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Deleted member 7828
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Well, I suppose it depends on the shooter, but the variable aperture is what kills it for me. I read a review on it and I think it said by the time you get to 50mm you're already at f5.6. No thanks...I'm willing to give up the wide end for more reach, a constant 4.0 aperture and IS which I think is a decent compromise that makes it a good travel/walkaround lens.
Also nice to have better image quality, a sturdier product and higher resale value. But by all means, the 15-85 sounds like a fine lens- for those that demand it.
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Cornershot
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For me the choice is simple. It isn't so much about which has better bokeh, though that's a nice thing to have. It's about light gathering and low light performance. The 24-70 will have much better low light focusing and better capability in darker scenarios. The focus on the 24-105 will hunt more in low light and require higher ISO, hence noise.
In bright daylight, I'd go for the 24-105 because it probably is as good and offers more flexibility. The 24-70 isn't the end all. My 16-35 and 70-200 will out shoot the 24-70. Oh, how I love those two former lenses. But the 24-70 is the only viable all condition choice in that zoom range and with that aperture.
In bright daylight, I'd go for the 24-105 because it probably is as good and offers more flexibility. The 24-70 isn't the end all. My 16-35 and 70-200 will out shoot the 24-70. Oh, how I love those two former lenses. But the 24-70 is the only viable all condition choice in that zoom range and with that aperture.
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Loswr
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zerotiu said:
So, are you talking about bokeh or not? Technically, there are two aspects to the out of focus blur you're talking about. One is quantity - how much OOF blur. That's a function of depth of field, which is determined by:
[list type=decimal]
[*]aperture
[*]focal length
[*]subject distance
[*]circle of confusion (i.e. sensor size)
[/list]
In practice, aperture is the primary determinant, since everything else gets normalized for by shot framing (e.g., if you want to take a tightly-framed head shot, you can frame it with a 135mm lens at 5' or an 85mm lens at 3' on FF, or an 85mm lens at 5' on APS-C, etc., but in all cases you're changing focal length, subject distance, and/or sensor size to compensate for the necessary framing, leaving aperture as the only independent variable).
Depth of field determines the quantity of the OOF blur - thinner DoF (wider aperture) means more OOF blur. So, if that's what you mean by 'how good is the background can be blurred when I shoot my object /subject', the 24-70/2.8 will deliver more OOF blur than the 24-105/4, for the same subject.
The other aspect is the quality of that OOF blur, and that's what 'bokeh' means. Is the OOF blur 'smooth' or 'jittery'? Are specular highlights round, and if so, are they uniform discs, or dimmer at the edges? Is the bokeh 'pleasing' or 'nervous'? Lots of subjective terms there, because in essence, bokeh is subjective.
One easy way to evaluate bokeh is if there are specular highlights in the OOF area (there's more to bokeh than how the highlights are affected, but they're an easy way to judge). That's probably the reason Flake previously responses that the image posted by YoukY63 had no bokeh (it does, but there aren't any specular highlights in the OOF-blurred area).
So, the bottom line is that the 24-70 will produce more OOF blur than the 24-105, and both lenses have similarly good (but not great) bokeh.
zerotiu said:
Getting the 24-105 means with f/4, you may have to work a little harder to ensure adequate physical separation between your subject and the background. At the other end of the spectrum, my 85mm f/1.2L II can blur out a background that's literally just behind the subject (e.g. a head resting on a pillow, the pillow is OOF) - but the trade off is you have to work to get both eyes in focus...
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As always I agree with Neuro's analysis however yes, the 24-70 will give MORE, no much, but more OOF than the 24-105. In a typical portrait, in practice an F4 will typically get most of the face if not all in focus... 2.8 you may get the nearest eye in focus with the second eye slightly OOF. Wider you go the more OOF you get. I think the original poster realizes if he wants and fully cares about bokeh, he wants and will need to get into fast primes... Also rememeber F4 to F2.8 is 1 stop, but on the same hand, it's only 1 stop. Will the 24-105 give you pleasing OOF WHEN you shoot in a situation to get good OOF? yes. I would even go as far as saying when applicable, the OOF area is as pleasing as the 24-70 when shot in situations where the OOF areas are similar. This once again falls into the situation of knowing what equipment you are using and being comfortable with your equipment when you need to. I would still recommend going to a camera store and testing the lenses out there... As long as the store is under the impression they're going to make a sale, i'm sure they will allow you as much time with the equipment as possible until you make your mind up. Then go home and buy online for cheaper, haha. 
