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03-31-2013, 06:31 AM   #1
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3D effect on MF lens

Hi guys

I have shot a few pictures as following using MF lenses on my K-r. I read somewhere in the forum that old lenses help bring 3D effect to the photos, can you please confirm if those are qualified as having such effect? People normally say the object stands out of the photo so I'm not sure if it can also be perceived as 3D effect.

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I've got those shots more by chance than having an adequate skill. I really appreciate if you can share any articles/ books that provide further information about this technique.

Many thanks

Lushdimple

03-31-2013, 06:41 AM   #2
hcc
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The 3D effects is not related to MF (vs AF), but rather the depth of field (DOF). Further some lenses tend to give a better 3D rendering than others

There have been several relevant threads on the topic:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/196988-pentax-...3d-effect.html
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/26977-question...-depth-3d.html
https://www.pentaxforums.com/forums/pentax-dslr-discussion/31294-3d-like-rend...yz-lenses.html

Hope that the comment may help.
03-31-2013, 08:10 AM   #3
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As hcc said, the effect is the result of the depth of field. 3 things affect depth of field

1) aperture -- the more open the lens is the smaller the depth of field. If you really want a nice 3d effect, usually you want to shoot at F2.8 or smaller
2) focal length of the lens - the longer the focal length (telephoto lens are best at producing the result) the smaller the depth of field.
3) distance from the subject - the closer you are to the subject the more pronounced the effect is going to be. similarly, the further the background is away from the subject again, the more pronounced the 3d effect.
03-31-2013, 09:38 AM   #4
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Lighting is also key.

03-31-2013, 11:39 AM   #5
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I like the depth of field on this photo by rob1234.
Post #3976

https://www.pentaxforums.com/forums/pentax-medium-format-645-6x7-645d/87027-p...hotos-266.html
03-31-2013, 12:13 PM   #6
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Caveat for the DOF size - you want the subject in focus but the background blurry, so a super narrow DOF isn't going to cut it. You want something wide enough for the subject to (mostly) remain totally in focus and have the background blurred. You can pull this off with just about any lens, but its the quality of the bokeh and the contrast thats going to dictate if the 3D effect is going to kick in.

If it was strictly a matter of a narrow DOF with creamy bokeh, then this photo I took should pop with a 3D effect - which it doesn't.




You see it (somewhat) more clearly in a shot like this because my kid is completely in focus with a blurred background - and this was probably shot around f/8 or so on a long telezoom (a 75-260mm manual beast of a lens I love dragging out every so often).




I don't have any true '3D' lenses, or at the least I haven't mastered the technique enough to say I can pull it off easily, but I felt I had to chime in on the subject here.

EDIT:

This one shows it perhaps better than the one above.




Subject is in complete focus, everything else is not in focus. This causes her to pop. If I had a better lens/better bokeh that day the effect probably would have been even more heightened. If it had been an isolated body shot where you could see her entire body head to foot, it would also (probably) have been even more pronounced. The trick is fooling the eye into layering the subject on top (or behind) the rest of the image. Its a matter of sharp subject/unsharp everything else going on, while maintaining the brains ability to identify what the out of focus stuff actually is. This mostly eliminates telephotos as they blur bokeh into oblivion, and makes wider angle lenses more desirable since the distortion shoves the background further away and allows you to isolate your subject better. Of course when dealing with portraits, wider isn't better, so you wind up with a pretty narrow window of usable lenses that ride that balance between 'long enough to not distort' and 'short enough to retain the background'. At this point you start to also factor in lens quality and you suddenly start talking the pixie dust factor with the better quality stuff in the normal to short telephoto range.

Last edited by Sagitta; 03-31-2013 at 12:33 PM.
04-02-2013, 10:24 AM   #7
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Many thanks guys for your kind help. Your info is really helpful, especially the bit about using the tele lens can produce similar effect. I need to play more with it to develop my intuition for this technique.

Cheers. L.
04-02-2013, 12:54 PM   #8
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As you can see above, good separation between the subject and the background, both in distance and in the nature of the lighting is the key - that's a tool you can use with ANY lens. And it's FREE as well!

H2

04-02-2013, 01:39 PM   #9
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Get a copy of DOFMaster (either for your PC or for your phone) or a Depth of Field table.

40 years ago (If I Remember Correctly - please correct me and I will AMEND this post if I am wrong) I was taught that, to isolate a subject against a background, position yourself 1/10 the distance in feet of the lens Focal Length in MM from your subject (so for a 200mm lens, stand 20 feet away from your subject). Then, at f/5.6 on a 24x36 sensor (35mm film) you should have about 12" of in-focus area to work with and your subject should fall in theis "Total Depth of Field." At f/5/6 the ratio seems to work for all focal lengths (that's what DOFMaster is for). You can make a close approximation in a DoF Table (or DOFMaster) for APSc (which is about 8" of Total Depth of Field @ f/5.6). f/8 gives about the same 12" on APSc, but less flexibility with the background blur. Perspective will be different on APSc.

If your subject is also 1/10 the FL distance in feet away from the background (or more) the background should be blurred. In this way your subject will tend to "pop" out of the 2D photo plane, or have that 3D effect. The trick is to have your ENTIRE subject in focus - and very little else, and to know that in nature you can't always arrange elements to suit this formula. Then you have to start compensating with aperture, shutter speed and tripod - and maybe you just can't make the shot at all.

