[Pål Jensen]

Equivalence seems to focus on "wide open performance." For instance, I am sure the 645z would not have a lens to match the performance of a 35mm f1.4 lens on full frame. At least, not wide open. But, if you are planning to shoot studio or landscape it is highly unlikely that you would want to shoot at that place anyway, in which case it doesn't matter.

I truly believe that people buy lenses based on angle of view and not on ability to minimize depth of field, which is where the whole equivalence argument seems to lead.

It should be labeled "wide open DOF equivalency at the expense of everything else". It is problematic and biased because either DOF is part of equivalency or it isn't.
Eg. the lenses claimed to be equivalent aren't. They typically don't display the same DOF range or the same maximum DOF (but somehow this doesn't matter as it doesn't support the agenda, but of course it matters for photographers). In addition, they won't have the same close focusing distance (also interfer with DOF possibilities) or equal maximum magnification. There is reason why the manufacturers label a F:2.8 lens as 2.8 regradless of format: it is the only true equivalency....

[Kunzite]

As I feared, caught up on an irrelevant analogy as if it somehow proves a point on this topic. Btw, in most cases you can't "test drive" systems/lenses in the conditions you need them, no more than you can go to a dealer and tell them "let me test drive all your cars on this steep, rough, backcountry road 100 miles away that I regularly go up".

All right, and if I'll tell you how my car behaves in the 4th gear, would it help? No, because your backcountry road is steep and you'll use a lower gear.

Sure, here you go: AOV = 2 arctan(d/2f). Also, please let me know a good technique to memorize what all angles of view in degrees looks like without referencing any other camera/lens.

Why would you do that?
Again, you're intentionally complicate things that can be done in a simple and efficient manner while conveniently "forgetting" issues with the "equivalence" system . Google "angle of view calculator", for example (there are some that accepts the sensor size, instead of "crop factors"). You might know by heart all the values for the 35mm format (do you?), but I don't, and I'll have to use one anyway.

Now the real question is, do any of you people who regularly complain about this affront to your eyes that is "equivalency" actually use multiple systems? Because I do, and no I do not have an FF camera (besides an old film one). I use both Pentax APS-C and Micro Four Thirds.

Is this an appeal to false authority fallacy?
Even if I'm an APS-C user, I used 35mm (film) in the past; and occasionally I would grab some other format. It's usually when I don't have the camera in my hands that I'm applying "crop factors"; when I do, a simple mental hint and - most important - the visual clues by looking through the viewfinder are enough and I'll build up the memory of how that format behaves. No need of constantly applying "crop factors" on the field.
But then, I'm not doing precise inter-format AoV and DOF calculations.

By the way, what you're doing is "converting" both systems you are using to one you're not. Just add about 30% to the m4/3's focal lengths and you'll get the focal length that would give you approximately the same angle of view on APS-C.

Now I didn't bother wasting any money on a m4/3 kit lens. One of my favorite lenses to use on Pentax APS-C is the FA 31mm f/1.8 for reasons of AOV and DOF. The first lens I bought for m4/3 was the 25mm f/1.4. Wanna know why? Because I knew that the approximate FOV and DOF of the FA 31 in 35mm terms is ~47mm f/2.7 and the 25mm f/1.4 is 50mm f/2.8, so about the same. I did this by memorizing two very simple numbers: 1.5 and 2. Using these two numbers, I can calculate in my head in seconds and visualize any equivalence between lenses of the two systems I do use APS-C <-> 35mm <-> M4/3. Somehow, knowing FF equivalence makes my life so much simpler. Shocking isn't it? And if Pentax ever releases an FF, well I don't need to learn any more numbers because I already did.

The problem with the "equivalence" advocates is when they don't understand the limits of scenarios like the above.

Now please tell me why the hell I should go and run through complex, impossible to do in your head (and in the case of DOF, not precisely defined) formulas to get AOV in degrees and DOF in terms of length, and somehow figure out a way to associate visualize that, instead of visualizing things in terms of something I'm already familiar with (APS-C AOV and DOF) with a very simple 2 step multiplication process.

To prove how difficult things are, without "equivalency"?
I thought you're visualizing things in terms of something you're not familiar with, i.e. 35mm.

By the way, all those precise in-your-head calculations becomes useless after a simple crop.