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Flake
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Sorry Neuro but focal length does not affect DoF it's yet another myth which has been perpetuated, nor does subject distance.
http://www.luminous-landscape.com/tutorials/dof2.shtml
Magnification affects DoF which is why Macro has such a thin DoF & aperture, circles of confusion are not really anything to do with the sensor size, again that comes down to magnification, you need more to fill the frame on a FF camera.
In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot.
http://www.luminous-landscape.com/tutorials/dof2.shtml
Magnification affects DoF which is why Macro has such a thin DoF & aperture, circles of confusion are not really anything to do with the sensor size, again that comes down to magnification, you need more to fill the frame on a FF camera.
In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot.
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Flake said:
While to a degree I agree with you and the link regarding focal length to the extent that yes, you take the 400mm and take the wide angle and zoom in tight to the same crop and perspective of the 400mm, all things being equal, if the lenses are good, the OOF should be the same, however as you can see with the full image, it is easier for the layman to physically see the OOF on the 400mm and it's harder for most people to conceptualize that if they get very close and crop to the same size, it will be the same.
I do have to disagree about the subject to background not making a difference... macro you have a razor thin focal plane because you are focusing inches away from the lens. I shoot daily studio small product photography for a local company and at f8, at a distance of 12-18 inches, I only get a focal plane of about an inch, inch and a half. I dont dare go to F11-16 on the 50D because of the lens sweet spot and wider apertures will give me less than an inch focal plane. Distance of subject to foreground/background has EVERYTHING to do with bokeh. Why do you think the iphone has like 4-5 depth of field calculators... just so people can get focal plane info in a pinch while out in the field shooting.
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Loswr
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Flake said:
Sorry, Flake, but it's not a myth - it's fact. In the article you link, the author is changing the both focal length AND subject distance simultaneously (decreasing both focal length and subject distance), in order to keep subject size equivalent. This was, in fact, the point of my statement that aperture is the primary determinant, in practice, as in the example of the head shot.
Pick the DoF calculator of your choice, e.g. DOFMaster, change only the focal length, and DoF changes. So yes, focal length affects DoF - but only if you keep other factors constant. To reiterate, in practice we care about those other factors. If you just go by the numbers, you can get more OOF blur with the 24-105/4 than the 24-70/2.8. For example, I can frame a head shot with my 70-200/2.8 IS II at 70mm f/2.8, and then zoom in to 105mm and stop down to f/4 - and I'll get more OOF blur at 105mm f/4. But I won't have a head shot anymore, I'll have an eyes-and-nose shot, and I don't want that. So I'll have to walk backwards to frame the whole face at 105mm, and have less OOF blur (but if I stop down to f/2.8, I'll have the same OOF blur as at 70mm f/2.8, with increasing focal length and increasing distance effectively canceling each other out, again reducing it to a matter of aperture).
Flake said:
Yes, I can read wikipedia, too, and even copy and paste from it. Understanding what you read or copy/paste is not the same thing. If you go one line up from where you copy/pasted on wikipedia, you'll see: "For the closely related topic in microscopy, see Point spread function," - PSFs are something I work with routinely in an experimental setting. Circles of confusion are, arguably, the most important determinant of the DoF, in the strictest sense. By definition, 'depth of field' is that part of an image which is acceptably sharp, as opposed to that which is blurred. CoC is what determines what is sharp and what is not, and thereby determines what is within the DoF and what is not. What makes CoC confusing (pun intended) is that real CoC depends not only on the way in which the image is captured, but also the way in which the image is viewed. For example, an image that appears acceptably sharp when viewed at 600 pixels wide on an LCD display may be a blurry mess when printed at 20x30", even if the resolution supports a large print.
