Magic Lantern Forum

Using Magic Lantern => Shoot preparation => Topic started by: NoHinAmhherst on November 12, 2019, 03:48:20 PM

Title: Infinite focus in low light shooting
Post by: NoHinAmhherst on November 12, 2019, 03:48:20 PM
I am looking for some basic tips to have less depth of field in low light situations. Specifically, if my daughter is performing in a mostly darkened room on stage and my camera is on a tripod, what are my best settings to make sure she isn't just in focus on one part of the stage and blown out if she moves forward or back? My goal is infinite focus, which can be tough in low light.

ISO, aperture, and any hidden ML tricks?

Also, perhaps is there a thread with post-processing compression techniques? I don't need 20GB for a kid's play.
Title: Re: Infinite focus in low light shooting
Post by: Walter Schulz on November 12, 2019, 04:50:16 PM
If you are using a lens reporting focus distance you get a screen like this
(https://www.magiclantern.fm/forum/proxy.php?request=https%3A%2F%2Fabload.de%2Fimg%2Ffocus_1bcjz0.png&hash=c6eb894d73d69abd9834645db5090ce5)
with all informations you need at the bottom: Distance and DOF. Ignore "This feature only works in LiveView". This refers to highlighted menu item. Lookup "Hyperfocal Distance" if needed.
If your lens does not support this:
Measure or estimate distance and get yourself an oldfashioned focus distance card http://dofmaster.com/ or an app for DOF calculation.
Title: Re: Infinite focus in low light shooting
Post by: NoHinAmhherst on November 25, 2019, 01:10:40 PM
I guess I'm not sure what's been suggested as the solution. What are the steps?

I can find this menu, but it's unclear what I need to do.

Thank you.
Title: Re: Infinite focus in low light shooting
Post by: Walter Schulz on November 25, 2019, 01:30:23 PM
DOF near = Distance to stage (front)
DOF far = Distance to stage (rear)
AF off and adjust aperture and focus distance to your needs. Then set shutter speed according to aczors speeds. Then adjust ISO (or let ML adjust ISO for you).

Depending on lens' focal length, distance, available light, movements on stage you may not be able to adjust all settings as wanted.

I suggest to read/watch some DOF related tutorials. It is quite basic stuff to know (for DSLR shooters). See http://dofmaster.com/dofjs.html and other sources.
Title: Re: Infinite focus in low light shooting
Post by: 2blackbar on December 07, 2019, 10:05:21 AM
What camera? You can get CCTV lenses that are like f1.4 and when you stop them down a bit you have a lot in focus.
Title: Re: Infinite focus in low light shooting
Post by: Walter Schulz on December 07, 2019, 03:08:50 PM
I suppose we're not talking cropped RAW/MLV here ...
Title: Re: Infinite focus in low light shooting
Post by: meanwhile on January 28, 2020, 02:52:54 PM
I am looking for some basic tips to have less depth of field in low light situations. Specifically, if my daughter is performing in a mostly darkened room on stage and my camera is on a tripod, what are my best settings to make sure she isn't just in focus on one part of the stage and blown out if she moves forward or back? My goal is infinite focus, which can be tough in low light.

That the room is mostly darkened shouldn't matter as long as your daughter is well-lit. Not unless you want to record detail in the parts of the room too, in which case you need low light ability plus massive dynamic range.

Also I think you mean MORE dof, not less.

Basically -

- Adjust your aperture to get the dof you want (put on app on your phone or print a table out)

- Set your exposure for your daughter, not the dark parts of the room. Assuming she has white-pink skin, use false color like this

https://www.premiumbeat.com/blog/how-to-use-false-color-nail-skin-tone-exposure/

...The only element of exposure you change is ISO, so put it up to what you need. This may introduce quite a bit of noise, but we'll come to that next...

- Then denoise in post. Avisynth provides a lot of denoisers and is free:

https://www.google.com/search?client=firefox-b-d&ei=Tj0wXtWdHIyegQaaiJSoDw&q=avisynth+denoise+tutorial&oq=avisynth+denoise+tut&gs_l=psy-ab.3.0.33i160.2287.3775..5137...0.2..0.336.801.1j1j1j1......0....1..gws-wiz.......0i71j0i22i30.MVKhJbhNRio

Assuming reasonable stage lighting and a reasonable position, this should get you an ok result. If it doesn't, you need a new camera like an A7s or maybe a latest generation Fuji. Companies like lensrentals.com will rent you a camera for a day or two and deliver and pick it up by courier.

Oh - I'd suggest turning your in camera noise reduction off: it won't do as good a job as NR in post and using both makes artefacting more likely.

Also, buying a dummy battery and shooting with a USB powerpack may help. Heat in the camera = noise, and batteries are a major source of heat. So are screens: if the camera is going to be locked down, you might want to turn the screen off.

And if you do need to shoot at high ISO, raw will probably work better than any of the picture profiles.

Quote
Also, perhaps is there a thread with post-processing compression techniques? I don't need 20GB for a kid's play.

Super-easy:

https://www.gizbot.com/how-to/tips-tricks/5-easy-steps-compress-large-video-files-with-vlc-media-player-036522.html

Finally, try to shield the lens from glare from stage lights etc - use a lens hood, etc.
Title: Re: Infinite focus in low light shooting
Post by: Robby24 on April 23, 2020, 10:29:06 AM
When shooting moving objects or taking pictures with your hands, there is a high likelihood of motion and blurry images. This is because the shutter speed is too long for this scene. Increasing the sensitivity of the sensor will slow down the shutter speed. Thus, increasing noise, we reduce blur and as a result we get a clear picture, although not of perfect quality. Without an increase in ISO, a shot would not work at all. Often you have to compromise between a low quality image and a terrible quality image. And, as you know, from two evils.. (https://gothicy.com/). Before raising the ISO, it's worth trying to take a picture with a flash. If this is the right option for your scene. then you can stop.