Originally posted by demp10 The image on the sensor is 4928 x 3264 while the LCD is 640x480 (times 3 for RGB to get the listed 921600 pixel count).

If you divide 4928/640 = 7.7 and 3264/480 = 6.8, so 8X is the closest approximation.

I understand that you calculated it 1-dimensional (length), whereas I did it 2-dimensional (area).

To match that to the problem, I would have to know whether the Pentax display zoom numbers (1x...32x) are related to length or area.

I may check that tomorrow, I am too tired now (near midnight in Germany).

Making a picture of a ruler and check this may be sufficient.

EDIT:

Just checked it for my K200D, there display magnification numbers are length related. If this is the same for the K5, your calculation is the correct one for this problem.

But as sensor and display resolution have changed with Pentax models over time, 8x zoom may be not the optimum for all Pentax DSLRs.