[Cannikin]

Is this an appeal to false authority fallacy?

I love how you people don't use situations where this is useful and make assertions that it is useless and misleading and everyone should abandon it, as if you were some authority on the subject. I provide a direct, first hand counter-example that refutes your assertion. What solution do you provide? What benefit does your advocation of the elimination of equivalency from discussion give?

By the way, what you're doing is "converting" both systems you are using to one you're not. Just add about 30% to the m4/3's focal lengths and you'll get the focal length that would give you approximately the same angle of view on APS-C.

Why would I do that? Everything is already expressed in 35mm terms. As I said before, 35mm is just an arbitrary number, it doesn't matter what the standard is as long as it's a standard that most people reference. Saves me a whole lot of trouble of researching conversions between each and every single format to APS-C, unless you think everyone should also express everything in APS-C in the first place for some arbitrary reason. Yes, I can do a 2 step second grade math problem in my head. No, I do not feel like researching, calculating and memorizing conversions that grow exponentially the more formats you consider.

To prove how difficult things are, without "equivalency"?
I thought you're visualizing things in terms of something you're not familiar with, i.e. 35mm.

No, I am not visualizing things in terms of 35mm. I am making things into a very simple math problem. 1.5A = X, 2B = X, 0.79C = X. I don't need to know X in order to very easily convert between any of them. X could be anything as long as it is consistent. Basic algebra. When converting from kilograms to milligrams, do you need to instinctively and visually know what a "gram" is, or do you need to memorize that kg = 1000000 mg, or do you simply need to know that kg = 1000g, mg = 0.001g? The developers of the SI system understood this basic principle when they made the base SI unit of mass the "kilogram" even though all SI prefixes are applied to the word "gram". As long as you know what a "kilogram" is, and how to get to a "gram" with any SI prefix, you don't need to actually know the gram, and somehow people are not confused.

[Aristophanes]

@aristophanes et al -- following Henry Ford's Model T price-lowering approach, what price do you think would GREATLY increase sales, and still make Ricoh a profit, taking into account lower costs from volume production? More to the point, do you think that if the price were greatly reduced... like to $3,995... would there be a huge upswing in sales? Or -- and please don't laugh -- would the price have to drop below $1000 before you can sell into a high-volume market?

EDIT -- re comment above -- (stupid) people buying a k-500 instead of a D3100? Seems like they're smart to me. And, following this high-low concept... could Ricoh make a 'low-end' K-500-type stripped-down version of the 645Z... and sell it for $2,995?

Yes, it is a halo product, but in a more traditional sense that it demonstrates a "pro" company and not some run-of-the-mill retail brand (like Casio). It's not the Apple halo where one product in a category (iPod/iPhone) will spur sales of an integrated product (Macs) based on shared resources (iTunes/iPhoto etc.).

Of course if the price were dropped to $4,000 per body sales would skyrocket, but so would costs. Ramping up production would infer a massive capital risk for Ricoh to the point where I doubt they could make a profit. At some point the cost to increase production (dozens of outsourced parts, assembly line training, distribution) can erase profits, and quickly.

It's a large camera with a dedicated mount and expensive glass. It's niche produce that will sell very well within its niche, but it can only nibble around the FF market, curious crumbs, so to speak. For a few thousand people worldwide it is likely to be a step up from a D800, especially in the portable outdoor studio market.

---------- Post added 04-17-14 at 09:08 AM ----------

I believe we cannot even guess the market for the MF cameras, because MF is used outside the traditional photography consumer market.
If the 12,000 cameras a year is estimated size of that end consumer market (professional photography), then the industry, services, science, military and government sectors may encompass substantially larger numbers. In other words, numbers you are playing with are worthless and most likely way off the mark.

Also, your estimates on R&D and manufacturing cost, and possible profitability from presumed sales numbers, are also off the mark, because MF used in sectors mentioned above lead to contracts and deals that far exceed initial investments. It is also conceivable Ricoh will never reveal a total number of cameras ordered and produced, but only tell the number of cameras allocated for the consumer market, as other numbers are of strategic business importance.

The ICI market (industrial, commercial, institutional) for cameras is important, but not very large. If anything MF has been more traditional photography than outside it. The continuance of MF in the 135 roll film era was dominated by fine art and, especially wedding and event photography. The ICI sector rarely required those products and if they did, contracted out.

