Portrait lens help?

[sarahr_7]

I'm looking for a portrait lens (I know there is no "specific" lens that is for portraits only but just one that will be good). I am looking to do all types of portrait work (head, full body, etc)

I currently have a Canon 70D & Canon 50mm 1.8

I was really interested in the Canon 135 f/2 but I'm afraid it'll be too long on my cropped body, any opinions? I also like the 85mm 1.2 or the 70-200mm 2.8 but I just don't know! I'm trying to spend under $1000 on a used lens. ANy sugestions or advice would be much appreciated! 🙂

Attached are some photos I've done with my nifty-fifty:

[diverhank]

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@kvbarkley wrote:

Wouldn't this mean that every lens shot wide open would have the same Bokeh? As far as I know, this is not the case.

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The shape of the aperture opening will dictate the bokeh quality (you can tell from light sources which looks like round circles) - the more blades usually approximate the perfect circles better than less blades but even with the same number of blades, some look more circular than others.

The old 50/1.8 only has 5 blades and its bokeh was often criticized.  The new 50/1.8 STM has 7 blades.  The 85/1.8, 85/1.2 and 70-200 all have 8 blades.

[kvbarkley]

So I will say it again, when you shoot wide open - when the blades are completely out of the way - should all lenses have the same bokeh. I am not-so-subtly hinting that bokeh is more than aperture blades.

[diverhank]

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@kvbarkley wrote:

So I will say it again, when you shoot wide open - when the blades are completely out of the way - should all lenses have the same bokeh. I am not-so-subtly hinting that bokeh is more than aperture blades.

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Even at wide open, the blade opening and its shape is still there. This is true with the old FD lenses. I haven't played with the modern lenses I own out of fear of breaking them.  

And I agree blades are just one factor but it's the one that makes the most difference...I don't really know much about bokeh and the technical workings of it but I'd imagine lens diameter and sensor size play a part also.

[ScottyP]

Bokeh is a loosely defined (and imperfectly translated) Japanese word roughly meaning blur.

There is a quantitative aspect: more blur is better than less.  Quantity of bokeh is affected by focal length of the lens. More background blur is produced by longer lenses, less blur from wider angle lenses. 

There is a qualitative aspect:  yes, aperture blade number and shape matter, but so too do all the pieces of glass in the camera, their arrangement, and coatings. People use descriptions like creamy bokeh vs nervous bokeh. The bokeh balls you get from OOF highlights may have onion-like concentric circles in them, or there may be a dark outline around the balls, both of which are considered to be lower quality bokeh. 

[Waddizzle]

"If on the other hand you are confusing bokeh, as lots of folks do, with 'out-of-focus' (OOF) background, it is an entirely different thing.  Large apertures are really needed for OOF backgrounds..  The aperture blade shape has little to do with OOF backgrounds."

Is that shot OOF or bokeh?  At the time, I thought of the background as simply being OOF, because it was well past the DOF.  The fog says this was ~400mm [Sigma 150-500mm] f/8, and the bird was about 50-80 feet away.  The background rocks were another 50 feet away, and then more another 50 feet away..  The fog says the shot is cropped at 50%, too, just to remove other birds on  the same set of rocks.

[ebiggs1]

Bokeh is actually diffraction patterns. Bokeh is the blurred area of over-lapping circular rays of light. The bokeh takes the shape of the lens aperture of the diaphragm. If the aperture is a perfect circle, then overlapping images blend beautifully and backgrounds look smooth.  If you don't have the correct diaphragm, you will not get good or quality bokeh.  That is why bokeh is mostly dependent on the aperture and diaphragm. Of course a wide angel lens and the smaller the f-stop the less likely you will get good bokeh.  Or whether you will get it at all.

Bokeh's main factor is the diaphragm and aperture. That's it!

[ebiggs1]

"Is that shot OOF or bokeh?"

It is OOF.  Bokeh really needs strong points of light to be super dramatic but it can happen with less.

[ScottyP]

Found this little summary of bokeh and the multiple things in a lens that make it good or bad. I think the "Nissen bokeh" is what American reviewers call "nervous bokeh" but not sure.  In addition to aperture blade roundness, which is irrelevant when shooting wide open, and focal length there are issues with the mold making for molded aspherical elements, etc. 

Interestkng little read. 

http://toothwalker.org/optics/bokeh.html

[ebiggs1]

"Interestkng little read"

Maybe so but a long web site article doesn't indicate he is 100% correct.  Try to get good bokeh with any lens that has improperly shaped aperture blades. You can't do it.

[ScottyP]

Blocky blades or too few blades vs. 8 or 9 curved blades will mess up bokeh for sure, except if you are shooting wide open when it doesn't matter because the blades are fully retracted and not in the shot.  My old nifty fifty with the 5 flat blades made ugly distracting pentagons out of all the bokeh balls but wide open they were at least nice and round.  Not necessarily great bokeh, but perfectly round. 

Of of course you can't shoot wide open all the time. Can be too bright in the daylight even at max shutter speed, and way too little depth of field for a lot of shots.