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Author Topic: Adjusting Aperture While Shooting  (Read 4146 times)
RFPhotography
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« on: May 04, 2013, 11:45:35 AM »
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This is something that I haven't been fully able to reconcile.  Some people adjust the aperture while shooting.  Why?  Some lenses are marketed as having stepless aperture rings for this very purpose (e.g., Samyang/Rokinon cine lenses and Leitax offers a conversion mount that's stepless).

If I determine a look I want for a shot including depth of field I'm not going to want to change that during the shot.  If I do, my exposure is going to change as well if I'm in Manual mode.  If I'm in Av mode, my shutter speed will change which will change the look and feel of the shot.

What's the supposed advantage of changing the aperture during a shot?

Thanks.
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Sareesh Sudhakaran
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« Reply #1 on: May 04, 2013, 01:17:19 PM »
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There is no ISO 'ring'. You can't change it in minute increments for a smooth transitions. The only thing that allows this at present is the aperture ring.
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RFPhotography
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« Reply #2 on: May 04, 2013, 01:48:15 PM »
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So you're saying you'd use it in situations where the light changes during a shot? 
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Chris Sanderson
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« Reply #3 on: May 04, 2013, 02:20:28 PM »
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Normally done during a camera move where the lighting changes dramatically from one end of the scene to the other.

The art is to hide the 'stop-pull' during a visual transition - unless the over or under-exposure is a desired effect.
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Christopher Sanderson
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RFPhotography
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« Reply #4 on: May 04, 2013, 03:15:02 PM »
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Thanks, Chris.  I can understand how hiding the change could be difficult.
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Sareesh Sudhakaran
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« Reply #5 on: May 04, 2013, 10:34:51 PM »
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Sorry, Bob, I'm so absent-minded these days I forgot to answer your primary question. Chris has answered.

The location change from interior walls to exterior usually masks any DOF or distortion change, but that's dependent on the blocking of the shot.

The focus puller must be on the money, and that's more difficult on his or her eyes when light changes.

All things considered, I think it's a lazy practice. If the shot is important enough to warrant such an exercise, it is the duty of the filmmakers to ensure they use lighting as the correct way to control exposure.
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RFPhotography
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« Reply #6 on: May 05, 2013, 06:21:50 AM »
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No, I understood what you were saying the first time Sareesh and Chris confirmed it.  I agree with your point on the lighting.  Where I can see it being used is in a purely documentary or run-and-gun type of situation.
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fredjeang2
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« Reply #7 on: May 05, 2013, 06:51:52 AM »
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Imo, you should not limit that practise
On Run and gun situations, nor is necesarly
The consequence of bad planification.

It can be used on purpose to help the narrative
And create a complex shot.

Think for ex as an object in extreme close-up
In a part of the frame and an action occurs
In another zone that has to be litted differently
On purpose. Changing the ap can catch the attention
Where you want it.
As always, the important thing is to use techniques
On purpose.
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RFPhotography
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« Reply #8 on: May 05, 2013, 10:57:17 AM »
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Seems that the situation you're describing may still fit with what I was thinking, Fred.  If you're doing a planned shoot and going from an extreme close-up to a wider shot then you're going to take the time to light those two shots properly.  But if you're doing pure documentary or journalistic type shooting where you can't light the two things differently, then the aperture may come into play as a quick way to make the necessary adjustment.  Am I missing something?
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bcooter
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« Reply #9 on: May 05, 2013, 11:01:36 AM »
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Imo, you should not limit that practise
On Run and gun situations, nor is necesarly
The consequence of bad planification.

It can be used on purpose to help the narrative
And create a complex shot.

Think for ex as an object in extreme close-up
In a part of the frame and an action occurs
In another zone that has to be litted differently
On purpose. Changing the ap can catch the attention
Where you want it.
As always, the important thing is to use techniques
On purpose.


I think Fred is spot on in today's world.

Film is a different process and the days of one long take where someone walks from the bright outside into a dark tunnel and the light is balanced on one long take might be a technological success, but usually makes for one long boring short.

Everybody has ADD, when it comes to watching video.  We have cuts that are seconds, not minutes and they play better than long takes.

Think about the walking into the tunnel shot.  First you master the tunnel with the subject at the end somewhat blown out, then cut to the subject going into the tunnel, then cut to the subject going through the transitional lighting, then another cut with an exposure and lighting change of the subject in the tunnel.  

This may seem disjointed, but if shot with interesting angles in today's time it will probably hold the viewers attention better than the long take and use a lot less equipment..

Or if you simplify the cut and drastically change exposures as the subject goes  through the change, even throw focus in an out, it adds a style of believability that is interesting.



