Sat 29-Dec-12 01:46 PM | edited Sat 29-Dec-12 02:03 PM by Lnease
Hi, I'm a new member and am deciding on a macro lens for my d7000. I have about decided on the Nikon 105 f2.8 Ed-if af-s vr micro, but had one question. I do plan to use this primarily for macro (mostly flowers, plants and he occasional bug), probably mostly on a tripod. The only criticism i've read of this lens is that at close focusing distances the magnification changes, necessitating reframing, which could make use with a tripod more difficult.
I would love to hear from 105 users if this is really an issue, or just more theoretical problem. The overall reviews of the 105 look great. The other main lens I'm considering is the tokina 100, but I've been so pleased with my other nikon lenses, I'm leaning toward the 105. Any help appreciated.
I have the Nikon 105 f/2.8 and nearly always use it on a tripod. There is some change in focal length as it's racked from infinity to MFD due to magnification being achieved by internal focusing (the IF in the lens ID). I've never had a problem with it. And I've done focus stacking with the lens where I'm changing focus points from a fixed position.
I did read that criticism in a review a while ago but I haven't experienced any problem with it and I'm not sure the author ever did either frankly.
If and when that becomes a problem, you can always buy a focusing rail. This allows several inches of camera movement on the tripod, solving the problem — you can rack the camera front or back without moving the tripod (some more sophisticated models allow lateral movement, too).
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I don't know how you'd avoid the "problem" anyway - are there any macro lenses that don't change like that? At any rate, I have used a whole raft of macro lenses and they all do the same thing. And I usually shoot macro on a tripod, too.
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There's no way to change the focal length, since it's a 105mm lens. The closer you focus, the greater the magnification ratio.
Once you get to a certain distance, moving the tripod small amounts becomes problematic. A 2-way focus rail will solve this issue, allowing you to move the camera/lens up to 12" (depending on the rail you purchase) without moving the tripod.
You can also purchase 4-way focus rails (or buy two 2-way rails and put them together yourself), which will not only allow front-to-back movement, but side-to-side as well
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>There's no way to change the focal length, since it's a 105mm >lens.
Well actually it's pretty well known that the effective focal length of most modern macro lenses does indeed change (get smaller) at or near the minimum focus distance. I know my Tamron 60f2 is only about 50mm at its MFD.
>There's no way to change the focal length, since it's a 105mm >lens. The closer you focus, the greater the magnification >ratio.
The lens in question is an IF (internal focus) lens; IF is achieved by reducing the effective focal length of the lens in order to achieve closer (than infinity) focus. In general, the quoted focal length of a lens is its FL when focused at infinity.