[jsherman999]

I admit I went into extreme just to prove a point.
But you can also take 3 instances that are talked about all the time around here, micro 4/3, APS and FF.
You mentioned above you just care about the final result, the picture. So let's just say you want a normal lens.
How would you know what a normal lens without equivalence? Look through the viewfinder? Ok, I will order 3 separate cameras from amazon. Then order a few lenses from each mount and hope they are in the correct ballpark. Or you can do the same by walking into the camera store, looking through a view finder of each camera with separate lenses.

Or you can multiply focal length by 2, then by 1.5 and another by one, and not even need to look through a viewfinder, not set foot into a camera store etc.
You can dance around it all you want, but that simple calculation...which everyone here does whether or not they want to admit to it, is equivalence.

So, looking at normal lenses, 25mm for Micro 4/3, 30-35mm for APS-C, 50mm for FF.
If someone wants the look of a run of the mill cheapie 50mm f1.7 wide open, then they have to look at equivalent apertures for APS-C and Micro 4/3. You can go through the effort and exercise of looking through the viewfinder of 3 separate format cameras. Or you can just bite the bullet, admit that equivalnce is useful tool and you can add a stop in your head for APS-C and 2 stops for micro 4/3, all without leaving your couch.

Then of course the next logical step is to compare the prices of the lenses that will give you that look that you want.

How is that not useful in comparing gear?

It's extremely useful.

.

[Kunzite]

You mentioned above you just care about the final result, the picture. So let's just say you want a normal lens.
How would you know what a normal lens without equivalence? Look through the viewfinder?

A lens is "normal" for a given format if it has a focal length about equal to the diagonal of the frame.
For example, on my camera a normal lens would have about 28mm. I don't have to care that with a 44mm lens on 135 I could get equivalent photos regarding "perspective, framing, DOF, shutter speed, and display dimensions".

[cali92rs]

It's extremely useful.

.

People are tap-dancing, tip-toeing, mamba-ing around the word "equivalence" just because they feel it is used only to further the "full-frame" agenda.

---------- Post added 05-28-14 at 11:35 AM ----------

A lens is "normal" for a given format if it has a focal length about equal to the diagonal of the frame.
For example, all I have to know is that on my camera a normal lens would have about 28mm. I don't have to care that with a 44mm lens on 135 I could get equivalent photos regarding "perspective, framing, DOF, shutter speed, and display dimensions".

Or you can multiply the focal length by a simple factor, and not even need to know what the diagonal of the frame is...
Why is one way better than the other?

[Rondec]

I admit I went into extreme just to prove a point.
But you can also take 3 instances that are talked about all the time around here, micro 4/3, APS and FF.
You mentioned above you just care about the final result, the picture. So let's just say you want a normal lens.
How would you know what a normal lens without equivalence? Look through the viewfinder? Ok, I will order 3 separate cameras from amazon. Then order a few lenses from each mount and hope they are in the correct ballpark. Or you can do the same by walking into the camera store, looking through a view finder of each camera with separate lenses.

Or you can multiply focal length by 2, then by 1.5 and another by one, and not even need to look through a viewfinder, not set foot into a camera store etc.
You can dance around it all you want, but that simple calculation...which everyone here does whether or not they want to admit to it, is equivalence.

So, looking at normal lenses, 25mm for Micro 4/3, 30-35mm for APS-C, 50mm for FF.
If someone wants the look of a run of the mill cheapie 50mm f1.7 wide open, then they have to look at equivalent apertures for APS-C and Micro 4/3. You can go through the effort and exercise of looking through the viewfinder of 3 separate format cameras. Or you can just bite the bullet, admit that equivalnce is useful tool and you can add a stop in your head for APS-C and 2 stops for micro 4/3, all without leaving your couch.

Then of course the next logical step is to compare the prices of the lenses that will give you that look that you want.

How is that not useful in comparing gear?

But "wide open performance" is an odd way to judge a system. Yes, you can calculate what it would take to match wide open performance in one system and another, but I trust (hope) that most people don't shoot wide open all of the time. But honestly, very few people start off with a full frame camera. If you start off with an SLR or mirrorless that is a smaller sensor size, you might as well get the most out of it before you move up. Maybe you do need a full frame for your style of shooting, but even narrow depth of field photography is more than possible with APS-C.

[jsherman999]

A lens is "normal" for a given format if it has a focal length about equal to the diagonal of the frame.
For example, on my camera a normal lens would have about 28mm. I don't have to care that with a 44mm lens on 135 I could get equivalent photos regarding "perspective, framing, DOF, shutter speed, and display dimensions".

How about if you decided you wanted to shoot FF, then how would you pick a FL that would be Normal? Or if you wanted to shoot m43? If someone was shooting m43 and asked you what would be a 'normal' lens for them, how would you answer?

