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03-15-2013, 10:04 AM   #16
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QuoteOriginally posted by aleonx3 Quote
I can understand that more focus point helps AF tracking... but I can't understand that it helps accuracy. I have seen many photos taken by Canikon cameras with focus point cluttered all over the places - sometimes distances from the camera are so far apart (for example, a point on the person's face and another point 30 feet behind the person). How does the camera pick those points (obviously, most of these shooters just let the camera choose those points). How does the camera pick the focus with the DOF deep enough to cover both subjects. Therefore, my overall impression when I look at those pictures are not sharp at all.

So, IMHO, more points will provide better tracking, but for still, there may be an optimal number of cross-type focus point as someone suggested (more than 11 but less than 39). Your thoughts?
It may help accuracy - not in the way you think.

In my example, if we take the E-3's focus points and overlay a person's face. Let's pretend that the eyes is what I want to focus on, and it lands between two focus points. A camera with larger/less focus points will have difficulty being precise, as Joe Penn said. It might select the eyes, it might select the ear, it might select the nose, the brow, etc.

A camera with more points (thus smaller), will let you select a point that covers the eye more precisely. This is all assuming you are shooting with the ability to change your focus point. This method is much more accurate in getting the right focus point than focus and recomposing - because as Finn said, recomposing changes the plane of focus.

03-15-2013, 10:22 AM   #17
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QuoteOriginally posted by JinDesu Quote
It may help accuracy - not in the way you think.

In my example, if we take the E-3's focus points and overlay a person's face. Let's pretend that the eyes is what I want to focus on, and it lands between two focus points. A camera with larger/less focus points will have difficulty being precise, as Joe Penn said. It might select the eyes, it might select the ear, it might select the nose, the brow, etc.

A camera with more points (thus smaller), will let you select a point that covers the eye more precisely. This is all assuming you are shooting with the ability to change your focus point. This method is much more accurate in getting the right focus point than focus and recomposing - because as Finn said, recomposing changes the plane of focus.
If the camera selects all those point shown,... then at the very best, it is an average (not optimal unless taking DOF in consideration)... for example, I got this from a friend's shot. None of the people in this picture is sharp.

https://www.pentaxforums.com/forums/pentax-k-r/161465-how-many-users-set-focu...focus-c-3.html

Unless, of course you select only one point (that you are most interested in) suggested by the camera....
03-15-2013, 10:34 AM   #18
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If you want that much control, is it faster to use selective focus points, or just use manual focus lenses? IN a shot like this...



I selected with as much of the wire cage in front of the bird as possible. In essence placing the bird at the back end of the Depth of Field. Is that type of shot even possible with AF? I don't want the Birds Eye as the center of my DoF I want a spot somewhere ahead of it on the cage, but I won't know exactly where, because it's having the bird in acceptable focus, but not the sharpest possible focus that matters. My guess is that AF doesn't handle this very well on any system. SO once you admit you're going to have to use manual focus for maximum effect, you reduce your argument to what's possible in an AF camera. I'm guessing there is no AF that can anticipate every possible situation. How does a smaller sensor help, if you have to cycle through all the points to get the one you want? Isn't that going to cause missed shots while the camera is cycling?

Having never used a camera with smaller and more focus points I really have no idea. Once again, the fact that some may prefer more focus points based on what they shoot and how, does that make it better for everyone? or does it become an un-necessary nuisance in some situations.

Given that I shoot mostly landscape and macro... there are very few times I need additional focal points, and on those occasions the Pentax selective focus has always gotten it done for me. All these examples of situations that I haven't experienced in the field have me scratching my head.
03-15-2013, 10:43 AM   #19
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QuoteOriginally posted by normhead Quote
If you want that much control, is it faster to use selective focus points, or just use manual focus lenses? IN a shot like this...



I selected with as much of the wire cage in front of the bird as possible. In essence placing the bird at the back end of the Depth of Field. Is that type of shot even possible with AF? I don't want the Birds Eye as the center of my DoF I want a spot somewhere ahead of it on the cage, but I won't know exactly where, because it's having the bird in acceptable focus, but not the sharpest possible focus that matters. My guess is that AF doesn't handle this very well on any system. SO once you admit you're going to have to use manual focus for maximum effect, you reduce your argument to what's possible in an AF camera. I'm guessing there is no AF that can anticipate every possible situation. How does a smaller sensor help, if you have to cycle through all the points to get the one you want? Isn't that going to cause missed shots while the camera is cycling?

