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01-14-2012, 07:50 AM   #136
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QuoteOriginally posted by Jüri Quote
I don't acutally think it's that simple. Because the edges of APS-C are cropped compared to FF, in order to take similarly composed photo with a APS-C you'll have to move further from the subject. And that will alter DoF, perspective, angle etc.


I'm not sure I understood what you mean, but equivalence makes a lot of difference to me. A 28mm lens is very wide on my FF camera, but almost normal focal length on APS-C. So that's something I always need to consider when choosing what to use.
I think he means, if you work in one format, you know what lens gives you what FOV. There is no thinking of equivalence if you use one format, regardless of what format it is.

01-14-2012, 08:17 AM   #137
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QuoteOriginally posted by JinDesu Quote
I think he means, if you work in one format, you know what lens gives you what FOV. There is no thinking of equivalence if you use one format, regardless of what format it is.
That's true. If you never intend to use more than one format, the whole concept of equivalence shouldn't matter one bit. It starts to matter quite a bit when you're discussing shooting more than one format, or wondering what it would be like to shoot your lenses on another format, and then it matters both with FOV (sometimes simplified to 'crop factor') and DOF.

For example if you're starting from aps-c and looking at FF, you probably want to understand that your 28-75mm f/2.8 zoom on aps-c doesn't 'behave' like an 28-75mm f/2.8 zoom on FF. It behaves like an 18-50mm f/2.8 zoom with regards to FOV + exposure/shutter speed, and an 18-50 f/1.8 zoom with regards to FOV/DOF.



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01-14-2012, 08:22 AM   #138
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QuoteOriginally posted by JinDesu Quote
I think he means, if you work in one format, you know what lens gives you what FOV. There is no thinking of equivalence if you use one format, regardless of what format it is.
Yes, exactly. If I have a camera in my hand, why would I be thinking about what the shot I am taking right now would be equivalent to in some other format I'm not even using? Also keep in mind what we were talking about is how to explain the concept to a newbie -- if you are really walking around with different bodies of different formats and that big bag of lenses, then sure you've got choices to make it it will be helpful to know what is roughly equivalent between them. But if you are such a person, then you won't need the concept explained to you, eh? I'm not suggesting that no one should ever think about these things, but there seems to be rush to bombard someone just trying to understand the basic idea of "crop factor" with a mountain of overwhelming complex stuff about DOF, etc when the answer is so simple.
01-14-2012, 08:42 AM   #139
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If you think of actually using a camera, you look through the viewfinder, you compose, you shoot, your eye works with what you have. IN essence it's the same for every non-dynamic camera. But looking through the viewfinder, I've never once thought "I wish I had a full frame camera" or I wish I had a 645. I have looked and said "I wish I had tilt front and back focal planes... but that's a whole different issue. In essence all fixed focal plane cameras are the same. The differences mean you win in some situation, and lose in others, you have less depth of field when sometimes you want more, you have more depth of field when sometimes you want less, but those are balanced out by the times you have more depth of field with an APS-c and you want every bit of it, or you have less depth of field in FF and you want it even narrower. As soon as you have people talking about the strengths of a system without talking about the trade-offs, what they gave up to get that strength, they're talking trash. I shoot enough different situations.. there is no system that's going to do everything I want. I want front and back swivel and tilt and an 8x10 focusing screen, on a camera that fits in my pocket. The question is not what is the best system... the question is which is the series of compromises that best fits my shooting style? That is always going to be a 1 at a time, every man for himself decision. But people trashing other people's systems and saying i can't get what i want out of APS-c, and should be using full frame... come on people. First of all, that assumes you know what I need better than I do... 9 times out of 10 that's not going to be true. Most free advice is worth what you pay ofr it. Never project your personal decision onto someone else's needs and we can all get along here.

