Was that supposed to be directed at me (who used what is essentially the 'unsharp mask' algorithm minus a step or two, regardless of who it came from)....or "louis" for calling me a fool?
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USM causing misinterpretation of AF accuracy?
- Thread starter rdbruski
- Start date
DavidP #28649
Forum Pro
Louis4, Louis44, and Louis444 (if there's no Louis4444, ..., already).
Those 3 are trolls. Ignore this family
John
Those 3 are trolls. Ignore this family
--
John
Pearl Rider
Senior Member
You'll soon learn that there are rules for David and then there are rules for everyone else. If you follow a statement with an "LOL" or any emoticon, the statement is still considered at face value. And as silly as it seems, you might find some people are actually offended by YOUR use of an emoticon but never raise this concern towards David and he's one of the most prolific emoticon user here. If David insults anyone but follows it with an "LOL" or any emoticon, it's negated. Furthermore, if he feels like badgering someone into submission, it's perfectly acceptable. And DON'T claim your camera works fine because it must pass David's inspection process before it will be regarded as fact.I followed that with a LOL. If you don't understand that then look
it up.
As far as the focal plane goes I could care less the picture is
sharp and clear and that is that.
Jeff S
WB9ZPO
Pearl Rider
Senior Member
And one other thing that draws people to the conclusion of an AF issue is that the shoes are MUCH more distinctive being of such high contrast than the comparatively LOWER contrast of a person's face. The white stitching on the brown shoes definitely stands out as an eye catcher. What seems to be assumed here by some people is HOW you took the shot. They seem to place their own technique into the equation, assume you did the same thing they would, and declared their conclusion based on the assumption. I was glad to see someone inject the "camera angle" aspect into the mix because it does have an effect on where the apparent plane of focus resides. This point was sorely overlooked.
Of course, there are some here who feel compelled to examine each and every 10D image with a fine tooth comb to try and find a problem with it. For some reason, they feel this NEED to do so. Maybe they got a bad camera. Maybe they expected it to perform as well as a camera costing a LOT more and it didn't. ONE person here just does it for fun. Others, just enjoy looking at the beautiful images like your fine crop of children. They probably favor their momma. ;-)
Pearl Rider
Senior Member
I'd also like to add that if David wouldn't stick ONLY to the "AF issue" threads and spread a little of his knowledge around, it'd make a positive difference.
Pearl Rider
Senior Member
Oh, that's right! Phil would ban you... AGAIN. ;-)
Dan Honemann
Senior Member
From your original post above:
Dan
I think the reason David and others have remarked about the plane of focus rather than the composition or other qualities of this image is because you were offering it as an example of a properly focused image.
Dan
He's got the data, he's got the brain. What have YOU got besides your endless ASSuming? LOL
You don't even own a fast lens. Doesn't this make you blind, "AF accuracy"-wise?
People will talk Mishkin regardless. Because he's analyzing what people need and what they can't find in any of the reviews.
You don't even own a fast lens. Doesn't this make you blind, "AF accuracy"-wise?
People will talk Mishkin regardless. Because he's analyzing what people need and what they can't find in any of the reviews.
DavidP #28649
Forum Pro
Hmm, I know he owns the 28-135 IS.
What other lenses does he own?
The answer could go a long way to explain why some never see any AF issues.
http://www.outboundmusic.com
Your link to independent music!
What other lenses does he own?
The answer could go a long way to explain why some never see any AF issues.
--
http://www.outboundmusic.com
Your link to independent music!
Mishkin's math skills are an insult for anybody with experience in theoretical and applied math, I can assure you that a 100%...
...but that's not the point. The image shown to seemingly indicate "sharpness" works by filtering for edge contrast (use the high pass filter or work with difference layers in PS). The reason why such a method fails to identiy the plane of sharpness set on the camera can be on objects with very little edge contrast. It's therefore not possible to determine plane of sharpness in PS. End of story.
