Is it possible to pull focus on a lens while crash zooming?

Ryan Elder · January 24th, 2019, 02:02 PM

Oh there is only one Wild Bunch, and there are crash zooms in it. There were not any remakes I am aware of. Even though it's from 1969, there are still modern movies that do crash zooms, such as Rise of the Planet of the Apes for example.

Quote:

Originally Posted by Paul R Johnson

If the idea is to do a really fast crash zoom, then surely only the two ends need to be in focus if it's for effect? I can't quite visualise what you are doing, to be honest?

Well basically I wanted to start out on a closer up shot of an actor's face and then zoom out to reveal the people waiting behind pillars to ambush him, for the shot I had in mind.

If I can't get a lens that is like that, then I can try using a gimbal and ramping the speed in post like it was suggested, hoping that the actors do not move too fast. I just thought if they have a DSLR lens that crash zoom and still be in focus like the film riot video, then it seems possible (shrug).

Josh Bass · January 24th, 2019, 07:52 PM

We're saying if it's a fast zoom, will you even be able to see that it's soft during the zoom itself? It should only matter that it's in focus when you're close and in focus when you're wide. The in between should be so quick as to be unnoticeable.

Ryan Elder · January 25th, 2019, 02:35 AM

Oh okay, well what about this example I posted before, is it fast enough that you don't really pick up on it?

Josh Bass · January 25th, 2019, 03:08 AM

No, you have a point. That's definitely noticeable and it looks pretty janky. I would also say it takes it a beat after the zoom is over for it to be in focus again which is part of the problem.

Brian Drysdale · January 25th, 2019, 06:27 AM

You need to hire/buy a cine/video (parfocal) zoom lens if you intend to do this type of crash zoom shot. In the end, it's the right tool for the job, still camera zooms are not intended for this type of stuff.

Ryan Elder · January 25th, 2019, 11:41 AM

Okay thanks. I didn't think it was possible with a still camera lens either, but in the film riot video I posted before, they actually did crash zooms while keeping focus on a still lens on a DSLR. So what was the trick as to how they pulled it off in this video? It's at 4:30 into the video:

I know people are saying to use a gimbal or dolly instead and move the camera fast, but in the video, they actually pull off a zoom completely in focus with a still DSLR lens, and so it can be done it seems.

Brian Drysdale · January 25th, 2019, 05:58 PM

Some DSLR lens will hold their focus quite well, although the examples given in the video aren't zooming that much and others involve exteriors, so the lens may be stopped down. You really need to research which DSLR zoom lenses do keep reasonable focus when zooming, then run a test to see if it's acceptable.

Jeff Donald · January 25th, 2019, 06:10 PM

Your looking for parfocal lens, a lens that stays in focus as you zoom/change focal length. Most lenses today are varifocal and change focus/magnification as you zoom. This can sometimes be related to focus breathing. Focus breathing is the change in magnification as you focus closer or further away. The focal length of a lens is determined when the lens is focused at infinity. As you focus closer and closer the focal length of the lens decreases. In other words a 70~200mm lens may be 200mm at infinity. When focused at 10 feet, the focal length may be 185mm. In poor lens designs the focal length may be as little as 135mm or even less.

Ryan Elder · January 26th, 2019, 12:36 AM

Okay thanks, that makes sense. It's just the one on film riot seemed to be doing a pretty good job so I thought there must be some DSLR lenses out there that can stay in focus during the zoom, without being parfocal.

However, if I have to, I can just run with the gimbal instead to reveal the ambush. It's just I feel it will look like a slow reveal as a result and will have to speed it up in post, like I was told to on here. It's just whenever I do that to footage, it looks sped up, and looks cheesy. I was told that crash zooms can look cheesy, but how do make sped up footage not look just as cheesy by comparison...

But I think the only reason why people associate zooms with looking cheesy is because we are use to seeing them in cheesy shows, such as reality shows and The Office. When they do it in a movie like Rise of the Planet of the Apes, during the action scene on the bridge, which they did, then it looks good. So it pretty much looks cheesy if you use it in a cheesy show, compared to a non-cheesy movie. Unless I am wrong?

