Luminous Landscape Forum
Site & Board Matters => About This Site => Topic started by: Kevin Raber on March 23, 2018, 05:49:30 pm
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We just published another in our continuing series of the Rediscover series, this one about MTF Charts and understanding them. There are many people that find MTFs hard to understand and with this article you should be able to understand MTF charts and how they can help you understand the performance of a lens. Check it out HERE (https://luminous-landscape.com/rediscover-understanding-mtf-charts/).
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I don't wanna know. Can you dig it?
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I don't wanna know. Can you dig it?
Is this supposed to be a joke or are you trying to say something serious? What's the point?
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No joke I just am not interested in reading an MTF chart.
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Are you trying to infer that because YOU aren't interested in this material it shouldn't be published? Or are you OK with it being published because other people may find it instructive?
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Doug - I don't want to read that you don't want to read. Dig it?
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Are you trying to infer that because YOU aren't interested in this material it shouldn't be published? Or are you OK with it being published because other people may find it instructive?
What is your problem or are you just a natural troll?
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I don't have a problem, I'm trying to understand what motivated your initial post. Personal attacks are not tolerated on this website.
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I don't think I owe anyone an explanation. You are reading things into it that I never said.
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I don't think I owe anyone an explanation. You are reading things into it that I never said.
Nope, not reading anything into anything; I just asked you several questions to clarify where you are coming from, but it is indeed your privilege not to answer them, devoid of personal insults of course.
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What is your problem or are you just a natural troll?
Doug, you are contributing nothing useful to this thread and that remark is gratuitously offensive. You are banned from posting for a week.
Jeremy
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Doug, you are contributing nothing useful to this thread and that remark is gratuitously offensive. You are banned from posting for a week.
Jeremy
That's a bit unkind; after all, he only said he had no interest in such charts.
There may be an interpretation difficulty (a little as in wardrobe malfunction) with the "Can you dig it?" sentence, which to me, comes over as nothing more than an alternative to "Would you believe it?". (And yes, he did not begin with any apparent intent to attack; if anything, it could be read that the attck came to him, first.)
And personally speaking, yes I can believe it. I have zero interest in charts either, because due to my too many years in this photographic life I have come to realise that most of the stuff written about lenses and their characteristics makes no difference at all in any real-life situation. Two fashion shots, one made with a Rollei armed with a 2.8/Sonnar and the other through a second Rollei with its Schneider alternative would be indistinguishable beyond model pose variation. I suggest that the people who obsess over these charts and tests and experiments are not actually all that interested in photographs as photographs, but more so as in test vehicles for their overarching interest in science above art.
Which is perfectly okay too, with the proviso that it should not be assumed (or even implied) that those people are greater or more dedicated photographers than those who just want a tool that works for them.
As Alan said, a tough life in the hot seat...
;-)
Rob
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I naively opened this thread thinking it was discussion of the article and it was my intention to comment on how much I enjoyed Michael's writing. I certainly miss his contributions to this site. As to the actual topic of this thread: the snarky comment should have gotten the response it warrants which, in my mind, is to ignore.
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I think we should all understand and accept several basic principles, including but not limited to:
(1) There is something to be said for dignified tolerance.This website caters to a very large number of people who have all manner of different interests in the vast and multi-faceted world of photography. Some things interest some people more or less than others, and Kevin is doing his best to reflect that with the variety of material from the artistic to the scientific published here. Any one who doesn't get warm and fuzzy over a particular topic, say MTF charts, is free to not read about them.
(2) Insulting other members is against the rules and even if there were no rules, it's common decency not to go there. Unfortunately, decorum in public discourse can't be taken for granted these days, so it's necessary to protect acceptable standards of conversation.
(3) Our unfortunately departed founder built this website on the basis of writings about artistic and scientific aspects of photography that are classic - in the sense that they will not lose their timeliness or utility any time soon. Kevin thought it fitting and useful to bring back a curated number of these articles, of which some will be of more or less interest to different people; this too should be respected as a matter of interest to the membership as a whole and an on-going tribute to our founder, regardless of whether a number of members warm-up to a particular topic or not.
Turning to the particular matter at hand - MTF charts - yes, not everyone's piece of cake, not something to ruminate about in the field making photos, but definitely very useful when deciding what lens to buy. A time and place for everything.
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MTF=Modulation Transfer Function
As mhelm pointed out, the acronym “MTF” should be defined, preferably at the beginning of the article. Funny how often this happens, an explanation of something that is identified only by an acronym.
As for the comment by DougDolde, I don’t sense any sarcasm. A bit of fun, yes. As Rob pointed out, not all photographers are fascinated by technology. Reading the comment I admit to a sense kinship.
