Godox SL100W Lux versus GN

Started Nov 29, 2020 | Discussions
Tom Ferguson Senior Member • Posts: 2,320
Godox SL100W Lux versus GN

I realize LUX (continues light) is real different than GN (flash). But, I'm hoping someone can give some guidance for my specific situation.

I'm primarily a product photographer and use fairly big moonlight flash units (mostly Calumet Travelite 750). I'm almost always tethered to a computer. Typical shutter speed (which isn't terribly important for my flash work) is 1/125. Primarily set there to limit any ambient light in the room.

I would love to be able to use "Live View" while tethered for setting up shots, but the white balance from my 3200K Travelite modeling lights is terrible and without resetting everything on the camera... the image is dark.

So, my idea is to get a couple Godox SL100W continues LEDs. They are daylight balanced and take the same reflectors as my Travelights. Clamp two of them to my two primary light stands, and only turn them on when using live view. They would have to be underneath my soft box or umbrella, but would "approximate" my lighting.

So, two questions I'm hoping someone can help me with:

1) A rough guess at LUX versus GN for this setup. The Godox is 6500LUX at 1 meter. I can't (well, don't want to) be changing the shutter speed. It will stay at about 1/125 in both shooting and live view. Many/most of my work is high speed/pressure enough that I don't want to be resetting the camera for live view and then forgetting to reset it for shooting.

2) The remote control for the Godox, can it turn the lights on and off? They advertise how good the remote is for changing power settings, but that isn't what would be important for me.

Thanks!

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OP Tom Ferguson Senior Member • Posts: 2,320
Re: Godox SL100W Lux versus GN

Updating my own post, maybe I'm overthinking this? If I knew how much brighter the Godox SL100W was than my Travelite 750 modeling light, that might be enough info! I just measured my Travelite 750 modeling light in a standard reflector at 1meter and got ISO 100, speed 1/125, f-stop 4.5.

Any idea what I would get out of a 6500LUX (I meter) Led at the same 1/125 speed and same 100 iso?

I would still love to know if I can turn the Godox units on and off from the remote.

Thanks

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tugwilson Veteran Member • Posts: 3,700
Re: Godox SL100W Lux versus GN

Tom Ferguson wrote:

I realize LUX (continues light) is real different than GN (flash). But, I'm hoping someone can give some guidance for my specific situation.

I'm primarily a product photographer and use fairly big moonlight flash units (mostly Calumet Travelite 750). I'm almost always tethered to a computer. Typical shutter speed (which isn't terribly important for my flash work) is 1/125. Primarily set there to limit any ambient light in the room.

I would love to be able to use "Live View" while tethered for setting up shots, but the white balance from my 3200K Travelite modeling lights is terrible and without resetting everything on the camera... the image is dark.

So, my idea is to get a couple Godox SL100W continues LEDs. They are daylight balanced and take the same reflectors as my Travelights. Clamp two of them to my two primary light stands, and only turn them on when using live view. They would have to be underneath my soft box or umbrella, but would "approximate" my lighting.

So, two questions I'm hoping someone can help me with:

1) A rough guess at LUX versus GN for this setup. The Godox is 6500LUX at 1 meter. I can't (well, don't want to) be changing the shutter speed. It will stay at about 1/125 in both shooting and live view. Many/most of my work is high speed/pressure enough that I don't want to be resetting the camera for live view and then forgetting to reset it for shooting.

2) The remote control for the Godox, can it turn the lights on and off? They advertise how good the remote is for changing power settings, but that isn't what would be important for me.

Thanks!

The Calumet Travelite 750 is a 750 Ws strobe, The Ws value is the amount of energy supplied to the flash tube, The Xenon tube converts about 60% of that energy into visible light.

The SL100W puts 100W of power into that LED which converts about 50% of that power into visible light. That means it delivers the equivalent of 100 Ws of energy every second.

For the purposes of this comparison we can neglect the slight difference of efficiency.

The Travelite 750 will deliver all the 750 Ws of light produced within 1/125 second.

The Sl100W will deliver 100/125 Ws of light in that time That's 0.8Ws. A GN 60 speedlight is ~ 70 Ws at full power.

TL;DR it won't work.

OP Tom Ferguson Senior Member • Posts: 2,320
Re: Godox SL100W Lux versus GN

Thanks Tug,

That is what I was afraid of after measuring my modeling lights. I realized the LED would need to be a minimum of 4x brighter (2 stops) than my modeling lights to get me into the f-stop range I needed. A 100W LED is (I assume) nowhere near 4X as bright as a 250W modeling light

My camera has some "user setting" banks I can setup. I've never used them. I'll grab the manual and see if perhaps I could setup "user bank 1" for my normal flash settings and "user bank 2" for tungsten WB (modeling lights) and a MUCH higher ISO to allow for live view. Perhaps a better plan!

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tugwilson Veteran Member • Posts: 3,700
Re: Godox SL100W Lux versus GN

I think the MK 2 series of the SL lights are a far better bet than the original version.

The SL100W is 4,100 Lux at 1 metre the SL150II is 58,000 Lux at 1 metre. Part of this difference is, of course, because the SL150II is a more powerful light but the bulk of the difference is that the SL150II has a very efficient reflector which is optimised for the COB in the light. If you are using it in a softbox you won't see the massive difference in light output.

OP Tom Ferguson Senior Member • Posts: 2,320
Re: Godox SL100W Lux versus GN

Thanks again Tug. After experimenting with the "User bank"  on my Nikon, I've decided that is a FAR better option for me. I can setup a User bank for a slower shutter speed, a higher ISO and tungsten WB when using Live View and then just switch back to "Manual" and all of my flash shutter speeds, F-stops, custom WB and ISO are still there. Yes, I might occasionally forget and start shooting "for real" in "User bank"... but it would be soooooo wrong with my flashes going off that even "I" would notice

Now, if anyone knows why Live View is noisier and grainer in Capture One compared to Nikon Camera Control 2... I would love to know!

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Klaus dk
Klaus dk Veteran Member • Posts: 8,325
Re: Godox SL100W Lux versus GN

It sounds to me like you're using live view with exposure simulation. Since the camera can't know that there'll be a flash lighting the scene, it will think the picture will be severely underexposed at your settings.

See if you can turn exposure simulation off. If you can, the LED will show you how the picture would look in the current (model) light if the camera was set to auto.

This is at least how it works with my Canon EOS R.

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OP Tom Ferguson Senior Member • Posts: 2,320
Re: Godox SL100W Lux versus GN

Thanks Klaus, that is exactly what I did wrong. When I metered the scene with my modeling lights, I somehow set the camera way wrong! Once I corrected that silly mistake, everything looks fine

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