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10-09-2014, 02:12 PM   #76
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QuoteOriginally posted by ChristianRock Quote
There are some aspects where equivalence makes sense (comparing DOF or FOV)
The only instance I can think of where it makes sense is if you regularly switch back and forth between two formats. My Ram pickup takes a different amount of throttle movement for a different amount of time to accelerate to 65 MPH than a Toyota Camry would. Since I don't have a Camry, the equivalent throttle movement/time to get one to 65, or the speed that the Camry would be travelling after the same time and movement is as irrelevant as FOV/DOF equivalence SHOULD be to anyone who doesn't have cameras of different formats.

Anyone who disagrees with that clearly doesn't understand it.


Last edited by Parallax; 10-09-2014 at 02:20 PM.
10-09-2014, 02:17 PM   #77
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I agree, it's only for the 35mm-centric. It's a reference, as I said. Once you know what it refers to, you can forget about it.
10-09-2014, 02:22 PM   #78
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QuoteOriginally posted by ChristianRock Quote
Once you know what it refers to, you can forget about it.
10-09-2014, 02:23 PM   #79
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Comparing FOV is not equivalence, is geometry
"Equivalence" is nothing more than a very specific, rigid, limited way of comparing different formats; it did not invent the mathematical and physics apparatus it's using, it brings nothing new other than its particular (mis)application.
"Equivalence" is useless because it can be applied only in very few circumstances (e.g. forum fights). "Equivalence" is a fraud because its proponents are attributing to it the math and physics notions, some discovered ages before even photography itself. And because it's claimed to be useful and used in every situation.

10-09-2014, 02:53 PM   #80
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QuoteOriginally posted by Kunzite Quote
When it's actually the likes of Northrup who should be blamed...
QuoteOriginally posted by redrockcoulee Quote
Many people who move into MF or LF cameras use their dslr for a light meter ....
QuoteOriginally posted by ChristianRock Quote
Yeah I wouldn't say equivalence is a fraud or is useless. But it's nothing more than a reference point,... It is what it is.
QuoteOriginally posted by ChristianRock Quote
I agree, it's only for the 35mm-centric. It's a reference, as I said. Once you know what it refers to, you can forget about it.
QuoteOriginally posted by Kunzite Quote
Comparing FOV is not equivalence, is geometry ....
Thank you guys.... I owe you big!!!!

Just one hour ago, just for the heck of it, I asked my grandaughter (9) who was hearing music with here Ipod thingie.... "Honey, how many LP records can you fit in that thing? How many WHAT?????

Of course, I knew how she would answer me (sort of), but what can I expect from someone that has no idea what is an LP record and has never seen one?

Unfortunately, digital photography is too young. It is until very recently, that newcomers can say they were born, raised and educated when digital was the standard and no film was used anymore. So photography is suffering with OUR own fears or resistance of change. We are old timers and some resist more than others the idea that film photography no longer is available (as easy or widely) as it was 15 years ago.

When I got into this fascinating hobby, sure 35 mm was available, but the professionals used medium format. Photo studios around town used their Mamiya C330. No one even dared to call themselves professional and use a 35 mm film for portraits. 35 mm film was only used by the "cheapo" school shooter or social even paparazzo, somtimes with their Olympus Pen rangefinders because they got 72 pictures out of each roll.

I witnessed the transition of some pro friends from medium format to 35 mm to portrait, during the late 70's, and I put God as my witness that I never heard something like "Hey, this 55 f/1.4 Nikkor is equivalent as the 80 mm in the Bronica (6x6...)" BTW, since cameras were all mechanic and batteries were for the light meter only, they never even cared for the battery. They simply used same ASA (now ISO) film and use the same exposure as with their medium formats...

