What lens for best dof?

[leslie_cheung]

<p>Peter---</p>

<p>I think he took "circle of confusion" too literally and just left:) I would like to know if it was helpful for Nicholas also.</p>

[rayyeager]

<p>Peter Hawking couldn't have explained it better. After this advice, I think he smashed that D5000 on his forehead. Now he can only see with shallow DOF.</p>

[jose_angel]

<p>The topic is still alive... nobody has mentioned yet a discussion about the convenience of a digital bellows camera system + adapter for selective DoF control based on the Scheimpflug`s principle... :P</p>

[joseph_smith3]

<p>I have found these two links contain some of the best information available to educate you on depth of field and related matters. I suggest you take a look at them:<br>

<a href="http://www.luminous-landscape.com/tutorials/understanding-series/dof.shtml">http://www.luminous-landscape.com/tutorials/understanding-series/dof.shtml</a><br>

http://www.luminous-landscape.com/tutorials/dof2.shtml<br>

Joe Smith</p>

 

[tom_mann1]

<p>@Joe S - Thanks for posting those useful links. I had seen demos like this and was just in the process of looking for them when you posted the links to Luminous Landscape.</p>

<p>@Dave R - In the 2nd link posted by Joe S, look carefully at the series of images in the section titled, "The Depth of Field is Essentially the Same". Note how the tower in the background is much larger and appears very soft in the shots taken at long focal lengths compared to shots taken at short focal lengths. In fact, in the first of the two 17 mm shots, ie, the one where the magnification (ie, size of the subject) is held constant, the tower and background buildings appear almost sharp. This is what I meant when I said that once and object is well outside the DOF range, the amount by which OOF objects are blurred is much larger (ie, its OOF image is spread out over a much larger area). </p>

<p>I believe the flaw in your argument is that you are comparing the blur of the OOF objects while keeping THEIR magnification constant, not keeping the magnification of the primary subject constant and then looking at the degree of blur in the OOF objects.</p>

<p>Cheers,</p>

<p>Tom M.</p>

<p>PS - BTW, not to add more confusion to this topic, but I noted a relatively minor error in one statement in the Luminous Landscape article -- he refers to a 1/3rd - 2/3rd rule. This is simply not so. The distances of the near and far thresholds for being OOF vary smoothly from 1:1 all the way to 1:infinity as you approach hyperfocal conditions. In addition, most DOF calculators make simplifying assumptions (eg, paraxial rays, etc.) that somewhat affect their results. Let them guide you, but don't think the value of the numbers they produce are exact.</p>

[joseph_smith3]

<p>Here is an excellent article about the myth about 1/3 rd and 2/3rds rule:<br /><a href="http://www.naturescapes.net/docs/index.php/category-photographic-technique/57-the-mathematics-of-depth-of-field-part-two-crop-factor-magnification-and-the-13-myth">http://www.naturescapes.net/docs/index.php/category-photographic-technique/57-the-mathematics-of-depth-of-field-part-two-crop-factor-magnification-and-the-13-myth</a><br />The real answer is that the ratio changes as your focal point/hyperfocal distance changes. And there is a minimum of 1/2.<br />As a practical matter if you are a long lens shooter, the actual result is more likely to be 50-50 or 1/2 in front and 1/2 behind for subjects that are close to you. This is how I discovered the myth, by looking at my out of focus beaks on birds. <br />Joe Smith</p>

[dave_redmann]

<p>Tom Mann, you are absolutely correct that using lenses of different focal lengths will affect how wide a view of the background you get, even assuming you change the subject-to-camera distance so that the framing / magnification of the primary subject is the same.</p>

<p>Also, I see what you're referring to about the DoF dropping faster. Indeed, the longer lense will make the backgroun more magnified and therefore blurrier on a per-pixel (or whatever) basis. But of course the additional magnificant also makes the details more visible. So I guess in a sense I agree with what you said, while disagreeing that this is usually a real-world useful trade-off.</p>

<p>Jose Angel--true, but now we're getting <em>really</em> complicated! Also, whether tilting the plane of focus produces a useful practical reduction in DoF depends on the subject and surroundings. Often it works, but sometimes it produces unpleasant side effects.</p>

<p>And of course, as we get more and more exotic / expensive, masking and blurring in the digital darkroom look like better and better solutions!</p>

 

[nicholas_martinson]

<p>Hello! Thank you everybody for responding. I learned some new things and understood most of it. Thank you Peter for being straight forward and more relevant. I bought the 35mm f1.8. </p>

<p><a href="http://www.facebook.com/photo.php?pid=4703692&id=733160736">here</a>< is a picture I took and 'shopped it for shorter dof. Its what made me really want a new lens because I want that kinda picture soc.</p>

<p>A couple of albums:<br>

<a href="http://www.facebook.com/album.php?aid=179971&id=733160736">http://www.facebook.com/album.php?aid=179971&id=733160736</a><br>

<a href="http://www.facebook.com/album.php?aid=152932&id=733160736">http://www.facebook.com/album.php?aid=152932&id=733160736</a><br>

What do you guys think of my pictures? Am I alright for a noob? I know I over edited some of them.</p>

[Peter_in_PA]

<p>You are good enough (for a "noob") that you probably want to learn all that esoteric "circles of confusion" stuff.</p>

<p>Glad we could help!</p>

[Matt Laur]

<p>Nicholas: just so you know, your links take most people to a redirected Facebook login page, denying them the ability to see the images until they join or log in. Also: FB tends to really make a mess of most images (quality-wise), so when you want to share images in the context of threads like this, you might want to use Flickr or some other service that doesn't require visitors to sign up for a third-party service in order to see them. As you do more of this, and do more exploring, that issue is going to come up more often - so, time to get out in front of it. Keep at it!</p>