It is strange isn’t it

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mike
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#1
you read all the answers and everyone talks about crop factor and relates everything back to full frame 35mm including phone cameras having an equivalent focal length when surely they mean field of view

And yet 10x8 relates even further back to full plate cameras, 5x7 is also a plate sized camera, you get 6x8 frames but the correct full frame would be 6x9 so our printing sizes Are even older related

Then there is photoshop using Ruby as the masking colour and the term unsharp masking both of which come from B&W Darkroom’s and nothing to do with digital imaging

And when did I stop being the photographer and start being the author - maybe that started when the camera wrote to the memory card
 
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#2
I think this is a video where the Northrups go over some of these and how unintuitive and meaningless certain photography terms are:
View: https://www.youtube.com/watch?v=lWXCYotT230


Focal length is definately the worst and how everything is referenced back to "full frame" equivalent (which itself doesn't really mean a lot). It is completely arbitrary!
 
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#6
I still relate back to 35mm as that's what I grew up with. These days most people will I guess own APS-C kit and many will never have used film because all that was before they were born so I suppose it'll make less sense for them.
 
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#8
We need a reference point. Almost no-one knows or cares that a lens has a field of view (or should that be angle of view? ;) ) of 46.8 degrees (now is that horizontal, vertical or diagonal) but most people know roughly what to expect from a 50mm lens equivalent on a (so called) full frame camera.

We had this discussion just a few weeks ago - we have a pretty much universally recognised reference point which *may* seem illogical, but works for most people.
 
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#9
Are they really that hard to understand ?
You missed the point...no they are not hard to understand they are just not intuitive, logical terms, meaning they have to be explained.

We've decided that focal length is the measure for what is actually angle of view, even though it means nothing by itself. We also decided that 35mm "full frame" is the golden standard by which focal length should be referenced. If everyone used angle of view it wouldnt matter what sensor size you have, it would all match, and it would be easier to explain!

As it turns out the technical aspects of photography are pretty easy to get to grips with, that's why it's stuck I think.
 
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#10
I haven’t missed the point I just happen to agree with the post above yours regarding recognised reference points and full frame isn’t the golden standard just the original.
 
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#11
Agreed that equivalent focal length is odd and anachronistic but it’s adantage is that it is an absolute value for any given lens whereas angle/field of view is variable depending on the format (ie 1x1, 3x2 etc) chosen for the photo. Diagonal vs height vs width has already been mentioned above.
 

StewartR

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#12
We've decided that focal length is the measure for what is actually angle of view...
No we haven't. The focal length is a physical property of the lens.

I think you're talking about the equivalent focal length, which is a completely different thing.
 
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#13
I haven’t missed the point I just happen to agree with the post above yours regarding recognised reference points and full frame isn’t the golden standard just the original.
Except there’s nothing ‘original’ about it.
Which is the point in the OP. ‘Gold standard’ is a better description than ‘the original’ as in the whole history of photography the popularity of the 35mm format came late and you could argue has had its day, but it’s a convenient standard to use, particularly as baby boomers consider it ‘the norm’.
 
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#14
No we haven't. The focal length is a physical property of the lens.

I think you're talking about the equivalent focal length, which is a completely different thing.
It is, but that's not how people use the term. Focal legth is almost always used to describe the angle of view of a photograph, not the physical properties of the lens it was shot with. For example, I know without looking that a picture shot with 12mm on a micro 4/3 lens is going to be wide angle, but I couldn't begin to explain what that means about the physical properties of the lens (and I'm sure many others couldn't either). Equivelant focal length becomes important only when describing what angle of view you'll get with various focal lengths on a system you are not used to...once you are used to it there is no need to use a reference focal length.

I do completely get the point about aspect ratio though, and that's where using angle of view falls down. It seems there is no catch all to describe every situation without referencing at least 2 pieces of information!
 
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#17
I think this is a video where the Northrups go over some of these and how unintuitive and meaningless certain photography terms are:
View: https://www.youtube.com/watch?v=lWXCYotT230


Focal length is definately the worst and how everything is referenced back to "full frame" equivalent (which itself doesn't really mean a lot). It is completely arbitrary!
Last people I would trust are the rent an expert couple

Mikw
 
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#18
It seems that humans have always wanted to use an easily visualised comparison of measure; in the UK you only have to read a cheap tabloid newspaper to know that height is measured in double-decker busses and area is measured in football pitches (if the area exceeds 1000 football pitches then Wales is often used)!

