Question ok fcp

[Sergio]

Hello waterpixlers,

 

i’m participating on a workshop doing model shooting in a pool. The back of the pool was covered with white sheets. 
I now have a behavior I do not quite understand and am hoping someone here does 😉

Everyone else is shooting  classic wide angle and rectilinear lenses and using 1/200, f11 iso 400 and the water column comes out nice and blue. 
When shooting the fcp I have to go down to 1/120, f8 and iso 1600 to get the picture half way properly exposed - it’s actually still a little dark. I also get a strong green tint. 
now, I assume the fcp must screw up my autom white balance, probably because of the color of the glass? I can easily correct that in post, but it seems that it also looses quite a bit of light which would be the reason I have to use those settings? Does anyone have more information?

 

cheers

sergio 

[Chris Ross]

This seems very odd, the difference between 1/200@f11 ISO400 and 1/125@f8 ISO1600 is 3 2/3 stops, this is quite a significant difference in light.  Cameras might be up to one ISO number out from true ISO, but it is very difficult to see how this could work out to be such a difference in exposure. 

 

I'm assuming you were framing the subject the same way for example a dark subject filling the frame will have a different exposure reading to the same subject much smaller in the frame against a white background.   Also you were shooting from the same spot and had the same sheets in the background so had the same reflected light?

 

Additionally were they using the same or different cameras to you?  Was anyone for example the same lens as you but behind a WACP instead?

 

This review mentions a slight greenish cast and also talks about the more limited depth of field seen with this lens:

 

review on scubaboard

 

some commentary in the comments as well.  There is speculation that the aperture when it reads f13 might optically be wider open, but it seems this is the opposite to what you are experiencing.

[Sergio]

Thanks Chris. I meant to add/correct my statement as the typical rookie I am, this actually wasn’t the issue but the fact that my strobes weren’t synced with my camera and therefore also not with the remote strives which led to my photos to be very darks. Sorry for bringing something to this board that isn’t actually an issue. The color issue still was visible though when shooting in ambient light in a pool, but then it might just be the light that was present there and my auto white balance not doing a good job. The color casting was very visible when shooting against the light and not really with the light.

[Chris Ross]

11 hours ago, Sergio said:

Thanks Chris. I meant to add/correct my statement as the typical rookie I am, this actually wasn’t the issue but the fact that my strobes weren’t synced with my camera and therefore also not with the remote strives which led to my photos to be very darks. Sorry for bringing something to this board that isn’t actually an issue. The color issue still was visible though when shooting in ambient light in a pool, but then it might just be the light that was present there and my auto white balance not doing a good job. The color casting was very visible when shooting against the light and not really with the light.

No problem, good you figured it out.  It does appear that the FCP imparts a slight green cast, your strong green cast could be fluorescent lighting?

[Sergio]

Could very well be the case. It was in a pool with lots of in artificial light and very likely some fluorescent light as well. Will keep an eye on things going forward and update as I find out more 😉