Most big bokeh between these lenses...

Biggest bokeh I should say... What would give me the most blur on a full body (head to toes with a fair margin) shot
between a 85mm f1.4, 135 f2 and 200mm f2.8?

I was going to get the 135L as my next lens but when I was on crop, I always wanted something longer than the 85mm. That mean I should go for the 200mm on FF because the 135 is the same as the 85mm on crop.

For faraway candid in low light, like this one:
85mm f1.8 - t3i

IMAGE LINK: http://www.flickr.com …/24246728@N05/8​261004298/

You will generate more background blur in general by using longer lenses from greater distances, even when the longer lenses are a bit slower. In the specific case requested here, the three lenses all wide open will probably create a similar degree of background blur owing to the speed of the shorter lenses, but the actual differences will depend a lot on how far back the background is.

As a side note, the word 'bokeh' refers to the aesthetic quality of the blur region. If you want to ask about the 'most blur', then just go ahead and use the existing English word "blur". "Blur" is a perfectly serviceable word that is widely understood.

I use the 85 1.4 most frequently for full body shots. It really makes some excellent subject "pop" and beautiful bokeh. I liked its effect more than I liked the 135L for full body shots. It's also a much more workable focal length.

Thanks drzenitram for the exemple. Very convincing.

On this link you can see that the 85mm f1.4 (nikon) produce more blur than the 135f2.
http://beingelvish.mul​tiply.com/reviews/item​/9

As for the focal lenght;

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Amount of Blur ∝ Diameter of Aperture

• 85mm/ f1.4 = 60.7
  
• 135/ f2 = 70
  
• 200mm/ f2.8 = 71.4
  

• 85mm/ f4 = 21.5
  
• 135/ f4 = 33.7
  
• 200mm/ f4 = 50
  

Wilt, that's a great comparison!

I can't help but notice how much nicer the blur is on the image to the right. The "quality" of the blur is simply smoother and more aesthetically appealing, whereas the blurred area on the image to the left is somewhat "choppy"..

By the way, what lenses did you use to take these images? I saw that you mentioned 3 prime lenses earlier in your post, the 85, 135, and 200mm. And then you said what focal lengths they were taken at, 116mm and 193mm - so I am assuming zooms of some sort? Anyway, I just didn't see any mention of what lenses were used, and I am curious to know what they were.

Wilt, I've seen you(or someone) post that comparison before, but I just didn't have the same real world results between an 85 1.4 and a 135L. The 85 showed more blur in my experience, just like in the link earwax posted above. I don't know how that is explained, but in real world use that's what I gathered.

In fact, in real life scenarios I thought the 85 1.4 had the MOST blur of those 3 @ f1.4, the 135L had the second most @ f2, and 200mm @ f2.8 had the least blur.

Tom Reichner wrote in post #15423745
Wilt, that's a great comparison!

I can't help but notice how much nicer the blur is on the image to the right. The "quality" of the blur is simply smoother and more aesthetically appealing, whereas the blurred area on the image to the left is somewhat "choppy"..

By the way, what lenses did you use to take these images? I saw that you mentioned 3 prime lenses earlier in your post, the 85, 135, and 200mm. And then you said what focal lengths they were taken at, 116mm and 193mm - so I am assuming zooms of some sort? Anyway, I just didn't see any mention of what lenses were used, and I am curious to know what they were.

Both shots were made with the same lens....70-200mm f/4 L IS

It is commonly discussed that bokeh 'wide open' can be considerably different than when 'stopped down'. In this case, the aperture was wide open for one shot, and partially 'stopped down' for the other.

drzenitram wrote in post #15423811
Wilt, I've seen you(or someone) post that comparison before, but I just didn't have the same real world results between an 85 1.4 and a 135L. The 85 showed more blur in my experience, just like in the link earwax posted above. I don't know how that is explained, but in real world use that's what I gathered.

In fact, in real life scenarios I thought the 85 1.4 had the MOST blur of those 3 @ f1.4, the 135L had the second most @ f2, and 200mm @ f2.8 had the least blur.

If both lenses are used at same f/stop, most would say that the longer FL gives 'more blur', even ignoring the affect (or not) of aperture diameter.

Atkins has this article
http://www.bobatkins.c​om …okeh_background​_blur.html

which might explain your observation, which states,
"If the background is far enough away (well outside the depth of field) and the subject if fairly close (well inside the hyperfocal distance) the degree of blurring is related to the absolute physical size of the lens aperture. For a 56mm f5.6 lens that would be 10mm and for an 85mm f5.6 lens it would be 85/5.6 = 15mm. So you'd expect the far distant background blur of the 85/5.6 to be about 50% more than that of the 56/5.6, and, in fact, it is!