Josh Bass · January 26th, 2019, 12:41 AM

Something you may have missed though someone earlier said it is that your lens has the appearance from that test clip of being servo-controlled or fly-by-wire focus, meaning that you are not directly moving the lens elements back and forth when you zoom; there’s another...something (I dont know the tech side of this) in the middle of the process that tells the lens to move as you turn the ring. A DSLR lens that has an actual finite focus ring would work better...where turning the ring directly moves the elements.
Does your focus ring turn in either direction forever? That’s probably not a true manual focus (maybe using wrong terms here). The kind of focus you want will have a hard stop where you simply cant turn any farther once you get to either the wide or telephoto end of the focus range.

Ryan Elder · January 26th, 2019, 12:56 AM

Okay thanks. Yes the lens has a focus ring that turns forever in each direction. I can set focus marks, it's just I cannot turn the lens fast enough to focus during the zoom, since the crash zoom is so fast.

When you say fly-by-wire, and that I am not directly moving the elements, what do you mean by that exactly? I am moving the lens with hand to zoom, so wouldn't that be directly moving it, or do you mean something else?

Brian Drysdale · January 26th, 2019, 03:07 AM

I wouldn't say all zooms look cheesy, only those that are done without thought or motivation can be cheesy. You can bury zooms inside tracking and crab moves, so that they're not as obvious.

Like all shots, zooms have had a period of over use because they're fashionable, the same will probably happen with drone shots that are done because you can do them, rather than being done for a purpose. Although, currently the UK TV fashion of focusing on a meaningless object (grass or a painted doorframe) in the foreground while the two shot of the interview is defocused in the background, has gone well past it's sell by date.

Josh Bass · January 26th, 2019, 03:57 AM

I'm simply saying when you turn the ring on a fly by wire focus lens, it's not directly turning gears that move the lens elements, the way a purely mechanical focus lens does; there's another step in between where turning the ring causes electronics to control a motor that moves the lens elements. It causes a lack of precision that's probably responsible for your lens behaving the way it does during a zoom, and the way it takes it a fraction of second to snap back to focus after the zoom stops. Search for "fly by wire focus lens" or similar to learn more. If you can get your hand on a lens with purely mechanical focus ring (even just to play with it at a local store), you'll feel the difference in how it responds.

You keep asking how film riot guy could do zoom with a still lens and have it work out well...more than likely they were using a mechanical focus ring lens.

Pete Cofrancesco · January 26th, 2019, 10:08 AM

My god how many times can you circle around to the same question despite it being answered repeatedly by a number of people.

Your lens can’t do that technique. Either rent/buy a lens that will or don’t do a crash zoom for that scene! Crash Zooms are rarely used and not essential to film making and is generally frowned upon as cheesy technique.

Ryan Elder · January 26th, 2019, 12:25 PM

Okay thanks, sorry just trying to establish all the possibilities, since the focus ring thing was pointed out now.

As it for it being cheesy, I mean it is used in big budget Hollywood movies like Rise of the Planet of the Apes being the most recent I can think of where I saw it, so I figured if it's good enough for that, than it must not be so bad.

But if I have to, I can just run with the camera on a gimbal and speed it up, like it was suggested to. How do you make it look like it's not obviously sped up though, when it is?

January 24th, 2019, 07:52 PM	#62
Josh Bass Slash Rules! Join Date: Apr 2002 Location: Houston, Texas Posts: 5,472	Re: Is it possible to pull focus on a lens while crash zooming? We're saying if it's a fast zoom, will you even be able to see that it's soft during the zoom itself? It should only matter that it's in focus when you're close and in focus when you're wide. The in between should be so quick as to be unnoticeable. __________________ The Bass' camerawork The Bass on IMDB

January 25th, 2019, 02:35 AM	#63
Ryan Elder also known as Ryan Wray Join Date: Nov 2017 Location: Saskatoon, Canada Posts: 2,880	Re: Is it possible to pull focus on a lens while crash zooming? Oh okay, well what about this example I posted before, is it fast enough that you don't really pick up on it? zooming test - YouTube