IMO

BC
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fredjeang2
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« Reply #10 on: May 05, 2013, 11:18:19 AM »
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... you're going to take the time to light those two shots properly. ...
But that means you are in cine config.

The latest cine plateau I was, about 5 months ago, there was this interior shot in a Madrid building at a third floor appartement. To lite properly as you say
there were 2 enormous HMI outside located on 2 cranes just for the "natural" light that enters from outside through the 2 windows. (and it was daytime)
And the interior was full of lite for the walls, the talents etc...the guys in the exterior were connected by walky talky to the set inside.

At the minimum travelling, if you want to control the light within the elements as traditional cine crew would do, you'd need serious equipment, crew and knowledge involved. This is not like
lightning a scene for stills, where you lite once for awhile and have the time to rebuild, because everything moves, camera moves, shots change, atmosphere change in a few seconds.

So, as James says, better to embrasse the possibility that offers the aperture change in a creative manner so it can result more dynamic and interesting.

If you want to keep the orthodox approach, you'd need cine set very fast.  

« Last Edit: May 05, 2013, 11:21:49 AM by fredjeang2 » Logged
RFPhotography
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« Reply #11 on: May 05, 2013, 01:13:35 PM »
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OK, I see the point.  Less expensive.  Less time.  'Video game effect' attention spans.
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« Reply #12 on: May 17, 2013, 03:20:31 AM »
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Iris pull on movies is not uncommon. I'm talking about feature films with lighting and crew.

Yesterday I needed to photograph an actor inside a car and then getting out into the bright sunshine. I had the ability to light the I interior of the car, and I did with a big HMI lamp. But to fully light the interior to match the sunlight looked very unnatural. So we did an iris pull when he exited the car. It's very hard to see this transition in the shot.

It's not just a technique for documentary and light starved film makers !

It's an important technique to master.
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Bruce Alan Greene
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« Reply #13 on: June 15, 2013, 03:45:49 PM »
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I'm really late coming into this but thought it maybe worthwhile making a comment.

I've used the GH2 for broadcast production work but never pulled iris on a paid shoot. That said, I use the GH2 daily for family video.
I use two pre-sets and have them saved on C2 and the other on C3. I use both with a variable ND filter. The filter is one way I adjust  exposure if need be on the fly. The other is AUTO ISO. Basically these are both for use in uncontrolled lighting setups, not unlike many documentary situations where lighting can be unpredictable.
C2 is like Auto run and gun. I use Shutter priority set a 1/50 (PAL) in HBR 25 mode. Dark scenes are then automatically exposed by AUTO ISO. For bright scenes there is obviously some iris stepping and I know this is anathema to most purists, but honestly, try it because especially when you're shooting wide open and AUTO ISO kicks in, it's damn smooth. (Unless your darkest scene is 1600 ISO or more!)
C3 I've set up as fully manual. Shutter at 1/50 and aperture anywhere between f1.7 and f5.6 depending lens and desired effect for the shot. The variable ND becomes my exposure control. And as we all know, exposure in the GH2 is displayed clearly inside the viewfinder and it's easily ignored when compensating for backlit scenes etc. The benefit with this method is that there is no aperture stepping and flicker issues. It's taken some practice but I really now I really enjoy using the variable ND.
I'd like to say also that I haven't taken to the GH3. The only reason is that I pull my own focus on moving subjects using the viewfinder. The GH2 has a slight viewfinder aliasing not seen on the recorded video which acts as a kind of viewfinder peaking. The GH3 viewfinder IMHO is far inferior. It appears smaller, softer and has no form of focus assist what-so-ever.
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RFPhotography
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« Reply #14 on: June 17, 2013, 07:56:49 AM »
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Which VND are you using?
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fredjeang2
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« Reply #15 on: June 17, 2013, 09:43:46 AM »
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I'm really late coming into this but thought it maybe worthwhile making a comment.