That's good because this creates an excellent learning environmen.! And you would definitly benefit from such an environment.
Hope that helps.
Your experience in theoretical and applied math? ROTFLMAO!!!
Then it should be piece of cake for you to show Mishkin's math is wrong. Why don't you do it?
Mishkin's method can be improved by dividing the derivative (when you shift layers by 1 pixel and set blending to Difference, you essentially calculate the absolute value of derivative) by the image itself, to "normalize" the derivative. When this is done, sharp edges with low difference between the two sides of transition will show sharpness correctly. However, there's no function "divide" in PS. Mishkin's method still does a good job in showing the sharpest parts of the image.
Show us YOUR method of finding the sharpest part. Where's YOUR beef?
Pearl Rider
Senior Member
Except that I and some others with this lens have gone to the extreme miniimum focus range and you can see the shallow DOF and the target was tack sharp. Now I might see some deviation if I get a faster lens and get the DOF down to a razor blade width but I don't shoot that way and never have. If I want to try and make the AF system fail, I'm sure it will. What does that tell me? It's not perfect. That's old news or at least it should be common sense. Now you and Mish, er, I mean, "Processor" can chastise and ridicule all you wish to but the fact remains that the 10D is a good camera for most people... just not you and Mish, er, "Processor".
DavidP #28649
Forum Pro
I disagree with the last statement, simply because of this fact: Imagine the focal plane being on something devoid of almost all detail, while there's lots of detail on image planes at exactly 1/3 DOF behind and in front of the real focal plane.
The methodology presented (done in Photoshop) would show two sharp planes of focus, with a plane of poor focus in between.
The method works great, though, for things with uniform amounts of detail throughought the image.
http://www.outboundmusic.com
Your link to independent music!
The methodology presented (done in Photoshop) would show two sharp planes of focus, with a plane of poor focus in between.
The method works great, though, for things with uniform amounts of detail throughought the image.
--
http://www.outboundmusic.com
Your link to independent music!
It's safe to ASSume from your words that your don't know elementary optics of photography. The fact that DOF appears shallow to you, doesn't mean high AF accuracy. You should dig into Mishkin's equations, particularly the elementary one, [CoC due to misfocus]=[AF offset from focal plane to sensor plane] [F-stop]. At close distances, DOF is very shallow, however, AF can still be off by a significant amount (just not clearly visible due to everything being razor-thin), due to large F-stop.
Then why you do you troll in the threads of serious amateurs and professionals who DO shoot fast apertures regularly and do see AF issues?
There's no need to make AF system fail - it fails for itself at f/2.8 and faster. It destroys valuable shots and upsets people. That's why they discuss these issues here.
OK, now you admit that 10D is not perfect. Are you Canon basher now? LOL
Now, tell us, is D60 not perfect, too? Obviously it is. But why it's AF accuracy was well-matched with 7.4u pixels? Why the successor did not retain this accuracy? Why those who shot f/2.8 and faster, got pixel-sharp 6MP pics consistently with D60, and only sometimes 6MP with 10D?
Do you agree with Canon Germany that 10D requires higher precision AF sensor than Elan 7, and yet, 10D's sensor is Elan7's, so that AF errors are more visible and more frequent with 10D?
Do you agree that taking Elan's AF sensor and soldering it in 10D was a bad decision?
if by "most people" you mean f/5.6 shooters, than yes. But it's no good for f/2.8 and faster shooters. Canon should have specified AF accuracy in published specs to allow people make an educated purchasing decision. If I knew that 10D's AF was less accurate than D60, I wouldn't have bought 10D, I either would've left my D60 or bought a 1D.
I agree that Mishkin's method doesn't work on surfaces devoid of all detail. In such areas, even eye has difficult time determining whether this surface is in focus.
