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Forum: General Photography
01-31-2019, 03:26 PM
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I don't know that anyone really thinks it's all that complicated, more that the explanation (even to the simple purpose of rote application) is very often muddled and generally not clear under what conditions things are valid. I know when I was first starting out, I'd swear if I read a half a dozen different explanations of how format influences DoF I'd get half a dozen different answers that somehow all contradicted each other. When you don't know anything, it can be tricky to evaluate a source of information - this internet of ours is a great and terrible thing.
Since many manufacturers list 'equivalent focal lengths' I think it's pretty clear that the idea isn't going to go away. I feel like I'm leading into a "if you aren't talking to your kids about equivalence, then who is?" after school special.... I'll cut it short before cheesy 80's music rolls in - all you can really do is ensure that information leaving you is accurate, concise, and appropriate for the person who is supposed to benefit from it.
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Forum: General Photography
01-31-2019, 07:29 AM
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You're just not looking in the right forums:D. I've seen some heated arguments about small flashes vs studio lights, on camera vs off camera flashes, natural light vs. artificial, etc. For any topic you can name, there are people on the internet fighting about it.
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Forum: General Photography
01-30-2019, 07:13 PM
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True, you have to scrub that crappy aps-c lens with 600 grit sandpaper for them to be equivalent. Err, or is that 267 grit? I forget which way it goes.:confused:
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Forum: General Photography
01-29-2019, 06:34 AM
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No problem! I've run into enough people adamant that the statements you've made were correct that I've become half convinced there's a different definition of DoF floating around out there:hmm:. When asked about it, no one's ever been able to provide a definition or reference that agrees with them, and few are ever willing to challenge their own understanding. So big props on your open mind and willingness to learn:).
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Forum: General Photography
01-28-2019, 07:43 PM
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So what's your definition of depth of field then? You can get as exact and technical as you like (actually I'd prefer it). e.g what does "less in focus" mean to you?
So you know where I'm coming from, the online description I prefer is here: Depth of field with derivations here: The DOF equations
(sadly no longer a live webpage, but archived).
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Forum: General Photography
01-28-2019, 07:13 PM
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Are you sure about this (the DoF part)? If so, how are you defining depth of field?
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Forum: General Photography
01-28-2019, 04:08 PM
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I pop mine inside a container suitable for the "bottle tossed into the sea" shipping method. Delivery time varies from between 0 to 5017 days and destination is somewhat random. Freshness of product is also not guaranteed. But I also have plenty to share:):
Side note (to this side note:)) - looking back at this photo from 7 years ago reminds me that I still suffer from "crop-too-close-itis". Had I left a bit more space above, I would have captured more of that delightful greasy smoke puff. I am in therapy for this issue, and continue to improve.
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Forum: General Photography
01-27-2019, 07:09 AM
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Thanks for your use of orthogonality (I know it well from the math side, but hadn't seen the comp-sci usage) and your reference to Dijkstra's essay (essay is here for the interested, I have a passing familiarity with him from where math and comp-sci are well intertwined). I have a better understanding now of your use of the word "Harmful".:)
I agree to all that, especially the misapplied part. But I would also point out that forgetting to consider under what conditions a thing applies is pretty standard practice, and is not limited to FoV/DoF comparisons:p.
---------- Post added 01-27-19 at 09:19 AM ----------
You could raise your math and physics knowledge:). A big impediment to learning is not seeing any value in what you're trying to learn, you have a goal of understanding lens design so you're past the hurdle of "learn the math or you won't graduate" as your only motivation. I've no doubt that you're capable of getting more out of your books:). The next big hurdle is time, and it's unfortunate that by the time we typcially clear the first hurdle, the second is rushing towards us with the full weight of adult responsibilities:(.
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Forum: General Photography
01-26-2019, 01:22 PM
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As I said, I misunderstood what you were asking.
So ask "Equivalence" to prove it's better, not me. I'm not defending anything as being better than anything else (I don't even know what metric you'd use to define 'better' here), just that I found utility in being able to relate FoV and DoF across formats. From this thread I know there are several other Yeti like me out there, so that's nice. We can hang out in the mountains with our cameras and draw DoF charts in the snow.
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Forum: General Photography
01-26-2019, 11:53 AM
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Sure! But it sounds like you also accept the existence of people who can benefit from 'equivalence' stuff?
I really don't know the best general approach, if there even is one. When someone asks a question here, they usually end up with answers from several different directions and viewpoints. This is good! What's bad is when the question answerers start bickering with one another about what way is 'best' or how they personally don't have any use for approach X or approach Y, and I think this happens more than it should (I don't mean discussions pointing out actual errors, that should always be acceptable). Let people present their explanations, let the question asker follow the path that works for them.
LOL at pudding:D.