Remember guys... we are the "transition" generation between analog and digital photography. We have to be careful on what we try to teach the coming generations, 'cause who knows, it may come one day when one of us while wandering the halls of some photo exhibition (20 yrs ahead), may say something like..."Great depth of field, nice bokeh, smooth grain and good noise handling.... he was probably using a Pentax 645z with postprocessing in PS CC34" and someone behind our back will say "What grandpa... 'you on dope or what? That's a straight print done at the local Duane Reade drugstore, directly from my smartphone ring here in my pinky finger!"
10-09-2014, 03:13 PM   #81
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QuoteOriginally posted by rburgoss Quote
So photography is suffering with OUR own fears or resistance of change.
I guess you're right... I might be afraid of some ISO standards being changed, elementary optics, perhaps even the metric system... I should give up and go with the flow
10-09-2014, 04:37 PM   #82
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QuoteOriginally posted by Kunzite Quote
I guess you're right... I might be afraid of some ISO standards being changed, elementary optics, perhaps even the metric system... I should give up and go with the flow
There was a time when you could walk into any fast food joint and ask for a large cheeseburger with everything on it. But now (depending on where you are, you have to ask for a Whopper, a Deluxe Quarter Pounder, a Hot'n Juicy 1/4 pounder, the 1/3 pound original six dollar burger, etc, and who knows how many "variations" of each there are.

If you walk into one of this franchise places, you cannot ask for a large cheeseburger with everything on it, because they all speak different languages... my God, and what about Taco Bell? Everything has four word names on which at least two of them are in Spanish, two in English and the combination sounds always strange: "Chiken Gordita Supreme Enchilada", Mexican Double cheese Pizza Tostada" or "Southwest Chalupa Supreme Gordita"... and wanna know something? They all taste the same!

Cheers
10-09-2014, 05:08 PM   #83
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QuoteOriginally posted by marcusBMG Quote
You can't multiply the focal length by the crop factor and NOT multiply the aperture by the crop factor .
What a load of crap.

That lens is f2.8 regardless if it's on a full frame or a crop sensor camera. End of story. It transmits just as much light regardless of body.

The sensor on a crop camera merely uses less of the circle than a FF would otherwise use, but the light density is the same no matter what.

And as to multiplying but the focal length... that is merely to get field of view, but not any added 'zoom'.

Crop has some disadvantages but it certainly does not change the amount of the f stop on any lens.

10-09-2014, 05:21 PM - 3 Likes   #84
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You are right (with caveats)

QuoteOriginally posted by marcusBMG Quote
Tony Northrup got similar responses. I (and he) never said that the focal length or aperture of the lens changes. I (and he) are saying that if you want to think in terms of full frame equivalence then its both aperture and focal length that need to be multiplied by the crop factor. And the fact is that many do - only yesterday I pm'ed a fellow forum member who had written that a classic 135mm f2.8 would give 200mm!! at f2.8!! And the fact is that many don't appreciate the effect on DoF.
But at the end I agree with Dartmoor Dave that if you don't switch formats you shall just be familiar with the Dof and FoV on the format you use and thats all you in practical terms need - well put mate. But your first comment is just wrong, this is maths not misinformation, and your last comment misses the point: they advertise in terms of full frame equivalence. Bridge cameras are probably the worst offenders - check for yourself. Lenses marked being eg 28-400mm (equivalent) f2.8 except of course they're not! They're 6.5-80mm f2.8 OR 28-400mm f14 (I have assumed 5x CF) described as full frame equivalent.
This is not confusion it is enlightenment.
You - and Tony - are mostly correct.

I say 'mostly' because putting the equivalent aperture right on the lens barrel or camera face does three slightly negative things in addition to the positive things -

1) it doesn't necessarily help anyone's confusion about the subject. I and others have tried to explain equivalence for years now, and even some people who have read the articles, etc are still confused by it and reject it. You can see that by a few responders to this thread. Your average Joe who's just looking at a lens barrel isn't going to do any better than them. (well, he might. )

2) F-stop does affect exposure in a constant way (not Total Light), so it does affect shutter speed in the same way on all formats. Someone primarily concerned with shutter speed, vs. noise, DR, total light and DOF, will thus be confused.

3) It further establishes 135mm (FF) as the 'standard reference'. IMO this isn't bad - we need some standard so we know what AOV/aperture we're really talking about - but having 35mm be set up as the standard angers a few % of people who shoot smaller formats. This would just rub it in more.