It's the same with DSLRs; as these derived from 35mm SLRs the 'focal length' comparison for lenses was kept as an easily (at the time) visualised comparison. For those that grew up using 35mm film cameras (who were the target market for the first DSLRs) this was no problem and made sense. For 'youngsters' these days who've never used a 35mm SLR (or full frame DSLR) then it's probably more confusing than helpful, but as it's become an accepted standard you're stuck with it! :D

However, the focal length comparison only works with 35mm film cameras, go any bigger or smaller with your film format and a similar disparity between crop and full sensor digital applies; for instance, if using a medium format (120 roll film) camera then an 80mm lens gives a similar field of view as a 50mm lens on a 35mm camera.

Confused? You will be, just take a look at ISO, or is that ASA, and why did the name change for that measure of film speed? There were also a few fore-runners to that before ISO/ASA finally won out and became the generally accepted standard.

So if you've only ever used a digital camera then don't feel too disadvantaged as the world of photography has traditionally been riddled with alternative measure scales and comparisons.
 
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#19
[QUOTE="Mr Badger, post: 8341920, member: 84424"

So if you've only ever used a digital camera then don't feel too disadvantaged as the world of photography has traditionally been riddled with alternative measure scales and comparisons.[/QUOTE]

I like my 2 inch focal length portrait lens :)
 
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#20
It seems that humans have always wanted to use an easily visualised comparison of measure; in the UK you only have to read a cheap tabloid newspaper to know that height is measured in double-decker busses and area is measured in football pitches (if the area exceeds 1000 football pitches then Wales is often used)!

It's the same with DSLRs; as these derived from 35mm SLRs the 'focal length' comparison for lenses was kept as an easily (at the time) visualised comparison. For those that grew up using 35mm film cameras (who were the target market for the first DSLRs) this was no problem and made sense. For 'youngsters' these days who've never used a 35mm SLR (or full frame DSLR) then it's probably more confusing than helpful, but as it's become an accepted standard you're stuck with it! :D

However, the focal length comparison only works with 35mm film cameras, go any bigger or smaller with your film format and a similar disparity between crop and full sensor digital applies; for instance, if using a medium format (120 roll film) camera then an 80mm lens gives a similar field of view as a 50mm lens on a 35mm camera.

Confused? You will be, just take a look at ISO, or is that ASA, and why did the name change for that measure of film speed? There were also a few fore-runners to that before ISO/ASA finally won out and became the generally accepted standard.

So if you've only ever used a digital camera then don't feel too disadvantaged as the world of photography has traditionally been riddled with alternative measure scales and comparisons.
The Global Standards Authority for equivalences is The Register, here is their conversion page https://www.theregister.co.uk/Design/page/reg-standards-converter.html where you can convert yourfocal lengths in standard linguinie and areas into nanoWales but they have got angular measurements there though I’m sure they must have done a conversion at some time :exit:
 
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Gez
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#21
Except there’s nothing ‘original’ about it.
Which is the point in the OP. ‘Gold standard’ is a better description than ‘the original’ as in the whole history of photography the popularity of the 35mm format came late and you could argue has had its day, but it’s a convenient standard to use, particularly as baby boomers consider it ‘the norm’.
It is original regarding 35mm which is what I was commenting on, obviously not talking about plates. Perhaps they are right and we should idiot proof everything as that really annoying couple seem intent on doing. I remember doing some stuff for an estate agents a few years ago and they phoned me up and said could I only do wide angle as narrow angle shots didn’t fit their templates.
 