What if the m43 shooter asked you, "I want to have the same DOF and field of view that you have on aps-c with your 28mm as well, what lens should I choose?" How about if they asked, "Is there a lens I could choose that would give me the same noise performance you can get with your aps-c combo, because I'd rather stick with m43 and just buy a new lens if possible?"

Would you mutter "no comment" and wander off, would you berate them for caring about things they shouldn't care about? Pretend you didn't hear them?

Should we make up a new, more acceptable term to replace equivalence, like "same-same" or "likey-like"?

[cali92rs]

Lenses?Q7 | RICOH IMAGING

Ricoh is wasting their time for including the 35mm equivalent...
Because everyone knows the diagonal length of the 1/1.7" sensor.

[ElJamoquio]

But "wide open performance" is an odd way to judge a system.

What system? MF? FF? Q? Personally it's rare for me to stop down a Q. It's easy for me to figure out, though, I just use equivalence and BAM! Microseconds later I know what's going on even though I've just changed the crop factor by ~5x.

[Rondec]

What system? MF? FF? Q? Personally it's rare for me to stop down a Q. It's easy for me to figure out, though, I just use equivalence and BAM! Microseconds later I know what's going on even though I've just changed the crop factor by ~5x.

Maybe the Q is sharp wide open, but with the exception of my DA *55 and FA 77, my lenses benefit from being stopped down.

I am in the (apparently) unusual situation of only shooting APS-C for the last eight to nine years and so I am very APS-C oriented. 35mm equivalence has very little meaning to me and in point of fact, I do the translation in reverse -- converting 35mm focal lengths to APS-C rather than vice versa.

Equivalence doesn't have any real world value. Can you honestly tell me that you have ever taken a shot with your Q and then thought to yourself, now what exactly do I have to set my 28-70 lens at on my D600 and what aperture in order to get the same shot? I can't imagine that happening. If you want to take the shot with your D600, you take it. Zoom with your lens (or your feet), set your aperture to what you think is best and then take the photo. That's what photographers do and when they know the format they use, they just use it without some kind of weird constant translation to another format.

[cali92rs]

But "wide open performance" is an odd way to judge a system. Yes, you can calculate what it would take to match wide open performance in one system and another, but I trust (hope) that most people don't shoot wide open all of the time. But honestly, very few people start off with a full frame camera. If you start off with an SLR or mirrorless that is a smaller sensor size, you might as well get the most out of it before you move up. Maybe you do need a full frame for your style of shooting, but even narrow depth of field photography is more than possible with APS-C.

Why do you have to calculate it at wide open?
The ratio remains the same whether you are wide open or stopped down for maximum sharpness.

No doubt you are a great photographer and that is a great shot.
I see you shot that with your 55mm f1.4 @ f2.2.

You can get a similar shot with a 85mm f1.8 stopped down to about f3.2 and save about $300 bucks.
Yes, you have to shoot at a slower shutter speed...or bump up the ISO.
But a consumer can make the decision what he wants to trade.

How is that not useful to know? And how is what I did "complicated or confusing"?

---------- Post added 05-28-14 at 12:21 PM ----------

Equivalence doesn't have any real world value. Can you honestly tell me that you have ever taken a shot with your Q and then thought to yourself, now what exactly do I have to set my 28-70 lens at on my D600 and what aperture in order to get the same shot? I can't imagine that happening. If you want to take the shot with your D600, you take it. Zoom with your lens (or your feet), set your aperture to what you think is best and then take the photo. That's what photographers do and when they know the format they use, they just use it without some kind of weird constant translation to another format.

The value comes BEFORE you invest thousands of dollars in a camera system.

[jsherman999]

lenses?q7 | ricoh imaging

ricoh is wasting their time for including the 35mm equivalent...
Because everyone knows the diagonal length of the 1/1.7" sensor.

.

[ElJamoquio]

Can you honestly tell me that you have ever taken a shot with your Q and then thought to yourself, now what exactly do I have to set my 28-70 lens at on my D600 and what aperture in order to get the same shot?

I have absolutely thought to myself, I would take this picture at 70mm and F/11. Can I do that on this Q that I have with me?

I have absolutely thought to myself want to take a picture at (on FF) 28mm and F/4. Can I do that on the FF I have with me? Can I do it on the APS-C camera I also have with me?

Absolutely. A dozen times a day when carrying both.

[Kunzite]

Or you can multiply the focal length by a simple factor, and not even need to know what the diagonal of the frame is...
Why is one way better than the other?

You need to know the diagonal of the "reference" system; or you might choose to live in ignorance and believe a normal lens is some mythical beast "equivalent" to a 50mm on 135.

