Is there any difference between these 2 lenses other than the price and
f-stop? This is a common question that pops up frequently on forums everywhere.
While the general consensus is that these 2 lenses are almost identically sharp,
there are other factors that have not been fully explained or readily available.
And there are lots of wordy discussions but hardly any picture to illustrate.
Since I happened to have a new f1.4 together with my old f1.8, I decided to do
some tests to find out the answers myself. My test is focused on more apparent
difference at wide aperture rather than trying to find out split hair
difference.
Out of focus highlights
Out of focus highlights produced by the 8 diaphragm blades of the f1.4 look
more like a circle while those produced by the 5 diaphragm blades of the f1.8
take the shape of a pentagon. At f5.6, the pentagon shape becomes more apparent
and looks unnatural. At f22, point source of light is rendered like a star with
he f1.4 produces 8 pointed stars while the f1.8 produces 10 pointed
stars.
| |
EF 50mm f1.4 |
EF 50mm f1.8 MK II |
| f2.8 |
|
|
| f5.6 |
|
|
| f22 |
|
|
Barrel Distortion
Some photo.net members have complained about the f1.4 suffering from barrel
distortion. My test result shows that the f1.4 does indeed suffer from slight
barrel distortion. The f1.8 may or may not but it is at lest better than
f1.4.

The above pictures were shot at big aperture. It is interesting to note that
the 1.4 produced sharper and more vibrant colour than the f1.8. The brick wall
also the light fall off at the corners is more severe on the f1.8.
Flare
Shape of the flare produced are different. Although I preferred the flare
rendered by the 1.8, color becomes washed out and has less contrast.
| |
EF 50mm f1.4 |
EF 50mm f1.8 MK II |
Either @ f2
or f2.8 |
|
|
Light fall off

f1.4 vs f1.8
Light fall off is more severe with the f1.8 at big aperture.
Bokeh
For those who do not believe in bokeh, the following results should convince
you otherwise:
f1.4 @ f2 Check the out of foucs background behind the cans.
The bokeh produced by f1.4 has a very nice blend of grey and pink colours.
f1.8 @f2 Here, the blending of the colours in the out of focus
background produced by the f1.8 is more harsh.
Here's another example:
f1.4 produces distinctly better bokeh at f2. At f5.6, the difference becomes
less obvious.
|
|
| f1.4@ f2 |
f1.4 @ f5.6 |
|
|
| f1.8 @ f2 |
f1.8 @ f5.6 |
One more example:
Again, the background blur is nicer on the f1.4 at f2.
|
|
|
f1.4@ f2
|
f1.4 @ f5.6
|
|
|
| f1.8 @ f2 |
f1.8 @ f5.6 |
Although the bokeh is similar at f5.6, the highlights produced on the f1.8
take the pentagon shape. Here's the enlarged portion of the above pictures at
f5.6.
Enlarged portion of the previous images. f1.4 vs f1.8 shooting @ f5.6
Specifications:
| |
Canon EF 50mm
f1.4
|
Canon EF 50mm F1.8
II
|
| What Canon says
|
Standard lens featuring
superb quality and portability. Two high-refraction lens elements and new
Gaussian optics eliminate astigmatism and suppress astigmatic difference. Crisp
images with little flare are obtained even at the maximum aperture.
|
This is the lightest EF
lens of all at a mere 130g. Compact and high-performance, standard lens. Its
Gaussian optics provides sharp delineation from near to far focusing distances.
The colour balance is excellent for a standard lens.
|
Angle of View
(horizontal, vertical, diagonal)
|
40º, 27º, 47º
|
Lens Construction
(elements/groups)
|
7/6
|
6/5
|
| No. of Diaphragm
Blades
|
8
|
5
|
| Minimum Aperture
|
22
|
| Closet Focusing
Distance
|
45cm
|
| Maximum
Magnification
|
0.15x
|
| AF Actuator
|
Micro USM
|
Micro Motor
|
| Filter diameter
|
58mm
|
52mm
|
| Max Diameter X
Length
|
73.8mm X 50.5mm
|
68.2mm X 41mm
|
| Weight
|
290g
|
130g
|
©
Wee Keng
Hor
All rights reserved.
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