- Aug 10, 2021
Umm... that doesn't back up the flat earth at all, he says he's not sure.
Umm... that doesn't back up the flat earth at all, he says he's not sure.
Your point is wrong! My only challenge is finding a way for you to accept that. Why should I ‘accept your point of view’ if it is incorrect or, rather, counter to the definition of the term?You did crop the picture.
You are not saying anything incorrect.
But you are refusing to acknowledge or consider my point.
When you crop, print and decide how far away to view the picture, the DoF for that picture was already set inside the camera.
You could say that the DoF is already set for all the various combinations you decide.
Was that necessary?
I do the same. Look at my posting history I am in and out because half the time I just can’t be bothered, after all I am the one trying to correct a misstatement here yet I am the one accused of bullying and mansplaning, though I don’t know who the woman is I was supposed to be doing that to....Over the last few years you have corrected my statements, sometimes the correction had nothing to do with the statement being made or subject. On this forum it gets to the point there is a discussion I want to be involved in, spend a few minutes typing a post and just delete it because I know someone will correct think something in it isn't just right.
This is a correct statement.
"...changed the perceived sharpness...", but the depth of field really did not change. It is like saying that a smaller sensor gives you more depth of field, when all it is doing is allowing you to fill the frame with the subject at smaller magnifications and the drop in mag is responsible for the change in depth. Or like the illusion of depth that I create when I twist my wrist to lay the area of acceptable focus over the subject's face. The depth of field chart for the lens that I use only takes into account magnification and Fstop cause those are really the only two factors that matter when shooting macro.We can disagree, but only one of us is right. I suspect you don't understand the role of the circle of confusion (CoC) in determining the DoF. You may want to read up on that a bit. It's why, for example, an image viewed at a small size appears to have deeper DoF. Here's an example where the hair and flower appear in focus at small viewing size, but in reality only the flower is in focus. The reduction in size of the full image increased the DoF because it changed the perceived sharpness of the image. The same is true in reverse – enlarging an image results in a shallower DoF.
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I like the example that @unfocused gave in another reply: Depth of field does not change when I take off my glasses and everything is equally out of focus...IF. But that's not the case. As a very simple demonstration, @unfocused stated that this statement by @Dalantech is correct:
But, it is not correct. Depth of field is not fixed when the shutter button is pressed. To claim that a false statement is true is not giving accurate information. And he has declined to give any sort of definition. Those aren't semantics, unless claiming the earth is flat is just a semantic distinction from it being (roughly) spherical.
Over at the DP Review forum, a site that is a lot more toxic than this one, there are threads where people are wondering why forum participation is down. Some of them think it is just because more people are shooting with cell phones and not the increase of idiots who will say things, while hiding behind a keyboard, that they would never say in public.My rationale really has more to do with trying to make this more of a welcoming place. There are idiots who join this forum simply to make ridiculous statements and they deserve all the venom that they get. But there are others who get bullied for posts that are essentially correct. Over the years, I've seen many well-meaning contributors (including some very high caliber photographers) driven away because a handful of participants scour the site looking for arguments.
I will concede that you can change how depth is perceived, but you really cannot change depth of field after the shutter is pressed. The manual for most macro lenses has a chart that lists the depth of field at certain apertures and magnifications, but those are the only two factors that are taken into account. Can an image seem like it has more depth because you made a small print? Sure. But that does not mean that the actual depth changed.He was wrong. Assuming that skill at something automatically confers technical understanding is silly. Muscle energy is always in the mind of Olympic athletes because it is limiting to their performance. How many of those athletes can diagram the glycolytic pathway or understand the role of creatinine in muscle function? I’d guess not many. I cannot run 100 meters in 10 seconds, but I understand muscle physiology. The fact that @Dalantech takes astounding macro images doesn’t mean he automatically understands the technical aspects of DoF any more than Usain Bolt's astounding speed means he automatically understands the sliding filament mechanism.
You do realize that I have not disagreed with you on any of the points or statements you have made other than the initial.Your point is wrong! My only challenge is finding a way for you to accept that. Why should I ‘accept your point of view’ if it is incorrect or, rather, counter to the definition of the term?