It seems the current zeitgeist for sensitivity is in LuLa too. :D
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And here I thought the latest post in the Coffee Corner about guns is going to be controversial ... lemme go make some popcorn for this one too.
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:-)
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Is this supposed to be a joke or are you trying to say something serious? What's the point?
No joke, and the point is Doug simply answered the question:
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Slobodan,
Reply #13 says all I intend to say about this topic. I've got a ton of productive stuff to do today, so I'm signing-off it.
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I think we should all understand and accept several basic principles,
One of which is that abbreviated writing in an internet forum is a poor medium of communication lacking nuance and inviting misunderstanding. What did Doug's original post mean - is anybody sure? Did it merit all this self-righteous jumping up and down? Hard to believe!!
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One of which is that abbreviated writing in an internet forum is a poor medium of communication lacking nuance and inviting misunderstanding. What did Doug's original post mean - is anybody sure? Did it merit all this self-righteous jumping up and down? Hard to believe!!
So, Jeremy, were you bouncing upwards or coming down at the time of posting?
Concision is sometimes better than too much eloquence; for one thing, it helps to keep down the use of electricity and thus the heating up of the world through the hand (keyboard) of man. Of course, that many will not blame that hand is something entirely else, and I shall not go there unless invited... as you know, I'm one with a very keen dedication to the observing of thread sanctity.
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Thank you, Kevin, for putting this on the site again. I have looked at the original from time to time and it is useful to have somewhere to refresh my understanding if I am thinking of a new lens and such a chart is available.
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IMO if your intent with a post is to be wry or even snarky then you oughta include something to signal this. Otherwise you're likely to be read, regardless of intent, negatively. This is especially helpful when the atmosphere is already prickly. Being aware of the vibe is a Good Thing.
-Dave-
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IMO if your intent with a post is to be wry or even snarky then you oughta include something to signal this. Otherwise you're likely to be read, regardless of intent, negatively. This is especially helpful when the atmosphere is already prickly. Being aware of the vibe is a Good Thing.
-Dave-
Dave, that conclusion, indicating one will probably be misunderstood unless an arrow to the key within which one is posting is included, is both likely to slow responses and strangle them altogether out of frustration at the woeful lack of perfectly fitting emoticons.
Surely, part of the charm of communication must lie in the reader's ability to leap about confidently, understanding the greater picture? Suggesting he may not achieve that level of mental athleticism could, of itself, lead to action on behalf of a guardian angel! Beware! Ad hominem is a pretty broad swamp over which to leap.
:-) or, alternatively, :-(
Rob
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We just published another in our continuing series of the Rediscover series, this one about MTF Charts and understanding them. There are many people that find MTFs hard to understand and with this article you should be able to understand MTF charts and how they can help you understand the performance of a lens. Check it out HERE (https://luminous-landscape.com/rediscover-understanding-mtf-charts/).
Thank you for republishing this article, Kevin! I remembered it as one of the most accessible and informative pieces on this subject, as so many of Michael’s essays were. But I couldn’t easily find it on my own.
No, I don’t use MTF charts to buy lenses and plan no purchases in the immediate future. But understanding how to read an MTF chart certainly adds to the richness and enjoyment of photography for me. Thanks!
Sent from my iPhone using Tapatalk
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Hi,
I certainly look at MTF data before buying any lens.
Actually, I would say that MTF data is as good as any information we can get on lens, but there may be a significant sample variation.
The samples that manufacturers publish MTF data for may be very good samples. High quality MTF measuring gear is very expensive, so using it may be very expensive.
All that said, MTF data is probably the best way to exploit lenses. Is it better than making your own test? It is hard to say. To many variables in a user test.
One reason to test lenses is to screen bad samples from good samples. Jim Kasson has developed a test for screening lenses: https://blog.kasson.com/lens-screening-testing/
I did apply that test to three of my lenses, the Sigma 24-105/4L on the Sony, the Distagon 60/3.5 CF on the Hasselblad 555/ELD and the Planar 100/3.5 on the same Hassy. All those samples were pretty OK.
My take is that MTF data for a lens, that is about the best info you can get. But, you still need to look in the data...
Best regards
Erik
Thank you for republishing this article, Kevin! I remembered it as one of the most accessible and informative pieces on this subject, as so many of Michael’s essays were. But I couldn’t easily find it on my own.
No, I don’t use MTF charts to buy lenses and plan no purchases in the immediate future. But understanding how to read an MTF chart certainly adds to the richness and enjoyment of photography for me. Thanks!