The one time I'd say otherwise is, I've known people who belong to camera clubs etc. who've gone Nikon or Canon because that's what their closest buddies use, and they can share the learning curve and gear. In a case like that it becomes a social thing based on group needs rather than personal needs, but that's pretty much the only time discussion will out weigh a personal exploration of your options before purchasing a camera system. You can listen when other people talk about their gear, but you still have to find out what's right for you... and personally I wouldn't listen to anyone who says, you have to have APS-c or you have to have full frame. You have to have is the willingness to do the research to find out what the best thing for you is. And for a lot of us price is part of that. People who talk about FF APS-c as if they are the same money are by definition lunatics. IN every such discussion there needs to be a cost benefit breakdown... so the newbie understands what he's getting, and what he's paying for it.

How much is it worth to me to have narrower depth if field? Nada, wouldn't pay a cent for it. I'd actually be more interested in a smaller sensor with more depth of field, and less weight if the image quality was the same..Now if you're talking larger file size...maybe, but even then, I'm not sure I'll ever need to go over 16mb, and if I do, I'm going to need a faster computer with a bigger drive to handle the larger files.

01-14-2012, 08:42 AM - 1 Like   #140
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QuoteOriginally posted by vonBaloney Quote
... I'm not suggesting that no one should ever think about these things, but there seems to be rush to bombard someone just trying to understand the basic idea of "crop factor" with a mountain of overwhelming complex stuff about DOF, etc when the answer is so simple.
As long as your definition of "so simple" is "leave out half the information."

If you're talking to a 'newbie' who's casually asked about it at a party, and you're late for a movie or something and/or your 'newbie' isn't really particularly interested, go ahead and stick to the crop FOV difference. If you're discussing it with a 'newbie' who's bothered to log in to an online forum to ask the question - or when you're posting in a thread titled "APS-C vs FF format" - you'd better tell the whole story.


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01-14-2012, 08:55 AM   #141
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QuoteOriginally posted by jsherman999 Quote
As long as your definition of "so simple" is "leave out half the information."
As I've repeatedly said, that's the *starting point* to understanding and the foundation of all the other stuff you want to lay on them (whether they like it or not). It is the first thing they ought to be told, and it would be sufficient in many cases as the only thing because everything else follows quite obviously from it, i.e. a smart person doesn't necessarily be need to told the rest, or wouldn't even care once they knew the basic difference. It seems like some of you would like to hide the information for a while for some reason...
01-14-2012, 09:10 AM   #142
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QuoteOriginally posted by vonBaloney Quote
As I've repeatedly said, that's the *starting point* to understanding and the foundation of all the other stuff you want to lay on them (whether they like it or not). It is the first thing they ought to be told, and it would be sufficient in many cases as the only thing because everything else follows quite obviously from it, i.e. a smart person doesn't necessarily be need to told the rest,
I have quibbles with this. The DOF difference doesn't 'follow quite obviously from it', at least not quickly, which is why it bears explanation, even to 'smart' newbies.

When Joseph James started writing about equivalence relationships six years ago or so on dpreview and other places, a lot of non-newbie folks at first thought he was nuts, or getting something wrong, when he talked about the DOF shift at equivalent FOV and aperture. It took a lot of explanation and a lot of independent follow-up trials and tests by different folks before it became accepted by everyone. To this day it's still not well-understood, even by experienced shooters - take a look at some of the initial misinformation that was given in this thread.

It's not obvious, and it's effect is significant to some, so it should almost always be part of the discussion, IMO.

QuoteQuote:
or wouldn't even care once they knew the basic difference. It seems like some of you would like to hide the information for a while for some reason...
If you don't tell the whole story, isn't it you who is hiding information?


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Last edited by jsherman999; 01-14-2012 at 09:18 AM.
01-14-2012, 09:33 AM   #143
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this hoary reminiscence again

Back in the day (about 35 years ago now) my colleagues and I worked with multiple formats daily, including systems with mounts for the same lenses on different-format cameras. We never spoke of 'equivalence' nor crap.factors. We learned how various focal lengths performed in different situations. That's all.

