On Thu, Mar 18, 2010 at 1:16 PM, Larry Colen <[email protected]> wrote: > I know that when it comes to exposure, film has a much higher dynamic range > than does digital.
Personally, I think that's a myth in the general case. >From the perspective of the media, there are a few circumstances where film capture can record a wider range of values than available production cameras but those few circumstances almost invariably mean particular films, non-standard development, etc. The myth is descendent of the fact that digital capture is a relatively young medium with behavior and metrics very different from film media, which we have over 100 years of experience getting the most out of. The perception of limited dynamic range is a holdover from early digital cameras (and we're only talking less than a decade here between 'early' and 'state of the art'!) which were not yet capable enough along with a general mis-understanding of how to expose and process digital capture images correctly. As far as I can see from observing differences between my film and digital work over the past 18 years, any DSLR class camera made since 2003-2004 outstrips what film can record in dynamic range pretty easily. > What about the dynamic range of the image on the processed film? Negative images on film have lower contrast and show more dynamic range than positive images. This is essential since the process of printing a negative image, reversal to a positive, demonstrates contrast gain in almost all cases. > What about scanners and digital cameras? Do scanners have more dynamic > range than your standard APS camera? Scanner dynamic range is measureed in 'dmax' ... it's a logarithmic scale. The higher the number, the more of the film's tonal scale a scanner can capture in a single pass. A poor performer is rated around 1.6-1.8, a good performer around 2.3-2.8. Most affordable film scanners (like the Nikon Coolscan IV/V) achieve numbers in the 2.3-2.6 range when measured which is usually greater than the dynamic range of most color or BW negative films. Measuring that against the DR of an SLR class digital camera is tricky ... I haven't seen any published results. But I know from my own experience doing photo restoration work that in those cases where I could not capture a good original for editing with the scanner, I've been able to do so with ease using a copystand and raw capture with a DSLR class sensor. > If the image on film has more dynamic range than that on the camera, could > you recover more of that data with bracketing and HDR processing? How many > stops of bracketing would you need? Good scanners driven by good software excel at multi-pass scanning which enhances dynamic range. I have only once or twice seen the need for these kinds of techniques with any negative image. Slides ... that's another story. -- Godfrey godfreydigiorgi.posterous.com -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
