Focusing limit switch


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aaron80

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Mar 29, 2006
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#1
What is a focusing limit switch? Should I set it to full or to limit? Which one is better? Does it affect my focusing speed? Eg. I have a 70-200mm lens, what does the focusing limit switch do and what should I set it to?
 

kcuf2

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Dec 29, 2005
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#2
if u set it to full, the focus will focus from very near to very far away...this means that it will take a long time.

But if u set the focus limit, it makes the lens "go" from mid range to far range only, of course it will travel faster.

u imagine: I m at jurong now and I want to go changi airport. If u did not set the limit switch, the lens will go from jurong to changi and then back to jurong then lock focus on your object.

If u set the limit switch, the lens will go from city hall (halfway) to changi and back to city hall. Of course faster rite??

That is if ur desired location is city hall.

If u set the limit switch, ur lens wont be able to focus any thing between jurong and city hall.

understand the purpose of focus limit already?
 

jbma

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Dec 28, 2003
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#3
if u set it to full, the focus will focus from very near to very far away...this means that it will take a long time.

But if u set the focus limit, it makes the lens "go" from mid range to far range only, of course it will travel faster.

u imagine: I m at jurong now and I want to go changi airport. If u did not set the limit switch, the lens will go from jurong to changi and then back to jurong then lock focus on your object.

If u set the limit switch, the lens will go from city hall (halfway) to changi and back to city hall. Of course faster rite??

That is if ur desired location is city hall.

If u set the limit switch, ur lens wont be able to focus any thing between jurong and city hall.

understand the purpose of focus limit already?
haha Ilike the way you explained it.
 

aaron80

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#4
Thanks for the interesting explanation!:) I think I roughly understand liao.. Eg. If I zoom my lens to 135mm and set the focus limit then it will only focus from 135mm to 200mm range? But if I set it to full, it will go the whole range from 70 to 200? Is this correct?

if u set it to full, the focus will focus from very near to very far away...this means that it will take a long time.

But if u set the focus limit, it makes the lens "go" from mid range to far range only, of course it will travel faster.

u imagine: I m at jurong now and I want to go changi airport. If u did not set the limit switch, the lens will go from jurong to changi and then back to jurong then lock focus on your object.

If u set the limit switch, the lens will go from city hall (halfway) to changi and back to city hall. Of course faster rite??

That is if ur desired location is city hall.

If u set the limit switch, ur lens wont be able to focus any thing between jurong and city hall.

understand the purpose of focus limit already?
 

kcuf2

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Dec 29, 2005
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#5
Thanks for the interesting explanation!:) I think I roughly understand liao.. Eg. If I zoom my lens to 135mm and set the focus limit then it will only focus from 135mm to 200mm range? But if I set it to full, it will go the whole range from 70 to 200? Is this correct?
er...nono.. u cant set the exact position where u want the range to be, the exact position is already preset in the lens already..if u look at ur lens at the switch there, u see the words "FULL" and "oo - 2.5m" rite?

BTW, oo = infinity
For the "FULL" rite, the lens will focus from 1.5m - oo and for the "oo - 2.5m" it will focus from 2.5m - oo

Thus in effect, the lens "travel" 1m less of focusing.. but that also means anything within 2.5m range from u, u cant focus. it can only focus 2.5m and beyond..
 

aaron80

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#6
Thanks alot kcuf2!:D I fully understand liao.. Guess that means I will have to use the focusing limit switch according to situations lah.. If I am intending to shoot nearer subject, i will have to switch to full so that it will focus from 1.5m to oo.. Thanks!:thumbsup:

er...nono.. u cant set the exact position where u want the range to be, the exact position is already preset in the lens already..if u look at ur lens at the switch there, u see the words "FULL" and "oo - 2.5m" rite?

BTW, oo = infinity
For the "FULL" rite, the lens will focus from 1.5m - oo and for the "oo - 2.5m" it will focus from 2.5m - oo

Thus in effect, the lens "travel" 1m less of focusing.. but that also means anything within 2.5m range from u, u cant focus. it can only focus 2.5m and beyond..
 

Artosoft

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Aug 31, 2005
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#7
er...nono.. u cant set the exact position where u want the range to be, the exact position is already preset in the lens already..if u look at ur lens at the switch there, u see the words "FULL" and "oo - 2.5m" rite?

BTW, oo = infinity
For the "FULL" rite, the lens will focus from 1.5m - oo and for the "oo - 2.5m" it will focus from 2.5m - oo

Thus in effect, the lens "travel" 1m less of focusing.. but that also means anything within 2.5m range from u, u cant focus. it can only focus 2.5m and beyond..
Depend on the lens. My Nikkor 60mm f/2.8 AFD Micro can set "FULL" and "LIMIT".

When I set from "FULL" to "LIMIT", and the distance is under limit (IIRC, 2.5m, say distance is 1m), it will only auto focus from nearest distance to 2.5m.
When I set from "FULL" to "LIMIT", and the distance is over limit (say distance is 5m), it will only auto focus from 2.5m to infinity.

Regards,
Arto.
 

DeSwitch

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#8
on some lens, like my Tamron 90, Limit can be from min dist to mid point or mid point to infinity. If i wan the lower part, manually turn the focus to min dist and den switch to Limit. if want the uper half, focus to infinity den set limit seitch.


On my canon 100-400L lens, its either set to min focus dist @1.8m or 6.3M.




kcuf2 explination is the best. easy to visualise.
 

aaron80

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#9
Hmm..that means for different lenses, the limit and full actually work differently lah.. Guess the choice of either full or limit depends on situations. But is safe to say that when switching to full, the focusing speed will be slightly slower?
 

zac08

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Feb 21, 2005
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#10
Hmm..that means for different lenses, the limit and full actually work differently lah.. Guess the choice of either full or limit depends on situations. But is safe to say that when switching to full, the focusing speed will be slightly slower?
No... the focusing speed is still the same. But the time taken for it to hunt all over the range will be longer than when you limit it to a smaller range to hunt from.
 

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