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Using Magic Lantern => General Help Q&A => Topic started by: eightcore on October 02, 2012, 08:54:20 PM

Title: Record Video with fix exposure
Post by: eightcore on October 02, 2012, 08:54:20 PM
Dear community,

is it (logically) possible to lock the aperture during vide recording?


Thanks in advance

eightcore
Title: Re: Record Video with fix exposure
Post by: Francis on October 02, 2012, 09:49:09 PM
Yes. It depends on the model as far as how to.
Title: Re: Record Video with fix exposure
Post by: ilguercio on October 02, 2012, 09:55:08 PM
Quote from: eightcore on October 02, 2012, 08:54:20 PM
Dear community,

is it (logically) possible to lock the aperture during vide recording?


Thanks in advance

eightcore
You can use Exposure override to do what you want.
Title: Re: Record Video with fix exposure
Post by: eightcore on October 02, 2012, 10:14:30 PM
aperture, not exposure. Sorry.
Title: Re: Record Video with fix exposure
Post by: ilguercio on October 02, 2012, 10:15:38 PM
Quote from: eightcore on October 02, 2012, 10:14:30 PM
aperture, not exposure. Sorry.
???
Exposure override let's you choose any parameter by yourself. Set an aperture and don't change it, it's simple.
Title: Re: Record Video with fix exposure
Post by: eightcore on October 03, 2012, 12:17:39 PM
Thank you!

I have a 50D
Title: Re: Record Video with fix exposure
Post by: ZeroUnityGain on October 05, 2012, 10:19:12 AM
Can someone please shoot me because I really don't see how that can work.  If your lens is a zoom and not a fixed aperture the iris is going to change every time you zoom in or out. 
Title: Re: Record Video with fix exposure
Post by: ilguercio on October 05, 2012, 11:47:40 AM
Quote from: ZeroUnityGain on October 05, 2012, 10:19:12 AM
Can someone please shoot me because I really don't see how that can work.  If your lens is a zoom and not a fixed aperture the iris is going to change every time you zoom in or out.
Blame your lens then. The aperture will stay the same if that f/stop is available at each focal lenght you zoom through. Else, it will obviously change.
As said a million times, ML is a software, it can't do miracles

edit by nanomad: Language ::)
Title: Re: Record Video with fix exposure
Post by: Malcolm Debono on October 05, 2012, 01:13:03 PM
Quote from: ZeroUnityGain on October 05, 2012, 10:19:12 AM
Can someone please shoot me because I really don't see how that can work.  If your lens is a zoom and not a fixed aperture the iris is going to change every time you zoom in or out.

If you have an f/3.5-f/5.6 lens, you can always shoot at f/5.6 so that it remains constant at both sides of the focal length. If you're shooting at a lower aperture (for example at f/3.5 when the lens is at 18mm), don't use the zoom (besides, it's next to impossible to get a smooth zoom), especially with non-L lenses which I'm assuming you're using (from the non-constant aperture).
Title: Re: Record Video with fix exposure
Post by: ZeroUnityGain on October 06, 2012, 10:39:20 PM
Quote from: ilguercio on October 05, 2012, 11:47:40 AM
Blame your lens then. The aperture will stay the same if that f/stop is available at each focal lenght you zoom through. Else, it will obviously change.
As said a million times, ML is a software, it can't do miracles

edit by nanomad: Language ::)

Hmmmm (I like saying hmmmm)...The author asks, "Is it possible to lock the aperture during video recording."
And I'm very clearly saying that unless your lens is a fixed aperture throughout the zoom range, you can't!

Title: Re: Record Video with fix exposure
Post by: ZeroUnityGain on October 06, 2012, 10:45:06 PM
Quote from: Malcolm Debono on October 05, 2012, 01:13:03 PM
If you have an f/3.5-f/5.6 lens, you can always shoot at f/5.6 so that it remains constant at both sides of the focal length. If you're shooting at a lower aperture (for example at f/3.5 when the lens is at 18mm), don't use the zoom (besides, it's next to impossible to get a smooth zoom), especially with non-L lenses which I'm assuming you're using (from the non-constant aperture).

