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02-23-2013, 07:04 PM   #1
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What makes a lens "3-D"?

Hi, long time lurker here. I thought I'd finally jump in with my own imput because of a question that's been nagging me for a while.

It comes from reading lots of lens reviews here. I've seen quite a lot of lenses praised as having a "3-D" look. Before, I thought it was just a function of focal length. Telephotos, by their nature, flatten the depth of a photo. Wide angles, on the other hand, exaggerate the depth of a scene, making it look "3-D."

I've heard people say the Sigma 30 f/1.4 looks "3-D", and I have to agree, even though it's a normal perspective on APS-C. It was part of the reason I bought it, despite the mixed reviews. The picture I've attached was taken with that lens (could someone tell me how to upload a picture and put it mid-text??). It looks like her front paw is coming right out of the frame!

Then, I see someone praising the FA 77 Ltd. as having a "3-D" look, and I'm left scratching my head. On APS-C, the FA 77 is well into telephoto territory. Looking at the samples, I don't see any "3-D" effect at all. Is there something more to it, or was that reviewer just full of it?

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02-23-2013, 07:19 PM   #2
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It's a combination of bokeh, distortion, perspective distortion, and LBA IMO

Remember that wider lenses have more distortion (by nature) compared to normal lenses, and the closer your subject is, the more perspective distortion you get, resulting in the 3d looking effect. So a 30mm on APS-C will have a little more distortion than a 50mm on full-frame even though the field of view is almost be the same.

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02-23-2013, 07:24 PM - 1 Like   #3
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I think some of it has to do with microcontrast/clarity. My M50/1.7 has a nice 3D-ness to it because apart from its amazing sharpness, it "adds" contrast, especially to the edges of objects. This makes them stand out more, causing a 3D effect.
02-23-2013, 07:27 PM   #4
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QuoteOriginally posted by NitroDC Quote
I think some of it has to do with microcontrast/clarity. My M50/1.7 has a nice 3D-ness to it because apart from its amazing sharpness, it "adds" contrast, especially to the edges of objects. This makes them stand out more, causing a 3D effect.
Yes, this has to be part of the equation. Not all lenses at the same focal length manage to create that same sensation of depth.

02-23-2013, 07:33 PM   #5
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QuoteOriginally posted by Adam Quote
It's a combination of bokeh, distortion, perspective distortion, and LBA IMO
Ah, I was thinking distortion had something to do with it. The sigma is known for a bit too much barrel distortion, in the eyes of some.

But what about the FA 77 Ltd.? There's pretty much no distortion there. Okay, it's got plenty of contrast, and it's good at making the subject "pop." Is that the same thing as when people say "3-D"? To me, a focal length this long will flatten perspective too much to call it "3-D".
02-23-2013, 07:35 PM   #6
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QuoteOriginally posted by scratchpaddy Quote
Ah, I was thinking distortion had something to do with it. The sigma is known for a bit too much barrel distortion, in the eyes of some.

But what about the FA 77 Ltd.? There's pretty much no distortion there. Okay, it's got plenty of contrast, and it's good at making the subject "pop." Is that the same thing as when people say "3-D"? To me, a focal length this long will flatten perspective too much to call it "3-D".
I think the 3d illusion might be caused by soft, shallow bokeh. The 77mm produces some awesome bokeh, after all!

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02-23-2013, 07:46 PM   #7
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Does anybody have a picture or two (especially from a longer focal length) that they think has that 3-D look? Maybe you could convince me. And, could someone tell me how to put a picture in mid-post? Do I have to put it somewhere online, and use the URL?
02-23-2013, 07:50 PM   #8
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I would guess soft shallow bokeh, smooth transition and lack of bloom in the focused areas all lead to extra "pop". I think the lack of serious bloom often is overlooked when it comes to the 3D effect in a lens as the bloom smooths the subject to make the contrast to the background smaller and therefore makes the image flatter. Canon seems really good at lessen the bloom effect in their lenses and I think that is one of the reasons why many people find Canon shots really pop out of the screen.

02-23-2013, 08:12 PM - 1 Like   #9
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QuoteOriginally posted by VisualDarkness Quote
I would guess soft shallow bokeh, smooth transition and lack of bloom in the focused areas all lead to extra "pop". I think the lack of serious bloom often is overlooked when it comes to the 3D effect in a lens as the bloom smooths the subject to make the contrast to the background smaller and therefore makes the image flatter. Canon seems really good at lessen the bloom effect in their lenses and I think that is one of the reasons why many people find Canon shots really pop out of the screen.
Ah! Good point! When I shoot my Helios 40 wide open, everything looks kind of dreamy, maybe because the DOF is so tiny. If I stop down just a little, all the bloom disappears on the subject, and it really stands out, especially with that crazy bokeh. Stopping down really takes the energy out of the bokeh, though, so I usually don't do that. The first is wide open (f/1.5). I think the second is stopped down to f/2.8 (hard to tell with a preset lens). Still, at 85mm, it doesn't seem very "3-D" to me.

