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01-24-2019, 07:54 PM - 2 Likes   #16
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QuoteOriginally posted by reh321 Quote
In that type of photography, in common with 'street photography',
* Measurement is not a thing.
* Calculation is not a thing.
* Trial-and-error is not a thing {only one chance unless you have a 'way back' machine}

Typically you look for a value f/5.6 or higher (*) that satisfies 'exposure triangle' and hope that it works.
That is a major lesson of "f/8 and be there".
Perfectionists don't understand this.

(*) closer to f/11 or so the better
And yet the classic "f/8 and be there" rule varies with the format.

An APS-C user would say "f/5.6 and be there," an M43rds user would say "f/4 and be there," and a 8x10 user would say "f/64 and be there (with a big tripod)."

The smartphone user might be worried that their phone's camera can't even be changed but if they know about equivalence, they'd know that fixed wide-open f/1.8 is just fine for street -- "just be there" is their motto!

Even in street photography, there's equivalence calculations. But it's in the format-specific rule, not in the photographer's day-to-day shooting (unless they use multiple formats).

01-24-2019, 08:02 PM - 2 Likes   #17
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QuoteOriginally posted by normhead Quote
Or you can just learn an FF is one stop shallower DoF than the same lens on APS-c. (And not learn equivalence.)

No one is saying equivalence is worthless. But, it's possible to learn everything you need to know, other ways. Equivalence is overshadowed by more useful concepts.
As I said, IMHO, equivalence is make a work project.
Actually, FF is one stop shallower DoF than APS-C only if you use a 1.5X longer focal length on FF to replicate the field-fo-view you had on APS-C.

If you move the exact same lens from APS-C to FF (assuming it covers the larger image circle), you'll find that the lens has a much wider FoV on FF and has one stop deeper DoF at the whole-image print level.

(This is why so many people get confused -- the think about putting the same lens on two different formats but that has nothing to do with the actual concept of equivalence as BigMackCam and I would define it.)
01-24-2019, 08:12 PM   #18
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QuoteOriginally posted by photoptimist Quote
The smartphone user might be worried that their phone's camera can't even be changed but if they know about equivalence, they'd know that fixed wide-open f/1.8 is just fine for street -- "just be there" is their motto!
They don't need to know equivalence - they just need to know that their system provides essentially infinite DOF {they may not even know what DOF is, or that DOF is limited for larger cameras}. As processing gets better and better, as smaller sensors become better and better, the only people who care about all this will be those who cling to "subject isolation" .... and this is the place in the other thread where we started talking about "equivalence".

Last edited by reh321; 01-24-2019 at 08:30 PM.
01-24-2019, 08:28 PM   #19
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QuoteOriginally posted by photoptimist Quote
And yet the classic "f/8 and be there" rule varies with the format.

An APS-C user would say "f/5.6 and be there," an M43rds user would say "f/4 and be there," and a 8x10 user would say "f/64 and be there (with a big tripod)."
But none of this matters for some of us. As I indicated earlier, I typically select the minimum shutter speed that meets my needs, and the camera selects an aperture that makes the 'triangle' work, just as I did back in the days when I used FF {aka 35mm}; I suppose I'll have to learn more about how DOF works for APS as I make more use of TAv mode, but it will be APS guidelines (*) I learn, I have no need of FF guidelines.

(*) what aperture gives me a "comfortable DOF" within a certain focal length range

01-24-2019, 08:30 PM - 1 Like   #20
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QuoteOriginally posted by reh321 Quote
They don't need to know equivalence - they just need to know that their system provides essentially infinite DOF. As processing gets better and better, as smaller sensors become better and better, the only people who care about all this will be those who cling to "subject isolation" .... and this is the place in the other thread where we started talking about "equivalence".
Given how much money and technology smartphone makers are investing in synthesizing shallow DoF images, I think the smartphone makers realize that subject isolation is a very important tool in the photographer's arsenal.

Some scenes simply have too much extraneous, distracting, and even ugly background clutter. A skilled photographer can use shallow DoF to blur the garbage and focus on the subject. And the really skilled ones might even intentionally blur the subject (e.g., a person) to create a very strong mood of alienation, anonymity, or amnesia about that subject person with respect to the environment.