Sent from my iPhone using Tapatalk
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Dave, that conclusion, indicating one will probably be misunderstood unless an arrow to the key within which one is posting is included, is both likely to slow responses and strangle them altogether out of frustration at the woeful lack of perfectly fitting emoticons.
Surely, part of the charm of communication must lie in the reader's ability to leap about confidently, understanding the greater picture? Suggesting he may not achieve that level of mental athleticism could, of itself, lead to action on behalf of a guardian angel! Beware! Ad hominem is a pretty broad swamp over which to leap.
:-) or, alternatively, :-(
It's all about context…and prior behavior. If the overall vibe of a place is relaxed and jovial you likely don't need emoticons or other signals of intent, even though you may use 'em for emphasis. Same if you've shown yourself to be a quipster, or whatever your thing is, and other folks get this. But like I said: know the vibe.
-Dave-
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Also, I think Michael got Leica and Zeiss reversed early on in this piece. For most of the 20th Century Zeiss aimed for high contrast while Leitz opted for high res. "High" in the context of what was achievable at the time, of course.
-Dave-
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1) Thanks for the article; I am sure that it is of value to many readers of this site, even if probably a minority.
2) I am puzzled why people so often post just to say that they are not interested in an online posting ...
3) ... but the best response to such an apparently worthless comment is usually to move on silently (just as one might wish the author of the comment had done) ...
4) ... more so if it could be a misunderstanding or a failed joke, which is common enough with brief, typed online comments.
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1) Thanks for the article; I am sure that it is of value to many readers of this site, even if probably a minority.
2) I am puzzled why people so often post just to say that they are not interested in an online posting ...
3) ... but the best response to such an apparently worthless comment is usually to move on silently (just as one might wish the author of the comment had done) ...
4) ... more so if it could be a misunderstanding or a failed joke, which is common enough with brief, typed online comments.
My sentiments exactly.
Having avoided getting any understanding of MTF charts for many, many years, I am one of the rare individuals who is interested and thus pleased that this was rereleased.
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... I am puzzled why people so often post just to say that they are not interested in an online posting ...
Which wasn't the case here. He was simply answering the question posed, in bold and big letters, in the subtitle of the article. He also succinctly expressed an opinion that many share, i.e., that many photographers are simply not that into technical minutia. It is just as legitimate opinion as is the opposite one from those who drool over charts.
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Which wasn't the case here. He was simply answering the question posed, in bold and big letters, in the subtitle of the article.
Yes, and when asked, he answered:No joke I just am not interested in reading an MTF chart.
Cheers,
Bart
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Yes, and when asked, he answered:
Cheers,
Bart
An your point is? Other than confirming what I said?
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An your point is? Other than confirming what I said?
To explain the obvious, as BJL said, 2) I am puzzled why people so often post just to say that they are not interested in an online posting ...
Your answer that "He also succinctly expressed an opinion that many share, i.e., that many photographers are simply not that into technical minutia." doesn't answer that question.
If (many?) photographers are not into such issues, then why respond, to begin with?
Cheers,
Bart
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... If (many?) photographers are not into such issues, then why respond, to begin with?
Oh, Lord! He responded because the article asked for a response.
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Which wasn't the case here. He was simply answering the question posed, in bold and big letters, in the subtitle of the article.
Hence my point (4)
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Oh, Lord! He responded because the article asked for a response.
No, the article posed a question which it then sought to answer, as is pretty normal for articles. The article wasn't attempting to elicit a response.
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Hi,
I don't this is really relevant relating to MTF. MTF is per definition 1 at zero frequency and drops with increasing frequency.
My take is that the contrast discussed with regard to Leica and Zeiss is more related to veiling flare. Before antireflex coating there was a balance between using more air to glass surfaces, which allows for better correction, or minimising air to glass surfaces and keeping down veiling flare.
But, with introduction of AR-coating much of the issue was history.
Best regards
Erik
Also, I think Michael got Leica and Zeiss reversed early on in this piece. For most of the 20th Century Zeiss aimed for high contrast while Leitz opted for high res. "High" in the context of what was achievable at the time, of course.
-Dave-
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No, the article posed a question which it then sought to answer, as is pretty normal for articles. The article wasn't attempting to elicit a response.
Maybe the article itself wasn’t, but then the link to the article was posted in a forum, where, by definition, things, and articles, are supposed to be discussed. Especially those articles which start with a question, however rethorical it might have been. He provided a legitimate point of view, one of several possible. There was no reason to jump on him with conjectures.
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Maybe the article itself wasn’t, but then the link to the article was posted in a forum, where, by definition, things, and articles, are supposed to be discussed. Especially those articles which start with a question, however rethorical it might have been. He provided a legitimate point of view, one of several possible. There was no reason to jump on him with conjectures.
