why is my focus ring not working?

ph0toe

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trying to use manual focus. i have the 24mm-105mm lens switched from auto to manual. i also switch to viewfinder /video live view and magnify x5 to zoom in and then turn the focus ring but it isn't getting sharper. what am i doing wrong?

using mark 3 5d
 

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Are you closer than the minimum focus distance of your lens?
 
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ph0toe

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Are you closer than the minimum focus distance of your lens?

hi, thanks for the reply. can you explain to me in baby terms what that means? always confused by that. why each lens have different minimum focus?
 

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Are you closer than the minimum focus distance of your lens?

hi, thanks for the reply. can you explain to me in baby terms what that means? always confused by that. why each lens have different minimum focus?
The amount of movement a lens needs to focus will be dependant on it's focal length. Macro lenses are typically designed to focus closer than other lenses, it's just one of a host of parameters that are optimised by the manufacturer based on how the lens is expected to be used.
 
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ph0toe

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Are you closer than the minimum focus distance of your lens?

hi, thanks for the reply. can you explain to me in baby terms what that means? always confused by that. why each lens have different minimum focus?
The amount of movement a lens needs to focus will be dependant on it's focal length. Macro lenses are typically designed to focus closer than other lenses, it's just one of a host of parameters that are optimised by the manufacturer based on how the lens is expected to be used.


so what about a zoom lens? it can focus in and out as far as it allows (for me 24mm-105mm) , which is a large range.
is there a minimum focus distance for 24mm, to say 50mm to 85mm to 105mm?

and if so, what is it?
 

petrochemist

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It sounds as if you might be confusing the zoom control which changes the lenses focal length (& so it's field of view) with the focus control.
Most manual zooms are designed to have the same focus settings at all focal lengths, AF zooms can vary slightly but it's usually fairly small amounts.
I do have one adapted lens where the zoom control makes a vast difference to the focusing distance, zoomed out it's macro only, zoom in far enough and infinity focus is possible, this is usual for lenses mounted on extension tubes but not to anything like this extent.

I don't have a 24-105 of any type in my lens hoard. I do have numerous 70-200 lenses & the minimum focus distance of each design will differ. Some will go into a pseudo macro mode at one end of the zoom & allow much closer focusing in this mode.

I did a quick google for canon 24-105 lenses & found the specs. of one version which quotes the minimum focus distance as 450mm (about 1.5 ft) I believe the Mk2 version is similar.

This is probably a limitation required for it's large zoom range as my 24mm prime focuses to less than half that, though the focus distance is fairly typical for 200mm lenses.
 

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trying to use manual focus. i have the 24mm-105mm lens switched from auto to manual. i also switch to viewfinder /video live view and magnify x5 to zoom in and then turn the focus ring but it isn't getting sharper. what am i doing wrong?

using mark 3 5d

Try connecting it to the camera.... Just kidding.
 

wfooshee

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Don't confuse focal length with focus distance. The 24-105 has nothing to do with the actual subject distance, that's just a measurement of the lens's focal length, which is a measure of it field of view, with a smaller focal length having a wider view.

A zoom lens set at 24mm focal length will not be able to focus on something only s4mm away.
 

weepete

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hi, thanks for the reply. can you explain to me in baby terms what that means? always confused by that. why each lens have different minimum focus?

Minimum focus distance is the closest your lens can be to a subject and still focus. If you are closer than that you won't be able to focus at all, and need to move the lens further back.
 
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ph0toe

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so from my understanding, every len has a minimum focus. as petrochemist alluded to, the specs for my len is about 1.5 ft. so moving my camera mounted on a tripod 1.5ft away or further should result in the image focusing.

with all the parameters (iso, shutter and iso) in my environment figured where the light meter dialed right at 0, i should get a correctly exposure clear crisp image, right?


well when i tested this using manual focus and then magnifying it on my camera , it is very blurry. i see people able to just tilt the focus ring which is the closest turn knob ( shows macros to infinity), it doesn't change the focus. not being to achieve this means if i want to shoot product photography, or if i want to shoot video and have it focus on a subject eye for example i am at a stall....
 

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Does your autofocus work? Can you manually focus on something much further away?
 
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ph0toe

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Does your autofocus work? Can you manually focus on something much further away?

autofocus does work. when i snap a picture on af it beeeps indicating so, and the image turns out sharp ,which is to be expected
 

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Pick a focus length on the zoom. Back away from subject, auto focus, turn on m focus, gradually move up and adjust m focus ring (not the zoom) until sharp. Keep moving forward until you reach the closest point where you can still achieve sharp focus. That’s as close as you’re going to get. You can play with the zoom to see if that makes a difference in getting you closer. Keep in mind that most zooms are not at their sharpest at either extreme.
 
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ph0toe

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Pick a focus length on the zoom. Back away from subject, auto focus, turn on m focus, gradually move up and adjust m focus ring (not the zoom) until sharp. Keep moving forward until you reach the closest point where you can still achieve sharp focus. That’s as close as you’re going to get. You can play with the zoom to see if that makes a difference in getting you closer. Keep in mind that most zooms are not at their sharpest at either extreme.


hi thanks so much. however, when when i manual focus and then i magnify it using the button near viewfinder it is blurry when i try to move my camera closer it is still blurry no matter how much i change the focus ring where it says the number in meters all the way to infininity. i try to adjust the diaopter to seee if it fixes anything (it is clear for my eyes on the viewfinder, not blurry, so i know this is not thee issue)
 

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Pick a focus length on the zoom. Back away from subject, auto focus, turn on m focus, gradually move up and adjust m focus ring (not the zoom) until sharp. Keep moving forward until you reach the closest point where you can still achieve sharp focus. That’s as close as you’re going to get. You can play with the zoom to see if that makes a difference in getting you closer. Keep in mind that most zooms are not at their sharpest at either extreme.


hi thanks so much. however, when when i manual focus and then i magnify it using the button near viewfinder it is blurry when i try to move my camera closer it is still blurry no matter how much i change the focus ring where it says the number in meters all the way to infininity. i try to adjust the diaopter to seee if it fixes anything (it is clear for my eyes on the viewfinder, not blurry, so i know this is not thee issue)

did you follow the steps above?
 

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