Gelling CITI600 / Godox AD600

[Scooter]

I keep coming back to this... I am too addled with opiates to do the maths and too injured to do a test but I don't think it's true.

It's notionally appealing that the inverse square law would apply to gels too but... I'm not convinced that gel efficiency is affected by the number of photons hitting it. The chance of any given photon getting through a gel is the same no matter how many other photons there are, surely?

Hi Simon - I just tested it using one red gel on the light and then another identical red gel on top. It does look more saturated, however a quick test in Lightroom putting the cursor over the same area on both images reveals that while the overall light is reduced, the colour mix is the same. As a further test, I then upped the light output by one stop, still using both gels and this 3rd shot, is almost identical to the first one in both colour and intensity. Sorry for testing your drugged up brain - I got this wrong, and I'm wondering now how I came to that conclusion. (I possibly used two gels of similar, but not identical colour once and the results looked more saturated. Not sure tbh, The results match Steven's diagram). Hope your recovery goes well.

 

[juggler]

Hi Simon - I just tested it using one red gel on the light and then another identical red gel on top. It does look more saturated, however a quick test in Lightroom putting the cursor over the same area on both images reveals that while the overall light is reduced, the colour mix is the same. As a further test, I then upped the light output by one stop, still using both gels and this 3rd shot, is almost identical to the first one in both colour and intensity. Sorry for testing your drugged up brain - I got this wrong, and I'm wondering now how I came to that conclusion. (I possibly used two gels of similar, but not identical colour once and the results looked more saturated. Not sure tbh, The results match Steven's diagram). Hope your recovery goes well.

Cheers Owen - and thanks for actually doing the test!

 

[sk66]

I got this wrong, and I'm wondering now how I came to that conclusion.

Probably for the same reasons I got it wrong... only considering the amount of filtration and distance while ignoring light output/power as a separate function. TBH, I don't think I've ever changed all three factors at the same time... I don't even use color filters much at all.

With this (new for me) information one might think you can go from a light blue to a dark blue using a light blue filter, simply by changing the light output, but that is not the case. *You cannot change the spectrum(s) of light, or their ratios by changing the power. You can only push them towards clipping white or black (similar to changing your monitor's brightness). This is why you cannot get anything but a pastel color from a pastel filter.

*this ignores subject color/reflectivity and mixing lights.

 

[Garry Edwards]

It doesn't matter, we learn by getting things wrong, the only real failure is when we don't learn from our mistakes, which is why I only got married once