Paper Maximum Density?

[PhilipRingler]

Hello,
Does photographic paper "Maximum Density" refer to the deepest black that can be achieved in the print? If so, I am a bit confused about how the numbers work.
Is 1.6 a satisfactory maximum density for reaching real blacks? For example, Kentmere Art Classic technical data sheet says that the max density is 1.6, but in reference to what? And what does that really mean?
:confused:

 

[keithwms]

It's a log base 10 scale; -log(Ireflected/I_incident) if I remember correctly. In which I define

I_reflected=I_r = light reflected
I_incident-I=light incident

So in other words Dmax 2 means -log(I_r/I)=2 so I_r/I=10^(-2) and 1/100 or 1% of the incident light is being reflected. If I did my math right, you'd better check it!

Obviously deeper Dmax means less light is reflected and the deeper the black. But Dmin is also a consideration, and the overall feeling of tonality has to do with how much ueful range lies between the two... and whether the reflection is truly neutral and black as opposed to some metamerized thing like you still get with some inkjet prints.

For reference, note that log(2) is ~0.3. So you can divide Dmax-Dmin by 0.3 and get a rough idea of the range in stops.

If I got my definition wrong, somebody will set it straight!

Anyway, the big point is that on rougher textured papers you will not see a high DMax. That doesn't mean that the blacks suck, it means that they are reflecting the light in a different way than glossy papers. Of course sometimes textured paper makes a print look better, sometimes it doesn't, that's up to you to decide. But generally if you want really deep blacks well distinguished from bright whites then you are looking for a smoother paper texture.

 

[Ole]

Some glossy papers reach Dmax as high as 2.3, some non-glossy papers only reach 1.6.

Yet the most convincing total black I've ever seen is from Bergger Art Classic Silver Supreme, which has been measured to only 1.6. Sometimes better numbers don't necessarily mean better blacks.

 

[dancqu]

For reference, note that log(2) is ~0.3.
If I got my definition wrong, somebody will set it straight!

Why the ~ and not an = ? Dan

 

[keithwms]

Well, according to google,

log(2)=0.301029996

And google must be right, you know.

Let's see, google also says

pi=3.14159265

and that's pretty close

 

[cao]

Why the ~ and not an = ? Dan

Because 2 raised to 10 does not equal 10 raised to 3.

Algebra left as an exercise for the reader.

 

[Photo Engineer]

Just FYI, the laws of physics prevent reflection print materials from achieving densities much above 2.2 due to internal reflections. By playing tricks with incorporated materials designed to overcome this, you can get as high as 3.0, but the result is fleeting as the paper emulsion absorbs moisture and changes texture.

Density also varies with surface, glossy paper being higher than matte paper.

PE

 

[jgjbowen]

I've been rereading the old Zone VI newsletters. In them Fred mentions that Oriental Seagull had a dmax of 2.05 and that Brillilant (circa 1985)had a dmax of 2.15.