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Infinity ????

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Caracal
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Infinity ????

Unread postby Caracal » Wed Feb 03, 2010 7:57 am

Please help....

When focussing on infinity which f-stop should I be using ???
My research into this topic is confusing :?
Some say F22 and some say wide open.
:huh:

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Josh of the Bushveld
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Re: Infinity ????

Unread postby Josh of the Bushveld » Wed Feb 03, 2010 8:03 am

Caracal wrote:Please help....

When focussing on infinity which f-stop should I be using ???
My research into this topic is confusing :?
Some say F22 and some say wide open.
:huh:

I might be missing something.
Your aperture shouldn't have anything to do with your focus. Your aperture should be controlled solely to achieve a particular shutter speed (in S or Tv) or to achieve a specific depth of field.
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Re: Infinity ????

Unread postby ndloti » Wed Feb 03, 2010 8:05 am

Big f-stop number for landscapes , small f-stop number for separating subject from background (taken from a Getaway on line newsletter)
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Re: Infinity ????

Unread postby Switchback » Wed Feb 03, 2010 9:59 am

ndloti wrote:Big f-stop number for landscapes , small f-stop number for separating subject from background (taken from a Getaway on line newsletter)


Agree, your AV will depend on lighting conditions, shutter speed, DOF, etc etc.

It really is up to you, not dependant on focussing. Obviously when you are at infinity, you most probably are shooting subjects / landscape some distance from you, so generally your AV shoul be about 8 or higher, but there's no rule as far as I know.
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Caracal
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Re: Infinity ????

Unread postby Caracal » Wed Feb 03, 2010 10:42 am

Thanks everybody
Yes I understand F-stops and depth of field...

So what is the point then of focussing on infinity.....I thought everything was in focus..depth of field wise...when on infinity :? Wouldn't I be getting the same effect then on F22 for instance ???

In other words I don't think I understand the purpose of infinity.

When, how and why should we use infinity ?????

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Re: Infinity ????

Unread postby Josh of the Bushveld » Wed Feb 03, 2010 10:53 am

Infinitiy is a fictitious pount of focus. Effectively the lens is focused 'very far away', i.e. at the end of its focus range.

I'm not sure why you're getting confused, but focus and aperture are completely orthogonal - i.e. they are not connected and changing one has no effect on the other.

The point of foscusing at infinity is to focus very far away, e.g. for landscape shots.

Asking 'why would you want to focus at infinity' is like asking 'why would you want to focus on the bird 2 metres away'
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Re: Infinity ????

Unread postby bert » Wed Feb 03, 2010 11:10 am

Understand your confusion caracal
But why use autofocus for landscapes F22?

Dont think that the infinity/autofocus/landscapes should be problem
F22 and shoot. Can still use autofocus, but it might hunt searching for a autofocus point.

So i would suggest. Manual focus, bean bag or manual with the image stab on.

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Re: Infinity ????

Unread postby DuQues » Wed Feb 03, 2010 11:22 am

Check this page and print the chart(s) for your lens(es).
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Re: Infinity ????

Unread postby Josh of the Bushveld » Wed Feb 03, 2010 11:37 am

Hyperfocal distance is a new term for me. I'll have to look it up.

I guess focus point (on the lens) and depth of field are not orthogonal (at the hyperfocal distance)
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Re: Infinity ????

Unread postby Switchback » Wed Feb 03, 2010 11:59 am

The only time I have really use the infinity mark on my lenses is when I am shooting landscapes and focus manually, but even then I focus most of the time on the 1/3 plane auto focus.

The only other real time I use the infinity mark is when shooting in the dark, especially lightning that is quite far away. The lens can't auto focus on a dark subject so far away, thus the infinity mark gives me a reference for me to know my shot will be in focus. I still play around with my apperture / ISO / shutter speed etc.which is obviously not related to my focussing degree.
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Re: Infinity ????

Unread postby onewithnature » Wed Feb 03, 2010 12:09 pm

Focussing on infinity does not allow one to maximise the depth of field. This should be done by focussing on a distance that allows infinity to be just in focus (based on the depth of field the aperture will cover); that way, the maximum part of the picture - from infinity to as close as possible - will be in focus. In many of the older cameras, there were gradations on the lens itself that allowed one to do this with ease. I don't know about the modern cams.
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Re: Infinity ????

Unread postby Sprocky » Wed Feb 03, 2010 1:21 pm

This is my biggest gripe with digital cameras and technology! :wall: In days gone by you would HAVE to know the basics pricipals of light and a whole lot of other things like "Hyperfocal Distance" and an old favourite, "The Inverse Square Law". :shock: :whistle:

Now days everyone has become a "photographer" simply because you spend bucks, get a camera that can think halfway for you and you get alrightish results. Now when you try something new, you don't have a clue what to do or don't understand a word of the instructions, because you have never heard of, or learnt the terminology and used it in practice.

Anyone one ever heard of "Scheimflug's Law"? :whistle:

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Josh of the Bushveld
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Re: Infinity ????

Unread postby Josh of the Bushveld » Wed Feb 03, 2010 1:57 pm

Sprocky wrote:This is my biggest gripe with digital cameras and technology! :wall: In days gone by you would HAVE to know the basics pricipals of light and a whole lot of other things like "Hyperfocal Distance" and an old favourite, "The Inverse Square Law". :shock: :whistle:

Now days everyone has become a "photographer" simply because you spend bucks, get a camera that can think halfway for you and you get alrightish results. Now when you try something new, you don't have a clue what to do or don't understand a word of the instructions, because you have never heard of, or learnt the terminology and used it in practice.

Anyone one ever heard of "Scheimflug's Law"? :whistle:

I'll admit I haven't heard of some of those terms (and I'm one for technicalities). Please point out more holes in my knowledge :)
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Re: Infinity ????

Unread postby Sprocky » Wed Feb 03, 2010 3:32 pm

:hmz: The seven in your head. :twisted: Just joking!!!!! :lol:

There are lots of terms and calculations that used to be part of the photographic training, not sure if that stuff is still taught. Self proclaimed photographers will hardly ever get anywhere close to this jargen unless they do a reputable photographic course.

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Re: Infinity ????

Unread postby Josh of the Bushveld » Wed Feb 03, 2010 4:15 pm

Which sparks the 'philosophical' question in my head: does one need to know these techniques to take good pictures? (From a creativity point of view). Yes, sometimes you do need a technical technique to achieve an affect (like depth of field) - you can't paint without knowing about paints and media etc.

Personally, I think I focus too much on the technical and not enough on taking photos.

(Yes, I did know about the law of inverse squares, and I read up on Scheimflug's Law which I found interesting)
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