Lattitude

[rayonline_nz]

Hi, can somone advise me what is the rule of thumb for lattitude for slide, neg and b/w film please?

For slide is it .. 1.5 to 2.0 stops over graytone and for color negs maybe 3 stops on top and maybe a -1 under.


Anothre question is that, let's say there is a 2 stop difference between gray (foreground) and sky (highlight) late afternoon. Clearly color neg covers that. If I shot one with color neg alone and the 2nd with a 2 stop GND filter. What would I see?


Thanks

 

[Steve Smith]

For slide is it .. 1.5 to 2.0 stops over graytone

That's not lattitude, it's dynamic range. Lattitude occurs with negative film because you have a second stage (printing) to compensate for any variance in the negative.

i.e. if you overexpose and get a dark negative you can print it for a bit longer or you can use a shorter exposure to print a light, under exposed negative.

A slide is supposed to be the final product, therefore you need to get it right. This usually means exposing so you don't blow out the highlights although with a high contrast scene this can be difficult (or impossible) to do without losing shadow detail.


Steve.

 

[phaedrus]

YMMV

Hi, can somone advise me what is the rule of thumb for lattitude for slide, neg and b/w film please?

For slide is it .. 1.5 to 2.0 stops over graytone and for color negs maybe 3 stops on top and maybe a -1 under.


Anothre question is that, let's say there is a 2 stop difference between gray (foreground) and sky (highlight) late afternoon. Clearly color neg covers that. If I shot one with color neg alone and the 2nd with a 2 stop GND filter. What would I see?


Thanks

First paragraph: 5, 9 and "it depends" f-stops. It depends on the developer and film used, and any zone system fu (*1) applied.

Second paragraph: Those numbers are overly pessimistic.

Third paragraph: in the first case, a realistic depiction of the scene. In the second case you either took artistic license or followed a cliché. One would have to see the picture.

(*1) Which, as anyone knows, is a major part of FUBAR.

 

[tomalophicon]

i.e. if you overexpose and get a dark negative you can print it for a bit longer

Steve.

What do you mean by print it for a bit longer?

 

[markbarendt]

What do you mean by print it for a bit longer?

This is a simplified explanation.

Negatives that get more camera exposure will be "thicker", that just means the negatives block more light.

The negatives are an intermediate step.

For a thick negative when printing in an enlarger you add more exposure, with extra time or by opening the f-stop, to compensate for the "thickness" (density) of the negative.

Being able to adjust enlarger exposure allows you to print a "normal looking" image from negatives shot at various camera settings.

See this PDF from Ilford about XP2 Super http://ilfordphoto.com/Webfiles/20061301945161573.pdf With this film extra exposure actually gets you finer grain.

Slide film is essentially the finished product once developed, a transparent positive print if you will.

It is common for slide shooters to bracket, shoot a variety of exposures, in camera to make sure they get one good one.

With negatives bracketing isn't so important because the enlarger allows you to adjust exposure for the difference in density on the negative.

For a practical example consider disposable cameras. They normally use 800 speed C-41 negative film, they have no exposure controls, and are capable of usable exposures from noon till nearly sunset without a flash. Slide film can't do that.

 

[ic-racer]

Latitude is the difference between the scene range of values and the distance between the shoulder and toe (the usable portion) of the film curve. So, it depends on the film and the scene. A common situation might be an overcast day with T-max film. In that case there will be an extra 6 stops. Depending on how you meter that type of scene and your EI in that situation you could have 3 stops over and under, or any combination adding up to 6.