Tech Help?

[ollywood88]

Hi all,

Firstly happy new year .

I am after some advice, with the inverse square rule. How does it work in regards to F/T stops?

Unclear about how you work it regarding F stops.

Thanks

 

[Andrew Luczenczyn]

All calculations are the same. T-stops compensate for light loss internal to the lens, T stops are regarded as more accurate than F stops, but for all calculations, replace the Fstop with the T stop.

 

[ollywood88]

yup sorry i understand t stops and F stops.

Just unclear when you work out the inverse square rule.. (light fall off) how does this correspond to stops, for example 2ft square to 4ft. How do you calculate your f stop?/

 

[Andrew Luczenczyn]

oops I misunderstood.

Its easier to understand the inverse square laws in their linear format ei footcandles. This way it directly relates to F stops.

So, if you cut your foot candles in half, your double the size of your iris, aka, open one stop. its not exactly proportional, but functionally its pretty close. Most light meters do this calculation for you.

So, if you need to brighten an object by one stop, you half the distance between the source and the object.

 

[j1clark@ucsd.edu]

Hi all,

Firstly happy new year .

I am after some advice, with the inverse square rule. How does it work in regards to F/T stops?

Unclear about how you work it regarding F stops.

Thanks

The doubling of the distance results in 1/4 the light, therefore that would be 2 stops different.