Equivalent mm.

[csm]

Hi, I'm new to Fuji cameras. I noticed that Fuji lenses have a 35mm equivalent on X cameras. For example, the 56mm is the equivalent of an 85mm on a 35mm camera. Why is this? Would it not be better to have an 85mm lens that works as a 85mm on the APS-C sensor?

Thanks

Carlos San Miguel

[steviewonder]

This is not unique to Fuji. All cameras with APS-C sensors have a "multiplication" factor as the sensor is smaller than those on full-frame cameras, whose sensors are the same as the 35 mm standard. With Nikon, it is 1.5 times the lens (e.g. a 50 mm lens on a D7100 is equivalent to 75 mm full frame); with Canon its a 1.6 factor for their APS-C lenses (50 mm is equivalent to 80 mm full frame). You can't have a 85 mm lens be 85 mm equivalent unless you have a full frame camera. Make sense?

[csm]

So, FX lenses are for FF cameras? If I was to mount the lens on a FF it would work as the mm engraved on the lens?

 

Thanks

[Mike G]

No Fujinon FX lenses are for use on X mount cameras only! A crop factor of 1.5 is applied to the engraved focal length to give the equivalent focal length if used with a full frame camera, which they can't!

 

Fro instance the crop factors are -

CSC = 1.5 FF = 1 mu4/3 = 2 it all depends on the size of the sensor!

I.e. An FX 23mm f1.4 is the equivalent approx to a 35mm lens on a full frame camera

 

Fuji use the code FX for their lenses only

Edited February 7, 2017 by Mike G

[johant]

There's only confusion because people keep referring to 135 film equivalent as "full frame". Ironically that was small format film when introduced ...

 

Your lenses don't change. But your actual field of view changes with the sensor format. It's like cropping a larger picture; it is still taken with the same lens, but you get a smaller field of view.

[Mike G]

I blame Oskar Barnack!

 

FF has become common parlance for the 35mm film format of old

[milandro]

Equivalence values are a tradition in photography.

 

They are at least ever since there were cameras around with a sensor smaller than 24 x 36mm, which was the size of the analog film, first invented for the moving pictures cameras and then used by Oskar Barnak when he invented the LEICA camera around the film format in order to use the widely available double perforated film.

 

Conventionally the “ standard lens" value is give by calculating the diagonal, in millimeters, of the format. The les closest to this value is the so called “ standard lens”.

 

Of course once you change the format this values also change but traditions are hard to kill.

 

So people still refer to the values relative to 24 x 36mm (or full format) simply as a mannar to communicate. So the 35mm ( which on a FF would be a medium wideangle) is the “ standard” lens on the APS-C used by Fuji.

 

Really there are some consequences also concerning the relative aperture and sone like to point this out, but frankly this is a rather useless exercise.

 

You are right, it would be better to use another way to talk about lenses like for example the field angular view ( how many degrees of an angle the lens shows) and refer to it alone.

 

But traditions are hard wearing.

 

Of course nowadays there is a generation ( and maybe OP is one) of photographers who were born when film cameras were already gone and don’t even know what a 24mm was on a 35mm film camera.

[milandro]

... double post

Edited August 17, 2017 by milandro

[csm]

So. the equivalence on 35mm camera, really refers to the angular view.

[Mike G]

No

[milandro]

no, but it would be better if it would

 

50mm : F.F= 35mm : Aps-c.... 

Edited February 7, 2017 by milandro

[csm]

I found this: "The 35 mm equivalent focal length of a particular lens–sensor combination is the focal length that one would need for a 35 mm film camera to obtain the same angle of view."

https://en.wikipedia.org/wiki/35_mm_equivalent_focal_length

 

So, if my Fuji 56mm lens has an 85mm equivalence, then I would need an 85mm lens on a 35mm camera to achieve the same angle of view as the 56mm on the Fuji camera. I think I got it. :-)t

[Mike G]

Phew!

[matek81]

The equivalence refers to a) angle (field) of view aperture size. As the sensor is 1,5 (approx.) smaller, the angle of view is also smaller, and aperture is also smaller. Imagine the A4 print as equivalent of full frame. Now the APS sensor is just rectangle in the middle not covering the whole A4 print (the . Which means that the APS sensor, from the same perspective and distance, "sees" less of the picture (and light gathering is also "weaker"). So in terms of length of the optical system (lens) is the same as in full frame (35 mm is always 35 mm but angle of view and light gathering capability is smaller. So using APS compared to FF gives you: a) "zoom" effect" larger depth of field (smaller aperture). kind regards, mat

[Tim Pierce]

On 2/7/2017 at 12:38 AM, Mike G said:

No Fujinon FX lenses are for use on X mount cameras only! A crop factor of 1.5 is applied to the engraved focal length to give the equivalent focal length if used with a full frame camera, which they can't!

 

Fro instance the crop factors are -

CSC = 1.5 FF = 1 mu4/3 = 2 it all depends on the size of the sensor!

I.e. An FX 23mm f1.4 is the equivalent approx to a 35mm lens on a full frame camera

 

Fuji use the code FX for their lenses only

Fuji uses the XF destination not FX

[Tim Pierce]

On 2/6/2017 at 11:52 PM, csm said:

So, FX lenses are for FF cameras? If I was to mount the lens on a FF it would work as the mm engraved on the lens?

 

Thanks

yes Nikon FX lenses are Full Frame (FF) the numbers you see engraved will work on full frame mounts

however for crop lenses like Fuji's X-mount (aps-c) you have to calculate the 35mm (FF) equivalent ie: a fuji 18- 55mm (x 1.5) would be equivalent to 27mm -82.5mm full frame lens

Edited May 11, 2019 by Tim Pierce
some minor corrections