Question about Bokeh and Lenses

G

greytail

Well-known member
Can someone inform me please about bokeh. I just read that a full frame sensor and lens system like the Canon 5D Mkiii equipped with an 85mm portrait lens can make better bokeh than a 45mm Olympus lens attached to an AF100. This is because the full frame sensor and the big lens do a better job of it. But, what happens if you take a Canon 50 mm lens or perhaps the same Canon 85mm lens and stick it on the AF100 with a decent adapter like the Redrock Micro Live Lens? Do you get the same effect as from the Canon? Or, can the AF100 never achieve the same effect no matter what lens you use because micro two thirds just can't do the same thing?

Sorry if this sounds a bit ignorant but I am trying to understand what lenses I need to use to achieve the same effect as those Canon 24-70mm and 85mm and Zeiss 85mm.

Thanks in advance

Greytail
 
Putting stuff out of focus and having pleasing bokeh are not the same thing. Large sensors do have shallower focus depth, simple physics... well, somewhat simple. Bokeh isn't quantifiable, and has to do with a series of lens characteristics that affect the shape and gradation of out of focus areas.
 
You're right, though, that the size of the circles of confusion in your field of view will be proportional to the size of the sensor. It's also proportional to the focus distance and focal length, so if you want large bokeh on a small sensor, you need to compensate by reducing your focus distance and increasing your focal length.
 
greytail said:
Can someone inform me please about bokeh. I just read that a full frame sensor and lens system like the Canon 5D Mkiii equipped with an 85mm portrait lens can make better bokeh than a 45mm Olympus lens attached to an AF100. This is because the full frame sensor and the big lens do a better job of it. But, what happens if you take a Canon 50 mm lens or perhaps the same Canon 85mm lens and stick it on the AF100 with a decent adapter like the Redrock Micro Live Lens? Do you get the same effect as from the Canon? Or, can the AF100 never achieve the same effect no matter what lens you use because micro two thirds just can't do the same thing?

Sorry if this sounds a bit ignorant but I am trying to understand what lenses I need to use to achieve the same effect as those Canon 24-70mm and 85mm and Zeiss 85mm.

Thanks in advance

Greytail
Click to expand...

I mostly agree with mcbob - all thing being equal, the larger the sensor or film stock, the more shallow the depth of field. The quality or look of that out of focus part of the frame is bokeh. Often times you'll hear bokeh described as "sharp" or "creamy" which is due in some part to the amount of blades used to control the F stop, and of course the quality of the glass.

As far as how to get shallow DoF on smaller chip cameras, the answer is usually a combination of lots of light and/or a fast lens. The more light/faster the lens, the easier it is to achieve. ND filters are often used so shooters don't need to stop down - which in turn means the DoF stays shallow. If you stop down, the DoF increases. In other words, you could use the lenses listed above, but you might need more light.

Reality is though, the sensor size/film stock size does box a shooter in to a degree one way or the other. A lot of people have tried to shoot features w/ a Mark II, only to realize what an insane nightmare pulling focus is. For me, S35 is the sweet spot.
 
So, based on this are lenses like the new Olympus 75mm f1.8 and the 45mm f1.8 along with the Voightlanders 25mm and 14mm the way to go?

What about the Canon 50mm f1.2mm with an adapter?

Are there any others to consider?
 
MFT's 2x crop factor means you need a lens 2 stops faster to achieve equivalent focus depth, and half the focal length to yield the same field of view as a full-frame sensor... Thus "matching" the look of a wide open 24-70/2.8 and 85/1.2 mounted on full frame would require a 12-35/f1.4 and 42.5/f0.7 lens. About the best fast/wide lens currently available for m43 is the Voigtlander 17.5/0.95, which yields a looks somewhat like a full-frame camera with a 35/2 lens.

if you want a full-frame look, just use a full frame body. If you only need pleasing bokeh, figure out what you like and find lenses that deliver it.
 
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greytail said:
So, based on this are lenses like the new Olympus 75mm f1.8 and the 45mm f1.8 along with the Voightlanders 25mm and 14mm the way to go?

What about the Canon 50mm f1.2mm with an adapter?

Are there any others to consider?
Click to expand...

What exactly are you shooting?
 
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