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Old Dec 18, 2006, 7:38 AM   #1
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I'm hoping someone can explain something to me about my new lens. I just got a Tamron 70-300mm Di lens with the Macro switch. I admit that I haven't really had a chance to sit down to read the information it came with, but it doesn't look like it's very informative.



Here's my question: What exactly does that switch do? I mean, obviously it's for taking macro shots, but I can't see what it changes. I know that I can't engage the macro switch unless the focal length is between 180 and 300mm. The thing is, I've tried a few shots playing around with that switch and I honestly can't see the difference. Itdoes seem to allow me to focus onobjects a littlecloser, but I don't see a difference in detail. If anyone can give me a short tutorial on what this feature does or how to use it, I would greatly appreciate it! Thanks in advance.



Here's the lens I have: http://www.tamron.com/lenses/prod/70300_di_a017.asp
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Old Dec 18, 2006, 7:46 AM   #2
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hi, don't know the tamron but have a sigma 70-300 macro and the switch lets it focus closer (quite a bit actually; you can get 1:2 when its on). put it on manual focus and try it with the switch on and off and you should be able to see the difference.

once you get used to the lens i'd love to see some close-up shots. i've considered selling my sigma and getting the tamron. (the sigma only does macro at 300mm which can be limiting.)

hope this helps, eric
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Old Dec 18, 2006, 7:52 AM   #3
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ejbrusselsprout wrote:
Quote:
hi, don't know the tamron but have a sigma 70-300 macro and the switch lets it focus closer (quite a bit actually; you can get 1:2 when its on). put it on manual focus and try it with the switch on and off and you should be able to see the difference.

once you get used to the lens i'd love to see some close-up shots. i've considered selling my sigma and getting the tamron. (the sigma only does macro at 300mm which can be limiting.)

hope this helps, eric
That does help...a lot. Thank you. I will try that later today if I can. I did notice that it allows me to be closer to an object when I focus on it. I guess I just need more time to play. I really like the lens so far. It's great to have that reach.
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Old Dec 18, 2006, 7:57 AM   #4
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I don't have this lens either but I do have a couple of other lenses that havespecialized macro features.

On my A70-210/4, the macro setting on the focus/zoom ring activates a limited focal length mechanical path within the focusing mechanism that allows close focusing only in the 70mm focal length. I suspect your switch is most like this feature. The function is to allow a limited use of the optical path in a range within which the macro feature will be effective without other deleterious optical effects occuring (mostly color aberrations I suspect).

On my FA100/2.8 macro, there is a focus limit switch thatkeeps the autofocus mechanism from hunting too much by limiting the range offocustotelephoto only. It is used in non-macro situation to keep the motor from having to search through the entire range of focus to find the focus point.

RG
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Old Dec 18, 2006, 7:57 AM   #5
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the switch unlocks the barrel of the lens and allows it to get longer for macro distances. this helps control how much distance the AF has to deal with. it's a great feature.

eric, the newer sigmas do macro between 200-300, as far as i know.

roy
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Old Dec 18, 2006, 8:56 AM   #6
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Thanks guys. I'll have to make time this week to play around with it. The weather has been unseasonably warm this week, so there may be a few insects around to test it on.
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