So instead of putting it on the lens, IMO what should happen is *all* professional/commercial review sites and entities should mention the equivalent aperture range for a given combo they review - like they mention the equivalent FL range now - and commercial sales sites like B&H and Adorama should also always mention it.

Dpreview has started doing this in a graphical way, and good for them (chart below.) IMO this chart is nearly perfect, it tells you much about what you're actually buying in one glance:




Incidentally --> this is a good, easy article on the subject.


Below is a fantastic practical example of why this is important - look at the Lumix (25-600 f/2.8!!) and Olympus Stylus 1's impressive numbers - and then look again... maybe not so impressive when you know the equivalent aperture range. (and note yellow highlighted below (from dpreview) :



---------- Post added 10-09-14 at 06:53 PM ----------

QuoteOriginally posted by JinDesu Quote
....no.... that's not how physics or the sensor works...

A cropped sensor will receive the same quantity of light per area as a larger sensor. The larger sensor will always have more photosites/pixels than the smaller one - so when you look at an equivalent FOV image between a larger and a smaller sensor, the larger sensor has better noise signal when SCALED to an equal pixel count.

I.e. 36MP D800 vs 16MP cropped mode - at 100% crop the noise is the same. You can literally see this in person if you have a D800. You can also see this is true by comparing 100% crops of a D800 to a D7000. The noise at the pixel level is the same in quantity and size. However, upon scaling to equal (whether you scale the 36MP down to 16MP or scale the 16MP up to 36MP), the signal to noise ratio favors the larger sensor.

A larger sensor does not absorb more light than a smaller sensor of the same technology. It just has more pixels/photosites. That's all.
Jin, you have this wrong.

Consider FF sensors that have the same or less pixels than say 16MP - and yet they still show the 1+ stop SNR advantage. Downsampling can't account for those situations.

Here's what's happening in a nutshell - the larger sensor is absorbing more total light specifically because the physical aperture being used to get the same FOV from the same distance is greater. Understanding this requires that someone understands the basics of equivalence...

Here - two formats, let's assume same sensor efficienncy/generation - same FOV and F-stop and shutter speed (same exposure) :

FF: 70mm f/2.8 = 70 / 2.8 = 25mm physical aperture
m43: 35mm f/2.8 = 35 / 2.8 = 12.5mm physical aperture

So even though they have the same exposure (light density,) the FF image would have more Total Light due to twice the physical aperture used to get the same FOV, and thus it would have two stops better SNR, better DR - and also two stops less DOF. This is precisely how FF get's it's noise advantage.

And this ^^ happens independently of # of pixels.

.

Last edited by jsherman999; 10-09-2014 at 09:40 PM.
10-09-2014, 06:09 PM   #85
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QuoteOriginally posted by jsherman999 Quote
You - and Tony - are mostly correct.

I say 'mostly' because putting the equivalent aperture right on the lens barrel or camera face does three slightly negative things in addition to the positive things -

1) it doesn't necessarily help anyone's confusion about the subject. I and others have tried to explain equivalence for years now, and even some people who have read the articles, etc are still confused by it and reject it. You can see that by a few responders to this thread. Your average Joe who's just looking at a lens barrel isn't going to do any better than them. (well, he might. )

2) F-stop does affect exposure in a constant way (not Total Light), so it does affect shutter speed in the same way on all formats. Someone primarily concerned with shutter speed, vs. noise, DR, total light and DOF, will thus be confused.

3) It further establishes 135mm (FF) as the 'standard reference'. IMO this isn't bad - we need some standard so we know what AOV/aperture we're really talking about - but having 35mm be set up as the standard angers a few % of people who shoot smaller formats. This would just rub it in more.

So instead of putting it on the lens, IMO what should happen is *all* professional/commercial review sites and entities should mention the equivalent aperture range for a given combo they review - like they mention the equivalent FL range now - and commercial sales sites like B&H and Adorama should also always mention it.

Dpreview has started doing this in a graphical way, and good for them (chart below.) IMO this chart is nearly perfect, it tells you much about what you're actually buying in one glance:




Incidentally --> this is a good, easy article on the subject.