A metaphor: Say you've got some hammering to do. Do you calculate the equivalence of each hammer? Or do you just learn which hammer is best for which target? Now, apply that to lenses. Hay, some lenses can be used as hammers! My Lil'Bigma 170-500 is great for crushing Chihuahua dogs too. But I digress.

To me, these FF vs HF / APS arguments are absurd. That the arguments become vicious is even more absurd. Princeton Uni president Woodrow Wilson said that academic disputes are so vicious because the stakes are so low. And of course there's the Special Olympics metaphor for Internet arguments. Pretty depressing...

01-14-2012, 09:45 AM   #144
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QuoteOriginally posted by RioRico Quote
Back in the day (about 35 years ago now) my colleagues and I worked with multiple formats daily, including systems with mounts for the same lenses on different-format cameras. We never spoke of 'equivalence' nor crap.factors. We learned how various focal lengths performed in different situations. That's all.
How would you explain it to someone who asked, who maybe didn't have your hands-on experience? I'd assume you'd use casual terms as folks in this thread have done, 50mm f/2.8 = 35mm f/1.8, etc. In doing that, you're actually talking about equivalence, even though the term wasn't used back then.

The differences you were seeing first-hand in FOV and DOF mounting those same lenses on different formats are actually explained by the concept of equivalence, and described well by folks like Joseph James and simplified by folks like Bob Atkins.



QuoteQuote:
To me, these FF vs HF / APS arguments are absurd. That the arguments become vicious is even more absurd. Princeton Uni president Woodrow Wilson said that academic disputes are so vicious because the stakes are so low. And of course there's the Special Olympics metaphor for Internet arguments. Pretty depressing...
You think this discussion is 'vicious'? (Also, I'd refer you to the title of the thread. Is there a more appropriate place this should be discussed?)



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01-14-2012, 09:57 AM   #145
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QuoteOriginally posted by vonBaloney Quote
I really don't understand this talk about enlarging a crop and having it change -- the DOF doesn't change, nor does anything else -- everything is just relatively larger, rescaled.
But the depth of field does change, because you've enlarged the circles of confusion. What was acceptably sharp at say 50% may no longer be acceptably sharp at 100%. That's why pixel-peeping can show focus issues.

(All the more so if the cropped sensor has more pixels per inch than the full-frame sensor. Two lenses that look the same on full-frame may look different on the cropped sensor, if the cropped sensor has enough resolution to expose the differences between them.)

QuoteOriginally posted by vonBaloney Quote
In real life, the difference only really matters when you are picking out a camera to begin with because you do have a choice now.
And it matters in threads like this that are discussing the benefits of different sensor sizes.

(And a newbie shouldn't even consider FF for their first camera, unless they just won the lottery.)
01-14-2012, 10:26 AM   #146
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QuoteOriginally posted by vonBaloney Quote
Why in the world would a newbie need to hear about the *subjective* flattening of perspective (since it isn't really) compared to a format they don't have?
First of all perspective is not a lens or sensor size thing! Perspective has everything to do with your view/stand point.
You can photograph with a 10mm lens on FF and photograph with 600mm on APS-C, as long as you stay standing on the same point your perspective will be the same.

Not that is cleared up.

If someone is willing to spend $2K on a FF camera i surely hope they at least have a bit more understanding then the beginner and so they should be able to understand this.


Also 300mm f/4.5 is not the same on FF as 200mm f/2.8 on APS-C, what about the light gathering of the lenses?
There is just so much going on that it's silly to compare the two like this, just thread them as different, know the strength of both, stop comparing and move on...
01-14-2012, 11:38 AM   #147
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QuoteOriginally posted by Anvh Quote
If someone is willing to spend $2K on a FF camera i surely hope they at least have a bit more understanding then the beginner and so they should be able to understand this.
Depends on how well off you are. I know people that would think nothing to spend $2K on a camera they knew nothing about if they heard it was "the best".

