Tom W
28th of April 2005 (Thu), 18:54
OK, since the 50's worked out fairly well, the lights are still set up, and the weather is less than ideal, I decided to pull out the 85 mm lenses for bokeh testing. The test is similar to the one I used on the 50's, with some minor lens-to-lens adjustments made to accomodate the minimum focus distance of one of the lenses.
The lenses I used were the 85 mm f/1.8, the 70-200 f/2.8 IS, and the 28-105 f/3.5-4.5. Lighting was a combination of overhead general lighting, two diffused clamp lights, one direct reflector clamp light, and overcast outdoor light directed at the subject with vertical blinds.
The tests were done at f/4, with the exception of the 28-105 which was tested at f/4.5 due to maximum aperture limitations. Once again, the test is merely to get a good look at how the diffused OOF circles are rendered, as that has a relationship to the smoothness of the bokeh.
First, the test setup, taken with the 85mm at f/2:
http://www.pbase.com/photosbytom/image/42699652.jpg
Now the lenses - first, the durable 28-105, shot wide open at f/4.5:
http://www.pbase.com/photosbytom/image/42699653.jpg
Note the hard, bright ring at the periphery of each OOF circle. This contributes to choppy bokeh. Of course, this lens wasn't bought for its great bokeh. That's generally the territory for faster lenses anyway. Later, I'll post an image of how this lens performs at f/5.6.
The next lens is the 70-200 f/2.8 IS zoom, tested again at f/4 and 85 mm. I had to move things back a bit with this lens, since the close focus distance isn't as tight as it is on the other two lenses (this is at the shorter end of this lenses' zoom range). Anyway, note that the bokeh is considerably smoother than the consumer zoom. There is a very slight bright ring on some of the OOF circles, but it is much less noticeable compared to the 28-105. The boundaries are still well-defined (well, it is f/4) but blending is much smoother.
http://www.pbase.com/photosbytom/image/42699654.jpg
Finally, we test the 85/1.8 at f/4. Here, you can see the outline of the aperture blades, since the lens is stopped down a ways, but the out-of-focus circles have no harsh ring around their circumferance. They blend nicely, again providing a smooth mix.
http://www.pbase.com/photosbytom/image/42699655.jpg
Once again, the prime appears to have the potential of having the smoothest bokeh, followed closely by the "L" zoom. The relatively inexpensive consumer zoom places back a ways, though it certainly wasn't designed with bokeh as its primary characteristic.
Here's a couple more images at f/2.8, first with the 70-200 L:
http://www.pbase.com/photosbytom/image/42699656.jpg
And the 85 prime:
http://www.pbase.com/photosbytom/image/42699657.jpg
Both images at f/2.8 again show the value of larger apertures. The OOF circles in both cases are larger and more diffuse, with an even less sharp defining border.
Finally, here's the odd shot - the 28-105 at f/5.6:
http://www.pbase.com/photosbytom/image/42699658.jpg
The good news is that stopped down a bit, the harsh bright rings are much less prominent on the out-of-focus circles. The bad news is that at f/5.6, the background in most cases will not be sufficiently blurred. It can be used, but only when the background is sufficiently far from the subject to allow the smaller OOF disks to blend.
OK, that's enough for now. Time to put a dent in that Chivas bottle that I've been staring at for the last hour. :)
The lenses I used were the 85 mm f/1.8, the 70-200 f/2.8 IS, and the 28-105 f/3.5-4.5. Lighting was a combination of overhead general lighting, two diffused clamp lights, one direct reflector clamp light, and overcast outdoor light directed at the subject with vertical blinds.
The tests were done at f/4, with the exception of the 28-105 which was tested at f/4.5 due to maximum aperture limitations. Once again, the test is merely to get a good look at how the diffused OOF circles are rendered, as that has a relationship to the smoothness of the bokeh.
First, the test setup, taken with the 85mm at f/2:
http://www.pbase.com/photosbytom/image/42699652.jpg
Now the lenses - first, the durable 28-105, shot wide open at f/4.5:
http://www.pbase.com/photosbytom/image/42699653.jpg
Note the hard, bright ring at the periphery of each OOF circle. This contributes to choppy bokeh. Of course, this lens wasn't bought for its great bokeh. That's generally the territory for faster lenses anyway. Later, I'll post an image of how this lens performs at f/5.6.
The next lens is the 70-200 f/2.8 IS zoom, tested again at f/4 and 85 mm. I had to move things back a bit with this lens, since the close focus distance isn't as tight as it is on the other two lenses (this is at the shorter end of this lenses' zoom range). Anyway, note that the bokeh is considerably smoother than the consumer zoom. There is a very slight bright ring on some of the OOF circles, but it is much less noticeable compared to the 28-105. The boundaries are still well-defined (well, it is f/4) but blending is much smoother.
http://www.pbase.com/photosbytom/image/42699654.jpg
Finally, we test the 85/1.8 at f/4. Here, you can see the outline of the aperture blades, since the lens is stopped down a ways, but the out-of-focus circles have no harsh ring around their circumferance. They blend nicely, again providing a smooth mix.
http://www.pbase.com/photosbytom/image/42699655.jpg
Once again, the prime appears to have the potential of having the smoothest bokeh, followed closely by the "L" zoom. The relatively inexpensive consumer zoom places back a ways, though it certainly wasn't designed with bokeh as its primary characteristic.
Here's a couple more images at f/2.8, first with the 70-200 L:
http://www.pbase.com/photosbytom/image/42699656.jpg
And the 85 prime:
http://www.pbase.com/photosbytom/image/42699657.jpg
Both images at f/2.8 again show the value of larger apertures. The OOF circles in both cases are larger and more diffuse, with an even less sharp defining border.
Finally, here's the odd shot - the 28-105 at f/5.6:
http://www.pbase.com/photosbytom/image/42699658.jpg
The good news is that stopped down a bit, the harsh bright rings are much less prominent on the out-of-focus circles. The bad news is that at f/5.6, the background in most cases will not be sufficiently blurred. It can be used, but only when the background is sufficiently far from the subject to allow the smaller OOF disks to blend.
OK, that's enough for now. Time to put a dent in that Chivas bottle that I've been staring at for the last hour. :)