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How to improve DOF with a VR Micro 105 mm when used as a telephoto lens?


georges_walker

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<p>Hi there,<br>

Some days ago I tooked some pictures in a concert. That day decided to use my VR 105mm lens although it is intended to be used as a macro lens. The quality is really outstanding but DOF is not if I compare the results with a real telephoto lens.<br>

The following picture was taken with a F2.8 and the people in the background were about 2 meters behind the musician at the foreground.<br>

<a href="../photo/13160313&size=lg">http://www.photo.net/photo/13160313&size=lg</a></p>

<p>I will appreciate your comments.</p>

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<p>Of course decreasing the size of your aperture will increase your dof. What iso were you shooting at? For every stop you could increase your iso you could decrease the size of your aperture. That said, I like the dof in the photo that you provided, it clearly indicates who is the main focus of the shot. And the reality is that your dof is not going to be very large under any circumstances in a lighting situation such as this one.</p>
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<p>Nice shot. Not sure how far you are away, say about 10 m, at f2.8 your DOF is about 1 m, regardless of what kind of lens, so no wonder the people in the background are out of focus (I think it actually nicely isolates the musician in the foreground). DOF is dependent on aperture, I find <a href="http://www.dofmaster.com/dofjs.html">this</a> online calculator helpful. What is the aperture on you other telephoto?</p>
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<p>I`m in the believing that there could be slight differences in defocus areas between (same focal lenght) lenses, probably due to bokeh characteristics.</p>

<p>DoF must be the same, either you use a 105mm telephoto or 105mm macro.</p>

<p>If you want to increase the DoF, simply shoot at smaller apertures. Think that diffraction will affect sharpness if you close the diaphragm beyond the "diffraction limit".</p>

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<p>You are right Bob, actually I want to decrease DOF in order to have less detail for the background.<br>

As I said, the picture I'm referring to was taken with a F2.8. I was about 20 meters in front of the main musician. For a regular telephoto, that distances are good enough to produce les DOF with a F 2.8</p>

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<p>Jorge - I think you're confusing us by not thinking of a 105mm as a "regular telephoto". The DoF isn't any different because it's a macro lens (except it focusses close and has decent close-range correction), and 105mm <i>is</i>, moderately, telephoto. If you want the background to go away, you either need more aperture (e.g. 105 f/2 DC) or you need a longer lens, which will enlarge the blurry section of background you're looking at, and therefore make it look more blurry. That's why a 200mm f/2.8 is better at losing the background than a 105mm f/2.8 (well, that and you're obviously seeing less of the background because the field of view is reduced, so you have more control over what's behind the subject).<br />

<br />

Different lenses at the same aperture might have different <i>quality</i> of background (bokeh), but the amount of background blur shooting the same subject from the same place with the same camera just comes down to focal length and aperture.</p>

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<p>You have a short tele in the 105mm. The closer you get to the subject at a given f-stop the less DoF you will have. The greater the distance between subject and background will give increased out of focus behind the subject. From your example it seems the solution would be a faster lens. Getting closer would change the composition using the 105mm and you can not do anything with the distance behind the subject. There is an older Nikkor 105mm that has a larger aperture and several Nikkor 85mm tele's.</p>
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<blockquote>

<p>"<em>Any lens of the same focal length, with the same distances between you, the subject, and the background, is going to produce exactly the same DoF."</em></p>

</blockquote>

<p>Exactly. The only difference between the 105mm VR Micro and a "regular" 105mm telephoto is that the Micro can focus much closer. At normal distances, such as the 20m you were shooting at, there is no difference in DoF at f/2.8. At close distances (under 2m) you will probably see differences in DoF since the 105mm Micro shortens focal length at close distances, and won't actually be a 105mm focal length in the closeup range.</p>

<p>You may, and probably will, see a difference in the characteristics of the out of focus background elements at normal distances between a Micro and regular 105mm, but the actual zone of DoF will be the same.</p>

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<p>A 85/1.4 would be the closest focal length that can make a real difference in the DOF and be highly suitable for that kind of photography. You can also blur the background effectively with a 105/2 DC or 135/2 DC but those are not quite as crisp for the main subject at f/2 as the 85/1.4 would be.</p>
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<p>If you keep the working distance the same, an 85mm lens at f/2 will actually have more DOF than a 105mm lens at f/2.8 An 85mm lens at f/1.4 will have just a bit less DOF than a 105mm lens at f/2.8, but may also be a little lens sharp. A 105mm f/2 DC or the 135mm f/2 will have even less DOF at f/2 than even the 85mm lens at f/1.4 </p>

