Difference between 3.3 and 3.6 dynamic range

[brien_szabo]

My Nikon scanner finally spit the bit. After many years of service (about 8) and 2 repairs, it is done. I don't scan

much anymore but do need to from time to time - sometimes for submission but not often. I was looking at getting a

Plustek. Without wanting to spend money on something that isn't going to be used but a handful of times a year, I

was wondering if there is a significant difference in detail gathering of shadow areas of mostly Velvia slides between

a scanner with a D rangge of 3.3 and 3.6 - the difference in dollars is about 75 bucks but hey, nowadays, 75 bucks

is a tank and a half of gas. I'd rather have more cash for gas to shoot than worry about possible minutia in D-range.

[roger_smith4]

I don't know what Nikon you used but the difference between a low and high Dmax for slides like Velvia is the

difference between scannable and unscannable slides without heroics like scanning multiple times at multiple

exposures and combining (and watching out for problems with alignment).

 

I would ignore all published dynamic range figures as they are unrealistic and based on reading reviews, don't believe

any Plustek has a reasonably Dmax. If you're shooting color negatives it doesn't matter but for color slides I wouldn't

buy anything but a Coolscan V. I have a Canon FS4000US and find some Velvia and Provia slides to be

unscannable without scanning multiple times and blending exposures together. A Coolscan 5000 (simlar to the V) I

used gave good results in one pass.

 

Roger

[sfcole]

"nowadays, 75 bucks is a tank and a half of gas. I'd rather have more cash for gas to shoot than worry about possible

minutia in D-range."

 

I disagree. I would rather find a way to not use a tank of gas--like combining shopping trips, walking, riding my bike, or

simply not going somewhere I didn't have to--and investing the $$ in equipment that will yield better results for a period of

years. Use the $$ for gas and it A. evaporates, never to be seen again. B. pollutes the atmosphere C. causes us to use

less calories, thus shortening life expectancy while making us susceptible to disease D. creates wear and tear on the car

and increases risk for traffic accident death at the hands of some jerk yakking away on the phone.

[geoff_portas]

Density range is measured on a logarithmic scale, so the difference of 0.3 represents a doubling of the dynamic range, ie equivalent to one f-stop. If you're concerned with shadow detail it's worth it.

[Ed_Ingold]

DMax is not dynamic range. It is the maximum density of the film which results in a useful signal level (above the noise level). Density is a logarithmic scale. If you take the difference (3.6 - 3.3 = 0.3) and divide by 0.301 (log 2) you get the difference in f/stops (1 stop).

 

To know the dynamic range, you would need to know the minimum film density which would result in a signal distinguishable from a blank cell. This would depend on the gain. If it were zero, then the dynamic range would be 3.6/.301 or nearly 12 stops. My educated guess is that the value is closer to 8 stops - which is that of Nikon CCD cameras of similar vintage.

[roger_smith4]

I think Edward is on the money. A 1 stop increase in shadow detail is significant for a slide like Velvia or you get crushed blacks and overall limited tonality (there are bad Velvia scans all over the net- you'll know them when you see them).

 

One thing I'd watch out for is whether the Dmax comparisions are apples to apples.

 

My scanner, the Canon FS4000US has significant shadow noise on dense slides and yet claimed a dmax of 4.2 in 16 bit mode, which is the same as the far superior Coolscan 5000.

 

This chart gives a comparison of scanners and their claimed Dmax:

http://www.normankoren.com/scanners.html