Proof that you can do better than the Masters. If you're asking it from others, it's fair to ask it from you I think:). However ... I think I may have misunderstood you and I think you're asking for proof of a better teaching method (I was initially thinking you meant proof of better photos). Either way, no, I'm certainly not better:) and there are many existing teaching books that are far, far better than I could come up with. I have a loaner copy of "Light, Science and Magic" for a reason:D.
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Forum: General Photography
01-26-2019, 11:00 AM
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Very true. I have several random photography books from the 80's (library book sales are great!) and the bulk of the content is still very much relevant. The writing and style can be slog, but often worth it. I would vote any updated presentation keeps the female models with enormous hats and the male models with big sideburns, these things are timeless.
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Forum: General Photography
01-26-2019, 10:20 AM
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+1 :)
By quoting you:p
I wholly agree that the 'normal lens' approach is nice and straightforward. I've enough teaching experience (academic stuff) in my past and know enough photography enthusiasts who glaze over at the phrase 'focal length' that expecting everyone to understand it is overwhelmingly optimistic, and I guarantee there are some beginners who will be confused. I apologize if you're not implying every beginner will understand this approach, but please allow me to find the thought amusing from a pedagogical standpoint:).
A slight aside - I wish I could remember his name, but I remember reading about a successful (and awesome) commercial photographer who operated with essentially zero knowledge of focal lengths or really anything technical. He'd tell his assistant "give me that lens that lets me see ..." and then spread his arms wide. His assistant handled the technical stuff and equipment setup. It was interesting to read about his process and I'd bet I could learn an awful lot about photography from watching him work for a day.
You first?:)
(I don't claim to better than Adams or anyone else, but I've cleverly hidden links to some of my work in my signature if you're interested)
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Forum: General Photography
01-26-2019, 09:32 AM
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Did I say you didn't? Honestly, please quote where I said you don't understand what happens.
Did I say anyone does? Seriously, I'm not sure what you're even replying to, but it doesn't look like anything I wrote.
I don't think I claimed having a monopoly on anything? Everyone works and thinks differently, and there's no universal path to understanding photography to the point where you're capable of creating the images you want to create. That people have different processes is a good thing, actually a fantastic thing, and I honestly pass no judgement on anyone who wants to work or think differently than I do.
Sure it's simple and I agree straightforward to you and me, but I guarantee you it will not result in some sort of immediate path to knowledge for every beginner. It is a problem when you start thinking one approach is somehow enlightening for everyone (this goes for equivalence, practical approaches, or any other method you can muster).
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Forum: General Photography
01-26-2019, 07:39 AM
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I have to laugh a little at the thought of any explanation that will be so universally understood:D.
For the record, I found the idea of relating FoV and DoF between different formats immensely useful when both learning photography and transitioning between formats. I began my first real attempts at learning photography with a P&S (it had manual controls!) and a stack of photography books, most from the film era. As such, the examples of settings I had were largely 35mm (with some larger formats thrown in). Being able to find out how these translated to my little sensored P&S helped me learn what it was and wasn't capable of (I don't think I had heard of the term 'equivalence' at the time, but I can't recall). When I was looking at upgrading, I was pretty comfortable with what my little camera could do and being able to translate how it compared with m4/3 or aps-c, or ff was also extremely useful.
Everyone learns differently. I'm comfy with with numbers and comfy translating my practical experience to the theoretical and vice versa. I wouldn't in any way presume to force this on anyone. In fact, if someone finds the explanations like we have in this thread difficult, I've often suggested that aps-c digital users with FF FoV angst drop $20-30 on a k1000 with a 50mm prime to get some first hand experience of what happens when you move a lens from 35mm to aps-c (and maybe they'll get a bit of film experience too:)).
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Forum: General Photography
01-25-2019, 09:54 PM
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This doesn't work. Your 54mm lens will have a 37 degree horizontal field of view on a K-1. If you put the same lens on a K-3 it will have a 25 degree horizontal field of view, no matter how you mislabel the focal length (focal length of a lens does not change by putting it on a camera with a different sensor size).
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Forum: General Photography
01-25-2019, 03:58 PM
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So that whole frame is supposed to represent film that's 8x10inches and the little rectangle is supposed to represent a 24x36mm frame? You might want to check that again. 10 inches is about 254mm (not 2440mm or anything near that size), so the 24x36 frame should be about 1/7th the width (254/26 = 7.05...).
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Forum: General Photography
01-25-2019, 12:16 PM
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Including FOV is a good plan. On the lens itself will probably never happen as you say, but I've long wished it was standard for manufacturers to include it with lens information (like the database here at PF does). Include a line for each sensor size that the mount lives in front of (e.g k-mount would have FF and APS-C). It's probably an uphill battle to get people thinking in terms of an angle measure though.
Note - a way to not list lens information can be seen at Ricoh Canada's website, e.g. the PENTAX-DA 300mm is said to have a focal length of 5.4 degrees. It could be worse I guess, at least the aperture isn't measured in coulombs.
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