However, when discussing CoC in terms of cameras, we have no control over viewing/printing - therefore, 'standardized' values are used based on an assumed print size (A5, if memory serves). Those standard values are applied to different sensor sizes, and APS-C has a smaller CoC than FF. The take home is that the standard values for sensor formats mean smaller sensors will have deeper DoF for the same subject framing (and MF/view cameras have larger CoCs, meaning they have shallower DoF for the same framing compared to FF/35mm. So yes, CoC values are relevant for both sensor (or film) sizes and for determining DoF.
Does Macro have a thin aperture? That's a new on on me. I didn't even know apertures had measurable thickness. But yes, DoF is thinner with macro distances. In fact, most of the approximations that underlie typical optical formulae do not hold at near 1:1 magnification or greater (and when you get significantly higher magnifications, i.e. microscopy - there's a whole new set of formulae).
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WarStreet
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Flake said:
Flake, thanks for the link. As you know, on another post I calculated the background blur of the 400mm 5.6 to see if it is good enough for my intended framing. I have the impression that DOF is different from background blurring.
example:
Using a FF camera (24mm sensor height) shot in landscape orientation framing a 2m height subject and 100m between the camera and background
(1) 400mm @ 5.6: subject distance : 33.73m, subject to background distance 66.27m
gives 2.39m DOF, and 0.56mm spot diameter on background
(2) 300mm @ 5.6: subject distance : 25.30m, subject to background distance 74.70m
gives 2.39m DOF, and 0.47mm spot diameter on background
(3) 300mm @ 4.0: subject distance : 25.30m, subject to background distance 74.70m
gives 1.71m DOF, and 0.66mm spot diameter on background
From what I did, the magnification and aperture seems to determine the DOF, and background blurring is a different measure than DOF. The 400mm 5.6 has same DOF of 300mm 5.6 but it blurs the background more. I am new to all this, so would like to verify this with all of you, since I am using this math to determine which lens to purchase.
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Act444 said:
Well, I'm asking because I e-mailed CR before I got any lenses and that was his starting recommendation . . . I soon after regretted not getting the L and lusted after it.
Weatherproofing omitted, the 15-85's build quality rivals the 24-105. I understand if one feels the need for a constant aperture, but it's f/5 at 50mm, so, barbaric as that seems, I've missed more not being able to drop below 24mm on a crop vs. what 2/3 of a stop can buy me at 50mm.
Don't get me wrong, I swear by EF (because I know I'll upgrade) and hate the concept of a crop sensor . . . it just seems as if a lot of people are shooting on the 24-105 because it's a good FF (and decent crop) lens and the pros swear by it . . . I just haven't seen anyone who's taken a lot of shots with it and chosen the latter over it.
Then again, what do I know, I think the 50mm f/1.4 is a great lens, and I'll argue that 50mm is more usable than 85mm on a crop body . . . call me a redneck with a camera
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zerotiu
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okay, now I understand, this is what I get :
24-105 with :
[105mm * f/4 * 3 meters ]
from subject will give the same OOF as :
24-70 with :
[60mm * f/2.8 * 2 meters]
* So if I want the DOF more shallow , get closer to the subject but like neuro had said I won't get the whole image, maybe just nose or something else.
I've said it on my comment before that I know that f/4 can't beat f/2.8 in making OOF background. I want to know can f/4 make okay OOF background too so the subject can still be distinguished.
FYI, previously I compare the OOF with my old 18-55 f/3.5-5.6. With f/4 I still get decent OOF background (it is on my t2i. I believe I'll get shallower DOF on FF body). Then I found someone said that 24-105 produce spikey bokeh but all your images shared is good for me. So 24-105 isn't always produce it.
wow, thx again for the OOF background information
24-105 with :
[105mm * f/4 * 3 meters ]
from subject will give the same OOF as :
24-70 with :
[60mm * f/2.8 * 2 meters]
* So if I want the DOF more shallow , get closer to the subject but like neuro had said I won't get the whole image, maybe just nose or something else.
