I gave a talk to the Marlborough Camera Club on 11 May 2006, using a PowerPoint presentation.
The text on the slides appears below.
Click here, or on any one of the titles, to view the complete slides, including images.
or, more precisely:
Smallest object you can distinguish
Amount of information.
Depends both on the
And on the image
This projector resolves
1024 pixels horizontally and 768 pixels vertically
A computer screen typically has
70 to 100 pixels per inch
A high resolution photographic
resolves 300 pixels per inch
e.g. a 12"x8" print has 3,600 x 2,400 pixels
A sharp 35 mm slide has several
thousand pixels per inch.
Depends on either
resolution in your file
the display resolution,
whichever is less.
High resolution (large file)
Cropping and other computer
Low resolution (small file)
Images suitable for emailing or
Number of images in your camera
Number of images on your computer
Number of images on a CD or DVD
for archiving or distribution
Hiding defects like noise,
graininess, soft focus.
For the same resolution:
Different file types give different file
Adjust your camera resolution to its highest practical setting
Recommended file type in camera:
RAW + JPEG or
largest, highest quality, JPEG
Disadvantage is less images per card
buy a larger card.
Use your image editing program on the RAW file, if you have it
First, re-save your image as a TIFF or PSD and keep the original as well
Edit the image and save it before changing the resolution or file type
Save the image at the resolution you want, probably as a JPEG file.
Lens quality and cleanliness
(e.g. focal plane, mirror shake
Film or sensor size
(e.g. APS, 35 mm, medium format etc. film or
5 Mpixel, 8 Mpixel, 16 Mpixel etc. for digital)
Film speed (graininess) or ISO rating (noise)
Camera motion (shake)
Subject motion (motion blur)
Contrast in the subject.
Pixels per inch (dots per inch)
300 dpi for printing
72 dpi for screen (or email)
4000 dpi for a 35 mm slide
Potential maximum resolution is 1/300 inch or 1/72 inch or 1/4000 inch.
Pixels per inch
total number of pixels in your
1 million for a cell phone
2 to 8 million for a
point-and-shoot digital camera
6 to 16 million for a digital SLR
My EOS 350D
image size is 3456 x 2304 = 8
horizontal resolution is 1/3456.
Pixels per inch
total number of pixels in
or, file size for an
uncompressed 8-bit TIFF file L.