Spot metering and B&W film dynamic range

[ian_s]

Having struggled a little to get exposures accurate for my initial film rolls (woodland scenes with dark shadows and bright patches of sunlight) I have been doing some background reading and have bought a second hand spot meter (Sekonic L-508)

The accepted advice seems to be to spot meter for the darker areas you want detail in and then compensate (underexpose) for 2 stops.

However I believe b&w negative film has a bigger dynamic range so is it appropriate to compensate for more that 2 stops ?

I couldn’t get a consistent comparison between multiple types of b&w negative film on its exposure latitude or dynamic range in stops. Some sources indicate 9.5 stops, compatible with mid-range digital cameras and other suggested much more.

If it has a dynamic range of 10 stops then a compensation from mid grey to zone 2 would be three stops. Its possible that different films may have more highlight (above mid grey) dynamic range than below mid grey.

Does anybody know of a resource that compares directly the dynamic rangein stops of different films types (Tri-X, XP2, Delta and colour films too etc).
Advice also suggests that for digital cameras the advice is similar for slide film, meter for highlights and compensate and then over expose by 2 stops.

If the under and over expose 2 stop rule is used widely it would imply film only has a dynamic range of only 6 stops or so.
With digital cameras having up to 12 stops of dynamic range I assume the overexposure could be more ? Of course a direct comparison may not be appropriate.

Opinions appreciated

 

[Joanna Carter]

is it appropriate to compensate for more that 2 stops ?

No.The extra dynamic range has to come in the top (highlight) end. You can recover bright highlights but it is much harder to recover blocked shadows.

With digital cameras having up to 12 stops of dynamic range I assume the overexposure could be more ?

Digital cameras work the other way around, because they are essentially positive "film". My Nikon D850 has a DR of 14.6 stops, but the measured highlight exposure can only be between two to three stops above 0EV. However, shadows can be recovered at anything down to 12 stops under 0EV

 

[Flack]

I use the Sekonic L858D and always have it set to minus two stops when shooting B/W, I use my meter to read the dark parts I need detail in then meter the highlights, then average it out, it seems to work for 99.9% of the time.

 

[ian_s]

I use the Sekonic L858D and always have it set to minus two stops when shooting B/W, I use my meter to read the dark parts I need detail in then meter the highlights, then average it out, it seems to work for 99.9% of the time.

I did have a look at the L-858 but it seems a very complicated (but capable) solution, the manual running to over 200 pages, I needed something simpler as I am not intended to do any flash work. Although I am realising that the L-508 can't average readings in Aperture priority mode, only shutter priority which is a shame for a landscape photographer. I assume fixed shutter speed and vary the aperture is a flash / studio photography technique.

 

[ian_s]

No.The extra dynamic range has to come in the top (highlight) end. You can recover bright highlights but it is much harder to recover blocked shadows.



Digital cameras work the other way around, because they are essentially positive "film". My Nikon D850 has a DR of 14.6 stops, but the measured highlight exposure can only be between two to three stops above 0EV. However, shadows can be recovered at anything down to 12 stops under 0EV

Thanks for the reply. When you refer to 0EV I assume you mean, the middle grey exposure level at that ISO ?
Another definition I found, perhaps for absolute EV, was EV 0 is f=1 t=1.0s @ISO 100.
Its curious that digital cameras that have far better tone measurement (number of effective bits resolution) in the highlights - ETTR and less in the shadows, but clearly in some way this translates into superior shadow recovery. I assume its the characterisation with respect to ISO