Sekonic L758 Cine Question.

[Stewart Read]

Hi All

So.. I get how to use the Delta function in Incident Mode (determining the Ev/f Stop difference between two readings).

However if I take one reading in Incident mode, hit the Delta function and then switch to Spot Meter mode, I don't get a Delta reading (the difference in stops between the two readings). It seems to me that you can only produce an Ev/f stop difference reading when performing two readings from the same mode - i.e. two Incident Meter readings.

Is that the case - if so it's a bit annoying !

Grateful for any advice on this.

Thanks !

 

[Tony M]

Both are entirely two different ways of measuring.
And trying to do what you are doing would bound to lead to errors.

The difference in incident reading of two light sources is bound to be different from the difference in the reflected readings (spot); since reflected readings is secondary and depend on the surface the incident light reflects from.

 

[Stewart Read]

Thanks for replying Tony - appreciate it. Is it not common practice to incident meter your Key light and then spot meter your background (say for an interview) to work out contrast ratio in stops ?

How do you personally meter this scenario ?

Thanks for any insight !

 

[Anton Shavlik]

One mode measures light coming from an object and the other measures light falling on an object, light in v. light out, so to make a comparison you have to make an assumption about what % of light hitting the object is reflected (light going in that then goes out again). The point of a light meter is to not make assumptions like that, so you can just compare two measurements made in the same mode and get an exact comparison.

 

[Tony M]

You have to know why you need to use the Delta function: For Contrast function, right? I am assuming that is it, maybe.

Stick with measuring either using the incident meter reading... Or using the spot meter. Don't mix both modes. Each of them have its own purpose.

For the scenario you mentioned.... You can get all the measurements using the incident reading, both keylight, fill light, b.g light... e.t.c. And you will still get there.
But you have to know that the incident reading doesn't take into factor the surface measured i.e its reflectance...if it is a white subject or black subject.

One trick/short cut to keep in mind is that you get a more accurate f-stop reading for whiter (high reflectance) subjects, by double-checking with the spot meter. For black subjects (low reflectance), the incident reading will be more accurate.

So, looking at your scene, you can decide where it is best to use which mode.
For example, You can start with incident mode, and get close to final reading, and use the spot readings to hone it in.

For contrast ratios (and most times), Incident mode tends to work best though.
Spot mode can be essential for subjects you can't reach (a distant background maybe).

 

[Tony M]

One way to understand the difference between the two modes is to use a white subject and a black subject.

Measure both modes, and you will see there will a difference in EV on the same subject.

Cinematographers (when they use the meter) tend to point the meter at the keylight, get the f-stop they need (or adjust if they need to), set that value in the camera, and then start to make adjustments, on the scene; placing values below and above it, to achieve contrast.
Here, the spot mode comes in handy to quickly check.

Remember,
For incident mode measuring, You stand at the position of the subject, and point towards the light.
For spot mode, You stand at the camera position and point towards the subject.

 

[Stewart Read]

Thanks for the clarification Tony.