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03/18/2010 10:14:33 PM · #1 |
Do teleconverters change the focus at all? Meaning if my lens focuses from 2 feet to infinity, will it still focus from 2 feet to infinity (and can I still trust that turning the ring all the way will still focus it to infinity and not beyond?)?
Message edited by author 2010-03-19 19:01:29. |
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03/19/2010 08:04:50 PM · #2 |
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03/19/2010 08:19:35 PM · #3 |
If you have one, just try it out. If you are thinking about getting one, and want to know, I can try it with one of mine. I never thought about it that way re where minimum and max focus would be. I have noticed that a lot of the Nikkor lenses will focus beyond infinity if you turn the ring all the way. I have a feeling that feature might be useful for extreme conditions like shooting in the heat of a desert or cold of a polar zone where the lens would be expanded or contracted by the temperature.
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03/19/2010 08:21:38 PM · #4 |
As far as infinity, that will not change. By the way, most lenses focus slightly *past* infinity, so don't think that when you twist the ring all the way to that end you are perfectly focused on infinity.
As far as closest focus, I can't guarantee that the minimum focus distance won't change somewhat, but the difference should not be big. |
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03/19/2010 09:39:37 PM · #5 |
Originally posted by kirbic:
By the way, most lenses focus slightly *past* infinity |
There's gotta be a Nikkor or two that have a limit at infinity ("hard stop?") |
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03/19/2010 10:33:11 PM · #6 |
Originally posted by George:
Originally posted by kirbic:
By the way, most lenses focus slightly *past* infinity |
There's gotta be a Nikkor or two that have a limit at infinity ("hard stop?") |
One of the reasons that lenses focus (slightly) past infinity is temperature changes. You don't want to find that at certain temperatures, you aren't able to get quite to infinity anymore. Another reason is manufacturing tolerances. Controlling the focus stop to be *precisely* at infinity for all camera bodies is nearly impossible. A third reason (especially with older lenses) is compatibility with infrared, which has a slightly different infinity focus setting.
So the short answer is "no, there are no lenses that can ensure that you are precisely at infinity focus when you rotate the focus ring all the way to the stop. |
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03/19/2010 11:29:24 PM · #7 |
Infinity is a long way out there anyway, so it don't really matter if you miss it by a couple of feet. : )
I am careful to avoid shooting focused to the stop, unless it's a grab shot and I know that aperture will give me enough DOF to reach the horizon.
I keep one of these things Vivitar 2X Macro Focusing Teleconverter in my bag of tricks, and it seems to work pretty good up close, and fair with a tele lens at normal shooting distances. It works best with a tele lens where there is plenty of bright light, so that I can stop down a couple of clicks with the lens. I don't know if they have an AF version of this item though. They seem to go for about $40 or 50 on eBay.
I have a couple of manual Micro Nikkor's, so I don't use it too often for close work, except when I want an unusual shot with a fisheye.
Here are a couple of images shot with it.
  
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