Some lenses are better at this than others. Usually 85mm and longer are easier than the 50's and shorter, but the FA Limiteds break this rule.
04-02-2013, 01:59 PM   #10
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One peak's worth a 1000 calculations

QuoteOriginally posted by monochrome Quote
. . . position yourself 1/10 the distance in feet of the lens Focal Length . . .
I don't recall ever learning it in that particular manner, but if I had I'm sure the formula was very quickly forgotten when I discovered the DoF preview button on my Spotmatic.

H2

But studying DoF tables for your lenses does offer insight into the relative change associated with distance and aperture.
Depth of Field Table
04-02-2013, 04:04 PM   #11
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QuoteOriginally posted by pacerr Quote
I don't recall ever learning it in that particular manner, but if I had I'm sure the formula was very quickly forgotten when I discovered the DoF preview button on my Spotmatic.
H2
But studying DoF tables for your lenses does offer insight into the relative change associated with distance and aperture.
Depth of Field Table
Well I imagine he thought DoF Preview was a crutch. He probably thought you needed to position yourself where you should be. Our instructor wanted us to shoot at f/5.6 whenever possible for the 3D effect and at f/5.6 on a FF snesor you get that magic 12" Depth of Field (for photographing a person, he said) with the 1/10th Rule.

At f/11 you get 2 feet which would no doubt work in bright sun but you might lose some 3D pop.. I'm sure there's some math you do in your head but I don't remember it.
04-03-2013, 01:33 AM   #12
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What's so magic about 12inch? the math is at least solid though for 135 format. With other formats the CoC is different so it does not add up anymore
04-03-2013, 02:09 AM   #13
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QuoteOriginally posted by Anvh Quote
Lighting is also key.
Another trick seems to be to have the out of focus zone still recognisable, i.e. not completely blurred out. Presumably because this is how our eyes/brain normally see the world. Many lenses fail, giving annoying 'motley' bokeh, when just a bit out of focus.
04-03-2013, 08:27 PM   #14
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My take would be,

1) determine the required DoF so as to ensure that the subject falls entirely within the plane of focus.
2) lens used must be REALLY sharp within the focal plane. **this is where the FA Ltds shine, including certain other lenses including Siggy 30/1.4, 50/1.4, 85/1.4**

Why is f/5.6 more "magical"? Because for those that has lenses with distance scale, take a look at it... On a crop sensor, most of the time, the subject distance is/are between the maximum distance and infinity. Whereas on a FF, f/5.6 literally ensures that the subject would "always" fall within the DoF/focal plane.

e.g. My 28mm shows up to 3m/10feet before infinity.
Therefore, by looking at the aperture marking, setting my aperture @ f/4 for my shot would mean that my focal plane/depth of field is between 3m and infinity.. -_-"....
One reason why FF is more 3D... Because using the same lens enable the user to maximize the flexibility in DoF over a given distance...

Whereas if you take a look at longer lenses, e.g. FA 77:

1) It's sharp especially stopped down
2) It's 6m on the distance scale before hitting infinity. Therefore, you have somewhat useable aperture from f/1.8 to f/10 before hitting infinity. One would definitely be shooting at aperture wider than f/11..

BUT, taking that into consideration, use that FA77 for a full length body shot and woops! That 3D effect would not be as strong... One would then need an EVEN longer lens to extend the range of useable f/stop before infinity.

If you understand what i mean, you'll understand it would mean, using a crop sensor, one has to "somewhat" use x1.5 FL to achieve a somewhat similar effect, composition and perspective if on FF. And that means standing somewhat x1.5 further in comparison too..

Last edited by SyncGuy; 04-03-2013 at 08:39 PM.
04-03-2013, 09:46 PM   #15
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QuoteOriginally posted by SyncGuy Quote
My take would be,

1) determine the required DoF so as to ensure that the subject falls entirely within the plane of focus.
2) lens used must be REALLY sharp within the focal plane. **this is where the FA Ltds shine, including certain other lenses including Siggy 30/1.4, 50/1.4, 85/1.4**

Why is f/5.6 more "magical"? Because for those that has lenses with distance scale, take a look at it... On a crop sensor, most of the time, the subject distance is/are between the maximum distance and infinity. Whereas on a FF, f/5.6 literally ensures that the subject would "always" fall within the DoF/focal plane.

e.g. My 28mm shows up to 3m/10feet before infinity.
Therefore, by looking at the aperture marking, setting my aperture @ f/4 for my shot would mean that my focal plane/depth of field is between 3m and infinity.. -_-"....
One reason why FF is more 3D... Because using the same lens enable the user to maximize the flexibility in DoF over a given distance...

Whereas if you take a look at longer lenses, e.g. FA 77:

1) It's sharp especially stopped down
2) It's 6m on the distance scale before hitting infinity. Therefore, you have somewhat useable aperture from f/1.8 to f/10 before hitting infinity. One would definitely be shooting at aperture wider than f/11..

BUT, taking that into consideration, use that FA77 for a full length body shot and woops! That 3D effect would not be as strong... One would then need an EVEN longer lens to extend the range of useable f/stop before infinity.

If you understand what i mean, you'll understand it would mean, using a crop sensor, one has to "somewhat" use x1.5 FL to achieve a somewhat similar effect, composition and perspective if on FF. And that means standing somewhat x1.5 further in comparison too..
No idea what you are trying to say or achieve. I am looking at the FA77 and I don't get what you are saying.
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