Beginner aperture and bokeh question

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lionofjudah

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I am looking to shoot distant objects e.g wildlife, which will be at least 2m away from background. I am thinking of a focal length of say 200mm. say my current lens at that focal length can give me widest aperture of 5.6 - how good a bokeh can it achieve?
I am trying to justify purchasing a f2.8 zoom lens and thinking do I really need it if lighting is good enough for a good exposure, and main consideration is bokeh - will a smaller aperture give me a good enough bokeh for the distant object.
 
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Everything in the kitchen would be much simpler if the cook knew to the milligram
what the diners will need; no shortage and no leftovers! It is pretty much the same
thing in photography: nor the cook nor you knows what's coming next. It is always
better to have too much than not enough. If your can afford a ƒ2.8, go for it!

Bokeh is more directly "distance to background" dependant than aperture dependent.
In French we say It is aperture consequent and "distance to background" dependant
and the choice of words is important. So the wider aperture gives you more options!

The choice of lenses has also a role to play here since the longer the lens the shallower
the DoF (and greater the eventual bokeh).
 
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!++++++--mi,df
012,4
1++
VU7
 
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lionofjudah said:
I am trying to justify purchasing a f2.8 zoom lens and thinking do I really need it if lighting is good enough for a good exposure, and main consideration is bokeh - will a smaller aperture give me a good enough bokeh for the distant object.
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Bokeh is qualitative, not quantitative - you can't measure it, only judge it for yourself. There's more than aperture to consider - everything contributes to how the out-of-of focus areas will look:
  • Lens design
  • Lens coating
  • Position of light relative to the bore-sight of the lens
  • Quantity and quality of light
  • Distance to subject
  • Distance to background
  • Texture/luminous porosity of the background
  • Aperture
What do you consider to be "good bokeh"? - if you don't know you can't answer the question you've posed at the start of the thread...
(and it may be very different to what I or anyone else considers good bokeh)
 
chuckles said:
I knew it - you're a spy!
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Sorry folks…
someone entered my office armed with a heavy cloth with the determined will
to clean up my table top and my keyboard before I finished my text!
… communists!
 
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As mentioned quality of bokeh is down to lens construction not aperture, and bokeh is the quality of the out of focus area and not just the out of focus area. Aperture controls depth of field or how much is in focus.

f2.8 will give you more out of focus area/shallower depth of field than f5.6 and f2.8 telephotos do tend to have nice bokeh.

I'm slightly confused saying that you're planning on shooting far away objects with a 200mm though as 200mm isn't very long, even on a crop body.
 
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snerkler said:
As mentioned quality of bokeh is down to lens construction not aperture, and bokeh is the quality of the out of focus area and not just the out of focus area. Aperture controls depth of field or how much is in focus.

f2.8 will give you more out of focus area/shallower depth of field than f5.6 and f2.8 telephotos do tend to have nice bokeh.

I'm slightly confused saying that you're planning on shooting far away objects with a 200mm though as 200mm isn't very long, even on a crop body.
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Maybe he's taking pics of elephants...

I agree, 200 is not particularly big. It's good enough for head and shoulder shots at about 5m with a crop body.
 
snerkler said:
As mentioned quality of bokeh is down to lens construction not aperture, and bokeh is the quality of the out of focus area and not just the out of focus area. Aperture controls depth of field or how much is in focus.
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• everything about an image is down to lens construction
• the aperture determine the DoF (sharpness in not to be found here!)
• quality of bokeh is determined the addition of 3 factors:
— the distance behind to the subject ratio to subject /lens
— the aperture and the consequent DoF
— more importantly by the number of blades (min. 9!) of the diaphragm.​
snerkler said:
f2.8 will give you more out of focus area/shallower depth of field than f5.6 and f2.8 telephotos do tend to have nice bokeh.
Click to expand...
NO! All lens will produce fine bokeh if more of the previous 3 factors are added.
Longer lens do tend to have a shallower DoF.
snerkler said:
I'm slightly confused saying that you're planning on shooting far away objects with a 200mm though as 200mm isn't very long, even on a crop body.
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200mm may be ok to shoot a mountain across the valley but one has to be darn
close for birdies!
 
Kodiak Qc said:
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NO! All lens will produce fine bokeh if more of the previous 3 factors are added.
Longer lens do tend to have a shallower DoF.
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I didn't mean that they had nice bokeh just because they're 200mm, f2.8 telephotos are generally at the upper end of quality (and price) and lens construction and so on the whole produce very pleasing bokeh.

