Week 6 - 10 Questions

1. Does size matter with sensor arrays?

Yes, but bigger is not always better.

a. An APS-C sensor uses more of the centre of the lens which
normally has the better optics
b. Smaller lenses can use smaller and lighter lenses
c. Larger sensors normally have less noise as the pixels are larger
d. Larger sensors have a shallower depth of field
e. Crop factor can also influence lens choice e.g. a 1.5 crop factor
sensor using a 50mm lens would be the equivalent of a 72 mm lens
on a full frame sensor.
f. The viewfinder is normally larger and brighter on a full frame sensor
g. Larger pixels normally have a higher dynamic range

2. What size, in millimetres, is a full frame sensor?

36mm x 24 mm

3. What does ‘crop factor’ mean when talking about sensor arrays?

It is the sensors diagonal size compared to a 35mm full frame sensor e.g.
you have to multiply an APS-C sensor by 1.5 to equal a full frame
sensor.

4. If crop factor is the longest side of full frame dimension divided by the
smaller sensor dimension, then what would be the crop factor if the full
frame dimension is 36mm and the small sensor dimension is 23.6 mm?

1.5

5. Is resolution lower or higher with large photosites compared to small
photosites?

It is higher with large photosites as diffraction occurs at smaller
apertures.

6. What is digital noise?

It is the signal to noise ration that occurs on a photosite and appears
similar to grain in film. Small sensors normally have higher noise as
well as higher ISO.

7. What is blooming of photosites?

This happens when a photosite has reached its maximum charge and
photons spill over over into other photosites. This appears as
overexposure.

8. Define dynamic range in relation to sensors.

The level of shadow detail and highlights a camera can record. It can
also be defined as ‘The dynamic range of a sensor is defined by the
largest possible signal divided by the smallest possible signal it can
generate.’ – (Vincent Bockaert)

9. Does the human eye have a better or worse dynamic range than your
camera?

Better – it can see over a dynamic range of about 24 f-stops.

10. What is bit depth?

The number of bits that are used to determine colour (or shades of
grey) e.g. a bit depth of 1 will only have two values as opposed to 8 bits
which have 256 values. 16 bits has a possible 64K values.

Hyperfocal distance – the near limit of depth of field for a given aperture when
the lens is set to infinity. It can also be described as the focus distance which
places the maximum allowable circle of confusion at infinity. It is normally set
by putting the infinity mark on the relevant depth of field scale for the aperture
that is in use. However, people like Harold Merklinger argue that the circle of
confusion used to determine depth of field scales is too large for modern day
films and sensors.