There was a P&S model that came under Leica and Panasonic branding -- same camera, but the Leica version was hundreds more (I think $400 more). I was reading a blog post by someone that had bought the Leica version even though they knew the Panasonic was available, and they said that having the Leica logo there as a status symbol was worth the extra $400 to them. People are crazy.
01-14-2012, 01:14 PM   #148
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QuoteOriginally posted by bossa Quote
This is how I see this: Perspective is a spatially relative perception that takes into account the entire image circle of a lens' projection whereas a central crop ignores the closer (side/up/down) parts of the image. Magnifying a central portion of an image's perspective 'flattens' the form as it removes other relevant and relative visual information. After you enlarge that the extra little bit to satisfy your viewing requirements it is a multiple of the crop factor and as such changes relative aspects of the image.. i.e. DOF. Nothing has really changed, in a way, but the scale of the viewing situation relative to your own physical size and eyesight resolving power. The reason it is so hard to understand is because it is not an absolute quantifiable effect.
Perspective has nothing to do with how much the image is cropped. It is solely from the distance from the camera to the subject. Cropping an image does not change your perspective.
01-14-2012, 01:28 PM   #149
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QuoteOriginally posted by vonBaloney Quote
Depends on how well off you are. I know people that would think nothing to spend $2K on a camera they knew nothing about if they heard it was "the best".

There was a P&S model that came under Leica and Panasonic branding -- same camera, but the Leica version was hundreds more (I think $400 more). I was reading a blog post by someone that had bought the Leica version even though they knew the Panasonic was available, and they said that having the Leica logo there as a status symbol was worth the extra $400 to them. People are crazy.
Yeah i know some off them and it just sad...
They have a 5d mark II or something with a kit lens and they leave the hood turned on the wrong way around, it's indeed very sad for the camera...
01-14-2012, 09:53 PM   #150
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J,

I'd like to see if my understanding here of the little paragraph joseph wrote is correct. In Summary,

1. One can theoretically calculate the equivalent focal length required for say, a Pentax K5 lens to achieve the same shallow DOF as a 5D MK2. This is the reason for the argument that the DOF of FF isnt superior than a Crop sensor.
2. However, the actual lens required to have the same shallow dof and fov may not exist on the crop sensor format, if one hunts for shallow DOF only.
3. The opposite is true if one is hunting for a narrow DOF.

For example, if our 50-135 2.8 is roughly the fov for an FF 70-200 2.8, the same can not be said if I were to look for the equivalent DOF, because at 150mm i would need it to be a f2 to give me the same DOF. And since there isnt any zoom lens f2, for all intend and purposes, if shallow DOF is what I am looking for, a FF format is what I need.

Did I get that about roughly right?


Second part of the question : (derived from the first)

If say, the sweet spot for every lens is around F8 (F8 and be there), whether you own a crop or a FF, then basically, for the same given FOV, if I have a 50mm on an FF at F8, to achieve the same kind of sharpness on a Crop I would need to be at 75mm F12 or something..which means that if I had dialed F8 on the crop sensor for reasons of exposure, then I will always get a less sharper result.

Is this also correct?

In summary - an FF, given the lens that is right now out for sale, can always reach a shallower DOF, and will always be sharper at the same FOV given the same f stop.

?





QuoteOriginally posted by jsherman999 Quote
How would you explain it to someone who asked, who maybe didn't have your hands-on experience? I'd assume you'd use casual terms as folks in this thread have done, 50mm f/2.8 = 35mm f/1.8, etc. In doing that, you're actually talking about equivalence, even though the term wasn't used back then.

The differences you were seeing first-hand in FOV and DOF mounting those same lenses on different formats are actually explained by the concept of equivalence, and described well by folks like Joseph James and simplified by folks like Bob Atkins.





You think this discussion is 'vicious'? (Also, I'd refer you to the title of the thread. Is there a more appropriate place this should be discussed?)



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Last edited by D4rknezz; 01-14-2012 at 10:03 PM.
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