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do pro's ride the aperature


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#1 A.Oliver

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Posted 13 November 2005 - 01:21 PM

Hi, not sure where to post the question, so i'll try here. I have been using kodachrome for a few years now. When required i ride the aperature to give best exposure. Have been using neg stocks on and off for some time, do i need to ride the exposure on neg film. Say i am panning from T8 to T5.6, is there any need to ride the iris, set the iris midway or set to T8 and let the printer or T/K to make the adjustments.
THANKS
Andy
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#2 Stephen Williams

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Posted 13 November 2005 - 02:04 PM

Hi, not sure where to post the question, so i'll try here. I have been using kodachrome for a few years now. When required i ride the aperature to give best exposure. Have been using neg stocks on and off for some time, do i need to ride the exposure on neg film. Say i am panning from T8 to T5.6, is there any need to ride the iris, set the iris midway or set to T8 and let the printer or T/K to make the adjustments.
THANKS
Andy


Hi,

With just +/- 1/2 stop you don't need to worry. When there is a big change then it works well.

Stephen
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#3 A.Oliver

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Posted 13 November 2005 - 02:17 PM

Hi,

With just +/- 1/2 stop you don't need to worry. When there is a big change then it works well.

Stephen

So its best to ride the iris?
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#4 Fran Kuhn

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Posted 13 November 2005 - 02:17 PM

Hi, not sure where to post the question, so i'll try here. I have been using kodachrome for a few years now. When required i ride the aperature to give best exposure. Have been using neg stocks on and off for some time, do i need to ride the exposure on neg film. Say i am panning from T8 to T5.6, is there any need to ride the iris, set the iris midway or set to T8 and let the printer or T/K to make the adjustments.
THANKS
Andy


I'd avoid riding the aperture if possible, especially with only a 1-stop exposure change and especially since you're using negative stock, which has much greater latitude than Kodachrome. I tried doing it years ago and my Telecine guy had to go practically frame-by-frame to patch up my work.

In most cases I tend to favor the exposure setting that's best for the most important part of the shot. If all parts are equally important and I'm using negative stock, I usually try to give additional exposure to the darker portions of the scene, enough to make sure I have detail without completely losing the brighter parts of the shot. It's generally the opposite with reversal film: I try to avoid overexposing the brightest part of the scene because there's not much you can do to save overexposed reversal.

Edited by FKP-1, 13 November 2005 - 02:19 PM.

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#5 Stephen Williams

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Posted 13 November 2005 - 02:19 PM

So its best to ride the iris?


Hi,

Possibly at 2 stops for sure at 3 or more!

Stephen
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#6 Dickson Sorensen

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Posted 13 November 2005 - 02:54 PM

I have seen many DPs change the shutter angle (on cameras with that capability) to compensate exposure during a change in light levels. This method has the advantage of not introducing a change in the depth of field in the shot. It does however have the disadvantage of introducing a "skinny shutter effect" which can agrivate the strobing on quick pans and rapidly moving objects. In the end you have to weigh all the possibilities and decide which works best for a particular shot.

Edited by Dickson Sorensen, 13 November 2005 - 02:55 PM.

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#7 Laurent Andrieux

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Posted 13 November 2005 - 04:54 PM

FKP-1 :

Please, sign your posts ! Since you are a sustaining member, it would be great, well... just normal, that we know your real name...

"Riding" the iris works well if you do it smoothly and slowly. Don't know if your TK guy wanted every frame to be well exposed (wich would be, for me, close to total non sense) or if you changed too fast, but I can tell you I've been doing this often and it works really well. Do it smoothly, that's the trick.

One shouldn't be afraid of doing so.

Sure, if the contrast isn't that big beetween the different frames, one shoudn't worry that much, but one has to also consider the contrast of each of them...

Also, usually, post production is easier since you've been doing the iris change at the shooting, better than correcting in post. Anyway, if one frame is over/underexposed, post production will be frustrating anyway, so, better do it at the shooting...

Edited by laurent.a, 13 November 2005 - 06:30 PM.

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#8 David Mullen ASC

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Posted 13 November 2005 - 06:53 PM

You try and light a scene so you don't have to ride the aperture, so you only do it when it is the BEST way to handle the scene. I had to ride the aperture on a shot where I pulled back through a window looking on something outside and then panned over 180 degrees to a family sitting in the living room. I tried to hide the stop pull in the pull back / pan.

You can see Storaro doing iris changes in "Ladyhawke" in a few scenes, like when the camera pulls back with a priest entering the Bishop's bed chamber from the exterior corridor. Allen Daviau does it as well, like in a shot in "Empire of the Sun" where the camera pans Jamie running from a street into an alleyway.