"Based on this you can see why a 600/4 lens wide open (physical aperture = 150mm) will blur the far distant background far more than a wide open 50/1.4 lens (physical aperture = 35.7mm). In fact it will blur it 4.2x more. "However if shooting the same subject at the same magnification (let's say 0.01x, which would by typical for a full body shot of a person), the depth of field of the 50/1.4 will be about 1/3 of that of the 600/4 and so will blur close in objects more.

"There's no really simple 'rule of thumb' that will tell you whether relative aperture (f-stop) or absolute aperture (size of the aperture in mm) will be most important in determining the degree of blurring at a given distance behind (or in front of) a particular focus point. Hence the need for this calculator!"

I would jump to no conclusion based on the image that Earwax69 posted, since there is no second image to compare against. And I would also jump to no conclusion based upon the pair of images which you posted, as the distances between primary subject and 'backround' object are not identical ...not a true 'comparison' either.

I see, that's interesting. How does that mathematics explain for the fact that a wider aperture DOES make more blur?(200mm @ f5.6 vs 200mm @ f2.8).


Maybe it's just referring to a different kind of blur. For example, what I see that I constitute as "blur"(that a portrait photographer frequently seeks afer) is the amount that a subject is separated from the background by making the subject sharp and in focus and the rest of the background melted into out of focus areas full of blur. The smoother the background, the more "blur" in my opinion. I guess what I'm describing is simply a narrow depth of field.

In that case, for example, an 85mm lens would need to be shot(on FF) from 19 feet away to frame 8' in height when shot in portrait orientation(full body shot). 85mm @ f1.4 from 19 ft away results in 1.27ft depth of field.

a 135mm lens would need to be 30 ft away to frame 8' in height. 135mm @ f2 from 30 ft away results in 1.78ft depth of field.

A 200mm lens would need to be 44.5ft away to frame 8' in height. 200mm @ f2.8 from 44.5ft away results in 2.53ft depth of field.

So, I guess that by the way I measure blur, the order is 85 1.4 > 135 f2 > 200 f2.8.

edit:
I will add that even though I love the 85 1.4 for it's full body "pop", I wanted a 200 f2.8 ALSO because the compression makes for a completely different and also desirable look.

DOF size is not inherently linked to 'amount of background blur'.

For example, you can shoot 100mm f/2.8 and 200mm f/2.8, one at 15' and the other at 30' so that your primarily subject is identically sized in the frame for both shots and the DOF is virtually identical at 0.949' deep, but the 200mm f/2.8 will make a blurrier distant background in spite of the identical DOF for the two shots.

A 2010 Zeiss paper Depth of Field and Bokeh states, "...the maximum blurriness of the distant background differs. It is lower for shorter FL than for longer FL."
Later in the same article it states, "Another comparison in 35 mm format with a larger range of focal lengths but each with the same reproduction scale of the main subject: while the influence of aperture clearly dominates at very small levels of blurriness on the left and determines the order of the curves, in the far distant background the influence of focal length predominates. If the subject is to be truly separated from the background, one ideally needs both – a longer focal length and a high speed lens."
Later it states, "The decisive parameter for the quantity of the blurriness is therefore the physical size of the entrance pupil. If by 'bokeh’ you mean principally the ability to be able to represent the background as very blurred, soft and lacking detail, it is necessary to have an entrance pupil which is sufficiently large. A large photo format, a high aperture lens and longer focal lengths have the best potential in this direction."

I hear that, but if the DOF is narrower, that changes things. Maybe it's only a perceived amount of subject separation, but I perceive it every time.

I think we're using a different calculator, too, mine shows 100 f2.8 @ 15ft to be 1.14ft depth of field?

Wilt wrote in post #15423880
DOF size is not inherently linked to 'amount of background blur'.

For example, you can shoot 100mm f/2.8 and 200mm f/2.8, one at 15' and the other at 30' so that your primarily subject is identically sized in the frame for both shots and the DOF is virtually identical at 0.949' deep, but the 200mm f/2.8 will make a blurrier distant background in spite of the identical DOF for the two shots.

This is worth noting. DOF and blur are not 1:1 linked when comparing different focal lengths.

Here is a quick example I shot a long time ago. This compared a 200/2.8 shot to a 50/1.2 shot, with the camera moved for similar framing.

So note that the background blur is about the same in these two shots, but the 200mm shot has much, much greater DOF.

And just to see what happens with the DOF being the same, here is the 50mm shot at f/2.8 for equal DOF. The 200mm shot with the same DOF obviously also has much greater blur.

Here's my own comparison that I just made:

85 @ 1.4: