Crop factor

Started Oct 12, 2008 | Discussions
rjmsilva Regular Member • Posts: 119
Crop factor

Can someone explain to me in a simple way if it's correct to say 4/3 has a crop factor of 2x.

Thank you very much.

Rui Silva
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Louis_Dobson
Louis_Dobson Forum Pro • Posts: 27,361
Technically

there is no "crop factor" on 4/3rds systems, because the sensors and lenses are designed for each other.

The phrase "crop factor" refers to the point that most digital sensors are smaller than a bit of film and such only use part of the image circle that a lens designed for 35mm creates. The effect is as if you "cropped" a film shot.

HOWEVER while technically there is no crop factor, the term still has meaning. The result of the "crop" factor is that a shorter lens has the same field of view as a longer one on a film camera, and the "crop factor" is the multiple used to determine what this is.

So although a 4/3rds camera does not, technically, have a "crop factor", in practical terms it has a crop factor of two.

Here's the list:

35mmFF (Nikon D700), crop factor 1, 50mm lens acts as 50mm lens.

APS-C (Nikon D300), crop factor roughly 1.5, 50mm lens acts as 75mm lens.

4/3rds (E3), crop factor roughly 2, 50mm lens acts as 100mm lens.

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LJSmak Senior Member • Posts: 2,006
Re: Crop factor

rjmsilva wrote:

Can someone explain to me in a simple way if it's correct to say 4/3
has a crop factor of 2x.

I guess it depends on your definition of "crop factor".

For a given angle of view the needed lens is about 1/2x the focal length (compared to good old 24x36 film) making the conversion factor 2. (exact number depends if you're calculating horizontal, vertical, or diagonal since aspect ratio is 3:4 instead of 2:3.)

But: It is a completely new system with matching lenses and nothing is "cropped".

Personally I also use 35mm and 6x6 systems, and sometimes 4x5", and I simply use the lenses I need for each system; I won't be calculating which lens I need when I want the wideangle on my Medium-format system. It also doesn't confuse me at all that this 50mm 6x6-wideangle is a standardlens on 24x36 and a telephoto on 4/3.

Lourens

OP rjmsilva Regular Member • Posts: 119
Thanks

Thank you for your explanation, may I quote you in a Portuguese forum?
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Louis_Dobson
Louis_Dobson Forum Pro • Posts: 27,361
Of course

What forum? Queria sempre practicar...
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OP rjmsilva Regular Member • Posts: 119
Fórum

http://www.forumfotografia.net/

A prática faz a perfeição!

I've seen your pictures from Algarve. Do you live there, or you go to Portugal just for vacations?
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SirSeth
SirSeth Veteran Member • Posts: 9,882
Fear Factor

Sometimes folks speak of "crop factor" as if we are being asked to eat cockroaches. What you have been told is quite true as far as I've understood. Olympus has not crop factor because the 4/3rds image is not "cropped" out of the center of lenses that were built for a larger film format. I think Canon, Nikon, and Pentax APS-C cameras do have lenses that are made for the sensor size and therefor are also not cropped, but many of their lenses are from 35mm camera days and when fitted to a smaller sensor must use a cropped image circle.

We spend time clarifying that Oly isn't really cropped, and for many cropped factor is a negative or inaccurate term, however, it's not by nature a bad thing that Canon or Nikon APS-C sensors crop. The center of the lens performs best anyhow, and the effect that a smaller sensor has on effective angle of view is great for telephoto and macro applications. Olympus decided to make a system from scratch with a different sized sensor and lenses designed for that size. The angle of view is narrower than a larger sensor because of this. (Oly is 2x narrower an angle of view than the same focal length lens on a 35mm camera).

I guess basically, the effect of having a different sized system is just different. Not better or worse than 35mm. The term "crop factor" does irk me because it assumes that 35mm is the beginning and end of everything--the defacto standard. Well, it's a common standard, but I think there is room for systems of other sizes, so when using comparative terms, I usually speak of angle of view rather than crop factor, but there is nothing really horrible about crop cameras using APS-C IMO.

Cheerio,
Seth
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Louis_Dobson
Louis_Dobson Forum Pro • Posts: 27,361
I live

about 12K north of Faro, on the hills above Bordeira.
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OP rjmsilva Regular Member • Posts: 119
Re: Fear factor

The argument is since Olympus has a 2x crop it can't go very wide, guess people don't know the 7-14.
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OP rjmsilva Regular Member • Posts: 119
Re: I live

I'm from Aveiro, a beautifull city between Coimbra and Oporto, but currently I'm in São Tomé e Principe a small island country in the west coast of Africa, former portuguese territory.
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smokes Forum Member • Posts: 65
Crop factor is

the ratio of the imaging area compared to a 35mm format. Meaning that the larger the crop factor is the more cropped the scene will look through your viewfinder and ultimately this is how it gets projected on the sensor.

Martin Frost Senior Member • Posts: 2,149
No. What crop factor does a 36*48mm sensor have in a medium format camera ?

No. What crop factor does a 36*48mm sensor have in a medium format camera ?
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E330andE500

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Martin Frost Senior Member • Posts: 2,149
4/3 has a focal length multiplier of 2, but no crop factor [nt]

4/3 has a focal length multiplier of 2, but no crop factor [nt]
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pistulka Junior Member • Posts: 25
Re: 4/3 has a focal length multiplier of 2, but no crop factor [nt]

Martin Frost wrote:

4/3 has a focal length multiplier of 2, but no crop factor [nt]
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Same thing. focal length multiplier = crop factor. crop factor = focal length multiplier. Either way you look at it it means the same thing.

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Mike_PEAT Forum Pro • Posts: 12,736
Only time there is a crop factor...

Martin Frost wrote:

4/3 has a focal length multiplier of 2, but no crop factor [nt]

pistulka wrote:

Same thing. focal length multiplier = crop factor. crop factor =
focal length multiplier. Either way you look at it it means the same
thing.

No it isn't just like the sun and the moon revolving around the earth.

The ONLY time there is a crop factor is when you use a lens that's designed for a larger format on a smaller format, for instance if you use a lens designed for Olympus OM on a FourThirds camera THEN you have a crop factor as you are only using a portion of the lens. Otherwise it's a multiplication field of view factor.

Martin Frost Senior Member • Posts: 2,149
sorry, wikipedia is wrong because 90% of the authors are no 4/3 users [nt]

sorry, wikipedia is wrong because 90% of the authors are no 4/3 users [nt]

cheers
Martin F.

E330andE500

Typing errors are intended to provide a basis for global amusement.

John_McG Contributing Member • Posts: 618
Re: Only time there is a crop factor...

Are the Sigmas cropped?

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OP rjmsilva Regular Member • Posts: 119
Re: 4/3 has a focal length multiplier of 2, but no crop factor [nt]

So, what's the crop factor in the new Leica S2?
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RedFox88 Forum Pro • Posts: 27,127
Re: Crop factor

rjmsilva wrote:

Can someone explain to me in a simple way if it's correct to say 4/3
has a crop factor of 2x.

Olympus has a 2x crop factor because you need a 25mm lens to get a 50mm field of view in the 35mm standard format.

smokes Forum Member • Posts: 65
Good question :)

rjmsilva wrote:

So, what's the crop factor in the new Leica S2?

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