B&W exposure latitude

[Steve Smith]

Ralph's second graph shows in a clear and easily understood way, something which I have been trying to put into words. I don't need to bother now!


Steve.

[ic-racer]

The only thing I would think different is that the negative is not "overexposed" until it the high values start to fall off the shoulder and print quality has degraded. So, the dark gray box in the second diagram (nice diagrams by the way) I'd say "more than needed, but still OK exposure" rather than "overexposed."

In fact in large format photography (where high shutter speed is not needed), dense negatives show less dust when printing and in my hands, are preferred.

[RalphLambrecht]

ic-racer

Some people have an issue with the term 'overexposure', and I can understand why, because overexposed negatives print just fine and often better than normally exposed negatives. If we free ourselves from connecting 'overexposure' with 'bad exposure', the term gets is to digest. 'More exposure than needed, but still OK exposure' it a bit too lengthy for something we do so frequently. I prefer to stick to 'underexposure', 'normal or minimum exposure', 'overexposure' and maybe 'nuked'.

[mingaun]

Ralph, thanks for those images which speaks very clearly.

Mark

[fralexis]

So it IS a good practice to shoot at one half the rated ISO? I'm also struggling at getting consistently good exposures. With my spot meter, I find it hard to determine what is middle grey in a landscape. I want to try just placing a dark shadow in zone III. Otherwise, I'll use my digital meter

[Sirius Glass]

So it IS a good practice to shoot at one half the rated ISO? I'm also struggling at getting consistently good exposures. With my spot meter, I find it hard to determine what is middle grey in a landscape. I want to try just placing a dark shadow in zone III. Otherwise, I'll use my digital meter

No, use the box speed and do what you are already doing. If all your equipment is properly calibrated and you are using the light meter correctly, one rarely needs to adjust ISO to get the full shadow depth.

Some people make a career out of continuously test and retesting file. Their time would be better used actually taking photographs.

[markbarendt]

So it IS a good practice to shoot at one half the rated ISO? I'm also struggling at getting consistently good exposures. With my spot meter, I find it hard to determine what is middle grey in a landscape. I want to try just placing a dark shadow in zone III. Otherwise, I'll use my digital meter

IMO the most reliable type of meter is an incident meter. Reflective measurement can be done Very well too but it typically requires more experience. As you have found, it requires judgement to pick the right point in the scene.

Adjusting to 1/2 box speed adds more safety factor but there are downsides to using extra as a blanket fix, like slower shutter speed, more grain, ... It is not a magic bullet.

Personally I incident meter and shoot at box speed and develop normally; systemic failures are very, very, rare doing this.

[fralexis]

So, using an incident meter how is it used most effectively in the landscape? In my studio work, I aim the dome at the camera and meter. In a landscape I'm standing at the camera with no way to get to the subject a distance off. What methods seem to work best?

[markbarendt]

All you have to do is be in the same light, then you use it similarly to the studio.

If you aren't in the same light sometimes walking a few steps can get you there.

You can also do non-traditional measurements. If you are in shadow you will get a reading that will give you the equivalent of shooting at 1/2 or 1/4 box speed, for example. You can shoot there or adjust to correct, your choice.

BTZS is actually a zone system variant that uses incident readings normally, even preferentially for exactly what you are asking to do. I'm not suggesting you have to do that, just an example.

[Diapositivo]

IMO the most reliable type of meter is an incident meter. Reflective measurement can be done Very well too but it typically requires more experience. As you have found, it requires judgement to pick the right point in the scene.

Adjusting to 1/2 box speed adds more safety factor but there are downsides to using extra as a blanket fix, like slower shutter speed, more grain, ... It is not a magic bullet.

Personally I incident meter and shoot at box speed and develop normally; systemic failures are very, very, rare doing this.

I agree with Mark.

I would just add to remember that in high contrast situations (imagine a building which is half lit by full sun and half in shade) when using an incident light meter and a positive film you would take the measure by placing the light meter in full light (with the dome pointing toward the camera) while with an incident light meter and a negative film you would put the light meter in the shade (again with the dome pointing toward the camera).

Using an incident meter still requires to remember that with slides you expose "for the highlights" and with negatives you expose "for the shadows" when you have a scene in front of you with both zones in bright sun and zones in the shade.

Having said that, an incident light meter and "box speed" yields very good results in most situations, while spot metering is more prone to errors and I think is warranted only with high-contrast situations and slide film when you want to exactly understand the way the highlights will be rendered on slide film.