Digital Photo Printing
Digital vs. Film and Why does Effective Clarity matter ?
Digital cameras are a great alternative to film, but it's important to understand
and appreciate the differences.
- 35mm film does not have pixels, but the effect of 'film grain' gives the
visual resolution of about 5000x3333 'pixels'; depending on the ASA rating.
- This is about 16.6 Mpix in the digital world -- but with an ideal sensor!
- So far, film still has much better contrast and color depth.
- The distortion of film grain is different than the distorion of JPEG and other
factors which decrease the image Clarity below the Mpix rating. Film grain
is independent point-source error whereas JPEG is a lossy compression
technique where image information error affects blocks of 8x8 pixels;
the error is distributed.
- The reason why JPEG lossy compression is acceptable for photography, while film
contains so much more accurate detail, is that we easily accept the the JPEG
distortion with 'natural' images and 'fill-in' the rest from our own menory
and we are simply getting used to it.
- Because Digital Camera Clarity is only about 50% of the MPix rating, this widens
the distance between digital cameras and film.
- Assuming the Clarity 'ratio' for a Canon 40D of 0.42, a 40 Mpix SLR would be
required to compete with 35mm film resolution.
- Since both the availability and expected cost make this prosibility very near zero,
getting the most from a digital SLR is a worthy goal.