Sure, subject isolation might be over-used by some but let's not throw the very useful baby out with the instagram bath water.
01-24-2019, 08:39 PM   #21
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QuoteOriginally posted by photoptimist Quote
Given how much money and technology smartphone makers are investing in synthesizing shallow DoF images, I think the smartphone makers realize that subject isolation is a very important tool in the photographer's arsenal.

Some scenes simply have too much extraneous, distracting, and even ugly background clutter. A skilled photographer can use shallow DoF to blur the garbage and focus on the subject. And the really skilled ones might even intentionally blur the subject (e.g., a person) to create a very strong mood of alienation, anonymity, or amnesia about that subject person with respect to the environment.

Sure, subject isolation might be over-used by some but let's not throw the very useful baby out with the instagram bath water.
Yes, a few clever artists will worry about DOF - and some of the common folk will find synthesized DOF to be a fun toy to use .... like front-facing cameras or in-phone processing that magically changes the color pallet - but synthesized DOF will have little/nor relationship to any kind of equivalence.

Last edited by reh321; 01-24-2019 at 08:49 PM.
01-24-2019, 08:44 PM - 2 Likes   #22
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QuoteOriginally posted by photoptimist Quote
Actually, FF is one stop shallower DoF than APS-C only if you use a 1.5X longer focal length on FF to replicate the field-fo-view you had on APS-C.

If you move the exact same lens from APS-C to FF (assuming it covers the larger image circle), you'll find that the lens has a much wider FoV on FF and has one stop deeper DoF at the whole-image print level.

(This is why so many people get confused -- the think about putting the same lens on two different formats but that has nothing to do with the actual concept of equivalence as BigMackCam and I would define it.)
Most people never memorized the 35mm rules, so those who care about DOF will carry a DOF calculator around with them; I see little use for worrying about equivalence.
01-24-2019, 10:10 PM - 3 Likes   #23
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QuoteOriginally posted by BigMackCam Quote
This subject always generates a significant amount of heated conversation, which seems to become more-or-less polarised between two camps - those that think equivalence is a mis-nomer and / or of no practical use, and those who maintain the opposite (with a few folks in the middle ground between).
A concise and easy to follow explanation, how dare you make the topic so easily understood, how will keyboard warriors use their time now? Oh well, time to sit back and watch, Thanks

01-24-2019, 10:45 PM   #24
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QuoteOriginally posted by normhead Quote
Or you can just learn an FF is one stop shallower DoF than the same lens on APS-c. (And not learn equivalence.)

No one is saying equivalence is worthless. But, it's possible to learn everything you need to know, other ways. Equivalence is overshadowed by more useful concepts.
As I said, IMHO, equivalence is make a work project.
No matter what method you use, if you get the relations correct, you have learnt the equivalency between the formats.

The mathematical method is usually the quickest an most simple way to learn about equivalency, because the calculations are so simple.

If you understand that APS-C give you one extra stop DOF at the same FOV as FF, and for the same FOV you need to divide focal length by 1.5 for APS-C.
If you understand how exposure work, then it is basically everything you need to know about equivalency between APS-C and FF.

It is so easy that photographers that use multiple formats do not need to think about it after a few days.
01-24-2019, 11:34 PM - 2 Likes   #25
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QuoteOriginally posted by BigMackCam Quote
"Equivalence" between formats and lenses...
There is no such thing as equivalence because I tell the difference of two prints from apsc and medium format cameras, no need to even look close, the medium format wins on latitude and tone definition. Medium format is bigger, more expensive and deliver better images, so it's not at all equivalent to other formats.
01-25-2019, 12:23 AM   #26
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The degree of lacking understanding in these discussions can easily be judged by the number of times "shallow DoF" is being mentioned by people who do not focus most of their work on macro photography.

A lot of DoF is important in macro photography (to minimize the need for stacking), but in pretty much all other areas the one topic of interest is a lot of "background blur" (or as noobs express it: bokeh).

And everyone understanding "equivalency" knows that DoF and background blur are not in sync in any way. Down to the point that in more than enough cases one combo will have "shallower DoF" and the other will have "more background blur".

