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F-stop info on lenses

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badprop_za
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F-stop info on lenses

Unread postby badprop_za » Wed Dec 09, 2009 8:39 am

Morning you all,

Could someone please explain toi me what the F/stop info on the lenses mean?
For example: 70-300mm f/4-f/5.6 :huh:

I understand aperture and what the effect is on changing it, but the info on the lens confuse me. Does it mean that the lens will work at its best in the ration provided?
Why do time fly when you are having fun?

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Ah well on to the next planning phase.....

Sprocky
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Re: F-stop info on lenses

Unread postby Sprocky » Wed Dec 09, 2009 8:47 am

Badprop, in your example all it means is that at 100mm you will have a max aperture of f4 and at 300mm it will drop down to f5.6

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Josh of the Bushveld
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Re: F-stop info on lenses

Unread postby Josh of the Bushveld » Wed Dec 09, 2009 9:56 am

An F-stop is a measure of how wide the aperture is, compared to the focal length. Therefore the smaller the number, the wider the aperture (hole).

As Sprocky mentioned, the range of maximum apertures applies to the range of focal lengths. If you need more info, just shout! :)
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DuQues
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Re: F-stop info on lenses

Unread postby DuQues » Wed Dec 09, 2009 10:05 am

Does it mean that the lens will work at its best in the ration provided?

Actually, no.

Most lenses are at their sharpest stopped down a bit (closed a little).
In your case it will most likely be at f/8, just like my 100-400 f/4.5-5.6.

You will get slightly faster exposure times than with my lens as your lens can go to f/4 (at the short end) wide open where mine is stuck at f/4.5.
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Josh of the Bushveld
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Re: F-stop info on lenses

Unread postby Josh of the Bushveld » Wed Dec 09, 2009 10:06 am

I agree with Duco (but don't always follow the advice).

Check this link too.
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Scipio
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Re: F-stop info on lenses

Unread postby Scipio » Wed Dec 09, 2009 2:47 pm

You are all wrong, when this happens you pray, "Let him F-Stop" :pray:

Image

Sorry, couln't resist. :twisted:

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michel367
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Re: F-stop info on lenses

Unread postby michel367 » Wed Dec 09, 2009 4:06 pm

:funny: :funny:
That's what I call a short stop and a fast run. :lol:

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badprop_za
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Re: F-stop info on lenses

Unread postby badprop_za » Wed Dec 09, 2009 5:13 pm

Nice one Scipio!! :lol:


I don't run, I internally create a small island of you know what to protect myself
Why do time fly when you are having fun?

KNP - May'14 done and dusted :(

Ah well on to the next planning phase.....

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Switchback
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Re: F-stop info on lenses

Unread postby Switchback » Wed Dec 09, 2009 7:00 pm

Yip, agree with above.

At 70mm focal lenght the max you can open your apperture is F4 and at 300mm only F5.6. Of course, you can always close it down quite a bit.

That's why professional lenses like the 70 - 200mm F2.8 is so good, you can keep the lens open at F2.8 throughout the focal lenght.
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Sprocky
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Re: F-stop info on lenses

Unread postby Sprocky » Thu Dec 10, 2009 8:01 am

Scipio wrote:You are all wrong, when this happens you pray, "Let him F-Stop" :pray:


Scip, if he doesn't F-Stop then it is time to try another old darkroom technique called dodging. 8)

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Caracal
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Re: F-stop info on lenses

Unread postby Caracal » Thu Dec 10, 2009 10:58 am

Sprocky wrote:
Scipio wrote:You are all wrong, when this happens you pray, "Let him F-Stop" :pray:


Scip, if he doesn't F-Stop then it is time to try another old darkroom technique called dodging. 8)



:D :D :D :D

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Kicker Cat
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Re: F-stop info on lenses

Unread postby Kicker Cat » Fri Dec 18, 2009 9:29 am

Have a look at this site - http://www.dryreading.com/camera/ the info was posted on one of the threads before - helps to explain things in a practical way

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michaelpr
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Re: F-stop info on lenses

Unread postby michaelpr » Mon Jan 04, 2010 4:00 pm

Kicker Cat, That link helped me a lot, so thanks :thumbs_up:

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BushNuts
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Re: F-stop info on lenses

Unread postby BushNuts » Sun Mar 28, 2010 6:20 am

Sprocky wrote:
Scipio wrote:You are all wrong, when this happens you pray, "Let him F-Stop" :pray:


Scip, if he doesn't F-Stop then it is time to try another old darkroom technique called dodging. 8)


...or you'll find out how good your Shutter control is! :oops:
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