I have never seen any MF in police, coroner, surveying, or any other forensic service. And they are heavy users of photography. I would be very surprised if MF products made up even a measurable % of the MF market as a whole. Normally there is dedicated literature for sectorial services fro product manufacturers targeting their products at certain niches. I have seen none for MF equipment. MF marketing all seems to be strictly limited to advertising, fine art, landscape and architectural (tourism/historical/archival), and prosumer hobbyists. The latter will be far more price conscious and appears to be the main Pentax market. The former may rely on studio and pro support, so may opt for the pricey support from Hasselblad or Mamiya/Phase One.

[Rondec]

Yes, it is a halo product, but in a more traditional sense that it demonstrates a "pro" company and not some run-of-the-mill retail brand (like Casio). It's not the Apple halo where one product in a category (iPod/iPhone) will spur sales of an integrated product (Macs) based on shared resources (iTunes/iPhoto etc.).

Of course if the price were dropped to $4,000 per body sales would skyrocket, but so would costs. Ramping up production would infer a massive capital risk for Ricoh to the point where I doubt they could make a profit. At some point the cost to increase production (dozens of outsourced parts, assembly line training, distribution) can erase profits, and quickly.

It's a large camera with a dedicated mount and expensive glass. It's niche produce that will sell very well within its niche, but it can only nibble around the FF market, curious crumbs, so to speak. For a few thousand people worldwide it is likely to be a step up from a D800, especially in the portable outdoor studio market.

Even with a lot lower price, it would still be a niche product. It does not have an auto focus module or, lenses that focus fast enough for that matter to challenge upper end full frame for a lot of the things it does well -- sports, etc. I can see it being studio, landscape, and high end wedding camera. There just wouldn't be any point to dropping the price -- it should be the best selling medium format camera at the current price and wouldn't gain a bunch of sales if priced even several thousand dollars less.

[Kunzite]

I love how you people don't use situations where this is useful and make assertions that it is useless and misleading and everyone should abandon it, as if you were some authority on the subject. I provide a direct, first hand counter-example that refutes your assertion. What solution do you provide? What benefit does your advocation of the elimination of equivalency from discussion give?

Wasn't it you who were claiming the authority of being a multi-system user?
And another logical fallacy - this time it's a strawman. I'm not advocating the elimination of "equivalency"; my point is that it only works in limited situations, and it only has a limited use.
I even "confessed" using "crop factors" occasionally. With the medium format, I'd rather be interested in how is it different than APS-C, than how I can make it similar.

Why would I do that? Everything is already expressed in 35mm terms. As I said before, 35mm is just an arbitrary number, it doesn't matter what the standard is as long as it's a standard that most people reference. Saves me a whole lot of trouble of researching conversions between each and every single format to APS-C, unless you think everyone should also express everything in APS-C in the first place for some arbitrary reason. Yes, I can do a 2 step second grade math problem in my head. No, I do not feel like researching, calculating and memorizing conversions that grow exponentially the more formats you consider.

Everything? (looking at my DA Limiteds) Phew! Nope, they're still in the good old metric system.

You don't understand. Deciding on a "standard" based solely on a very limited set of parameters is the problem.
And as I told you, a simple crop will break this "equivalence". An occasionally useful tool, yes; but it's way too fragile to even resemble a standard.

[Cannikin]

Wasn't it you who were claiming the authority of being a multi-system user?
And another logical fallacy - this time it's a strawman. I'm not advocating the elimination of "equivalency"; my point is that it only works in limited situations, and it only has a limited use.
I even "confessed" using "crop factors" occasionally. With the medium format, I'd rather be interested in how is it different than APS-C, than how I can make it similar.

No, I was not claiming authority. Since people keep going on and on about how "equivalency" is just a "theory" of "questionable usefulness" without being in a situation in which it would be used, I was pointing to my experience in which I do use it, and it is very useful, as a counter-example.

You don't understand. Deciding on a "standard" based solely on a very limited set of parameters is the problem.
And as I told you, a simple crop will break this "equivalence". An occasionally useful tool, yes; but it's way too fragile to even resemble a standard.

