific about which one you've got.
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Old January 4th, 2019, 04:31 PM   #4
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Re: Is it possible to pull focus on a lens while crash zooming?

Quote:
Originally Posted by Ryan Wray View Post
I have a short film project coming up where I want to do crash zooms in a few shots.

However, when I do crash zooms on my Canon 70-300 lens, the lens goes out of focus during the zoom, and then snaps back into focus, right after the zoom is done.

I was told by others that I need to pull focus during the zoom. But I'm having a lot trouble cause I have to pull focus one way really fast, and then pull it the other way really fast, just as the zoom finishes, and I have to do the push and pull, all within a small fraction of a second, since it's a fast crash zoom.
Unless this kind of stuff is a piece of cake for you, I'd say no, it can't be done.

http://www.juggle.org/wp-content/upl...ra-944x590.jpg

To do this you need a true parfocal lens.
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Old January 5th, 2019, 09:49 AM   #5
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Re: Is it possible to pull focus on a lens while crash zooming?

One of the reasons DSLRs are very convenient, but often poorly equipped to do what conventional video cameras do without any issues. They're excellent value for money when you compare image quality, I realise this - but they have far too many limitations for me to use mine for video, unless it's a locked off, static shot, or handheld wide angle.
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Old January 6th, 2019, 03:30 AM   #6
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Quote:
Originally Posted by Chris Hurd View Post
Are you Ryan Wray or Ryan Elder?

There are four different Canon 70-300 lenses:

EF 70-300mm f/4-5.6 IS II USM, appx. $500
EF 70-300mm f/4-5.6L IS USM, appx. $1350
EF 70-300mm f/4.5-5.6 DO IS USM, appx. $1400
EF 70-300mm f/4-5.6 IS USM, discontinued 2016

Not that the circumstances change much from one of these lenses to the other, but it's always helpful to be specific about which one you've got.
I'm Ryan Wray. I have the first one on that list.

Quote:
Originally Posted by Seth Bloombaum View Post
You're running head on into some of the limitations of using a lens designed for still photography for video. AFAIK there is no magic bullet for the challenge you're facing.

A focus pull would need to be done in MF mode. In cinematography, it would be done by the 1st camera assistant (AC). And, with a rehearsal or two and some tape marks an AC could pull your focus. A follow-focus would allow easier repeatability, and a whip for it would get the AC's hands away from yours.

A zoom lens designed for video/film is parfocal, that is, if you accomplish sharp focus fully zoomed in, the design maintains focus throughout the zoom range. Such are a bit more expensive than most still lenses.

Some of Canon's still lenses will do better at this than others. I've not used the 70-300, but it's a USM lens, right? The STM designs I've used (18-135, 24 pancake, 55-250) tend to be more responsive in focus for video use, but I couldn't say how well they'd keep sharp with a crash zoom - never tried.

The 17-55 f2.8 EF-S is a USM, but, it's *almost* parfocal.

Could you do a slower zoom that has the focus characteristics you want, then speed it up in post?

No magic bullets...
Okay thanks. I keep trying to pull focus during the zoom but I can't pull it fast enough since I want a fast zoom.

I can't speed it up in post, cause I want to do the zoom while actors are moving fast, and if I speed it up, the actors will speed up too and it will be noticeable.
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Old January 6th, 2019, 09:14 AM   #7
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Re: Is it possible to pull focus on a lens while crash zooming?

Have actors move in slow motion.

Seriously that technique is a bit of a fad. You either need to get the proper equipment (which you most likely donít have the money) or do something else.
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Old January 6th, 2019, 12:20 PM   #8
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Re: Is it possible to pull focus on a lens while crash zooming?

Okay thanks, but is how is the technique a fad now though? I haven't seen it done in a movie in so long that I thought it would be a newer technique for today, compared to 30 years ago.

Mostly I just wanted to do a couple of crash zooms, to show reveals, like when an actor runs into a room then we quickly zoom back to reveal that their are men waiting to ambush him. That is what I wanted to use it for, things like that.

I was told to dolly back instead, but I can't move the dolly fast enough, and it then becomes a much slower reveal, instead of a fast reveal. The actors then have to wait for the camera to play catch up to their ambush, if I am dollying much slower, if that makes sense.

This is why I was told to pull focus faster, when doing the crash zoom. But is focus pulling during a crash zoom absolutely impossible then?
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Old January 6th, 2019, 10:40 PM   #9
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Re: Is it possible to pull focus on a lens while crash zooming?