Hi Mal,
Just to clear things up.  I don't have a problem.  I'm simply stating that the author cannot fix a constant aperture unless the lens is a constant aperture. 
Title: Re: Record Video with fix exposure
Post by: ilguercio on October 07, 2012, 03:08:00 AM
18-55 IS has a biggest common aperture of f/5.6 so i don't see the problem to lock the aperture to that value.
Title: Re: Record Video with fix exposure
Post by: Malcolm Debono on October 07, 2012, 03:48:17 AM
Quote from: ZeroUnityGain on October 06, 2012, 10:45:06 PM
Hi Mal,
Just to clear things up.  I don't have a problem.  I'm simply stating that the author cannot fix a constant aperture unless the lens is a constant aperture.

Sorry, I must have used the wrong quote. You're perfectly right.
Title: Re: Record Video with fix exposure
Post by: Francis on October 07, 2012, 06:57:52 PM
No where does the OP say anything about this being an issue of a non-constant aperture zoom. It sounds like they are unsure how to set exposure to manual in video mode.
Title: Re: Record Video with fix exposure
Post by: ZeroUnityGain on October 07, 2012, 11:29:16 PM
Quote from: ilguercio on October 07, 2012, 03:08:00 AM
18-55 IS has a biggest common aperture of f/5.6 so i don't see the problem to lock the aperture to that value.

I suppose what you are saying is that the 18-55 IS has its widest opening aperture of f/5.6 when at its max focal length of 55mm, and yes of course you can fix that so it stays at f/5.6 with Canon's own firmware to stay at that f stop even at its 18mm setting pulled right back.   But its widest opening aperture at 18mm is f/3.5 and you can't lock that to stay when you zoom out to the 55mm focal length, as it will automatically go to f/5.6.
Since eightcore asked can you "lock the aperture during video recording," I think the information is relevant if he is not using a constant aperture lens.

Cheers



Title: Re: Record Video with fix exposure
Post by: ZeroUnityGain on October 07, 2012, 11:38:41 PM
Quote from: Francis on October 07, 2012, 06:57:52 PM
No where does the OP say anything about this being an issue of a non-constant aperture zoom. It sounds like they are unsure how to set exposure to manual in video mode.

Hey Francis,
No he doesn't mention about non-constant aperture zoom, and it may simply be as you say a case of how to set the f/stop manually, but the information is very relevant if his lenses aren't constant aperture lenses.  For instance when I first started out with a DSLR shooting concerts I'd set the widest opening because of the lack of light and as I'd zoom the aperture would blow out to f/ 5.6 -- then a rival photog at a concert told me about constant aperture lenses, and I was thankful for the information.

Cheers

Title: Re: Record Video with fix exposure
Post by: ilguercio on October 07, 2012, 11:40:27 PM
But in that particular case he can, doesn't matter if he can't lock it at f/3.5.
The question is "can i lock the aperture?" not "can i lock the aperture at f/3.5?". Of course you can't lock the aperture to a value that is not shared among all the focal lenghts but it is so evident that i thought it was unnecessary to highlight this fact.
You can lock the aperture, that's the important thing. He didn't even mention non-constant aperture lenses so i don't see why you should divert the discussion onto that.
Title: Re: Record Video with fix exposure
Post by: ZeroUnityGain on October 08, 2012, 12:34:01 AM
Quote from: ilguercio on October 07, 2012, 11:40:27 PM
Of course you can't lock the aperture to a value that is not shared among all the focal lenghts but it is so evident that i thought it was unnecessary to highlight this fact.


Yes I know what you mean. It's like when they bring a weapon onto a film set, it's evident that it wouldn't be loaded.
I get it now.

Cheers.