January 25th, 2019, 03:08 AM	#64
Josh Bass Slash Rules! Join Date: Apr 2002 Location: Houston, Texas Posts: 5,472	Re: Is it possible to pull focus on a lens while crash zooming? No, you have a point. That's definitely noticeable and it looks pretty janky. I would also say it takes it a beat after the zoom is over for it to be in focus again which is part of the problem. __________________ The Bass' camerawork The Bass on IMDB

January 25th, 2019, 06:27 AM	#65
Brian Drysdale Inner Circle Join Date: Feb 2006 Location: Belfast, UK Posts: 6,143	Re: Is it possible to pull focus on a lens while crash zooming? You need to hire/buy a cine/video (parfocal) zoom lens if you intend to do this type of crash zoom shot. In the end, it's the right tool for the job, still camera zooms are not intended for this type of stuff.

January 25th, 2019, 11:41 AM	#66
Ryan Elder also known as Ryan Wray Join Date: Nov 2017 Location: Saskatoon, Canada Posts: 2,880	Re: Is it possible to pull focus on a lens while crash zooming? Okay thanks. I didn't think it was possible with a still camera lens either, but in the film riot video I posted before, they actually did crash zooms while keeping focus on a still lens on a DSLR. So what was the trick as to how they pulled it off in this video? It's at 4:30 into the video: The Difference Between Dolly & Zoom Shots - YouTube I know people are saying to use a gimbal or dolly instead and move the camera fast, but in the video, they actually pull off a zoom completely in focus with a still DSLR lens, and so it can be done it seems.

January 25th, 2019, 05:58 PM	#67
Brian Drysdale Inner Circle Join Date: Feb 2006 Location: Belfast, UK Posts: 6,143	Re: Is it possible to pull focus on a lens while crash zooming? Some DSLR lens will hold their focus quite well, although the examples given in the video aren't zooming that much and others involve exteriors, so the lens may be stopped down. You really need to research which DSLR zoom lenses do keep reasonable focus when zooming, then run a test to see if it's acceptable.

January 25th, 2019, 06:10 PM	#68
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	Re: Is it possible to pull focus on a lens while crash zooming? Your looking for parfocal lens, a lens that stays in focus as you zoom/change focal length. Most lenses today are varifocal and change focus/magnification as you zoom. This can sometimes be related to focus breathing. Focus breathing is the change in magnification as you focus closer or further away. The focal length of a lens is determined when the lens is focused at infinity. As you focus closer and closer the focal length of the lens decreases. In other words a 70~200mm lens may be 200mm at infinity. When focused at 10 feet, the focal length may be 185mm. In poor lens designs the focal length may be as little as 135mm or even less. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

January 26th, 2019, 12:36 AM	#69
Ryan Elder also known as Ryan Wray Join Date: Nov 2017 Location: Saskatoon, Canada Posts: 2,880	Re: Is it possible to pull focus on a lens while crash zooming? Okay thanks, that makes sense. It's just the one on film riot seemed to be doing a pretty good job so I thought there must be some DSLR lenses out there that can stay in focus during the zoom, without being parfocal. However, if I have to, I can just run with the gimbal instead to reveal the ambush. It's just I feel it will look like a slow reveal as a result and will have to speed it up in post, like I was told to on here. It's just whenever I do that to footage, it looks sped up, and looks cheesy. I was told that crash zooms can look cheesy, but how do make sped up footage not look just as cheesy by comparison... But I think the only reason why people associate zooms with looking cheesy is because we are use to seeing them in cheesy shows, such as reality shows and The Office. When they do it in a movie like Rise of the Planet of the Apes, during the action scene on the bridge, which they did, then it looks good. So it pretty much looks cheesy if you use it in a cheesy show, compared to a non-cheesy movie. Unless I am wrong?