Having never used a camera with smaller and more focus points I really have no idea. Once again, the fact that some may prefer more focus points based on what they shoot and how, does that make it better for everyone? or does it become an un-necessary nuisance in some situations.

Given that I shoot mostly landscape and macro... there are very few times I need additional focal points, and on those occasions the Pentax selective focus has always gotten it done for me. All these examples of situations that I haven't experienced in the field have me scratching my head.
Even on my k-x, I have used selective points to choose the point I want to use on the fly before. Usually for portraits. The Canon cameras have a little joystick that is used for this purpose, and I would assume that the selected point illuminates in the viewfinder - so you don't even need to take your eyes off it. You are assuming that it takes a lot of time to select the point. I have not found it to take that much time to select a point - no longer than it would take to try to manually focus.

In addition - how would you manually focus in such a situation above if you wanted to catch the bird's eye? Were you thinking to manually focus until the focus indicator says it's in focus? Or did you mean with live-view? Or a focusing screen? The first would be ineffective (focus and recompose), the second is not a good argument for "speed", and the third would be pretty hard to do on an APS-C camera.

QuoteOriginally posted by aleonx3 Quote
If the camera selects all those point shown,... then at the very best, it is an average (not optimal unless taking DOF in consideration)... for example, I got this from a friend's shot. None of the people in this picture is sharp.

https://www.pentaxforums.com/forums/pentax-k-r/161465-how-many-users-set-focu...focus-c-3.html

Unless, of course you select only one point (that you are most interested in) suggested by the camera....
You select the point you want. I wouldn't bother using full area AF unless it was for tracking.

03-15-2013, 10:45 AM   #20
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If I could somehow add 260 points to my K-7, it wouldn't focus any better. By itself, it's just a number, which appears to be less than the competition. Simply raising the number of points won't do anything without supporting hardware (Norm's point).
03-15-2013, 10:53 AM   #21
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I'll chip in with another take on this. We enthusiast photographers rarely use auto focus point selection, we want to be in control. But when I hand my camera to my sister- or mother-in-law, I am really glad to have auto enabled, otherwise I'm 100% the background will be really sharp.
03-15-2013, 10:54 AM   #22
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Norm, I agree with you on that point, the more point is probably better, but only when you know how to use them. As a seasoned photographer like you are (I enjoy your photos), I do the same, I seldom let the camera decide on the focus point to pick. I do manual focus a lot as well with my legacy glasses. Unfortunately most people believe that more points will lead to more 'sharp' picture magically.... those in that category don't even have a concept of DOF and hyperfocal distance. One person I know changes camera every time when there is a new model, starting with 50D, 60D, 7D and now a 6D with the believe that a better photos will come with better camera.
03-15-2013, 10:58 AM   #23
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QuoteOriginally posted by bdery Quote
I'll chip in with another take on this. We enthusiast photographers rarely use auto focus point selection, we want to be in control. But when I hand my camera to my sister- or mother-in-law, I am really glad to have auto enabled, otherwise I'm 100% the background will be really sharp.
I did exactly the same... only before handing the camera to another person who obviously don't know how to operate my camera (complete idiot proof) and turn on live view.

03-15-2013, 11:03 AM   #24
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QuoteOriginally posted by Just1MoreDave Quote
If I could somehow add 260 points to my K-7, it wouldn't focus any better. By itself, it's just a number, which appears to be less than the competition. Simply raising the number of points won't do anything without supporting hardware (Norm's point).

Another point I don't like about the focus point cluttering in the viewfinder. I have once hold a friends D200 to take a shot of the couple, I am completely astounded by the itched points on the viewfinder screen that I cannot see the subject very well - just like "swamp of bees" on the face of the person. Why are they etched on the screen? Why not lit up only when the points are in focus (or near focus)? Why did I not hear those people complaining about viewfinder cluttering? Am I the only one who cannot stand it?