Below is a fantastic practical example of why this is important - look at the Olympus Stylus 1's impressive numbers - and then look again... maybe not so impressive when you know the equivalent aperture range. (and note yellow highlighted below (from dpreview) :



---------- Post added 10-09-14 at 06:53 PM ----------



Jim, you have this wrong.

Consider FF sensors that have the same or less pixels than say 16MP - and yet they still show the 1+ stop SNR advantage. Downsampling can't account for those situations.

Here's what's happening in a nutshell - the larger sensor is absorbing more total light specifically because the physical aperture being used to get the same FOV from the same distance is greater. Understanding this requires that someone understands the basics of equivalence...

Here - two formats, let's assume same sensor efficienncy/generation - same FOV and F-stop and shutter speed (same exposure) :

FF: 70mm f/2.8 = 70 / 2.8 = 25mm physical aperture
m43: 35mm f/2.8 = 35 / 2.8 = 12.5mm physical aperture

So even though they have the same exposure (light density,) the FF image would have more Total Light due to twice the physical aperture used to get the same FOV, and thus it would have two stops better SNR, better DR - and also two stops less DOF. This is precisely how FF get's it's noise advantage.

And this ^^ happens independently of # of pixels.

.
You are right, assuming you want some sort of normalized output. Everyone seems to concentrate on pixel level noise/output, which is, of course pretty meaningless. The question is what happens when you print at a particular size or, view at a particular size and that is where full frame has the advantage. Otherwise, the D800 and K5 have the same pixel level noise.

Full frame is better, I just go back to the fact that for most folks, APS-C is "good enough."
10-09-2014, 06:18 PM - 1 Like   #86
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QuoteOriginally posted by marcusBMG Quote
thank you
(and your other points are all good, except you imply I said against them which I didn't!!)

---------- Post added 9th Oct 2014 at 14:13 ----------



Are you sure about that? See this Tony Northrup video from around the 8 minutes mark:
Crop Factor with ISO & Aperture: How Sony, Olympus, Panasonic, Canon, Nikon & Fuji Cheat You - YouTube
The idea that an APS-C sensor has inherently more noise than a FF is incorrect when the same technology is used in both formats. What brings the noise to our attention is the magnification of the output to our standardized viewing systems. If I shoot my D800E in "1.5x crop mode" I am using the same technology as when i shoot in 1x mode and the only thing that is making the "extra" noise more prominent is the magnification at output. If you printed/viewed APS-C images at a correspondingly smaller size in relation to FF you'd see no IQ difference at all.
10-09-2014, 06:24 PM   #87
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QuoteOriginally posted by Parallax Quote
The only instance I can think of where it makes sense is if you regularly switch back and forth between two formats.
Yes. Or if you only shoot one format but you're considering buying into another format.
10-09-2014, 06:31 PM - 1 Like   #88
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QuoteOriginally posted by carpents Quote
THIS.

Exactly the point when people talk about equivalence - a smaller sensor *should* afford you some creative options for lens design. Pentax has some success with this in designing great pancake primes by the way.
18-35mm f/1.8 is about the same as 28-55 f/2.8 on FF in all respects.

Not really all that impressive of a lens IMO.
10-09-2014, 06:33 PM   #89
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QuoteOriginally posted by jsherman999 Quote
Yes. Or if you only shoot one format but you're considering buying into another format.
Okay, fair enough. Anyone currently shooting APS-c and considering a switch to FF needs to take into account the .66 crop factor when converting the 24x36 to the APS-c equivalent. (90mm on 24x36 x .66 =60mm on APS-c.)
In other words, we should all be obsessing about APS-c equivalent, not "FF" equivalent.

Last edited by Parallax; 10-09-2014 at 06:42 PM.
10-09-2014, 08:08 PM   #90
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QuoteOriginally posted by marcusBMG Quote


So anyway, happy to have been of service in provoking an enthusiastic response, and to have improved my understanding of things .. at least a bit...
Marcus, if you're in a studio, and someone with a light meter yells back at you "5.6!", that's what you set both on your K-r and your m4/3.

And your D810 if you had one.

Sooner you ditch this 'equivalence of light quantity' thing, the better!

There are legitimate reasons for the excitement of Pentax Full Frame Fetishists, this isn't one of them.
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