I think the refinement of Mishkin's method - derivative divided by the the total amplitude of transition across the edge - would show sharpness better. Also, with such images as the one we discuss - resized for the web and sharpened - Mishkin's method shows some areas as sharp which were not actually very sharp in the unresized original. Mishkin's method should be used on originals, preferrably unsharpened.
John
I think the refinement of Mishkin's method - derivative divided by the the total amplitude of transition across the edge - would show sharpness better. Also, with such images as the one we discuss - resized for the web and sharpened - Mishkin's method shows some areas as sharp which were not actually very sharp in the unresized original. Mishkin's method should be used on originals, preferrably unsharpened.
--
John
DavidP #28649
Forum Pro
Adobe could build this "sharpness indicator filter" into the next version!
http://www.outboundmusic.com
Your link to independent music!
--
http://www.outboundmusic.com
Your link to independent music!
Also, you accused DavidP of discussing 10D's AF issues because he doesn't own 10D. But he IS the one who's qualified to discuss AF issues because he does own many fast lenses and shoots regularly with them. He knows what he's talking about. YOU DON'T. Because you don't own fast lenses. You're not qualified to talk about AF issues whatsoever.
Go spend $65 on 50/1.8, it will widen the pupils on your eyes. LOL
It's amazing that someone "AF accuracy-blind" can write THOUSANDS of nonsense posts "AF issues? what AF issues?"
Pearl Rider
Senior Member
processor wrote:
But even I DID have a focus issue with MY camera... that's MY camera and not anyone else's. I would never ASSume that it affects them all when I can read reviews and testimonials from people who DON'T have a focus issue with the 10D. That wouldn't be logical.
But even I DID have a focus issue with MY camera... that's MY camera and not anyone else's. I would never ASSume that it affects them all when I can read reviews and testimonials from people who DON'T have a focus issue with the 10D. That wouldn't be logical.
You're delving into Mishkin's theoreticals but I'm talking about in the real world. You're saying that the implied focus plane may not actually be the actual focal plane. So what? Like I said before, these cameras do not have perfect AI or AF. In the situaions where absolute precision is needed, the operator must take control. That's just common sense. Now if your aim is to just dog the 10D's AF, then you've made your point.
Some do and some don't. Like David, you tend to lean towards anyone who has HAD a problem as being representative of the performance of ALL 10Ds while disregarding those who haven't had a problem shooting the camera "regularly" at maximum aperture, which, I tend to do more often than not. Now if I get a different lens and it displays a significant problem, I'll get it fixed. Seems like that's taboo here.
SOME people have had problems... many OTHERS have NOT. But what you and David like to propose is only citing situations MORE likely to make the AF fail.
Well, Mishkin, I would be a fool to believe that imperfect people can manufacture a perfect product on an assembly line. Are you a fool?
There have been conflicting reports of this and, of course, you only highlight the ones who claim the D60 works (or worked) better and disregarding those who have experienced greater success with the 10D. I see you're a good study of David's techniques.
I'm not going to get embroiled in your theoretical BS. The 10D is what the 10D is... for better or worse. If it doesn't work for you, then what's keeping you from getting something else? Many others are using it, enjoying it, and sometimes buying a second (or third one) so why must you decide it's a "bad" camera?
I don't KNOW that they did that and, further, I'm not running the company and I don't think YOU and DAVID are either. They brought out a feature-laden camera that MANY more people are having success with than those who aren't for a price that many MORE people could afford than before it's appearance.
Maybe YOUR camera has issues at that aperture but I can see that others aren't having the problems you are so how can you say it affects them all? Oh, I forgot, you "measurbations" overrule any practical experience.
Pearl Rider
Senior Member
Not accurate. I said that David seems to spend a LOT of time and ENERGY dicussing AF issues concerning a camera he doesn't ANY vested interest in have or have ANY experience with.
... and if it STILL doesn't show an AF issue, well, you'll just claim I work for Canon and wouldn't admit it anyway so what's the point?
That's because I didn't. MANY others HAVE. I just get all the credit. ;-)
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