I've said it on my comment before that I know that f/4 can't beat f/2.8 in making OOF background. I want to know can f/4 make okay OOF background too so the subject can still be distinguished.
FYI, previously I compare the OOF with my old 18-55 f/3.5-5.6. With f/4 I still get decent OOF background (it is on my t2i. I believe I'll get shallower DOF on FF body). Then I found someone said that 24-105 produce spikey bokeh but all your images shared is good for me. So 24-105 isn't always produce it.
wow, thx again for the OOF background information
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WarStreet said:
as you see, bokeh is a complex issue, it depends on depth of field but also on perspective
you could have also included a 28mm lens, and you'd see that moving your subject closer (to see as much from it as with the longer lenses) and keeping the aperture at f/5.6, DoF is unchanged; but the look of the background changes big time: with a 28mm, you'll see a whole building behind your subject, and it will be out of focus but you'll still know it's a building, and recognize its features; with a 400mm lens, with the background at the same distance, all you see behind your subject is a small patch of wall, so it will not be just out of focus, it will be blurred beyond recognition. So depth of field is the same, but the background will be a lot softer on longer lenses.
I learnt about this when playing with my FoV and DoF calculator:
http://www.similaar.com/foto/dof/dof.php
and it lead me to write these notes:
http://www.similaar.com/foto/dof/dof_notes.html
anc reate this simplified DoF and FoV calculator, which I find much more useful than the usual ones:
http://www.similaar.com/foto/dof/dof2.php
I'm currently running bokeh tests on all my lenses (vintage leitz and carl zeiss jena), making them as scientific as I can; I expect them to be online next week
as with the sharpness tests I run some months ago, I'm learning a lot about my lenses in the process; everybody should run sharpness and bokeh tests on their lenses
(for example, I have two lenses whose bokeh is ugly as hell at maximum aperture, but gets much better slightly stopped down; but that's from tests that neutralize both aperture and perspective issues, so I still don't know if "quantity of bokeh" is enough to counteract this "quality of bokeh" effect)
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zerotiu said:
That's what I figured your question was regarding... the answer is yes, you can get decent OOF background if you need it. The "Spikey" bokeh is purely subjective and if you like what you have seen photo wise, then you wont be disappointed. Good luck with your purchase and feel free to let us know if and when you make your purchase and start shooting pictures with your new lens(es)
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WarStreet
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NormanBates said:
NormanBates, seems we came to the same conclusion. But now I am getting contrasting results. I added the 28mm @5.6 example, and the result of DOF is not similar to the other 5.6 lenses. I compared these results with the DOF master and are similar to mine. I might have a small error in my subject distance estimation, but the real reason for this unexpected result can be found from an article by DOF master.
from DOF master article : http://www.dofmaster.com/dof_imagesize.html
Depth of field is the same for all lenses when the image size is constant and the same f-stop is used.
This rule of thumb is approximately true when the focus distance for the shortest lens is less than about 1/4 of the hyperfocal distance for that lens.
For me, the calculation of the spot diameter on the background is more important. I am currently checking photos from flickr to map these values with the background visual results from the photos. It is a big guess to determine the subject and background distance, but my main aim is to get an idea. Maybe I will try to do some tests with my own photos in a rugby pitch, to get better estimates. It's quit an interesting subject. I wish to find some time reading about it and hoping to understand it better.
