F-stop , Shutter speed

Shamrock

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Hello all just a quick few question that i am sure you get ALL the time so i am sorry to ask it again lol but i know if you go up in f stops you have to go down just as many in shutter speeds ( i think ) but what i want to know is how do you pick the f stop ,does it come down to what you want in focus ? like picking a large aperture to blur the back ground or a smaller one for more detail and 2) is there a formula to help get the shutter speed to match your aperture ? IE: say at random i pick an aperture of 5.6 how would i know the shutter speed ? or does it matter i know faster shutter speeds stop motion , but does that also mean i would get greater detail ? or vise versa would i use a slow shutter speed for better detail ...or does it all depend on your meter readings ?????


P.S.
When it comes to Macro whats better ? i seen a lens with a macro ratio of 1:2 and also i seen one that was 1:3.9

LOL i'm so lost !!!!
 

ksmattfish

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You must previsualize the image you want. Then determine what is most important. It could be depth of field (DOF), or how you want a moving subject to appear. You might have to go with certain settings due to environmental or equipment issues. Then you adjust the other setting to achieve the proper exposure. If there are several important considerations, then you often must compromise. This is where your photo diverges from someone else's photo of the same subject.

When you pick f/5.6, you know what shutter speed to pick by reading you meter(in-camera or hand held). Or from experience you may be able to judge the light yourself.

A good rule to know is "Sunny 16". Outside on a bright sunny day (no clouds) the proper exposure is f/16 and your shutter set at 1/ISO(film speed). Add 1 stop if partly cloudy. Add 2 stops if cloudy. Add 3 stops if stormy, etc.... Then adjust aperture/shutter to your needs for the particular photo.

The advice for avoiding camera shake when holding the camera is to use a minimum shutter speed of 1/lens focal length. Some people are steadier and can hand hold at slower speeds. Some folks are pretty twitchy. Only experience will show you where you fit in.
 

Tyjax

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Great, great answer. Nothing to add. Brevity is the soul of wit. And information.
 

motcon

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you have to go down just as many in shutter speeds ( i think )

for an originally zone 5 metered exposure; you are correct.


but what i want to know is how do you pick the f stop ,does it come down to what you want in focus ? like picking a large aperture to blur the back ground or a smaller one for more detail and 2) is there a formula to help get the shutter speed to match your aperture ?

yep; the f stop is all about distance of focus.

http://www.uscoles.com/fstop.htm

IE: say at random i pick an aperture of 5.6 how would i know the shutter speed ?

if your camera has an aperture priority mode, then your shutter speed will automatically be selected. if you don't have aperture priority, then you need to expose for the correct ev (exposure value). you are correct; one stop of aperture is one stop of shutter in the opposite direction.

http://www.chem.helsinki.fi/~toomas/photo/ev.html

or does it matter i know faster shutter speeds stop motion , but does that also mean i would get greater detail ? or vise versa would i use a slow shutter speed for better detail ...or does it all depend on your meter readings ?????

stop motion min is an accepted 1/250 (depending on the velocity and speed of motion, of course). greater detail? no. the sharpest a lens can be is around 2 stops down from wide open. eg - an f2.8 lens is sharpest at f5.6. if i want 'sharp', i generally shoot at f8.

sharpness has nothing to do with meter readings; it has to do with the manufacturer of the glass (mtf) and the optimum aperture (above).

while brevity is a lost art, so is explanation.
 
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Shamrock

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I couldn't have got a clearer answer thanks so much.

I am thinking of getting a new lens for my Minolta maxxum 450si , she has never let me down , but i am being a bit picky because i live in canada and most things on line are in US $ ,that means add even more for me! so i am thinking either the Tamron 75-300mm f4-f5.6 marco ...ratio 1:3.9 or the minolta maxxum 75-300mm F4.5-5.6 macro ...unknown ratio . any quick suggestions it will be used to help get more into photograpy ,not any thing pro.
 

motcon

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here is a great site for mtf ratings. mtf is a measure of overall sharpness at different aperture values:

http://www.photodo.com/nav/prodindex.html


i can't find the tamron for the life of me.


here is the minolta:

Grade: 2.6 35mm/AF Minolta AF 75-300/4,5-5,6 II

the grading is on a scale of 0-5 with 5 being the best. that isn't too bad for being a minolta zoom.


fyi: it is not a true macro unless it is 1:1. if it isn't a 1:1, then the focus ratio is nothing more than a figure of closest focus distance. you will not get the close up shots of nose hairs with a 1:1.39.
 
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Shamrock

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THANKS everyone who has posted you guys have made it so easy to understand , not so lost any more lol thanks again!!!!!!


And as for my lens i think...THINK i found the one for me even tho its a bit more then i wanted to pay but it seems to me to be the best (in my price range ) that i have come a crossed ...IT's a Sigma Minolta mount...Sigma description: Sigma's 70-300mm F4-5.6 APO MACRO SUPER is one of several new tele zoom lenses. It is a compact Apochromatic tele zoom lens incorporating two Special Low Dispersion glass elements in the front lens group, plus one Special Low Dispersion glass element in the rear lens group, to minimize chromatic aberration. It is a Tele-Macro Zoom lens, capable of focusing down to 1:2 (half life-size) reproduction ratio at 300mm focal length

And it's around $150 us so all in all not bad i think ,any one heard of any problems with this lens ? thanks for all your help guys !!!!
 

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