One of the boldest (i.e. most obvious) stop pulls I've ever seen was in "White Nights" (DP David Watkin) when a jeep drives from inside a plane hanger out into the sunlight; the camera is mounted on the jeep shooting two people driving and talking. The camera lens just immediately stops down several stops to compensate once they emerge from the shade of the hanger. Normally you would design the shot in such a way as to hide the stop pull better, usually as the camera is changing backgrounds (rather than see the same background change in brightness).
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#9 Fran Kuhn

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Posted 15 November 2005 - 01:23 AM

FKP-1 :

Please, sign your posts ! Since you are a sustaining member, it would be great, well... just normal, that we know your real name...

You guys are relentless. Okay . . .it's there. Or at least it should be there if I've got the control panel wired correctly.

"Riding" the iris works well if you do it smoothly and slowly. Don't know if your TK guy wanted every frame to be well exposed (wich would be, for me, close to total non sense) or if you changed too fast, but I can tell you I've been doing this often and it works really well. Do it smoothly, that's the trick.

Hey, I'm with you on this. I mean, it seemed like a good idea up until I got the film to the telecine guy. I was shooting a motorcycle and the shot wrapped around from left profile to right profile, going from full sun to full shadow. I got my First to do a little gradual adjustment as we came around, a couple of stops, I think. Still, the colorist said it was a lot easier for him to fix it in post, to just pick a decent exposure for the overall scene and let the film do the rest. He's one of these $1500-an-hour characters, a partner at a big-time Santa Monica boutique place, so I kind of figured he knows what he's talking about. But I do agree with the other guys' posts above: I'm going to ride it again if it gets into three-stop territory.

Bonjour,
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#10 Dominic Case

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Posted 15 November 2005 - 05:54 AM

midway or set to T8 and let the printer or T/K to make the adjustments.

OK to let the telecine correct this, with a dynamic grade. If you are finishing on film, you will be in trouble as printers generally can't do a dynamic grade. It would need a DI to correct the grade.

Better all round as David said, to light the shot (if you can) so that the aperture doesn't have to be pulled.
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#11 Fran Kuhn

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Posted 15 November 2005 - 12:10 PM

OK to let the telecine correct this, with a dynamic grade. If you are finishing on film, you will be in trouble as printers generally can't do a dynamic grade. It would need a DI to correct the grade.

Better all round as David said, to light the shot (if you can) so that the aperture doesn't have to be pulled.


Thanks, Dominic. Yeah, all thing considered, I'd rather light properly than fiddle with the exposure mid-shot. It's just some of these jobs, well . . .you know how production gets when they see you trying to sneak a few extra HMIs and a second tracking vehicle onto the equipment list.

By the way, I managed to find copies of both of your books last week and I have a feeling I may learn a thing or two from these fine publications. Great work.

Edited by FKP-1, 15 November 2005 - 12:10 PM.

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#12 Mitch Gross

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Posted 15 November 2005 - 01:39 PM

One of the boldest (i.e. most obvious) stop pulls I've ever seen was in "White Nights" (DP David Watkin) when a jeep drives from inside a plane hanger out into the sunlight; the camera is mounted on the jeep shooting two people driving and talking. The camera lens just immediately stops down several stops to compensate once they emerge from the shade of the hanger. Normally you would design the shot in such a way as to hide the stop pull better, usually as the camera is changing backgrounds (rather than see the same background change in brightness).
[/quote]


When that movie came out on video I rented a copy specifically to frame-by-frame check out that shot. I was so impressed by it when I saw it in the theater. Whoever was flipping that trigger on the back of that Panavision had amazing timing. It happens in the course of a single frame and lags the passage into bright daylight by less than a single frame, meaning that when we see the actor's face hit daylight the compensation has already begun and the inside of the hangar is getting darker. By the next frame it is complete. Only the old Mitchell/Panavision design with the control on the back of the camera could have pulled off such a brazen effect so efficiently.

Another nice example is in "Cutter's Way" (aka Cutter & Bone), where Jeff Bridges walks from inside a house to outside. The camera is outside looking in through a glass atrium, and Jordan Crowenwith performs what looks to be about a 2.5 - 3 stop pull that is very noticeable but not particularly disturbing. He was a talented guy--his next film was Blade Runner.
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#13 John Pytlak RIP

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Posted 15 November 2005 - 05:01 PM

Try to match the light levels as best you can, so an exposure change is not needed. But if the difference is up to a few stops, color negative film exposure could be set for the lower light level, and then correct in post for the overexposed section of the pan (i.e., avoid underexposing the film). As Dominic notes, in telecine or DI, a dynamic change can be made. On a printer, where only discrete changes in printer lights can be made, you may be able to disguise the change as you pan across a door or window frame.

If you decide to change the lens stop during the pan, you should practice to be sure you can coordinate the exposure change with the light level, or "hide" it across a door or window frame.
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