No, the depth of field was not already set because I, as the photographer, have no control over what you find acceptable sharp!
Was it necessary? Well I don’t know how else to phrase it. There is a term with a definition, I fully understand that term and several people in this thread don’t. It isn’t my opinion, it is a fact as determined by the accepted definition of the phrase, I can try to help or just not bother, so far trying to help/educate/correct the wrong hasn’t done much for me personally...
If I have 10/20 vision and my wife has 40/20 vision what is sharp to her is not sharp to me, my very measure of acceptable sharpness is different from hers. Ergo my perception of depth of field is different to hers even looking at the same photo on the same wall from the same distance.
Blows your mind doesn’t it? The same picture from the same distance can have different depths of field, areas of acceptable sharpness (the very definition of depth of field), for two people standing next to each other.
So to ‘standardize’ things a bit we work to CoC’s. Acceptable focus used to be defined as a person with average eyesight viewing an 8”x10” print from 12” away, but that was too narrow a definition given the vast differences in viewing distance and reproduction size and the move away from 8“x10” cameras and contact images from them. So a more universal way of working things out needed to be thought up, fortunately there are a lot of smart people out there and they came up with a way of taking the various format sizes into account. The diagonal of the format divided by 1500. d/1500. This gave a good approximation of the traditional ‘average‘ persons eyesight viewing an 8”x10” contact print at 12” and worked across all formats larger and smaller. But it is still based on the angle of view the final picture represents, move that image further away and your coc gets smaller in your view so you get more dof, move it closer and the reverse happens, you get less dof.
So answer me this, if the dof/coc/area of acceptable focus is defined as viewing an 8”x10” picture from 12” for a person with average eyesight, what happens to that dof/coc/area of acceptable focus if you move the picture further away? The depth of field changes, it increases, by the very definition of the term depth of field/area of acceptable focus.
This incorrect statement perfectly sums up your mistaken belief (and I suspect is the basis for the ‘real DoF’ @unfocused believes in).The depth of field chart for the lens that I use only takes into account magnification and Fstop cause those are really the only two factors that matter when shooting macro.
Nowhere did I say "only by factors set at the image capture.."Understandably, many photographers want a way to determine DoF ahead of time, but in reality that is impossible because it cannot be calculated for any image before the image is displayed and viewed (and because visual acuity matters, the actual DoF of any image can differ from one viewer to another).
After reading the post above and the similar statements in just three of the many reputable sources on the subject, if you still believe that DoF values are determined only by factors set at the time of image capture I'd advise you to avoid any long ocean voyages because you may fall off the edge of the world.
You did not, but that's exactly what @Dalantech and @unfocused claimed, and it's patently false.Nowhere did I say "only by factors set at the image capture.."
I would be incorrect, if I had claimed that...but, I didn't.
Those aren't semantics, unless claiming the earth is flat is just a semantic distinction from it being (roughly) spherical.
Don’t worry, I fully understand that some people will argue black is white just before they get squished on the next zebra crossing.Yes, and I shouldn't allow myself to be drawn into this meaningless discussion. Same old flawed arguments and mansplaining from the same people. Same links to pseudo-science. Now, depth of field has become all about perception. I only need to take off my glasses and suddenly depth of field increases because everything looks to be of equal sharpness.
Not worth my time explaining. @Distinctly Average and @Dalantech you are still correct and don't be intimidated by the bullies on this forum who say otherwise.
Indeed, and some people will continue to argue that established facts are false or 'pseudo-science' while demonstrating a complete inability to provide actual evidence to support their erroneous views. That attitude has become even more popular with the rise of "fake news" that we've seen lately.Don’t worry, I fully understand that some people will argue black is white just before they get squished on the next zebra crossing.
While that’s probably true, when on one side you have fact backed up with information from multiple, reputable sources and on the other side you have statements made with no attempt to provide external supporting information and an ‘I’m going to take my marbles and leave because I don’t want to hear an explanation’ attitude, it’s quite evident who “won” even if those making incorrect and unsupported claims never actually capitulate.…no one ever "wins" an argument on the internet.