Using a FF camera (24mm sensor height) shot in landscape orientation framing a 2m height subject and 100m between the camera and background
(1) 400mm @ 5.6: subject distance : 33.73m, subject to background distance 66.27m
gives 2.39m DOF, and 0.56mm spot diameter on background
hyperfocal distance = 952.38m
(2) 300mm @ 5.6: subject distance : 25.30m, subject to background distance 74.70m
gives 2.39m DOF, and 0.47mm spot diameter on background
hyperfocal distance = 535.71m
(3) 28mm @ 5.6: subject distance : 2.361m, subject to background distance 97.639m
gives 3.21m DOF, and 0.06mm spot diameter on background
hyperfocal distance = 4.57m
(4) 300mm @ 4.0: subject distance : 25.30m, subject to background distance 74.70m
gives 1.71m DOF, and 0.66mm spot diameter on background
hyperfocal distance = 750m
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ok, maybe I went too far, 28mm is already wide angle and things start to change a bit there
with a 50mm, it's basically the same
with my DoF calculator (which seems to use a different CoC value):
400mm f/5.6 @ 33.76m --> DoF=2.00m
300mm f/5.6 @ 25.30m --> DoF=2.00m
200mm f/5.6 @ 16.88m --> DoF=2.00m
100mm f/5.6 @ 8.44m --> DoF=2.03m
50mm f/5.6 @ 4.22m --> DoF=2.12m
35mm f/5.6 @ 2.95m --> DoF=2.25m
28mm f/5.6 @ 2.36m --> DoF=2.43m
24mm f/5.6 @ 2.02m --> DoF=2.62m
http://www.similaar.com/foto/dof/dof.php?f_x=1&f_r=1.5&f_mm=400&f_f=5.6&f_d=33.76
edit:
plus: I think you'll like this:
http://prolost.com/blog/2011/1/9/the-shot-you-can-make.html
http://prolost.com/sycm
http://gallery.me.com/prolost
with a 50mm, it's basically the same
with my DoF calculator (which seems to use a different CoC value):
400mm f/5.6 @ 33.76m --> DoF=2.00m
300mm f/5.6 @ 25.30m --> DoF=2.00m
200mm f/5.6 @ 16.88m --> DoF=2.00m
100mm f/5.6 @ 8.44m --> DoF=2.03m
50mm f/5.6 @ 4.22m --> DoF=2.12m
35mm f/5.6 @ 2.95m --> DoF=2.25m
28mm f/5.6 @ 2.36m --> DoF=2.43m
24mm f/5.6 @ 2.02m --> DoF=2.62m
http://www.similaar.com/foto/dof/dof.php?f_x=1&f_r=1.5&f_mm=400&f_f=5.6&f_d=33.76
edit:
plus: I think you'll like this:
http://prolost.com/blog/2011/1/9/the-shot-you-can-make.html
http://prolost.com/sycm
http://gallery.me.com/prolost
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My bokeh tests are online, here:
http://www.similaar.com/foto/lenstests/bokehtests.html
I ran several scenarios:
* neutralizing both aperture and perspective:
http://www.similaar.com/foto/lenstests/bokehtests1.html
* neutralizing perspective:
http://www.similaar.com/foto/lenstests/bokehtests2.html
* keeping subject-to-background distance constant:
http://www.similaar.com/foto/lenstests/bokehtests3.html
* keeping camera-to-background distance constant:
http://www.similaar.com/foto/lenstests/bokehtests4.html
I learned a lot doing this
for example:
* I always thought my Carl Zeiss Jena Pancolar 50mm f/1.8 and my Carl Zeiss Jena Sonnar 180mm f/2.8 had great bokeh; it turns out, they both have pretty bad bokeh, but they make up for quality with quantity: the 50mm is relatively fast at f/1.8, and the Sonnar, at 180mm f/2.8, is both long and fast
* vintage glass is a lottery with regards to bokeh too: that Sonnar that came out so bad in my tests is considered one of the mythical "best bokeh ever" lenses:
http://www.rickdenney.com/bokeh_test.htm
(the other possibility is that other people also got fooled by the focal length and speed of this lens, but the fact that my other two sonnars, the 135 and the 300, have much better bokeh, seems to point to my 180 being sub-par)
* another thing that points to vintage glass being a lottery: I expected to come out of this with a conclusion to the tune of "how I learned to stop worrying and just buy Leitz glass"; but the 135mm is actually not stellar: at f/2.8 it's not great, and at f/4 the much cheaper sonnar 135 is actually better
* aperture affects both bokeh quantity and bokeh quality: I hardly ever use the pancolar wide open, because it becomes relatively soft in the corners; stopped down to f/2.8, it is both sharp and pretty nice in terms of bokeh
this bokeh thing is a very complex issue...
