BW film vs digital latitudes...

[Haigh]

I'v started spot metering the highlights with my dslr and letting the darker areas take care of themselves. Seems to have worked so far. It's the opposite with film, which is Tri-X in my case.

 

[Roger Hicks]

I said "true exposure index", meaning on the ISO scale, and went on to say that was with YOUR "film/developer/agitation". I supppose we could get into a discussion about how ISO is a compromise between ASA and DIN because DIN measures from a point on the toe where any gradiant at all just become noticeable while ASA was based on a mid point of the straight line portion of the H&D curve. Not all ASA 100 films were DIN 21.

Dear Al,

Sorry, disagreeing again. Speed points are always in the shadows (toe of the curve): they have to be. The speed point on DIN was a fixed density (0.10 above fb+f), while ASA was changed from the original fractional gradient (0.3x the average gradient of the straight line portion) to the same fixed density as DIN, for ease of measurement. ISO was always fixed density, not 'a compromise'.

There must obviously be a fixed gradient, so you need a second point, higher up the D/log E curve. There's a full description of ISO here and in its associated modules:

http://www.rogerandfrances.com/photoschool/ps iso speeds.html

If you develop to anything other than ISO contrast, you are not rating the film at an ISO speed.

In one sense, you are absolutely right: all you need is an exposure index (EI) and a development regime which gives the results you like. In another sense, it is important to distinguish between ISO speeds and EIs because once people start conflating them, they start imagining all kinds of strange things, most especially that films aren't 'really' as fast as their ISO speeds. They almost invariably are, but this doesn't mean that the ISO speed is necessarily what everyone should set on their meters.

Cheers,

Roger

 

[marke]

To be honest, I see darker shadows on the top image ,while the bottomest looks more balanced between highlights and shadows.

Really? Look at the top wood plank on the right side of the picture. The shadows are definitely darker in this area in the top photo.

 

[charjohncarter]

"Time is money" is one expression I've been hearing all my life!

The others include "Film is cheap!"

"Read the light, not the subject!" referring to making an incident reading.

How about "When in doubt bracket!"?

Is that why my DSLR has up to five brackets with up to 2 stops for each bracket? It still doesn't work that great at the beach or around a sunny pool.

 

[MRohlfing]

I checked and it was usually like 4 stops darker. Yesterday I had some time to walk the streets and most of my shoots where around f2, 1/500. f8 to f2 is quite a change eh?

4 STOPS DARKER!! That's close to impossible if the 450D works as it should, there must be something wrong. This can't be a matter of 'digital versus film'.

Did you have a look at the EXIF data? Can you post an example including EXIFs?

Are you sure you took the pictures with ISO 400? Did you try different measuring methods (matrix, average, spot)?

Do you have a light meter or another camera to compare the readings? If yes, try it with a uniformly lit surface, like a house wall.

Please tell us the results!