I've used the GH2 for broadcast production work but never pulled iris on a paid shoot. That said, I use the GH2 daily for family video.
I use two pre-sets and have them saved on C2 and the other on C3. I use both with a variable ND filter. The filter is one way I adjust  exposure if need be on the fly. The other is AUTO ISO. Basically these are both for use in uncontrolled lighting setups, not unlike many documentary situations where lighting can be unpredictable.
C2 is like Auto run and gun. I use Shutter priority set a 1/50 (PAL) in HBR 25 mode. Dark scenes are then automatically exposed by AUTO ISO. For bright scenes there is obviously some iris stepping and I know this is anathema to most purists, but honestly, try it because especially when you're shooting wide open and AUTO ISO kicks in, it's damn smooth. (Unless your darkest scene is 1600 ISO or more!)
C3 I've set up as fully manual. Shutter at 1/50 and aperture anywhere between f1.7 and f5.6 depending lens and desired effect for the shot. The variable ND becomes my exposure control. And as we all know, exposure in the GH2 is displayed clearly inside the viewfinder and it's easily ignored when compensating for backlit scenes etc. The benefit with this method is that there is no aperture stepping and flicker issues. It's taken some practice but I really now I really enjoy using the variable ND.
I'd like to say also that I haven't taken to the GH3. The only reason is that I pull my own focus on moving subjects using the viewfinder. The GH2 has a slight viewfinder aliasing not seen on the recorded video which acts as a kind of viewfinder peaking. The GH3 viewfinder IMHO is far inferior. It appears smaller, softer and has no form of focus assist what-so-ever.

HBR 25 is a good option, but I don't understand why
They wrapped interlaced and it confuses Avid on direct
Import. As a result, I have to use Squeeze and then
Place the folders in the media files and then the media tool
scanner to get my clips into the bin.

It's better for me to use 24p wich has higher bitrate
In a 24p project and import the bin in the 25p version,
Avid would motion adapt it and it avoids the roundtripping.

I don't get why they implemented a progressive into
An interlaced wrapper.
« Last Edit: June 17, 2013, 10:21:59 AM by fredjeang2 » Logged
tjbates
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« Reply #16 on: June 17, 2013, 12:17:44 PM »
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Which VND are you using?

I'm using the Ligth Craft Works LCW II 46mm on a pana 20mm 1.7 lens.

I've programmed my stills profile to C1 on the GH2 and accidentally stumbled on an inbuilt picture profile for stills that really works for the subject matter I shoot. Now shooting JPGs exclusively and avoiding hours in post.
After recently spending 5 weeks shooting video and stills in Australia where the light is so harsh, I simply left the VND on the lens for most of the time allowing me to easily shift between stills and video in a instant. I was pleasantly surprised as to how sharp the stills pictures came out. I've used similar Genus filters in the past but found the sharpness suffered. Aparently recent versions of Genus VND filters have addressed this fault.
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tjbates
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« Reply #17 on: June 17, 2013, 12:26:15 PM »
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HBR 25 is a good option, but I don't understand why
They wrapped interlaced and it confuses Avid on direct
Import. As a result, I have to use Squeeze and then
Place the folders in the media files and then the media tool
scanner to get my clips into the bin.

It's better for me to use 24p wich has higher bitrate
In a 24p project and import the bin in the 25p version,
Avid would motion adapt it and it avoids the roundtripping.

I don't get why they implemented a progressive into
An interlaced wrapper.

I fully understand your comment about 25p coming out of 50i. Many have done this in the past including Canon with their video (HV20) cameras.
I understand this to be simply the only way Panasonic could provide 25p in a firmware upgrade (after a lot of PAL country pressure) to provide 25p. Panasonic have admitted openly that this was not an ideal solution. But it was a solution non the less. Since that firmware upgrade, Panasonic addressed this design fault in the GH3.

I can't comment on the problems you have with Avid except to say that the last version of Final Cut Pro 7 seems to recognise my HBR 25p files as 25p and all is sweet.
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RFPhotography
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« Reply #18 on: June 17, 2013, 01:13:13 PM »
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I'm using the Ligth Craft Works LCW II

Thanks.

Quote
I've used similar Genus filters in the past but found the sharpness suffered. Aparently recent versions of Genus VND filters have addressed this fault.

I've read less than stellar reports about the LCW as well, but you're happy with yours so who knows.  I've read good things about the latest version of the Genus, yes.  The thing I don't like about the Genus is they took away the little handle.  That seemed like a nice feature but I guess depending on the angles, it could get awkward.
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tjbates
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« Reply #19 on: June 17, 2013, 01:51:09 PM »
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Thanks.

I've read less than stellar reports about the LCW as well, but you're happy with yours so who knows.  I've read good things about the latest version of the Genus, yes.  The thing I don't like about the Genus is they took away the little handle.  That seemed like a nice feature but I guess depending on the angles, it could get awkward.

I was expecting poor results from the LCW II after my Genus experience. To be fair there is one other consideration with regards VND filters. The Genus version I that I used on my 5DMKII is a 77mm filter whilst the LCW II that I currently use on my GH2 is only 46mm.
I've read that the bigger the VND filter (of any brand) the larger the possible quality differences.
After several thousand photos taken, I can't pick the difference in sharpness with or without my 46mm LCW VND filter attached.
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