Author Topic: [WONTFIX] Disable normal auto apeture change when zooming...  (Read 15122 times)

ScaSer

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[WONTFIX] Disable normal auto apeture change when zooming...
« on: February 21, 2014, 08:48:01 PM »
Hey..

when i record video with tele lens, i hit a problem. The apeture changes and the video will flicker.

you can see the problem in my thread here: http://www.magiclantern.fm/forum/index.php?topic=10520.0


what would be nice in the movies menu, ability to diable auto apeture, so if you select F8, then you are ALWAYS at F8 no matter if you are at 50mm or at 500mm
I tried to cover the contacts on the lens with tape, and everything was perfect, the camera compensated perfectly with auto ISO

the downside of the tape solution, is that you cant take pictures, get stabilazation, and AF. so basic, tape sux :( - but it showed that the auto apeture was causing the flickering.

is this hard to do? I know its doable. you are the ML dews :D
-Kasper

Canon 5D mark III

a1ex

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Re: Disable normal auto apeture change when zooming...
« Reply #1 on: February 21, 2014, 08:51:38 PM »
Well, I don't know how to make a software that breaks the laws of physics. Maybe you know ;)

dmilligan

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Re: Disable normal auto apeture change when zooming...
« Reply #2 on: February 21, 2014, 09:16:14 PM »
what would be nice in the movies menu, ability to diable auto apeture, so if you select F8, then you are ALWAYS at F8 no matter if you are at 50mm or at 500mm
I think what you mean is that the aperture blades are locked in the same position, not the same F number (the F number would actually be changing).

ScaSer

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Re: Disable normal auto apeture change when zooming...
« Reply #3 on: February 21, 2014, 10:30:47 PM »
yeah what dmilligan said...  :D
-Kasper

Canon 5D mark III

ItsMeLenny

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Re: Disable normal auto apeture change when zooming...
« Reply #4 on: February 22, 2014, 01:36:58 AM »
If the blades get locked in position, then while zooming you will have a massive exposure change.
Think of it like a magnifying glass. If you change the magnification then you change the fstop.
I though ML provided a smooth exposure option somewhere, to try to fix this problem somewhat using ISO.

dmilligan

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Re: Disable normal auto apeture change when zooming...
« Reply #5 on: February 22, 2014, 01:49:01 AM »
Considering most zooms typically cover a range not more than about 2x to 3x (16-35, 18-55, 70-200, etc), that's only 1 to 1.5 EV of exposure change. I'd hardly call that massive. I'd probably rather be underexposed by 1ev than have a bunch of flicker.

ItsMeLenny

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Re: Disable normal auto apeture change when zooming...
« Reply #6 on: February 22, 2014, 03:29:52 AM »
Considering most zooms typically cover a range not more than about 2x to 3x (16-35, 18-55, 70-200, etc), that's only 1 to 1.5 EV of exposure change. I'd hardly call that massive. I'd probably rather be underexposed by 1ev than have a bunch of flicker.

He said his lens goes from 50mm to 500mm. What would that equal? 3 stops? (No idea how to work it out :P )

dmilligan

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Re: Disable normal auto apeture change when zooming...
« Reply #7 on: February 22, 2014, 04:34:45 AM »
You were close ;)  log2(500/50) = 3.322

But I think he was just exaggerating about 50-500. I've never heard of such a lens. For an actual real lens there wouldn't be a terribly huge change in exposure.

Audionut

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Re: Disable normal auto apeture change when zooming...
« Reply #8 on: February 22, 2014, 04:37:03 AM »
Sigma does a bunch of extreme telephotos. 
Including http://www.sigmaphoto.com/product/50-500mm-f45-63-apo-dg-os-hsm

Still, being able to control the aperture blades with ML would be useful.  Just maybe not on that particular lens  :P