There are more factors to nice bokeh other than those you mentioned. My Tamron has 9 blades but bokeh is not as nice as my Nikon with 9 blades if I set all other variables the same (FL, aperture and distance to subject and background).
 
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Kodiak Qc said:
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And they are…
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Mainly how a lens corrects aberration, particularly spherical aberration. Apparently those that poorly correct spherical aberration show a better smoother more 'creamy' bokeh. Aperture shape also affects the bokeh.
 
There's a ring you can turn on DC Nikkors (85 & 135) :)
 
snerkler said:
… Apparently those that poorly correct spherical aberration show a better smoother more 'creamy' bokeh. Aperture shape also affects the bokeh.
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Do you mean chromatic aberrations?
 
We had a discussion elsewhere on here recently about focusing and maximum lens aperture. The outcome was that you will get more accurate focussing with a wider aperture so that might be a reason for buying an f2.8
 
chuckles said:
There's a ring you can turn on DC Nikkors (85 & 135) :)
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I think you might have miss typed unless you know of a new DC :) 105mm f2.0 DC and 135mm f2.0 DC are the only DC I know of.
I still have the 135mm but my friend persuaded me to sell him the 105 DC :(
I would love to see th DC lenses updated not that there is anything wrong with the current ones:)
 
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Lots of good advice here once again it always pays to ask:)
just remember what ever lens you have fitted the closer you are to the subject and the MFD with the widest aperture set you will achieve the minimum dof which will throw you background out of focus.
But Bokeh is about how the out of focus areas and highlights are portrayed :)
 
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Another excellent lens though Chuckles the 85mm :) Now a 85mm with DC would be something a bit special i bet ;)
 
Phiggys said:
Another excellent lens though Chuckles the 85mm :) Now a 85mm with DC would be something a bit special i bet ;)
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Yes, indeed. Maybe I made one of those Freudian slippy things and not a typo!
 
Like others have said bokeh is depenadant on distance as well as a small aperture. You need to be close to a subject and have good distance from the subject to the background. One thing to remember is your depth of field has to be of sufficient size to capture the subject sharp. Long focal lengths also help with wildlife to isolate a subject but it comes at the price of a smaller depth of field.
 
Thanks for answers. It was just a general question. Was thinking of investing in a 70-200 f2.8 lens but not sure what I really want it for hence posed the question. I suppose I need to go read up more about background blur etc and then try with current lenses to learn my limitations first.
 
lionofjudah said:
Thanks for answers. It was just a general question. Was thinking of investing in a 70-200 f2.8 lens but not sure what I really want it for hence posed the question. I suppose I need to go read up more about background blur etc and then try with current lenses to learn my limitations first.
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A 70-200mm f2.8 is a lot of money to shell out and so would recommend you certainly think about what you'd use it for and how much you'd use it.

It got a bit technical above but to summarise in simple terms wider aperture will give you more 'blur'/out of focus area, lens construction (amongst other things) will influence how the blurred areas will look.
 
Alastair said:
Bokeh is qualitative, not quantitative - you can't measure it, only judge it for yourself. There's more than aperture to consider - everything contributes to how the out-of-of focus areas will look:
  • Lens design
  • Lens coating
  • Position of light relative to the bore-sight of the lens
  • Quantity and quality of light
  • Distance to subject
  • Distance to background
  • Texture/luminous porosity of the background
  • Aperture
What do you consider to be "good bokeh"? - if you don't know you can't answer the question you've posed at the start of the thread...
(and it may be very different to what I or anyone else considers good bokeh)
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Good list - I'd only add one other thing : the number of iris blades forming the lens aperture. 6 is the minimum acceptable but 8 or over is far better and will form superior 'bokeh rings' (is that what they're called?)
 
I'd consider aperture blades a part of "lens design" - and the shape of the blades is as important as the number. As few as five blades with a rounded shape can match the bokeh of a 19 bladed "bokeh monster" when shot wide open. Although a higher number of blades gives better bokeh at a wider range of apertures - purely because they provide a rounder aperture.
 
Alastair said:
I'd consider aperture blades a part of "lens design" - and the shape of the blades is as important as the number. As few as five blades with a rounded shape can match the bokeh of a 19 bladed "bokeh monster" when shot wide open. Although a higher number of blades gives better bokeh at a wider range of apertures - purely because they provide a rounder aperture.
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A waterman stop will give better bokeh still , and it is just a hole in a thin shim of metal. It is purely down to the shape of the aperture not the number of blades to achieve it. That and plenty of and nicely controlled spherical aberration .
 
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