[fuent104]

I am surprised this topic has generated such heated discussion.

One thing I like about the video, is that, at the very least, it promotes looking deeper into things, and developing one's own understanding of these photographic concepts.

I have a pet peeve, which is when people are taught that long lens = shallow depth of field, as though relationship between focal length and depth of field isn't vastly more complicated.

[ElJamoquio]

Great video. Thanks.

A lot of people here don't like people saying that APS-C doesn't have advantages over FF, you'll just have to deal with that.

FYI You should've said 'you can't trust Fuji' as well.

---------- Post added 05-22-14 at 06:28 PM ----------

ou're telling me that focal length "sucks", and I should not trust manufacturers for stating the real focal length on their lenses

But they don't. They'll often put things like '24-70' on P&S sensor sized cameras.

Didn't read the rest of your post. If you correct your post (you suggested the videographer delete his!) I'll look at the rest of your post.

[jsherman999]

Great video. Thanks.

You're welcome, thank Tony. It seems to serve two purposes - first, it describes equivalence in plain language and with some clear photographic examples (the main reason I posted it,) and it promotes the notion that some camera companies are 'lying' when they don't publish equivalent aperture along with equivalent focal lengths. (the second purpose has a few folks frothing at the mouth )

I don't really think anyone is 'lying', although I think the m43 companies are benefiting from leaving some information out. I think that the F-stop needs to be carried forward in the same way it always has, because it's the component of exposure (not total light) that people concern themselves with the most. So it needs to stay presented the way it is.

However: I do think that sites like dpreview in it's reviews and sites like B&H and Amazon in their product summary pages should indicate the equivalent aperture range as well when they mention the equivalent focal length. It's physics, and it affects photographic choices and can affect purchase decisions. It should be there, and if it starts being there, we'll see less trauma and more acceptance of what's really a more full description of the physical relationship between formats. If they're going to bother to show one (equiv FL) they should show the other (equiv aperture,) up front, SOP. Especially professional review sites, that purport to give a full accounting of the product.

.

Didn't read the rest of your post. If you correct your post (you suggested the videographer delete his!) I'll look at the rest of your post.

I'll summarize:

1) He hates the video with a passion
2) He has never read Joseph James' or Falk Lumo's papers on equivalence (yet)
3) He hates equivalence too, or at least the term 'equivalence', although...
4) He uses equivalence (in part) when he's asked to convert a lens on one format to another, but
5) Will not admit to doing so. Because he thinks it's 'different' than what he does to convert. Why does he think that? See #2.

I've asked him to read this, because it encapsulates everything I've posted in this thread and much more.

.

[Kunzite]

But they don't. They'll often put things like '24-70' on P&S sensor sized cameras.

Didn't read the rest of your post. If you correct your post (you suggested the videographer delete his!) I'll look at the rest of your post.

But the video is about ILCs.
What I suggested was that the video is fundamentally wrong, so it's not a simple matter of "fixing the math". It's hard to understand this (and why it is so) without reading my posts.

I'll summarize:

1) He hates the video with a passion
2) He has never read Joseph James' or Falk Lumo's papers on equivalence (yet)
3) He hates equivalence too, or at least the term 'equivalence', although...
4) He uses equivalence (in part) when he's asked to convert a lens on one format to another, but
5) Will not admit to doing so. Because he thinks it's 'different' than what he does to convert. Why does he think that? See #2.

I've asked him to read this, because it encapsulates everything I've posted in this thread and much more.

You are not summarizing, you are simply making things up at your convenience. It appears that debating "equivalence" fans is like playing chess with a pigeon... all my arguments were ignored, no attention whatsoever to what exactly I was arguing for/against and you were certain you "won" even before the discussion started.

A real summary, not done by a pigeon but a rational human being, would be:
1) Using 135 as a baseline is irrelevant for most ILC users.
2) Focal length and aperture are the only things that can be written on interchangeable lenses.
3) Focal length is not a measure of angle of view.
4) ISO is not a measure of noise.
5) Aperture is not a measure of DoF.

---

Last edited by Kunzite; 05-23-2014 at 12:21 AM.

[jsherman999]

1) Using 135 as a baseline is irrelevant for most ILC users.

Equivalence itself does not require any baseline. Don't make the mistake of attributing that requirement to it. You know who does that? Folks who don't read the equivalence papers and understand the terms and concepts being used (<hint>).

Tony, in the video, is asking for a complete conversion (FL and aperture) instead of a partial conversion (FL only.) He's using equivalence to show why that's advantageous to do, but his assertion is not part of equivalence.