ScaSer

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Re: Disable normal auto apeture change when zooming...
« Reply #9 on: February 22, 2014, 09:24:28 PM »
well... it it the sigma 50-500 thread here: http://www.magiclantern.fm/forum/index.php?topic=10520.new#new video here:
i have tested it with disengaging the lens contacts.. and as i wrote the camera compensated perfectly with AUTO ISO and Exposure... and that lens is 10x zoom, so if it works on this lens.. it will work on them all

Like milligan said.. id rather have a darker video than a blinking one.
-Kasper

Canon 5D mark III

ScaSer

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Re: Disable normal auto apeture change when zooming...
« Reply #10 on: February 22, 2014, 10:37:38 PM »
i have made a video showing to problem and the "fix"
-Kasper

Canon 5D mark III

ItsMeLenny

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Re: Disable normal auto apeture change when zooming...
« Reply #11 on: February 23, 2014, 05:25:29 AM »
Wow, that's weird that when the lens is disconnected it doesn't change. That does seem to defy the laws of physics. Unless the lens is built differently?

ScaSer

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Re: Disable normal auto apeture change when zooming...
« Reply #12 on: February 23, 2014, 11:23:42 PM »
yeah... well i hope ML dews can disable it... its really annoying
-Kasper

Canon 5D mark III

ScaSer

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Re: Disable normal auto apeture change when zooming...
« Reply #13 on: February 26, 2014, 04:49:54 PM »
is this possible? -- Alex?
-Kasper

Canon 5D mark III

Audionut

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ScaSer

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Re: Disable normal auto apeture change when zooming...
« Reply #15 on: March 03, 2014, 12:25:04 AM »
ok. sorry... it just seems like noone is watching? and/or want to comment on, if it is possible...

If your date dossent return you first call... then you just dont call her anymore? (bump) - that really dossent show that you want her ;)
-Kasper

Canon 5D mark III

Audionut

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Re: Disable normal auto apeture change when zooming...
« Reply #16 on: March 03, 2014, 04:41:59 AM »
If the thread has not been tagged, you should consider the request open.

ItsMeLenny

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Re: Disable normal auto apeture change when zooming...
« Reply #17 on: March 03, 2014, 07:03:15 AM »
If your date dossent return you first call... then you just dont call her anymore? (bump) - that really dossent show that you want her ;)
Terrible analogy.

a1ex

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Re: [WONTFIX] Disable normal auto apeture change when zooming...
« Reply #18 on: March 03, 2014, 07:44:49 AM »
I've tagged it right now, because of OP's attitude :D

ScaSer

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Re: [WONTFIX] Disable normal auto apeture change when zooming...
« Reply #19 on: March 03, 2014, 09:41:02 PM »

I bought a canon cam. because of ML.. im disappointed by your bad attitude... :(
-Kasper

Canon 5D mark III

ItsMeLenny

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Re: [WONTFIX] Disable normal auto apeture change when zooming...
« Reply #20 on: March 04, 2014, 12:33:50 AM »
I bought a canon cam. because of ML.. im disappointed by your bad attitude... :(

But buying a Canon camera doesn't mean that devs get anything from that.
A1ex doesn't get money every time someone purchases a Canon camera.

If it could be done easily it would've been picked up.
The problem looks like a canon firmware thing, you should actually contact canon.

Because the lens seems mechanically designed to keep a persistant aperture.
Which all canon DSLRs do is try to correct an inconsistent  aperture lens.


ScaSer

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Re: [WONTFIX] Disable normal auto apeture change when zooming...
« Reply #22 on: March 05, 2014, 08:36:11 PM »
But buying a Canon camera doesn't mean that devs get anything from that.
A1ex doesn't get money every time someone purchases a Canon camera.

If it could be done easily it would've been picked up.
The problem looks like a canon firmware thing, you should actually contact canon.

Because the lens seems mechanically designed to keep a persistant aperture.
Which all canon DSLRs do is try to correct an inconsistent  aperture lens.

that was not what i meant... what i meant was..

i had a Sony cam.. and saw this fantastic ML addon, and RAW video.... then i bought a Canon cam.

in my eyes ML dews are total badass... so i was a disapointed to get that answer.
-Kasper

Canon 5D mark III