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#22
I remember doing some stuff for an estate agents a few years ago and they phoned me up and said could I only do wide angle as narrow angle shots didn’t fit their templates.
Perhaps you should have clarified by asking "you mean you want bungalow photos rather than two storey ones?" ;) :D
 
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#23
It is, but that's not how people use the term. Focal legth is almost always used to describe the angle of view of a photograph, not the physical properties of the lens it was shot with. For example, I know without looking that a picture shot with 12mm on a micro 4/3 lens is going to be wide angle, but I couldn't begin to explain what that means about the physical properties of the lens (and I'm sure many others couldn't either). Equivelant focal length becomes important only when describing what angle of view you'll get with various focal lengths on a system you are not used to...once you are used to it there is no need to use a reference focal length.

I do completely get the point about aspect ratio though, and that's where using angle of view falls down. It seems there is no catch all to describe every situation without referencing at least 2 pieces of information!
Yes - whichever way you cut it.

I don't understand why some people get all picky about this. There is no perfect answer and nothing any better than the terms we use. They've stuck, because most people can relate to them. What's the problem?
 
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#24
I've just had a rummage through my toy box and I have Fuji prime lenses of focal lengths of: 16, 23, 35, 56 and 90 mm
Not all focal lengths I'm particularly familiar with...until I convert the to their (Approximate) 35mm equivalents of: 24, 35, 50, 85 and 135mm
That's better, much more comfortable!
I'm sure there's a reason Fuji made their lenses with these "Odd" focal lengths. :)
 
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#25
Referencing lenses back to their 35mm equivalents is silly, especially to those of us who use 35mm, 120 in various formats and sheet film.

Much easier to know what the standard focal length is for each format you use and work it out from there.


Steve.
 
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#27
Referencing lenses back to their 35mm equivalents is silly, especially to those of us who use 35mm, 120 in various formats and sheet film.

Much easier to know what the standard focal length is for each format you use and work it out from there.


Steve.
Do you actually think in four or so different scales, rather than visualising a shot in the one you are most used to (say full-frame/35mm SLR), then mentally transposing that to the equivalent 'focal length' for the film or sensor format you are using at the time?
 

StephenM

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#28
I don't know how Steve does it, but I know what I'll "get in" with the standard lens on the formats I use (relatively easy, since the standard lens for each covers the same angle of view, format proportions permitting) and just multiply or divide according to how much less or more I want in. Being older and less mentally agile, I find this less arithmetically challenging than first converting to "equivalent focal length", calculating what "equivalent focal length" I want, and then converting this figure to the actual focal length. Then again, I'm also lazy...
 
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#29
I have a m4/3 camera and 3 zoom lenses (small, medium and large!), and pick the lens experience tells me I need (I never think "I need 100mm for this shot"), then, if I care enough about depth of field, which I usually don't, I set an aperture to get the depth of field I want (again without ever knowing or caring what the number is). The fact the numbers involved in this process would've been different on a system I don't have and have never used is irrelevant.

It's understandable to want to use a common frame of reference to compare things, but unfortunately that's not all it's used for, FF being the common frame of reference is sometimes used as a stick to beat other formats with.
 
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#30
Do you actually think in four or so different scales, rather than visualising a shot in the one you are most used to (say full-frame/35mm SLR), then mentally transposing that to the equivalent 'focal length' for the film or sensor format you are using at the time?

No. Just the one I'm using at the time.


Steve.
 
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Garry Edwards
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#31
However, the focal length comparison only works with 35mm film cameras, go any bigger or smaller with your film format and a similar disparity between crop and full sensor digital applies; for instance, if using a medium format (120 roll film) camera then an 80mm lens gives a similar field of view as a 50mm lens on a 35mm camera.

Confused? You will be, just take a look at ISO, or is that ASA, and why did the name change for that measure of film speed? There were also a few fore-runners to that before ISO/ASA finally won out and became the generally accepted standard
In fact, 80mm was only standard with 6 x 4.5cm and 6 x 6cm formats on 120 film. We also had 6 x 7, 6 x 8, 6 x 9 & 6 x 12cm in 120 and 220.
35mm equivalence has become a standard that works whether people understand its origins or not and whether it's logical or not.
 
