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/p/ Photography

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Mr.B 2013-02-20 23:16:12 No.1892134

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Ok. Prime lenses.

most are in multiples of 5.
30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 85mm, 90mm, 105mm, 135mm, 200mm, 300mm, 400mm, 600mm.

Why is there 24mm and 28mm... Wouldn't 25mm be a better fit?

Anonymous 2013-02-20 23:17:49 No.1892137

Mr.B 2013-02-20 23:20:35 No.1892142
0/10 on a legitimate question?

I understand the 14mm, 17mm etc on crop cameras based on what the FF equivalent will be. But 24 and 28mm been there since film days.

Ham 2013-02-20 23:26:03 No.1892147
Not sure, but maybe it relates to the angle of view? like, a 60 degree field of view could relate to 24mm or something. That way the whole numbers are in the degree, rather than the focal length required to achieve it.


Mr.B 2013-02-20 23:26:38 No.1892148
now that sounds logical. thx.

Anonymous 2013-02-20 23:34:21 No.1892154
There are plenty of 21mm and 25mm lenses so not sure what your point is

Mr.B 2013-02-20 23:36:43 No.1892156
25mm, multiple of 5.

I'll add 21mm to my question. Why not 20mm?

Anonymous 2013-02-20 23:38:26 No.1892158
They're done in roughly multiples of seven, not five. You start with 42 as the perfect normal. Add seven for 49 (eg 50). Subtract seven for a wide normal (35), seven again for a wide (28), seven again for ultrawide (21), seven for ultra-ultra wide.

Going up you have 85 (actually 84), 105, 133 (rounded up to 135), and the now-omnipresent 70-210.

Mr.B 2013-02-20 23:40:07 No.1892163
and this is the answer i was looking for. interesting. so the 7 answers why there is 14mm, 21mm, 28mm. Good.


Anonymous 2013-02-20 23:42:48 No.1892169
mfw i can't math

Anonymous 2013-02-20 23:47:37 No.1892171
They make 12mm 15mm 11mm 20mm 19mm 17mm 16mm 25mm and all sorts of in betweens what are you guys even suggesting?

BJDrew 2013-02-20 23:50:06 No.1892174

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While the early history of camera lenses and their focal lengths is by no means completely guided by one common rule... the Square root of 2 may have a lot to do with it.

Look at the standard f-stops. They are in multiples of the square root of 2 (~1.41). i.e. 2.0 x 1.41 is about 5.6... 8 x 1.41 is about 11. Do this for 1.4, 2.8, 5.6, 8, 11, 16, 22

Do the same thing with common focal lengths.

24mm x 1.4 = 34 (round to 35).
35mm x 1.4 = ~50mm
50mm x 1.4 = ~70mm (used to be a popular focal length)

What about 28mm?
Well - 28mm x 1.4 = ~40mm... a popular "normal" focal length, particularly earlier on. Actually, if you take the diagonal of 35mm film, it's closer to 40mm than 50mm. The "proper" normal field of view has been the subject of some debate.

This rule doesn't answer all questions about popular focal lengths... but it's good enough for a good conspiracy theory.

[EXIF data available. Click here to show/hide.]
Camera-Specific Properties:Equipment MakeLeica Camera AGCamera ModelM8 Digital CameraCamera Software2.005Maximum Lens Aperturef/1.0Image-Specific Properties:Horizontal Resolution92 dpiVertical Resolution92 dpiImage Created2011:07:13 22:52:52Exposure Time1/500 secF-Numberf/8.0Exposure ProgramManualISO Speed Rating320Lens Aperturef/8.0Exposure Bias0 EVMetering ModeCenter Weighted AverageLight SourceUnknownFlashNo Flash, CompulsoryWhite BalanceAutoScene Capture TypeStandardUnique Image ID00000000000000000000000000000B0F

Anonymous 2013-02-20 23:50:37 No.1892175
It's just the weekly thread where retards like to pretend they have some sort of keen insider understanding. Nothing to see here, move along.

Alphon 2013-02-20 23:56:23 No.1892179
24mm and 70mm? How many 24mm and 70mm primes have you seen in your life? Damn not only are you talentless but youre fucking retarded.

Anonymous 2013-02-20 23:57:04 No.1892180
What about: >>1892171

I think i've seen 38mm too.

Yeah, the OP question is kinda senseless since there's like all ranges of focal lengths primes.

