F-stop / Lumens

[Hector1959]

Is there any ratio or proportional relation between F-stops and lumens?
Knowing that changing a full F-stop reduces or increases by 2 the pass of light, Could we assume that doubling or halving the lumens of lights would have relatively similar effect on exposure?
Par example: would we have similar exposure with f4 and a light of 1000 lumens than with F5.6 and a light of 2000 lumens?
I don't expect to be the same since lumens are measured as the total light emmitted and lights are circular and frames rectangular. No way to shoot the total iluminated area. But, is there, at least, any rule of thumb to relate f-stops ans luimens?
Regards

 

[tbone1004]

Is there any ratio or proportional relation between F-stops and lumens?
Knowing that changing a full F-stop reduces or increases by 2 the pass of light, Could we assume that doubling or halving the lumens of lights would have relatively similar effect on exposure?
Par example: would we have similar exposure with f4 and a light of 1000 lumens than with F5.6 and a light of 2000 lumens?
I don't expect to be the same since lumens are measured as the total light emmitted and lights are circular and frames rectangular. No way to shoot the total iluminated area. But, is there, at least, any rule of thumb to relate f-stops ans luimens?
Regards

somewhat complicated. Your sensor needs lux not lumens. Lux is the amount of lumens per square meter. If you double the lumen output of the light, you should double the lux value and be able to go down a stop.
This obviously only holds true for the beam pattern, and doesn't account for any natural light, so unless you're shooting at night, or in a cave, that relationship breaks down heavily because of ambient light

 

[Hector1959]

Thanks. Interesting. I just was wondering. I saw a photo shot at f5.6 with 2000 lumens of continous light and I asked myself if similar results would be achived at f4 with 1000 lumens. I have thought of different variables affecting but I have not thought of ambient light.
Thans again.

 

[tbone1004]

Thanks. Interesting. I just was wondering. I saw a photo shot at f5.6 with 2000 lumens of continous light and I asked myself if similar results would be achived at f4 with 1000 lumens. I have thought of different variables affecting but I have not thought of ambient light.
Thans again.

glad to help. The ambient light really has the potential to minimize the effect of a light from a brightness standpoint. From what I understand, they are used mainly as color correction when shooting in daylight. I'm not a professional photographer though, so those guys will have to pipe in.

I will say a 1000 lumen light is not very bright when used in daylight, especially when it is designed with a video spread

 

[Hector1959]

I know 1000 lumen is not very bright in daylight but it makes some difference when shooting close. This was filmed with an action camera mounted on the head of a Tovatec Fusion 1000. The wreck is more than 60 feet deep. I wouldn't had those reds without the light. I will "experiment" this weekend with my G7X and two lights, this 1000 lm an another with 450 lm. Both film and photo.