And herein lies the issue of semantics. I agree it is a tool. Given that equivalency is based on well defined mathematical and geometric principles, I interpret the 35mm equivalency "standard" as "something to be compared with" mathematically for whatever purposes you need. Your interpretation of the use of the 35mm "standard" is "something to be judged against" which is a personal opinion. Indeed, there are many people who will use it as such, but in most cases it involves people selectively using portions of it to try to "prove" their point, whether for or against larger sensors, and I often want to smack them both. Use portions of equivalency for your own reference, as I do, but you cannot "prove" anything if you do not reference the entire principle, in which case it is something mathematically precise and not up to "interpretation".

Consider the SI system and US Customary units. There are direct, mathematically precise relationships between the two systems. Officially in US engineering and science Customary units are defined in terms of SI units. Like it or not, SI is the standard against which other systems are compared. Some people may deem SI to be the "standard against which everything should be judged" and say that it is inherently superior, but that is personal opinion, as American stubborness in adopting makes obvious. Personally, I was raised on US units, and even though I have plenty of science and math education, I still instinctually visualize a "meter" as "a little over 3 feet" or a "kilogram" as "2.2 pounds". And yet I recognize SI as the international standard because it is well defined, in wide use and has been for some time.

Equivalency is a well defined tool. Use it as you will, or not, but to question its usefulness or mathematical/geometric reality, is narrowminded IMO. And like it or not, 35mm is the standard for which things are compared (again "judging" is a whole other personal matter) because it is well defined and consistent as 36x24mm (none of this fudging of what "APS-C" or "medium format" is) and has been in common use for a very long time.

---

Last edited by Cannikin; 04-17-2014 at 07:35 AM.

[Sandy Hancock]

Way to kill a thread guys.
Move on.

[monochrome]

I have never seen any MF in police, coroner, surveying, or any other forensic service

Well there was that rumor about the Japanese military ordering an unspecified large number of units - enough to jump-start production - enough to suggest there will be follow-on sales to Police forces.

But that was just a rumor. Kind of an extension of the 'irrational' Abenomics / Kurota-san Stimulus strategy. And since Aristophanes hasn't ever heard of such a use - then of course it must have been an unfounded rumor.

[monochrome]

Way to kill a thread guys.
Move on.

^^ Thank you. You can write that. I can't.

FWIW everything should be equivalent to 6x7.

[D1N0]

Maybe lenses should get a (horizontal) Angle of view description instead of focal length. Then we would not have to talk about equivalence. For lenses that are Full Frame you would have a double angle description (also one for aps-c).

[Cannikin]

FWIW everything should be equivalent to 6x7.

You joke about it, but really it makes no difference to me, 35mm, 6x7, 1/2.3", whatever. As long as there is a standard that is consistent and commonly used. In the real world that standard happens to be 36x24mm. Don't see why people have to be so sensitive about this.

[normhead]

How about that new 645Z? When can I find a second hand 645D at an affordable price... come one guys, where's the rich guy who will let his 645D go cheap? ... it's a piece of junk now, practically worthless. OK, I admit it, I don't want to buy one, I want to steal one... from a willing victim. But hey, in a year or two the 645Z will be selling at 7k... A second hand 645 should be getting down to new D800 prices by then, don't you think?

[monochrome]

I'll try to bring this back to 645z - by using Q.

I don't convert a Q/01 on a Q to a 47 or on a Q7 to a 40 - I just shoot it since I 'sense' through practice what the FoV will be. Same holds true for the 5~15 and the 15~45 - they're 'equivalent' to FF standard zooms but I just don't think that way. I know which of the three lenses will do the job I need and mount it when I need it. I don't even know what the FL of the 03 Fisheye is - but I know when to use it.

Now I believe, but I do not 'sense' through experience, the same is likely true for experienced 645 users. I don't imagine an experienced 645 studio or landscape shooter converts a 645 lens on 645D (or z) @.79 to the 36x24 'Standard' before mounting it. Equivalency isn't relevant - experience with the format is enough.

[Edited: Removed non 645zx content]

[Kunzite]

Cannikin, the answers to your points (and - again - the attempted usage of real standard systems of measurement to support "equivalency") is in my previous posts. I will not repeat them.
And since you used a keyword ("narrowminded"), it's time to end our discussion.

Way to kill a thread guys.
Move on.

It can't be avoided. No matter the subject, we'll always end up discussing "full frame" (and the "equivalency" to it) or mirrorless, or both.
I resigned myself to the situation.