next step is to test my father's modern glass and see how it does
http://www.similaar.com/foto/lenstests/bokehtests.html
I ran several scenarios:
* neutralizing both aperture and perspective:
http://www.similaar.com/foto/lenstests/bokehtests1.html
* neutralizing perspective:
http://www.similaar.com/foto/lenstests/bokehtests2.html
* keeping subject-to-background distance constant:
http://www.similaar.com/foto/lenstests/bokehtests3.html
* keeping camera-to-background distance constant:
http://www.similaar.com/foto/lenstests/bokehtests4.html
I learned a lot doing this
for example:
* I always thought my Carl Zeiss Jena Pancolar 50mm f/1.8 and my Carl Zeiss Jena Sonnar 180mm f/2.8 had great bokeh; it turns out, they both have pretty bad bokeh, but they make up for quality with quantity: the 50mm is relatively fast at f/1.8, and the Sonnar, at 180mm f/2.8, is both long and fast
* vintage glass is a lottery with regards to bokeh too: that Sonnar that came out so bad in my tests is considered one of the mythical "best bokeh ever" lenses:
http://www.rickdenney.com/bokeh_test.htm
(the other possibility is that other people also got fooled by the focal length and speed of this lens, but the fact that my other two sonnars, the 135 and the 300, have much better bokeh, seems to point to my 180 being sub-par)
* another thing that points to vintage glass being a lottery: I expected to come out of this with a conclusion to the tune of "how I learned to stop worrying and just buy Leitz glass"; but the 135mm is actually not stellar: at f/2.8 it's not great, and at f/4 the much cheaper sonnar 135 is actually better
* aperture affects both bokeh quantity and bokeh quality: I hardly ever use the pancolar wide open, because it becomes relatively soft in the corners; stopped down to f/2.8, it is both sharp and pretty nice in terms of bokeh
this bokeh thing is a very complex issue...
next step is to test my father's modern glass and see how it does
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WarStreet
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NormanBates said:
Great work. It's really useful for me, who don't have the energy and time to do such detailed tests. I can't thank you enough for this.
Due to the vast information of your setup, the spot diameter on the background can be calculated and compared with the related visually result. The camera-to-background test is the one I am interested in as this simulates most sport scenarios.
At first I was surprised with the contrasting results of the 90mm @2.8 and 135mm @2.8
I wrongly assumed that you used an FF camera, which would have given the following results :
90mm @2.8 : spot diameter 1.96mm , spot diameter with an infinite background distance : 2.92mm
135mm @2.8 : spot diameter 2.21mm , spot diameter with an infinite background distance : 4.38mm
With an FF camera, in your scenario, the 135mm would blur the background more than the 90mm
Using a Canon APS-C camera, which I think it is what you have used in the test ( at least I hope so ! ) :
90mm @2.8 : spot diameter 0.91mm , spot diameter with an infinite background distance : 1.88mm
135mm @2.8 : spot diameter 0.65mm , spot diameter with an infinite background distance : 2.82mm
With APS-C, it's the 90mm which blurs the background more, and match with your visual results.
At enough background distance, the 135mm will always give more blurring.
Visually the spot diameter of 0.91mm produce a much better result than the 0.65mm. From my previous test (very rough estimates), I concluded that a 0.60mm - 0.70mm should give an acceptable blur, but one would still recognise what's in the background. The 0.91mm results in an unrecognised backgound (at least for me)
This shows why the big lenses in sports are so important. The 400 5.6 would produce some acceptable results, but won't achieve the unrecognised background blurring even when used on FF for a 2m hight subject. On the other hand, with a portrait orientation, or with a tight crop, this could be achieved.
Thanks again for sharing your work.
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yes, it's an APS-C camera (a 550D; I think it's said in the main page, but not in the pages with results)
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