detail expectation

[Ted R]

Film imaging has always been subject to limitations in the detail that can be recorded. When we start to look at detail very close up everything turns to mush, this is normal. Some of the limitations arise from the following factors. Film has a tendency to buckle slightly and may not be completely flat in the film holder when this happens this causes the image to be slightly out of focus in some places. The lens has a resolution limit due to the physics of optics and the finite wavelength of light. A very good lens focuses the corners and the center at the same film plane, an inferior lens focuses the corners and the center at different distances so on the flat film some parts of the image are blurred due to loss of focus. Cameras vibrate, especially when mounted on tall tripods, the vibration causes motion blur of the focused image, eliminating this requires the careful use of a shutter release cable or air operated release or delayed release. With very fine grain film developed in fine grain developer exposed correctly and with the problems described previously under control then the best negative sharpness is achieved, however even this will turn to mush when examined using powerful magnification.

There is an approximate rule of thumb for enlargement factors with film under favorable conditions a print size about five times the negative size will show good sharpness and contrast. The same negative enlarged ten times may start to show problems with lack of sharpness and film grain. More than ten times demands the ultimate in care and the use of the very best taking lens and the enlarging lens.

Note that viewing distance is a factor. It is very interesting to visit a museum where high quality original paintings are on display. The majority turn to mush when viewed from close up however when viewed from a distance of five or ten feet the effect intended by the painter is visible and the lack of detail is not apparent.

PS
Viewing scans of negatives is a good way to find disappointment, viewing the image on a monitor with the scale of the image size absent (the scan may be easily enlarged on-screen to be many feet across) the mush will be apparent. On the other hand making a print five times enlargement and viewing it from five feet may show an entirely satisfactory situation.

[Jac@stafford.net]

All I remember is how much the battery pack weighed.

Oh! You were referring to the big blue pack! It was like strapping a 6-pack of beer on your shoulder, but had no such utility after the event.

[Simos Xenakis]

To answer your question about how much detail you should be seeing, much depends on the quality of your scan. You can get a lot more from a decent drum scan than you can from a consumer level flat bed scan. The consumer flat bed scan is really only good for prints less than 4x enlargement in my book. A professional flat bed will get you to 8x, and a good drum scan can take you to the limits of what the film has to offer.

Bruce, would you mind expanding on what class of scanners you would consider "consumer level flatbed" vs. "professional level flat bed?"

And to clarify, when you say 4x enlargement, you're referring to getting 16 inches of print size out of 4 inches of film length, is that correct? Therefore, a pro-level scanner (capable of 8x enlargement) should be able to produce a satisfactory 32"x40" printed image from a 4x5 scanned neg, right?