what does this mean for bokeh?

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lorriman

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I was thinking of getting a 28mm f2 lens. However the one I found goes to infinity just after 3m, whereas there are other 28mm lenses with smaller apertures that go to infinity at 7m plus.

As it happens part of the reason I want that 28/2 is for bokeh. But with this focusing characteristic I fear that I'm not going to get as much as if I had one of those other smaller aperture lenses (which I can get for less money to boot).

Any opinions on this matter?
 
With a 28mm you won't see much bokeh effect after 3meters even at wide open.
If your looking for that blurry isolated effect a 28mm lens is not the best choice.
You can get it close in but then have perspective distortion to contend with.
 
Surely this is just a difference in the way the manufacturer has marked the lens ?

Any wide angle lens of 28mm is going to have a larger Depth of Field than a longer lens. If shallow depth of field is something you are looking for a 50mm may be a better bet.

The Depth of field on a lens is the result of mathematical calculations and would be same on all 28mm lenses regardless of what the manufacturer has marked on the focusing scale. The Bokeh of a lens is merely a way of describing how the out of focus parts of a shallow depth of field shot appear.

Chris
 
dof-calculator

dof-calculator

Good answers to your question by the previous posters.
It can be very enlightening to play around with this: http://www.dofmaster.com/dofjs.html

There are a number of pictures with 28mm in the f2 to f2.8 range (close in) here at RFF and on flickr that show that subject "isolation" can be done with a 28mm. I agree with the previous posters that subject isolation is not the primary forte of a 28mm lens... but it can be done and I have seen striking images that way. So, to answer your question: yes, if you want to maximize the possibility of throwing off-subject-parts of a scene out of focus with a 28mm, you should go for a f2 lens.
Now, what Juan says: if you can swing it, and if 35mm speaks to you, the 35mm f1.2 has the reputation of being a bokeh machine among wideangles ;-)
 
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Thanks for the answers.

I had understood that the exit pupil has an affect on dof, irrespective of the focal-length/aperture. And so there might be a possibility of a lens design - in this case of the quick-to-infinity lens - that for the bokeh person such as myself would be even less desirable especially where bokeh is already not so easy to obtain.

As for 28mm and bokeh: I'm not looking for whacking amounts of bokeh which I can get from my f1.2 lens if I really need it. I prefer smaller aperture bokeh, and from the pics I've seen there's enough at 28mm even at f2.8 for my purposes of contextual/environmental portraits. At the same time I've been looking for a lens to get a normal perspective on my brother's DSLR, when I have a need to shoot digital. 28mm is just the ticket for that.
 
hans voralberg said:
I think it's a matter of short or long focus throw, that's all. At the same aperture and the same distance the background will be similarly OOF, regardless of the lens marking should it not?
Click to expand...

That's my hope. Because of the little known effect of exit pupil on dof I had thought to ask since perhaps it isn't. The consensus so far reflects your words.
 
What does this have to do with bokeh?

Very, very little.

Bokeh is the quality of the out of focus image, NOT just the quality of the grossly out of focus image at full aperture.

Different lenses render the o-o-f image differently.

For a given focal length at a given distance, this depends solely on aperture and lens design. Lens designers do not design for bokeh -- they have more sense -- so the only way to check for 'bokeh' (with a given subject) is by experiment.

Cheers,

R.
 
There is the Nikon 28/1.4 that is pretty nice except they've doubled in price over the past four years.

The amount and location the out-of-focus area at a given focal point is going to be the same for any brand/type of lens of the same focal length at a set aperture, no matter what format size.

The quality of the out-of-focus area will depend on the lens design and the price paid for the lens. If you spend enough money then of course it has wonderful bokeh!
 
If focus close & at full aperture, even a 21mm can have very shallow DOF: cheers!
Olympus Zuiko21mmf2 @f2 on M8 with Novoflex adapter:
3019815060_c25576deaa.jpg
 


Taken with Nikkor 28 1.4 AF D on Nikon D3

I think that it's possible to get significant bokeh with a 28 wide angle. I personally like the look. I just bought a 28 1.9 Voigtlander and have some samples posted in that section, just nothing that fits the poster question, which is why I posted this particular photo as an example.



Taken with a Leica M7 and a Voigtlander 28 1.9 @ F1.9 on Ektar 100

Gregory
 
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