How about if you decided you wanted to shoot FF, then how would you pick a FL that would be Normal? Or if you wanted to shoot m43? If someone was shooting m43 and asked you what would be a 'normal' lens for them, how would you answer?

True normals are ~22mm on 4/3, ~28mm on APS-C, ~44mm on 135; usually you'd round upwards to 25, 30 and 50mm.

What if the m43 shooter asked you, "I want to have the same DOF and field of view that you have on aps-c with your 28mm as well, what lens should I choose?" How about if they asked, "Is there a lens I could choose that would give me the same noise performance you can get with your aps-c combo, because I'd rather stick with m43 and just buy a new lens if possible?"

Moving the goalposts, I see... Anyway:

#1. Unless you can think of a real situation in which a m4/3 user would follow me and attempt to perfectly replicate my images (which would get him arrested for stalking, as my pictures aren't THAT good), the situation is purely theoretical - and your "question" really is: "if I make up a scenario which require the partial use of "equivalence", what will you do?".

#2. Lens giving you noise? Oh, boy...
You didn't actually read Joseph James' paper, did you? He's very specific about this:
"The most controversial visual property of equivalent images is that people incorrectly assume that Equivalence is based on equal noise. Equivalence is based on the five principles listed above, which do not include noise, nor any other elements of IQ."
Equivalence

Noise should be measured and observed, not estimated by "equivalence". There is a quantitative side to it - which doesn't necessarily follow "equivalence" - and also a qualitative side (e.g. banding can be pretty nasty).

Would you mutter "no comment" and wander off, would you berate them for caring about things they shouldn't care about? Pretend you didn't hear them?

Chess. Pigeons.

[audiobomber]

The importance of equivalence is that it helps people to understand the differences between formats. I've been looking for a more capable p&s than my Q. Yesterday I looked at Sony's A5000 and RX100 III. The bodies are virtually the same size, the APS-C 16-50 f3.5-5.6 PZ lens is a bit bulkier. The RX100 has, as DPR calls it, a "24-70mm equivalent F1.8-2.8" Zeiss lens. Someone who knows nothing of equivalence would naturally assume that the RX100 is the better camera, both are 24-70ish equivalent, the compact has a much faster lens. The salesbot even said so. He also tried to sell me the RX100 II, because it goes up to 100mm and the A5000 only goes to 75mm. I told him it was just a cropped fov, I could make up the difference in my computer. The look he gave me was not very nice. Know-it-all salespeople don't like to be shown up.

Of course the right answer is to look at true equivalence, which says:

RX100 = 8.8-25.7mm, f/1.8-2.8 = 24-70mm, f/5.0-7.6
A5000 = 16-50mm, f/3.5-5.6 = 24-75mm, f/5.3-f/8.4

So they are very close, you could take a photo with either and have the same FOV, DOF and SNR. Neither system is more capable in these aspects. I chose the APS-C body because it was $486 cheaper. With the difference, I can add a 35mm f/1.8 lens and do things the p&s cannot do. Size was close enough for me, I don't intend to carry it in my pocket, I will use a belt pack.

[northcoastgreg]

How about if you decided you wanted to shoot FF, then how would you pick a FL that would be Normal?

Curiously, when I started shooting FF back in the eighties, there was no talk of equivalency. Amazingly, we managed to survive without it.

My first camera was a 110 that had two lenses that you could swap between. One was labeled "normal," the other "wide-angle." No focal length was given, nor would it have meant anything to me if it had been given. When I moved on the a 35mm SLR, the 50mm lens that came with it was described as "normal." Later I got a 28mm lens, which was described as "wide-angle." All that seemed important to me at the time is that the 28mm lens had a wider FOV. I only learned what 28mm and 50mm meant with FF through using them. Over time, via experience, I became use to thinking of FOV in terms of focal length on 35mm film SLRs. Thus when I moved to APS-C digital, I found FOV equivalency useful, but that's only because I was thoroughly familiar with focal lengths on FF. Without that familiarity, FOV equivalency would have been utterly useless to me.

After a while, when I had become accustomed to the focal lengths of APS-C (through the experience of using them), I no longer needed to calculate what FOV I needed by determining FF focal length equivalence. Later, when I started shooting m43, I had to briefly rely FF focal length equivalents again, but I caught on very quickly and now I'm thoroughly fluent in m43, APS-C, and FF. The larger point is FOV equivalency is only useful for people who are familiar, via first-hand experience, with a specific format. During the early years of digital, most serious photographers were familiar with FF, so that became the de facto standard. And it made sense at the time. But now that there's a growing number of photographers who never shot 35mm film, the insistence on the part of lens manufacturers on advertising 35mm FOV equivalency may be confusing more people than enlightening them.

[ElJamoquio]

I chose the APS-C body because it was $486 cheaper.

You should go back and buy the other camera. F/1.8 is clearly better.