Digital BW, The Print

The difference between film and digital is (excause the abuse of the 
term) how the grain shows up. In film the grain tends to show up at 
higher light leves - zones 6 up. In digital the "grain" which is really 
noise shows up at the lower levels - zones 3 down. The difference comes 
from different physics producing the effects of grain. In the digital it 
is the preamp noise that would be there - even assuming the sensor was 
noise free. The signal levels are simply closer to the noise floor and 
as such the values are impacted more my the noise than the high level 
signals resulting from bright objects. In other words in the shadows the 
signal to noise ratio is low while in the midleves up it is high.

As long as you have a pre amp and ADC in the circuit there is no way to 
eliminate this fully. As Paul noted placement of values is extremely 
important because of this and I suspect for critical work no mater how 
good they are the in camera meters are not sufficient and a good old 
fashion spot meter would prove very helpful. When I am doing critical 
work - be it with my 4x5 field camera or my digital - I use my spot meter.

It is very interesting to think that Adams developed the Zone System in 
order to get proper placement of values on film so as to control the 
highlights (minimize blocking and grain). With a digitial camera it is 
just as useful except in this case it is to minimimize the impact of 
noise on the shadows.

Truman

Paul Roark wrote:

>>... are you saying that if you had been using film, you could
>>have gotten the same or better results with a single exposure? and
>>less manipulation?
>>    
>>
>
>I'm not sure about the single exposure.  I didn't have my spot meter with me
>for the digital shot -- a mistake I won't make in the future.  Given the
>"slide-like" 7 stop dynamic range, I'm going back to carrying my Pentax spot
>meter.
>
>Medium format, Tech Pan film would probably have ended up making a better
>image with less manipulation, however.  Also, I would have been able to
>print larger than 16x20 with MF TP.
>
>MF Tmax 100 would probably not have made as good an image, however.  The
>grain in the foggy parts of the image would have shown.  With the Canon 8 mp
>image, the foggy areas are totally smooth, and I really like that.
>
>Paul
>www.PaulRoark.com 
>
>_
>


-- 

"If you want to make an apple pie from scratch, you must first create 
the universe."

- Carl Sagan