I'm kind of thinking that "3-d" is one of those highly subjective buzz words. Kind of like the famed Takumar "pixie dust."
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02-23-2013, 08:31 PM   #10
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QuoteOriginally posted by scratchpaddy Quote
Ah! Good point! When I shoot my Helios 40 wide open, everything looks kind of dreamy, maybe because the DOF is so tiny. If I stop down just a little, all the bloom disappears on the subject, and it really stands out, especially with that crazy bokeh. Stopping down really takes the energy out of the bokeh, though, so I usually don't do that. The first is wide open (f/1.5). I think the second is stopped down to f/2.8 (hard to tell with a preset lens). Still, at 85mm, it doesn't seem very "3-D" to me.

I'm kind of thinking that "3-d" is one of those highly subjective buzz words. Kind of like the famed Takumar "pixie dust."
Perfect examples, thank you! The bloom in the first shot negates the 3D more than the depth of field enhances it, instead it becomes more like a 2D painting. Nothing bad with a bloomy effect but I would say that if 3D is what you look for you should avoid it. The second shot really makes the subject pop due to the bigger contrast in clarity and sharpness between the subject and the background.

My Sigma 20/1.8 behaves like your Helios with a dreamy look wide open and a more 3D one at F2.8. I don't see this as a bad though though as it lets me choose between what I think fit the scene best.

One experiment if you got Photoshop Lightroom is to play with the clarity slider, both for the whole shot and with the brush tool, as it either enhances or decreases the bloom in a shot and there fore affects the "3D".
02-23-2013, 08:33 PM   #11
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3-D "pop" has more to do with position of subject within dof, distance from background, and lens drawing characteristics at the transition between in-focus and out-of-focus areas -- lenses with more micro-contrast seem to exhibit the pop more than those with less of it... IOW, ANY lens is capable of 3-D pop, given proper dof & distance to background.


edit:

Some lenses get known for 3-D pop more than others because they are more often used with dof setting, subject & background distances conducive to it...

Last edited by rhodopsin; 02-23-2013 at 08:39 PM.
02-23-2013, 08:42 PM - 2 Likes   #12
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When people refer to a image being 3-D it more about the subject being able to "pop" or stand-out from the rest of the subject/background within the image. It also very subjective depending on the person, personally I dont see it in the photos posted above ( no offence)
Its a combination of DOF, whats in focus and whats not, focal lenghts and subject distance's and background distance's that acheives the effect.

02-23-2013, 09:03 PM   #13
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That's just what I was looking for, Tougefc! I'd definitely say that picture looks 3-d. No offense taken, by the way. The first picture is the only one that looks "3-D" to me, and yours is a much better example in my eyes.

Still, I think there's a bit of confusion in terminology here. "3-D" isn't really the same as "pop". If a subject "pops," they stand out in a figurative sense, that is, they're easily distinguished from the background. If it's "3-D", it stands out in the more literal, spatial sense of the word. In Tougefc's picture, the alleyway clearly shows a spacial regression, and the boy is clearly in front of it all. He almost seems to jump out of the picture in a real, spatial sense.

I'm beginning to think the background is more important than the subject for this effect to appear.
02-23-2013, 09:10 PM   #14
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No worries mate

QuoteOriginally posted by scratchpaddy Quote
I'm beginning to think the background is more important than the subject
You are on the right track. Backgrounds are a key ingredient for the effect.
02-23-2013, 09:12 PM   #15
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Its much more the skill of the photographer than the lens, but having a lens that makes it easier to pull off helps. The bokeh should also not be so blurred as to make the background undecipherable. It's what allows the eye to see depth and know "Hey, that background object is ____ " instead of "That background is a swath of blue"

Here are a few longer focal length shots I think have 'pop' that I've taken.

Both of these were with my Sears 75-260mm, probably at 75mm using its close focus area.






Sigma 70-300mm, again, using its macro setting (which happens to be at 300mm on that lens)



And going the opposite route, the Sigma 10-20 at 20mm. Its less pronounced here because bokeh with the 10-20 is LOL difficult to produce.

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