Regarding an equivalent baseline (which is separate from equivalence, remember) - there absolutely has to some, either an AOV-equivalent baseline or a FL-equivalent baseline. The fact that 135mm (FF) was chosen simply makes the most sense to most people, manufacturers and review sites, but there has to be some baseline. If there were none, how do you describe to a buyer what this FL brings you in terms of FOV?



.
You say '135mm is irrelevant to most ILC users', yet ...

1) we have a very convenient end-point for formats that can easily and affordable share lenses - and that endpoint is FF. Medium format is priced out of range of 99% of shooters and can't natively mount lenses that can be shot on aps-c and FF cameras anyway.

2) 135mm SLR was in the hands of shooters who crossed the film-digital threshold, and

3) now we have FF cameras being sold new for $1600, and that's inching downward and the base is going to expand because of that. Some speculate that the majority of DSLRs sold in 10 years will be FF, with MILC taking over aps-c and m43.

So, switching the standard now doesn't make a ton of sense. That said, it doesn't matter much if the standard does change to something like aps-c - that won't magically make the smaller formats look any better when equivalent lenses are considered, it will just make the FF lenses seem really fast and wide compared to how they were labeled before In fact, if the 'standard' changed to aps-c, it would really shine a light on some of the advantages of FF because that equivalent relationship would be more obviously described.

2) Focal length and aperture are the only things that can be written on interchangeable lenses.

And yet we have had P&S's in the past that had equivalent focal lengths written right on the front of the lens barrel so people don't get confused when they see something like 5mm - 25mm, we have that data being recorded in EXIF, and we have B&H and dpreview and everywhere else listing the 'equivalent focal length' when they review or list the product.

It's a logical step forward to start listing the equivalent aperture in some of those places as well. If not on the lens, then, as I said, in the reviews and product pages. It's nothing revolutionary, it's only acknowledging physics and shooting realities.

3) Focal length is not a measure of angle of view.

No, but it directly affects AOV and will have a different AOV on different formats. I think FL != AOV is a semantic dodge in this context. When you have a 5mm on a P&S, what does that mean to you as a photographer? Do you need to look up that sensor size each time, do the math in your head so you know what equivalent FL (AOV) you're getting? No, you don't want to have to do that? I agree! Now, let's extend that logic to aperture.



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[Kunzite]

Equivalence itself does not require any baseline. Don't make the mistake of attributing that requirement to it. You know who does that? Folks who don't read the equivalence papers and understand the terms and concepts being used (<hint>).

How many times should I explain what am I arguing against? This is a trolling tactic, to defend an incorrect point of view (the video, subject of this thread - which by the way you think it's a "pretty good video on equivalence") by forcing the discussion into a direction which can be better defended.
But I'm glad you're now admitting I'm not one of the people making such mistakes. That's a progress!

Regarding an equivalent baseline (which is separate from equivalence, remember) - there absolutely has to some, either an AOV-equivalent baseline or a FL-equivalent baseline. The fact that 135mm (FF) was chosen simply makes the most sense to most people, manufacturers and review sites, but there has to be some baseline. If there were none, how do you describe to a buyer what this FL brings you in terms of FOV?

I will simply state the focal length; he would relate it to the format he's using. It would confuse him if I'll talk about other formats.
In case you forgot to say it's about a buyer into a new format - I'll ask what format he's currently using then say something like "this lens will frame just like an X mm lens would do on your old camera".

You say '135mm is irrelevant to most ILC users', yet ...

Of course it is. 135 is single digit in market share, most people are using APS-C and 4/3.

And yet we have had P&S's in the past that had equivalent focal lengths written right on the front of the lens barrel so people don't get confused when they see something like 5mm - 25mm, we have that data being recorded in EXIF, and we have B&H and dpreview and everywhere else listing the 'equivalent focal length' when they review or list the product.

I don't care about compacts; those:
- have a fixed lens (thus the issue of using a lens on different formats can't happen)
- have an "unknown" sensor size (we're usually told something like 1/1.7", 1/2.3" etc)
- are mostly sold to uninformed people who can't be bothered to learn the basics

No, but it directly affects AOV and will have a different AOV on different formats. I think FL != AOV is a semantic dodge in this context.

If your kind of "equivalence" is rejecting the notion of focal length, replacing it with this twisted sort of "let's express AoV in a different way but hey, I'll just use focal length instead - the h*ll with optics!", then it's wrong. There can be no negotiation about it, just like there can't be any negotiation about using "equivalent" kg or "equivalent" meter.

When you have a 5mm on a P&S, what does that mean to you as a photographer?

That I left my camera at home.

Now, let's extend that logic to aperture.

Let's not.