Yes, the forum elicits responses. His seemed devoid of much of anything beyond snark and when asked to clarify, he descended into name calling.
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Re: The actual article - very useful and a clear cogent explanation. I've always wondered about them and was glad of the Cliff's notes approach. Very good. Contrast vs resolution, another decision range to add to the many that seem to define photography.
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Re: The actual article - very useful and a clear cogent explanation. I've always wondered about them and was glad of the Cliff's notes approach. Very good. Contrast vs resolution, another decision range to add to the many that seem to define photography.
Exactly, and that why it should be relevant for many types of photography. It also explains part of the Medium Format 'look', which has to do with larger detail (more magnified in the sensor plane), and thus higher MTF/contrast in the microdetail (more realistic at larger magnification output sizes, and because usually less magnification is required).
Subjects like MTF and limiting resolution were mandatory parts of my official education to obtain a license as Professional Photographer when such licenses were still required in my country.
Cheers,
Bart
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It also explains part of the Medium Format 'look', which has to do with larger detail (more magnified in the sensor plane), and thus higher MTF/contrast in the microdetail (more realistic at larger magnification output sizes, and because usually less magnification is required).
Ah. Thank you. The few times I've used Medium Format I've always had this sense of being 'in' the optics, like I'd dipped my head into the lens itself. Your note points to part of why, the lens is more enveloping given its relative scale to my eye, but it's the contrast in the microdetail that hooks you in.
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I have to admit that I find MTF charts very useful when buying lenses: better a review of the data than a very expensive mistake. Having bought the lens I do of course test to confirm there are no unexpected behaviours.
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Re: The actual article - very useful and a clear cogent explanation. I've always wondered about them and was glad of the Cliff's notes approach. Very good. Contrast vs resolution, another decision range to add to the many that seem to define photography.
+1. This isn't a topic on my radar but I read it anyway and learned some new concepts. Even if I never use them, I'm glad I spent the minor amount of time reading the article! It's kind of shocking that people feel the need to spend time bitching about a piece that does nothing but add to one's understanding of the topic of photography. I guess such people practice the 'ignorance is bliss' approach to life and learning and other's have to spend more time replying in agreement than just reading the piece and learning. Sad but so common these days.
This seems so appropriate in light of the complaints:
Learning is not attained by chance. It must be sought for with ardor and attended to with diligence. -Abigail Adams
"It is better to say nothing and be thought a fool than to open your mouth and remove all doubt".- Abraham Lincoln
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Andrew, I gotta start collecting these quotes of famous authors ending some of your posts; they're classics.
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Yes, the forum elicits responses. His seemed devoid of much of anything beyond snark and when asked to clarify, he descended into name calling.
Not really, he made a joke based on the beginning of Michael's article, and when confronted with a holier-than-thou response from one of the forum "big hitters" declined to comment further. Then he got banned.
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Andrew, I gotta start collecting these quotes of famous authors ending some of your posts; they're classics.
(http://www.lincsdomesticservices.co.uk/wp-content/uploads/2015/07/ironing1.jpg)
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Not really, he made a joke based on the beginning of Michael's article, and when confronted with a holier-than-thou response from one of the forum "big hitters" declined to comment further. Then he got banned.
Nope, please re-read Replies 7, 8, 9, 10 for the correct sequence of the conversation and the real (and only) reason the Moderator intervened.
Anyhow, the constructive side of this discussion is that there are members who still believe (a) that MTF charts can be useful, and (b) the reposting of this article of Michael's was appreciated. It's not to say that every member has to agree with every editorial decision made on this website - that would indeed be a real impossible stretch, but good to know what clientele there is for what kinds of material.
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Just imagine what the forum would be like if every member posted "I'm not interested in this" in every thread in which he/she had not interest.
If I did that, I'd never have time for photography!
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Just imagine what the forum would be like if every member posted "I'm not interested in this" in every thread in which he/she had not interest.
If I did that, I'd never have time for photography!
And yet, here you are.
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I am an optical engineer and photographer, but my specialty is not imaging optics. I learned quite a bit from this post about reading lens manufacturer's MTF charts, but MTF itself was not really defined.
In a line pattern, modulation is the ratio min/max of brightness. An imaging lens transfers the object line pattern to its image line pattern with some loss of modulation. Thus "Modulation Transfer.
Modern lens design software can produce theoretical MTF charts for free with a keystroke. Theoretical MTF is useful for comparison, but as-built MTF can never be as good as theoretical. MTF is degraded by lens manufacturing tolerances, assembly tolerances and AR coating performance. It also depends on focus and zoom position.
P.S. I am also a mathematician, which is a requirement to pass LULU's Turing test.