Blackmagic Forum

I always shoot 60fps, as recommended by many real estate videographers on YouTube. However, this guy has flipped my mind and I guess he’s got a point. I honestly never thought that lower fps requires 3 times less light/illumination, which is good for me.

The only challenge is that I won’t be able to slow footage down. My movements should be slow and subtle instead.

My next project will be in 24fps, I hope it turns out good.

Hey Omar. This is not news, and I always like John's intellectual POV and he's right about 24fps. But good to know that you found a resource on YT that was helpful for you.

IME, there are two equations that I hang on to give me rough calculations of how much light I need. Your decision and choice will be based on what your final intentions are and depending on what creative thing you're doing. But generally, ...

Equation 1:
Like if the higher frame rate selection was to be able to slo-mo, then you'll need to compensate with the light to get equivalent exposure as if you shot it in a slower frame rate. The equation is rather simple: Let X = the frame rate you want to shoot at. Let Y = the natural frame rate usually used, for example 24fps. What I would do is divide X by Y to give me Z, Z being the multiple of light I need to add. For example, if I want to shoot at 400fps (all other cam params stays unchanged), then 400/24 = 16.66 or round it to 17. In this case, I will need 17 times the amount of light I currently have. Using a light meter and checking the amount of light, let's say it's currently at 100 lums to shoot it at 24fps. So, I will need 1700 lums of light to shoot at 400fps.

Equation 2:
Every time you double the frame rate you have to go up one stop. So 24fps to 48fps equals 1 f/stop. 48 to 96 is 2 f/stops, 96 to 192 is 3 f/stops, and so on. So going from 24 to 400, you'll need roughly about ~4.2 f/stops. So with the same lighting (no change in lighting setup) and you're at 24fps 8.0 f/stop, to shoot at 400fps, you'll have to set your aperture to be around f/1.8 - f/2.0.

That's how we (people who I work with) do it. BTW, it's not the only way.

Omar, if you’re shooting 24 fps while moving the camera, do you use sliders and jibs or handheld gimbals?

Ellory, many thanks for the explanation. I came from photography background - amateur not professional - I’m used to 1/3 stops if my calculation is correct, 24 to 60fps is 1.3 stop? And as per your equation, 60 divided by 24 equals 2.5. So if I was shooting at f5.6, I would need 1.3 or 2.5 stops? My wide-angle lens’s max aperture is 4.0, I struggle to keep things in focus sometimes. Therefore, I up ISO and step down with aperture to have larger focal area. Because I depend on natural light most of the time.

Rick, I use a gimbal, Ronin RS4 Pro. I recently bought a 100w light and waiting to put it into test. viewtopic.php?f=14&t=207783&p=1079266#p1079266

Omar Mohammad wrote:I always shoot 60fps, as recommended by many real estate videographers on YouTube. However, this guy has flipped my mind and I guess he’s got a point. I honestly never thought that lower fps requires 3 times less light/illumination, which is good for me.

If there’s one non-negotiable in professional real estate videography, it’s having abundant, high-quality lighting. While lower fps does allow for better performance in low-light settings, it should never substitute the need for properly lit scenes. Great lighting sets the foundation for any visually compelling property showcase

Omar, for the real estate videos, it may be perfectly fine to shoot with a shutter angle of 360 degrees which will give you an extra stop of light compared to the 180 degree shutter you may have usually been using.

If you are normally shooting at 60 fps with a 180 degree shutter angle and an aperture at f/5.6, shooting at 24 fps with a 324 or 360 degree shutter angle will give each frame more light allowing you to stop down to at least f/11.

Cary Knoop wrote:

Omar Mohammad wrote:I always shoot 60fps, as recommended by many real estate videographers on YouTube. However, this guy has flipped my mind and I guess he’s got a point. I honestly never thought that lower fps requires 3 times less light/illumination, which is good for me.

If there’s one non-negotiable in professional real estate videography, it’s having abundant, high-quality lighting. While lower fps does allow for better performance in low-light settings, it should never substitute the need for properly lit scenes. Great lighting sets the foundation for any visually compelling property showcase

Hi Cary. I totally agree; proper lighting is essential, even in photography. I used to use 2 flashes, take multiple shots from the same position and then blend them in photoshop. I'm no longer patient, I sold the flash, I instead take bracketed exposure and blend them.