The other key comment here is that different people's scenarios differ a lot, so the consequences for equivalency differ a lot as well (and very, very few understand that).
Here BigMackCam said his question revolves around constant subject-to-camera distances. Case A.
I personally couldnt care less for this, but I care for constant subject framing. Case B.
Any equivalency discussion which does not absolutely fix and agree on one of those two is going to be nonsense.

These are already two common pitfalls making up a matrix of four potential discussions, which will all lead to very different conclusions.
01-25-2019, 12:59 AM   #27
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May not be the right place?
I have always wondered why the lens manufacturer label there aps-c lenses (lenses that only work properly on
aps-c body's) the way the do.
Example
" Pentax-DA 18-50mm F4-5.6 DC WR RE" you can use it on a FF body, but it will not work properly. It was designed to be used exclusively on a crop sensor body. So why not call it what it actually is 27-75 lens. All the lens manufacturers have lenses designed to be used exclusively on aps-c body's if a lens false in that category they should be labeled properly based on the age old standards created in the film era.
I think this could of really helped with new photography's. I have talked to many new photographers that can't understand why they can't get as much in there photo (FOV) with there 18-50 kit lens as I am getting with my 24mm. I have to try to explain that I'm using a FF camera and so my 24mm is actually wider than there 18mm.
Well this normally gets the "deer in the headlights" look from them an often they say shouldn't 18mm be 18mm.
I normally respond "yep"
I don't know if this comment fits in this thread if not I apologize!!
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01-25-2019, 01:10 AM   #28
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QuoteOriginally posted by Photobill Quote
May not be the right place?
I have always wondered why the lens manufacturer label there aps-c lenses (lenses that only work properly on
aps-c body's) the way the do.
Example
" Pentax-DA 18-50mm F4-5.6 DC WR RE" you can use it on a FF body, but it will not work properly. It was designed to be used exclusively on a crop sensor body. So why not call it what it actually is 27-75 lens. All the lens manufacturers have lenses designed to be used exclusively on aps-c body's if a lens false in that category they should be labeled properly based on the age old standards created in the film era.
Because it's absolutely not a 27-75mm lens. An 18-50mm lens is an 18-50mm lens regardless of the sensor or film size used by the camera it is fitted to. But the image circle isn't large enough to cover a full frame sensor.

Consider the DA40 f/2.8 Limited. This is a 40mm lens designed for APS-C. When you fit it to a full frame K-1, it's still a 40mm lens designed for APS-C, but by happy coincidence in this particular case, the image circle is just about large enough to allow useful operation with the full format sensor.
01-25-2019, 01:48 AM   #29
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QuoteOriginally posted by beholder3 Quote
The degree of lacking understanding in these discussions can easily be judged by the number of times "shallow DoF" is being mentioned by people who do not focus most of their work on macro photography.

A lot of DoF is important in macro photography (to minimize the need for stacking), but in pretty much all other areas the one topic of interest is a lot of "background blur" (or as noobs express it: bokeh).

And everyone understanding "equivalency" knows that DoF and background blur are not in sync in any way. Down to the point that in more than enough cases one combo will have "shallower DoF" and the other will have "more background blur".

The other key comment here is that different people's scenarios differ a lot, so the consequences for equivalency differ a lot as well (and very, very few understand that).
Here BigMackCam said his question revolves around constant subject-to-camera distances. Case A.
I personally couldnt care less for this, but I care for constant subject framing. Case B.
Any equivalency discussion which does not absolutely fix and agree on one of those two is going to be nonsense.

These are already two common pitfalls making up a matrix of four potential discussions, which will all lead to very different conclusions.
The main difference between case A and B is that perspective change in case B, but is constant in case A.

Changed perspective is not really about equivalence, as constant perspective is part of equivalence.
Case B is more equivalent of switching between DFA50 and FA77 on K1 and keeping constant framing.
01-25-2019, 02:07 AM   #30
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QuoteOriginally posted by Photobill Quote
" Pentax-DA 18-50mm F4-5.6 DC WR RE" you can use it on a FF body, but it will not work properly. It was designed to be used exclusively on a crop sensor body. So why not call it what it actually is 27-75 lens.
Photobill
Focal length is the distance from the axis of the lens to the plane it is sharp at infinity focus. That is still 18-50mm, that doesn't change. On ff or apsc the lens is just as far from the sensor.
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