Anonymous 2013-02-20 23:59:31 No.1892185

every manufacturer makes a 24mm prime.


Those are much less common. There's no rule saying that lenses HAVE to be a certain focal length, it's just easier to follow convention.

Anonymous 2013-02-21 00:05:02 No.1892196
this makes sense in a "the government did 9-11" kind of way

>inb4 7 roughly equals 5 (for small values of 7 and big values of 5)

Alphon 2013-02-21 00:05:50 No.1892200
Its all about the history and competition for the next big thing. 24mm is just a wider 28mm. I remember when ultra wide was 20mm and then 19mm and now its 14mm or 17mm.

There's no rhyme or reason but capitalism.

BJDrew 2013-02-21 00:06:18 No.1892202

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24 is one of the most common focal lengths still... and when all this was being sorted out, 7cm lenses were quite common.

Today, the 24-70mm zoom is also common. Perhaps it's not an accident that 70mm was selected for the wide end?

I'll wait patiently for your very public apology.

[EXIF data available. Click here to show/hide.]
Camera-Specific Properties:Camera SoftwareAdobe Photoshop 7.0Image-Specific Properties:Horizontal Resolution92 dpiVertical Resolution92 dpiImage Created2011:09:26 08:47:02

Anonymous 2013-02-21 00:06:48 No.1892205
>24mm is just a wider 28mm
24 is what 28 should have been all along.

Mr.B 2013-02-21 00:09:27 No.1892207
and why the standard telezoom starts at 70mm. Nikon's (used to?) start at 80mm.

Anonymous 2013-02-21 00:12:52 No.1892211
In these modern days, numerically, it is largely based upon either historical precedents or arbitrary numbers. Usually the former.

As for the original reason for the calculation of those historical precedental numbers? No idea.

tl;dr this is an irrelevant and pointless discussion in 2013

Anonymous 2013-02-21 00:15:49 No.1892213

No, it makes sense in the keep-things-simple way.

BJDrew 2013-02-21 00:26:49 No.1892219

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Yeah. Alphon did accidentally say something correct.
Some of the popular focal lengths today did come from small improvements to older designs rather than some master mathematical plan. The 105mm length may trace back to the Ernemann Ernostar 10.5cm f/1.8 was based on some improvements to a standard 10cm design.

Today, there's really no rhyme or reason to it - just some mix historical precedent, marketing, and design constraints.

Attached - crazy Leitz 5cm f/1.5 Summarit

[EXIF data available. Click here to show/hide.]
Camera-Specific Properties:Equipment MakeLeica Camera AGCamera ModelM9 Digital CameraCamera SoftwareAdobe Photoshop CS5 WindowsMaximum Lens Aperturef/2.0Focal Length (35mm Equiv)50 mmImage-Specific Properties:Image OrientationTop, Left-HandHorizontal Resolution240 dpiVertical Resolution240 dpiImage Created2012-11-17T20:37:14+19:00Exposure Time1/90 secF-Numberf/2.0Exposure ProgramManualISO Speed Rating640Lens Aperturef/2.0Exposure Bias0 EVMetering ModeCenter Weighted AverageLight SourceUnknownFlashNo FlashFocal Length50.00 mmImage Width1000Image Height665Exposure ModeManualWhite BalanceAutoScene Capture TypeStandardUnique Image ID00000000000000000000000000000A77

Anonymous 2013-02-21 00:33:45 No.1892231
OP's question is kinda interesting, in a not doing anything else at the moment kind of way. So, considering that 8x10 view cameras were the original standard, let's see what those cameras used, and then look at the equivalents as film sizes decreased, thusly:

Approximate equivalents of lens focal length
35mm 4x5 8x10
20mm 65mm 120mm
24mm 75mm 155mm
28mm 90mm 200mm
35mm 115mm 240mm
45mm 150mm 300mm
52mm 180mm 360mm
63mm 210mm 420mm
90mm 300mm 600mm
105mm 360mm 720mm
135mm 480mm 900mm


Anonymous 2013-02-21 00:35:40 No.1892237
Alphon always posts a photo.

Anonymous 2013-02-21 00:36:17 No.1892238
The "normal" lens for a 8x10 is the 360

Also, too, manufacturers and designers label lenses as such and such when they are technically off by as much as 2mm for any given physical lens

Alphon 2013-02-21 01:16:10 No.1892261
Banned for shitposting again.

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