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12-06-2009, 08:39 PM   #16
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QuoteOriginally posted by junyo Quote
Nope. You'll find that a lot of shooters use center focus recompose even with AF lenses.

Sometimes the center point is faster to lock and/or more sensitive, and some are more comfortable with it since they have it as their old habit from MF days when center focus recompose via the split image/micro prism was the preferred method to achieve sharp focus, and some just never learned different.
please remember that K-x (marketing target) is for newbie not a pro.
-> an old habit MF is not a newbie.
for daily use, indoor (home), familiy vacation, ....-> talking about MF? recompose? nee

too much talking about very-entry-level camera being pro.
if you wanna pro camera or cannot accept minor focus-point-light just go for K-7.
if you still wanna cheap camera with focus point light, u can choose D40 with 3 focus point, i choose K-x with 11 focus point.

thera are a lot of great shots taken with center focus point only.

12-06-2009, 08:43 PM   #17
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Unforgivably stupid product neutering.
12-06-2009, 09:51 PM   #18
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QuoteOriginally posted by UnknownVT Quote
All this may sound like I think the red-flash AF selection points are a distraction....
BUT not quite, there are times in lower light levels it is hard to see the AF markings/brackets in the viewfinder -
so I had to develop my trick of estimating the intersection of imaginary diagonals from corner to corner to "guess" the central position -
this may seem pedantic - but even in low light I need to know where my AF point is.
Thing is, the focus sensor is much larger than the red square that lights up in the viewfinder of some camera. So all it ends up doing is give you false confidence. Even in dim light, I think you're actually better off *not* seeing it and using your diagonal technique or otherwise just eyeballing the approximate sensor, because that's all the precision the AF sensor gives you anyhow.
12-06-2009, 09:55 PM   #19
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QuoteOriginally posted by julia Quote
for me, it is strange recompose from center-point on AF lens while you can select another focus point on LCD
I don't know how many cameras I've owned or used over the years, but it's been a few - both AF and MF. And most of them only had one way to focus - using the center. To me, it seem mind-boggling anyone would mess with pressing buttons to focus, when using the center point with focus recompose strikes me as the most natural thing in the world. Using buttons to move a dot around screen - that's a video game, not a camera:-)

12-07-2009, 02:54 AM   #20
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Original Poster
Thanks for the words of welcome, and the advice.
I learned a lot from that thread.
Great, active forum here.
Good to see.

MB

Oh, by the way, Opiedog, what are the acronyms on your sign off? Got me curious.
12-07-2009, 04:23 AM   #21
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QuoteOriginally posted by Marc Sabatella Quote
To me, it seem mind-boggling anyone would mess with pressing buttons to focus, when using the center point with focus recompose strikes me as the most natural thing in the world. Using buttons to move a dot around screen - that's a video game, not a camera:-)
+1

I must admit I too find the whole issue rather weird. In my whole life I've never manually assigned a specific focus point for the AF, aside from center spot.
12-07-2009, 04:59 AM   #22
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QuoteOriginally posted by Marc Sabatella Quote
So all it ends up doing is give you false confidence.
C'mon Marc, the sensor areas are smaller than the whole viewfinder and it is useful to know which segment you are currently addressing. And no one who has learned the lesson once will be given "false confidence".

I personally don't understand how saving a few pennies can justify crippling a camera like that. A typical business man decision.

On the other hand, there are so many "centre point focus and recompose" shooters that it is almost a waste to include the additional AF points, let alone the indicators.

Focus technique is a matter of personal preference. While some don't see the need for more than "centre focus and recompose" others appreciate the improved precision on close distance / wide aperture shots and the advantages when trying to keep moving subjects in an off-centre composition in focus.
12-07-2009, 05:58 AM   #23
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QuoteOriginally posted by junyo Quote
Also, center point focus recompose is kind of a crappy practice anyway.
The same regurgitated response!

this only assumes that the centre point focus recompose technique keeps the camera at the same spot. What if the recompose involves not tilting the camera, but shifting it on the same plane as the sensor.

If I want my subject to the side of the frame, I will move the camera left or right accordingly, not just point it in the direction of the subject then recompose. This is an easy technique especially for short distance/macro. It would be harder for longer distance as the amount needed to shift the camera left/right would be too great, but hey, at that distance DOF is large enough to make it a non-issue anyway.

12-07-2009, 07:10 AM   #24
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QuoteOriginally posted by 68deluxe Quote
The same regurgitated response!

this only assumes that the centre point focus recompose technique keeps the camera at the same spot. What if the recompose involves not tilting the camera, but shifting it on the same plane as the sensor.

If I want my subject to the side of the frame, I will move the camera left or right accordingly, not just point it in the direction of the subject then recompose. This is an easy technique especially for short distance/macro. It would be harder for longer distance as the amount needed to shift the camera left/right would be too great, but hey, at that distance DOF is large enough to make it a non-issue anyway.
It's the same response because it continues to be true. Even if center focus recompose works perfectly it assumes that your intended focal point will still be in the same location after you've repositioned, or that you're working with enough depth to cover the difference. With tight portraits, with a big aperture lens wide open, that's often not the case; a slight shift or pause after focus lock might be the difference between getting the near eye perfectly focused versus an ear or the bridge of the nose. And it still involves moving the camera after focus is achieved. Which, unless your joints are indexed rack and pinions, is almost guaranteed to introduce error at some point.

Can it work? Surely. Flintlock muskets still work. That doesn't mean there's not a better way to hunt now.