It's worth mentioning that I'm a lone wolf, it's not easy to handle everything on my own especially when I have to carry all lights and stands, that's why I bought a small, portable 100W light.

rick.lang wrote:Omar, for the real estate videos, it may be perfectly fine to shoot with a shutter angle of 360 degrees which will give you an extra stop of light compared to the 180 degree shutter you may have usually been using.

If you are normally shooting at 60 fps with a 180 degree shutter angle and an aperture at f/5.6, shooting at 24 fps with a 324 or 360 degree shutter angle will give each frame more light allowing you to stop down to at least f/11.

Many thanks Rick! I always shoot 180, sometimes 217 when LED lights flicker. I appreciate your invaluable input

As much as I like 24 fps in cinema (I found HFR really spoils the experience), I'd be careful using it in your case.
First, many users on the internet will watch your videos on devices that are not capable of displaying true 24 fps. They may see motion artifacts, like tearing or stutter. But practically any display out there will be capable of showing 30 or 60 fps.
Second, using longer exposure times, like 360 degrees, is problematic too. In particular in combination with 24 or even 30 fps, you'll get more motion blur, which may look too soft when moving the camera. You can watch some night exteriors in "Collateral" to see what I mean. If you want your video to look sharp and crisp, don't. But if you decide to shoot and screen 60 fps for smoother motion, it's OK to compensate the light loss by using 360 degrees. You'll get the same exposure as for 30 fps with 180 degrees. Of course, this does not apply to footage you want to slow down in post.

Uli, many thanks for your comprehensive explanation.

Would you recommend that I stick to what I’m doing, 60fps @ 180°? In case of low light 360°? Because I would like to shoot in open gate so I get the most of the scene. I shoot 6K 2.4:1, however, when I export 4K DCI I lose portion of lateral view, because the footage gets zoomed in to fill upper and lower gaps.

That's fine, I'd say. You don't know which kind of devices your audience will use anyway.
There are many computer screens in 16:10, there are those in 16:9 (like TVs), and there are smartphones with aspects rations all over the place. There's hardly anybody out there with a DCI screen.
So, most will see your movies with some kind of black border, whatever you choose.

I thought 4K DCI is more widespread than 4K UHD especially mobile phones.

Omar. I was assuming you were shooting 60 fps so that everything would playback in slow motion on a 24 fps or 30 fps timeline in your deliverables. Can you clarify the project frame rate and the frame rate of your finished videos?

Let’s say you are using 24 fps playback. You could use 30 fps off speed recording to smooth out your playback sufficiently. Just do some tests to see what you think. Test with 180 degree shutter angle, 270 degrees, and 360 degrees.

rick.lang wrote:Omar. I was assuming you were shooting 60 fps so that everything would playback in slow motion on a 24 fps or 30 fps timeline in your deliverables. Can you clarify the project frame rate and the frame rate of your finished videos?

Let’s say you are using 24 fps playback. You could use 30 fps off speed recording to smooth out your playback sufficiently. Just do some tests to see what you think. Test with 180 degree shutter angle, 270 degrees, and 360 degrees.

Hi Rick. I always shoot 6K 2.4:1, 60fps, 180°, Q0 and then import footage into 60fps timeline. I slow motion clips in inspector to 50% (30fps). I export 60fps, 4K DCI and upload finished video to YouTube. That’s how I do for all my project.

I thought of off-speed recording; open-gate can do 24/30fps. I’ll do some tests.

Thank you Rick

Thanks for the clarification on your usual use of a 60 fps project frame rate. If you changed your project frame rate to 24 fps and used 30 fps off-speed recording, you would have modest slow motion to slightly smooth camera motion.

rick.lang wrote:Thanks for the clarification on your usual use of a 60 fps project frame rate. If you changed your project frame rate to 24 fps and used 30 fps off-speed recording, you would have modest slow motion to slightly smooth camera motion.

Many thanks Rick. I’ll give it a try on my next session. I appreciate your help.