<p>However, if you move backwards or forwards to keep the field of view the same, you will have a different story. The total amount of DOF is essentially independent of focal length (if you keep the field of view the same, by changing working distance). If you keep working distance constant, than you think of DOF as a function of focal length. </p>

<p>But yes, just to reiterate what others have said, it doesn't matter whether your lens is a macro lens, or not, if you have that angle of view at f/2.8, it will have the same DOF as any other lens at f/2.8 </p>

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<blockquote>However, if you move backwards or forwards to keep the field of view the same, you will have a different story. The total amount of DOF is essentially independent of focal length (if you keep the field of view the same, by changing working distance). If you keep working distance constant, than you think of DOF as a function of focal length.</blockquote>

 

<p>Before this becomes another repetition of the thread which I keep getting involved in, I'll just make this distinction to clarify what Samuel said: The <i>field of view</i> depends only on focal length; by changing subject distance, you can make the <i>size of the subject in the image</i> the same for two lenses of different focal length; if you do this, DoF is almost entirely a function of relative aperture (f-number) <i>but the amount by which the background appears to be blurred is greater for a longer lens</i> due to its magnification. Depth of field and background blurriness are not quite the same thing, and it's easy to talk about one when you really care about the other. HTH.</p>

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<p>i shoot a lot of concert/music pics, and also have a 100mm macro. i don't shoot that stuff with it. not because it's a bad lens--it's not--but because i have other lenses which are better suited for that app. that pic, i think, shows the limitations of the 105's bokeh, which might look better with a different subject--flowers in a field, say. it also seems a little too short for what you were trying to do-- a longer lens would have narrowed the isolation a bit--one problem is you are too far away--and for a d300s, i would recommend the sigma 50-150/2.8 and the nikkor 70-200 VR. an 80-200 would also work, as well as the previously-suggested 85/1.4 and 135/2. with the 85, you would get shallower DoF, and with a longer lens, you would get more compression, which gives the impression of shallower DoF. you could also upgrade to an FX camera, which gives shallower DoF, but then you'd still need a longer lens. like Elliot said, the shot itself isn't bad. that's not the problem. the problem is you used the wrong lens. honestly, i think you did the best you could with what you had to work with.</p>

 

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<blockquote>

<p>I was about 20 meters in front of the main musician. For a regular telephoto, that distances are good enough to produce les DOF with a F 2.8</p>

</blockquote>

<p>60 feet is pretty far away, IMO. i normally shoot from much closer, even with a 70-200. if you were seated in the audience and not able to move a longer lens is the best option, if your goal is subject isolation. OTOH, stopping down and increasing DoF to get everyone in focus might have worked better at that distance for that particular shot. your problem is you have too much background at that distance and that aperture.</p>

 

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<p>The basic rule is that the wider the lens, the greater the DOF and the longer, the less. Thus, as someone said, the only way to radically reduce the detail of the unfocused area (bokeh) would be to radically increase the focal length.<br>

However, that said, I believe Nikon makes some "de-focus" lenses that allow you to blur the background more, somehow.... that shows pretty much how ignorant I am of this technology. Can anyone recommend any of these lenses?<br>

And, finally, I like the picture the way it is. Great shot.</p>

 

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<p>Thanks everybody for your comments. I'm learning more.<br>

Eric, your are right but the point is that I don't have more lenses now. I have the 85/ 1.8 which I used also in the concert. Once I have the chance to afford a 200mm I will make it part of my set. <br>

From the comments of everybody I can change some of my techniques in order to improve so I'll be able to do the best with I have to work with. This is as much good as having more lenses.<br>

Thanks again everybody.</p>

 

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<p>I took this shot recently with a D300s and Sigma 50-150. Focal length is 135mm (equal to 202mm) and f/2.8. As you see the depth of field is shallower than the 105mm. I think for a crop sensor, this lens is absolutely ideal. (I'm actually considering trading it in for the new optical stabilized version.)</p><div>00Ynpg-363651584.jpg.46ca95213171582929e291f4ef79fc6b.jpg</div>
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<p>Jorge, one other not yet mentioned trick is to focus your lens slightly before your main subject at its 20m distance; say focus at 19.6m. Focused at 20m, the background musicians will become blurred when 1m or more off, and so will the ones now at 20.6 m off, and the ones 21 m behind will now be even more blurred, i.e., more out of focus. There is a trade-off here: the actual subject at 20m distance will not be as critically sharp as they would be if focused on correctly.</p>

<p>But other than using a wider 105 mm lens fully open or a lens of longer focal length, nothing will really help you here.</p>

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