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#32
In fact, 80mm was only standard with 6 x 4.5cm and 6 x 6cm formats on 120 film. We also had 6 x 7, 6 x 8, 6 x 9 & 6 x 12cm in 120 and 220.
35mm equivalence has become a standard that works whether people understand its origins or not and whether it's logical or not.
You're quite right about the differences, although 75mm was probably more common on 6x4.5 (also used on some German 6x6 folding cameras such as the Voigtlander Perkeo), with 105mm being fairly common on 6x9 as a 'standard' lens. To avoid confusion, It wouldn't matter if it were 120 or 220 format roll film though, as the only difference in terms of use is the length of the roll, with 220 giving twice as many shots as 120, with the 6cm width of the film remaining the same in both 120 and 220.

Quite right about using the 35mm standard, if it works why change it. (y)
 

StephenM

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#33
But why have it at all? I still have the feeling that it only came in with digital cameras because it meant that numbers could be inflated - everyone knows the bigger the better...
 
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#34
But why have it at all? I still have the feeling that it only came in with digital cameras because it meant that numbers could be inflated - everyone knows the bigger the better...
We'd been using it for years with 35mm cameras before DSLRs were even thought of... and that's why it became 'standard', because 35mm SLRs had pretty much become standard too for the average amateur photographer. By the advent of digital pretty much the only people using medium format (120/220) were professional photographers (generally excluding sport and press), as 35mm had pretty much won out everywhere else by then.
 
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StephenM

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#35
Strange, I never recall hearing about "equivalent focal lengths" back in the 1960s. I do recall a lot of articles though about the non equivalence (in terms of depth of field) of standard lenses on 35mm and 6x6. What happened in the dark ages of the 70s and beyond, I don't know.

It still seems a silly idea to me that makes it harder to get to grips with the essential points; but it doesn't bother me either way if I don't have to pick up the mess and confusion that the idea brings:D
 
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#36
The no one really cares what the focal length or angle of view actually is. What they care about is how big the image is and how much they can fit in with any particular lens. By experience and usage they soon learn to associate this with focal lengths marked on their lens. This by agreement it is usually the full frame equivalent, which is now the defacto standard. It is something we quickly get a feeling for. It might not be ideal or scientifically meaningful.... but it works...
 
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#37
Strange, I never recall hearing about "equivalent focal lengths" back in the 1960's
Of course you didn't, nobody found a need to compare their own film size to 35mm.
Large format users had a wide range of both film / plate sizes and lenses but knew enough to be able to work out AOV (and just about everything else).
Nearly all 120 cameras had whichever lens came bolted to the camera, with a tiny number of exceptions lenses were non-changeable, and people changed effective magnification and zoomed by moving their feet. Again, their users tended to be either professional or very knowledgeable amateur and AOV wasn't a problem for them.

Except for press and sport, 35mm was strictly amateur, and pretty amateurish too. It was only the clever marketing of Nikon - later copied by Canon - that persuaded many people that expensive 35mm cameras were professional.

It was only when digital became popular, and had a myriad of different and confusing sensor sizes, several of them deliberately deceptive, that the new generation of photographers needed some kind of comparative standard.
 

StephenM

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#38
the new generation of photographers needed some kind of comparative standard.
Is the "comparative standard" the key? Back in those days, camera reviews reviewed the camera in isolation. Which? popularised the "best buy" idea, and camera reviews became feature reviews comparing A to B. If you can't say "camera A is better than camera B because it has a zoom range of 3mm to 12mm whereas camera B only goes from 24mm to 72mm " since it isn't intuitively obvious, how can you compare unless you convert units?
 
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#39
My guess is that this came about because the first digital SLRs were esentially film SLRs with sensors stuck in them but (importantly in this context) taking the same lenses. Except the imaging area was now smaller so the lens produced an effectively cropped image.

Someone with a bag of lenses for 35mm film now had a bag of lenses which produced tighter framing from the same viewpoint. Hence the need to convert the focal length to one which gave an equivalent framing to 35mm on the smaller sensor to enable a lens to be selected to achieve the desired framing.

Then lots of other sensor sizes and aspect ratios came on the scene in interchangeable lens cameras and the 35mm base line was carried over - despite it not being precise it was close enough for rock'n'roll.
 
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#40
It probably is, necessary because digital users were using cameras with a very wide range of sensor sizes - and therefore an equally diverse range of focal lengths, and often didn't even know the size that they had.
 
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