I think what they mean by ďfadĒ is that it was in vogue for a time...that time (probably) being the 70s and 80s. At some point it fell out of fashion and now tends to make things look amateurish/dated unless used exactly right. I understand Tarantino brought it back in Kill Bill and Iím sure others have done it recently(ish) too, but itís all context...are you INTENDING a 70s look/feel? Or does it clash with a modern style youíre attempting?

I understand your issue with the dolly being too slow but ths makes me think perhaps the whole shooting plan for this sequence should be rethought...perhaps a blocking change, or a shot where the camera moving ever so slightly to the side or only having to dolly out a little (as opposed to the massive shot size you would get from the crash zoom) to reveal the bad guys would work. Or do it with edits instead of cam moves.
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Old January 6th, 2019, 11:03 PM   #10
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Re: Is it possible to pull focus on a lens while crash zooming?

No I'm not trying to have a 70s throwback but I just wanted to do a zoom back fast, to do a quick ambush reveal, just before the ambush happens. So I don't think it would look 70s, as long as I have a legitimate type of reveal for using it, but that is just my guess.

The reason why I wanted a zoom is cause it can cover more ground in a faster amount of time than I can run, with the camera on a gimbal.

I thought about doing it with an edit but I felt that the audience would lose the sense of space of where they are in the scene, cause all of a sudden we see a close up of the actor's face, then it cuts to where he's very far away in the scene, so far, that the audience has to re-orient themselves, to where they are, as oppose to doing a fast zoom, and then the audience will be able to keep up where they are geographically, instead of having to cut and the audience having to re-orient.

But I was told I could do the zoom if I learn to focus pull it faster, so is it just a matter of that?
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Old January 6th, 2019, 11:49 PM   #11
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Re: Is it possible to pull focus on a lens while crash zooming?

Crash zoom was made popular by The Office. They didn’t invent it but like most things there are styles of shooting that become hot. Everyone tries to emulate, eventually it gets over used and abandoned. It’s not to say it doesn’t have use and might work great for your intended scenes but if you can’t pull it off what’s the point?

Here’s a video where they pull it off by I think having a large dof so everything is in focus. But for all I know they could be using a parfocal lens .

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Old January 7th, 2019, 12:27 AM   #12
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Re: Is it possible to pull focus on a lens while crash zooming?

I tried doing the large DOF to have everything in focus but I would have to go beyone f20 and not sure if we can get lights bright enough for that to light a parking garage, where this ambush is suppose to take place.

Here's a test I did in the garage under it's natural lighting so far. And everything is in focus, but still goes out of focus during the zoom:


But I was told I could get the shot if I learn to pulls focus really fast during or get a focus puller who can, so is that possible then, or no?
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Old January 7th, 2019, 07:00 AM   #13
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Re: Is it possible to pull focus on a lens while crash zooming?

It's standard to pull focus during a shot, a shallow depth of field has become a fashion for many film makers.

However, the zoom lenses used on still cameras aren't designed for zooming and maintaining focus. They are varifocal lenses, so they will lose focus when zoomed. The zoom test you've posted is distracting because it loses focus in the opposite way to normal. In practice, you can get away with zooming in the opposite direction because, with fast moving action, audiences are used to focus hunting in news and documentaries after a crash zoom into the subject. Editors keep these in because of the energy, although camera people tend to get annoyed by them.

In this case, a cut (even a jump cut) would be better.
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Old January 7th, 2019, 12:25 PM   #14
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Re: Is it possible to pull focus on a lens while crash zooming?

Okay thanks, so when I was told I am able to pull focus during the zoom, then I cannot then at all?

Plus, you are saying that if the lens goes out of focus during the zoom, it's okay to go out of focus if you zoom forward, but not backward?
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Old January 7th, 2019, 01:22 PM   #15
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Re: Is it possible to pull focus on a lens while crash zooming?

It looks like in the video you posted you have auto focus on. The technique I use is set the focus manually to the zoomed in subject and leave it that way. When you zoom out to super wide anlge of view even if it’s out of focus the dof is so great it won’t be noticeable. Some modern cameras compensate for this and you might not be able to prevent it. Someone else pointed out earlier some lenses are less parfocal than others. Big part of idie film make on no budget you have to be creative and flexible to overcome these things.
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