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06-01-2009, 06:10 PM   #1
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focus point... is yours in the centre?

Just a quick question..

while using my split focus screen i noticed the centre AF point wasnt in the centre, i assumed it was the screen, after taking my split focus screen out and replacing with the original, the point isnt in the centre of that either.. it sits below left of centre

is yours?

could i of moved something when changing screens or could the focus sensor / focus point illumination of shifted position? i dont remember it being out originally

Thanks

Steve

06-01-2009, 06:32 PM   #2
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Steve, did you ever touch the focus setting to "Sel" ?
JP
06-01-2009, 06:42 PM   #3
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sorry should of mentioned that...

i only run on centre focus point.. its what im used to and its quicker for me to focus and recompose than select a point.

its only just down and left... not a significant amount.. but enough to be irritating!

Thanks

Steve
06-01-2009, 07:09 PM   #4
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Gotcha, Steve.
Well, I thought there might have been an accidental switch to the selective mode. I use the same method as yours, by the way.
I hope you can solve the problem ... sorry I can't offer much help!
Cheers.
JP

06-01-2009, 09:07 PM   #5
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QuoteOriginally posted by 5teve Quote
i assumed it was the screen, after taking my split focus screen out and replacing with the original, the point isnt in the centre of that either.. it sits below left of centre
The AF module sits in the base of the camera below the mirror and has nothing whatsoever to do with the screen.

By "off centre" are you referring to the little red LED that lights up or are you actually measuring where the focus point is?

I measured the AF range of my K100D Super by trying to focus on a small black dot on a piece of paper and found that the AF sensor covered about the following area:

06-01-2009, 09:27 PM   #6
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Mine isn't at the centre, no mattre which focusing screen I use. It took me sometime to figure out that why the focusing of the centre point wans't correct -- the little red dot not only point out which focusing point you are using but also the exact point where the camera focuses.
When I bought my K20D I checked 2 of them, the other one was even worse
06-01-2009, 10:04 PM   #7
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QuoteOriginally posted by Fable Quote
the little red dot not only point out which focusing point you are using but also the exact point where the camera focuses.
(
Not really. The red square that lights up in the viewfinder is much smaller than (and not necessarily centered upon) the AF sensor. You can only use it as a rough indication of where the camera is focusing.
06-01-2009, 10:53 PM   #8
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Mine appears to be located below the line in my split prisim screen. This seems to be normal as the stock screen may be configured differently and you are not the only one this is happening to.

06-02-2009, 10:08 PM   #9
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Just to re-iterate, the red light DOES NOT tell you where the AF point actually is - all it tells you is that you're using the centre AF point (as opposed to one of the other AF points).

The only way to tell the exact extent of your AF sensor is to do the focus test (draw a small black dot on a piece of blank white paper and try to get a focus lock on it as you repoint the camera so that the dot appears in the middle and slightly left/right/above/below the centre.
06-03-2009, 02:59 AM   #10
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thanks guys... good to know im not alone

Regarding some focus point experimenting i was doing last night... would i be right in saying that the focus points that ARE NOT the centre point and are not the extreme right / left ones are considerably smaller than the centre? if so would it be right that these are potentially more accurate than the centre point?

just thinking aloud!

Steve
06-03-2009, 11:42 PM   #11
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QuoteOriginally posted by 5teve Quote
would i be right in saying that the focus points that ARE NOT the centre point and are not the extreme right / left ones are considerably smaller than the centre? if so would it be right that these are potentially more accurate than the centre point?
I've only measured my centre AF point and so I can't comment on the relative area covered by the other points.

But I don't think it's right to say that an AF point that covers a smaller area is "more accurate". In my book "accuracy" of an AF point means it can bring an object within it's field of view to sharp focus. That's a different than saying it has a small field of view.

There seems to be a feeling among some of the posts I've seen that an AF point that covers a large field of view is a bad thing. I don't agree. If the AF point is very small then it's more difficult to make sure the subject you want to focus on is within that point's field of view. Making the field of view smaller is a tradeoff.

Since we don't have adjustable AF field of view (yet, anyway), we just have to understand how the camera works and use it accordingly, IMHO.
06-04-2009, 02:14 AM   #12
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i fully agree sean and i probably phrased my point a little poorly.

By accuracy i meant a smaller area from which the camera chooses its focus subject from? with the center point being large busy scenes can mis-focus (not saying this is any different to other brands either) so a smaller sensor area (or field of view as you elegantly put it) allows the camera to be resricted further on what it sees as the focal subject?

it was just a thought.. but...

does that make sense?

(im not complaining about accuracy of the focus nor speed or any of the common complaints either !)

Thanks

Steve
06-04-2009, 11:27 AM   #13
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QuoteOriginally posted by 5teve Quote
does that make sense?
I understand what you're saying. But I've learned that on Internet forums great huge all-out wars can erupt over different interpretations of a words' meaning - so I try to take care to choose the right ones...
06-04-2009, 03:41 PM   #14
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yes i also have seen that... however being an engineer i am stereotypically not well placed to describe things eloquently...

technically and simply yes... but eloquently and accurately no...

Thanks

Steve
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