[jsherman999]

How many times should I explain what am I arguing against? This is a trolling tactic, to defend an incorrect point of view (the video, subject of this thread - which by the way you think it's a "pretty good video on equivalence") by forcing the discussion into a direction which can be better defended.
But I'm glad you're now admitting I'm not one of the people making such mistakes. That's a progress!

Most of your confusion, anger, denial, and misrepresentation of the general subject of equivalence would be mitigated if you simply read the link I provided. As it stands you're spending a lot of time and energy arguing against what you think it means. You'd probably no longer refer to it as, and I quote you, an "abomination". (btw I'll be referring back to that, you sort of set the standard for equivalence-deniers in a moment of honesty.)

(I also think reading that link would also help you understand more of where the video is coming from. )

.

[Kunzite]

Are you sure you're not talking about your feelings?
There's nothing I should read to understand all the claims in that video. You are rude by attributing me imaginary states of mind (and if there's something that's making me angry, that's rudeness!) and by repeatedly claiming that I don't understand; even if my points are about most basic things, like the impracticality of marking an interchangeable lens with the AoV, or the definition of focal length (which is the first thing you'd learn when studying optics).
As much as you'd like it, you cannot defend the video - so you'll try to defend those articles instead. Except that I can't be bothered to attack them.

But since you switched from defending that abomination of a video with more rigorous and elaborate internet "papers" to personal "characterization", my discussion with you is done. Good bye, Mr. Pigeon.

[ElJamoquio]

The video was good. Keep up the great work!

[Poit]

You being a Pentax user has nothing to do it. Fail #1



That's not what he's saying at all. You're completely missing the point.... Fail #2



Where did he claim this? At what point in the video?



That's not what he said.



Again. Not what he said.



You are completely missing the point. The ASA/ISO standards was developed as a standard for sensitivity of film. Sensors don't operate the same way and we are dealing with digital gain, not sensitivity. Another point you seem to completely miss is that in the film days we didn't have so many lenses being used across so many different formats. Companies weren't designing for multiple formats with the same lens like they are today, so nobody really worried about equivalent FoV or performance. Companies didn't market lenses based on the 35mm equivalent. His point is that if companies are going to market the equivalent focal length to uninformed consumers, then they should also market the equivalent aperture. Since aperture is a function of focal length, you can't change the parameters of one and not change the other.

I'm so glad someone said it!!!!

[ElJamoquio]

I like taking pictures.


It would help if other consumers were well educated - it would keep the costs of 'appropriate' equipment down, I think.

Nevertheless, it's tilting at windmills.

[filoxophy]

How I love internet arguments!

[ElJamoquio]

How I love internet arguments!

No you don't.

[eyeswideshut]

This whole equivalence debate is probably just a misunderstanding. Technically, the arguments of Joseph James seem sound enough to me (but in truth I have only scanned his article and I am not fully expert).

Still, there is frequently something annoying about the use to which equivalence is put by some of those who feel "converted" to his paradigm. Moreso on other forums but I think most of us have had this experience at various points.

Let's say I'm in the habit of shooting black cats in coal mines around midnight with a Pentax Q and I find this parfocal zoom lens of 8-48mm fl and a constant aperture of f/1.0 So I go on the Q forum here and write a little post saying that this is a pretty cool lens for shooting black cats in coal mines around midnight. After all, it offers the ff equivalent of ca. 50 to 250mm at a constant aperture of f/1.0.

All of a sudden a troll jumps out of the woodwork preaching the good word of equivalence and points out that my mighty little f/1 zoom is actually only an f/8 lens on full format (or thereabouts. I haven't done the math). And then he (I guarantee you it will be He, never She) drags depth of field into it and pretty soon goes off on a tangent about exposure, light, photons and what not. After a while I wonder how I ever managed to even take a single well exposed photograph with my puny little Q.

What happened? The guy is right after all, the arguments are sound. So am I wrong? No. Because I never said that my goal was to create the exact same image with a Q that I could create with another format camera. And that is what equivalence is all about. To quote James:

"This essay is about relating different systems on the basis of five parameters (perspective, framing, DOF, shutter speed, and display size) and defining "equivalent photos" as photos that share these five visual properties. "

The reason I own various cameras with different sensor sizes after all is because they are DIFFERENT, not because they are the same. They produce different results - and that's what I want. Equivalence as defined by James is useful only if equivalence of photographic output accross different cameras/lenses is the issue.
When shooting black cats in coal mines around midnight, equivalence has no bearing.

Cheers

P.S: I actually hate shooting cats anytime, anywhere and that little lens I'm talking about is a dog actually...

[ElJamoquio]

That's awesome.

I could make the same picture with a FF camera as you did with the Q. If you used equivalence, so could you. Maybe you'd find you didn't need as much gear to do everything you want to do.