January 26th, 2019, 12:41 AM	#70
Josh Bass Slash Rules! Join Date: Apr 2002 Location: Houston, Texas Posts: 5,472	Re: Is it possible to pull focus on a lens while crash zooming? Something you may have missed though someone earlier said it is that your lens has the appearance from that test clip of being servo-controlled or fly-by-wire focus, meaning that you are not directly moving the lens elements back and forth when you zoom; there’s another...something (I dont know the tech side of this) in the middle of the process that tells the lens to move as you turn the ring. A DSLR lens that has an actual finite focus ring would work better...where turning the ring directly moves the elements. Does your focus ring turn in either direction forever? That’s probably not a true manual focus (maybe using wrong terms here). The kind of focus you want will have a hard stop where you simply cant turn any farther once you get to either the wide or telephoto end of the focus range. __________________ The Bass' camerawork The Bass on IMDB

January 26th, 2019, 12:56 AM	#71
Ryan Elder also known as Ryan Wray Join Date: Nov 2017 Location: Saskatoon, Canada Posts: 2,880	Re: Is it possible to pull focus on a lens while crash zooming? Okay thanks. Yes the lens has a focus ring that turns forever in each direction. I can set focus marks, it's just I cannot turn the lens fast enough to focus during the zoom, since the crash zoom is so fast. When you say fly-by-wire, and that I am not directly moving the elements, what do you mean by that exactly? I am moving the lens with hand to zoom, so wouldn't that be directly moving it, or do you mean something else?

January 26th, 2019, 03:07 AM	#72
Brian Drysdale Inner Circle Join Date: Feb 2006 Location: Belfast, UK Posts: 6,143	Re: Is it possible to pull focus on a lens while crash zooming? I wouldn't say all zooms look cheesy, only those that are done without thought or motivation can be cheesy. You can bury zooms inside tracking and crab moves, so that they're not as obvious. Like all shots, zooms have had a period of over use because they're fashionable, the same will probably happen with drone shots that are done because you can do them, rather than being done for a purpose. Although, currently the UK TV fashion of focusing on a meaningless object (grass or a painted doorframe) in the foreground while the two shot of the interview is defocused in the background, has gone well past it's sell by date.

January 26th, 2019, 03:57 AM	#73
Josh Bass Slash Rules! Join Date: Apr 2002 Location: Houston, Texas Posts: 5,472	Re: Is it possible to pull focus on a lens while crash zooming? I'm simply saying when you turn the ring on a fly by wire focus lens, it's not directly turning gears that move the lens elements, the way a purely mechanical focus lens does; there's another step in between where turning the ring causes electronics to control a motor that moves the lens elements. It causes a lack of precision that's probably responsible for your lens behaving the way it does during a zoom, and the way it takes it a fraction of second to snap back to focus after the zoom stops. Search for "fly by wire focus lens" or similar to learn more. If you can get your hand on a lens with purely mechanical focus ring (even just to play with it at a local store), you'll feel the difference in how it responds. You keep asking how film riot guy could do zoom with a still lens and have it work out well...more than likely they were using a mechanical focus ring lens. __________________ The Bass' camerawork The Bass on IMDB

January 26th, 2019, 10:08 AM	#74
Pete Cofrancesco Inner Circle Join Date: May 2004 Location: USA Posts: 2,997	Re: Is it possible to pull focus on a lens while crash zooming? My god how many times can you circle around to the same question despite it being answered repeatedly by a number of people. Your lens can’t do that technique. Either rent/buy a lens that will or don’t do a crash zoom for that scene! Crash Zooms are rarely used and not essential to film making and is generally frowned upon as cheesy technique.

January 26th, 2019, 12:25 PM	#75
Ryan Elder also known as Ryan Wray Join Date: Nov 2017 Location: Saskatoon, Canada Posts: 2,880	Re: Is it possible to pull focus on a lens while crash zooming? Okay thanks, sorry just trying to establish all the possibilities, since the focus ring thing was pointed out now. As it for it being cheesy, I mean it is used in big budget Hollywood movies like Rise of the Planet of the Apes being the most recent I can think of where I saw it, so I figured if it's good enough for that, than it must not be so bad. But if I have to, I can just run with the camera on a gimbal and speed it up, like it was suggested to. How do you make it look like it's not obviously sped up though, when it is?