Last edited by aleonx3; 03-15-2013 at 11:11 AM.
03-15-2013, 11:07 AM   #25
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QuoteQuote:
I have not found it to take that much time to select a point - no longer than it would take to try to manually focus.
I set the lens to MF, or in this case with the A-400 it's already set to MF. I bring the focal plane back towards the bird until the bird's eye was in sharp focus, then maybe another small rotation of the barrel, instinctive based on what my DoF is, and press the shutter release. it takes no time at all. These guys are hopping around all the time, very difficult to get a picture of. If the process wasn't fast, I wouldn't have this image. When I first started doing, it I was surprised how fast it is, because I never seek all the way to the end and then rotate all the way back. I know immediately if I'm going the wrong way and recover quickly. AUto-focus defintiely lets you shoot burst faster, but that doesn't always get me the shot I want. In MF as long as I get a shot off, it's more likely to be the shot I want. And I'll get as many shots as I want, without the camera resetting the focus while I'm shooting. I'm remembering why for years i thought AF was a gimmick not worth paying for. Don't get me wrong, I love my AF, but not as a tool for fine adjustments. For fine adjustments, at least IMHO you still need to go to MF. AF is a crapshoot.
03-15-2013, 11:15 AM   #26
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QuoteOriginally posted by normhead Quote
I set the lens to MF, or in this case with the A-400 it's already set to MF. I bring the focal plane back towards the bird until the bird's eye was in sharp focus, then maybe another small rotation of the barrel, instinctive based on what my DoF is, and press the shutter release. it takes no time at all. These guys are hopping around all the time, very difficult to get a picture of. If the process wasn't fast, I wouldn't have this image. When I first started doing, it I was surprised how fast it is, because I never seek all the way to the end and then rotate all the way back. I know immediately if I'm going the wrong way and recover quickly. AUto-focus defintiely lets you shoot burst faster, but that doesn't always get me the shot I want. In MF as long as I get a shot off, it's more likely to be the shot I want. And I'll get as many shots as I want, without the camera resetting the focus while I'm shooting. I'm remembering why for years i thought AF was a gimmick not worth paying for. Don't get me wrong, I love my AF, but not as a tool for fine adjustments. For fine adjustments, at least IMHO you still need to go to MF. AF is a crapshoot.
Norm, nice technique, thanks for sharing... would you do catch-in-focus in this case with manual focus lens by slipping a piece of aluminium foil under the base of the lens? Probably not as accurate as you would want as it would trip the shutter when the focus locks in from behind the bird or in front (such as the cage in that case).
03-15-2013, 02:03 PM   #27
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QuoteOriginally posted by thechumpen Quote
Why is it better to have more focus points?
Also may be of no practical purposes, I don't know, but think of the bragging rights against the other brands.
03-15-2013, 02:13 PM   #28
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QuoteOriginally posted by aleonx3 Quote
Norm, nice technique, thanks for sharing... would you do catch-in-focus in this case with manual focus lens by slipping a piece of aluminium foil under the base of the lens? Probably not as accurate as you would want as it would trip the shutter when the focus locks in from behind the bird or in front (such as the cage in that case).
Well this was another surprise. I learned to ignore the in focus red flash. Even with my glasses and poor eyesight, with the VF optics adjusted for use with my glasses on, I can detect perfect focus visually. You see the eye go sharp then start to go fuzzy and you rotate back an automatic 16th of a rotation or so and you're in perfect focus. For what i was doing, I actually rotate a bit beyond perfect focus to keep the DoF in front of the bird.

I have to say, for those of us who practiced hours on techniques like this before there was auto-focus, it probably comes a lot easier than for someone who has always depended on AF to get sharp focus.
03-15-2013, 02:31 PM   #29
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QuoteOriginally posted by JinDesu Quote
A camera with more points (thus smaller), will let you select a point that covers the eye more precisely. This is all assuming you are shooting with the ability to change your focus point. This method is much more accurate in getting the right focus point than focus and recomposing - because as Finn said, recomposing changes the plane of focus.
Focus and recompose, that is another talking point. I could never understand why these celebrity shots taken by so called "pro" photogs, that the beautiful ladies appear so short...because the technique they use focus-on-the-face, then tilt the camera down to take the full portrait shot.
03-15-2013, 02:38 PM   #30
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QuoteOriginally posted by kerrowdown Quote
Also may be of no practical purposes, I don't know, but think of the bragging rights against the other brands.
You are right... the general public just believe the more the better similar to the megapixel concept without understanding the value (or demerit value) of additional points.
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