Objectively, what's are the pronounced advantages to only using the center point and not selecting one?
12-07-2009, 09:30 AM   #25
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QuoteOriginally posted by Class A Quote
C'mon Marc, the sensor areas are smaller than the whole viewfinder and it is useful to know which segment you are currently addressing.
For the record I was talking specifically about using the center point only. We all know "about" where the center is, red dot or no red dot. And my point is that knowing the *approximate* location of the center is actually sufficient - knowing the *exact* center imparts no additional useful information when using the center focus point, since the AF point is *not* limited to tha exact center.

I do agree that *if* you are using a different focus point, needing to sneak a peak at the LCD or guesstimate the location of the AF point using the etched brackets would probably a bit awkward. That's a separate topic from the one I was addressing here. But since it is the topic of this thread, I'll just reiterate my view that for most people, it need not be an issue, as there *are* other perfectly viable ways of focusing for most purposes. If you happen to be one of the small minority of people who require this method of focusing (such as for the specific purposes you mention) and cannot live with the workarounds, then by all means, buy a different camera. But for the majority of the target audience, it need not be an issue at all. Like any of the other features that were left out in order to meet the price point (and weight point) they wished to meet, sure, it's a deal breaker to some, but not to others.
12-07-2009, 09:40 AM   #26
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QuoteOriginally posted by junyo Quote
It's the same response because it continues to be true.
It continues to be a *tiny* bit true, with the discrepancy noticeable only in a *very limited* range of cases. Or are you telling me the tens of thousands of perfectly focused pictures I've taken over the last few decades are, in fact, not in focus? Yes, I know in which cases there will be a problem - and I focus manually in those cases. Which is just as well, as in most of the cases where focus recompose can cause problems, so can using AF at all, since the AF sensors are far too broad to place focus *exactly* where you want anyhow.

QuoteQuote:
Objectively, what's are the pronounced advantages to only using the center point and not selecting one?
The only one that comes to mind is the only one I need: it seems more natural to me and undoubtedly faster in most of the cases I am concerned with than fumbling around with buttons.

Anyhow, I don't no one is saying focus recompose is objectively "better" - just that it is far more viable than its critics believe. And *subjectively*, for me and the way many of us think and work , yes, it is actually better.
12-07-2009, 09:47 AM   #27
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QuoteOriginally posted by junyo Quote
If you:
  • Do off center composition
  • At large apertures or relatively close distances
  • And don't like to center focus then recompose
...then it may be an issue. I do the above a lot, so I wasn't sure about the K-x. But I wanted the high ISO performance and a more modern backup body, so I took a flyer. It is a pain to not have the overlay. Not a deal breaker, but sometimes a pain. If none of the above apply, then it's a non-issue.
This isn't a problem with a K-x. The problem is when you need to do this without moving your eyes from the viewfinder - when the subject is moving or something, or you have bad memory. You can certainly still select a point.

Even then, it has been discovered that its only slightly less convenient but still very possible thanks to center AF point:

K-x AF point selection without moving eye from VF: easy: Pentax SLR Talk Forum: Digital Photography Review

Last edited by Eruditass; 12-07-2009 at 10:18 AM.
12-07-2009, 10:03 AM   #28
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QuoteOriginally posted by junyo Quote
Also, center point focus recompose is kind of a crappy practice anyway.
Thanks for that link - I had not thought of that.

It is correct if we are dealing with very shallow depth of field.

However for years with MF lenses there was only central focusing on SLRs and rangefinders (eg: Leicas) - where would photographers focus if they were doing a half or 3/4 length portrait? I would almost guarantee it would not be the center of the frame somewhere on the body/clothing - most of us did focus on face/eye and recompose.

Now I'd be the first to agree that just because the way it's been done does not necessarily make it the best, or even the right way.

However there is just too much empirical evidence in the overwhelming number of great photographs out there - before AF -
that clearly show center focus recompose to be very workable -
including I'll bet the person that you quoted in your own sig line - Robert Capa -
he would have to focus somewhere, and I'll wager it was not always at the center of the frame -
surely Mr Capa was not using "crappy practice"...... ?

However the article you linked to is correct -
and I have already taken note. Thank you.
12-07-2009, 10:11 AM   #29
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While perhaps scientifically crappy, center-point recompose has worked just fine for me for several years now. I don't miss the point overlays at all on my K-x after using it for a week, and my K-7 (as well as the K20D before it) has always been on center point. I get great results.
12-07-2009, 10:59 AM   #30
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QuoteOriginally posted by UnknownVT Quote
Thanks for that link - I had not thought of that.

It is correct if we are dealing with very shallow depth of field.
Also, the effect depends on how flat the focs field is. The author of the referenced article makes the completely false claim tha all but the cheapest lenses have perfectly flat focus fields. The reality is quite the opposite - only macro lenses and/or the most expensive primes tend to have very flat focus fields. Most tend to curve, and curve in the same way that you'd expect: more or less spherically, so the distance to the focus "plane" is much closer to constant across the field than the article suggests.

So in practice, with most lenses, you really don't see the effect described in practice at all: whatever tiny discrepancy might exist is normally masked by DOF. You kind of have to go out of your way to see the effect. But the aforementioned article does explain the effect well (while vastly overstating its magnitude). Reading the article then thinking through the implication does suggest how to force the issue should you wish to demonstrate it to yourself.

But it's probably not possible to reproduce the problem using the kit lenses. It's possible but still surprisingly difficult to reproduce it even with most f/2.8 lenses. Even with my DA70 at f/2.4, you can only barely see the effect. It's really only the f/2 and faster primes where you'd see it on a semi-regular basis.
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