Why is the 90mm f2 so BIG?!

[petergabriel]

I used to have a Nikkor 85mm f1.8 AF-D which is a full frame lens, and it was way smaller than the Fujinon. How is that possible?

[milandro]

don’t you think that if they could have made it smaller they would have done so?

[petergabriel]

Well yeah, but that doesn't explain the reason

[Aswald]

It's light and quite comfortable on both the Pro and T bodies. Good balance and produces superb images.

 

I also think it's the best pic. iq lens from Fujifilm.

[Mike G]

Maybe that's because one is a Nikkor and the other is a Fujinon!

 

Personally I don't regard the XF 90mm as a big lens, don't forget the XF 90mm is really a 135mm!

[milandro]

well, the reason is that quality and speed came at a price and that price is size.

 

anyway, on line there are many other asking the same question. The answers are, of course only speculations.

 

 

http://www.fredmiranda.com/forum/topic/1318898

 

https://www.dpreview.com/forums/thread/3843781

 

http://www.fujixseries.com/forums/topic/7985-xf-90mm-and-the-size-of-fuji-lenses/

 

You could write a letter:

 

“ Dear Mr. Fuji..."

 

I held it for 5 minutes in the shop and thought that one has to have lost of the FUJI mirrorless unique selling point ( size and practicality) to buy this lens, but I think the same of all the ginormous X lenses , they have some sort of function but I can’t see mylsef ( a person who chose this system for its compactness) ever buying any of these large lenses.

Edited March 4, 2017 by milandro

[petergabriel]

But still, a FX Nikkor is smaller than a slower DX Fujinon, and the Nikkor is optically just as superb.

Perhaps the quad LM AF system in the Fujinon is the culprit?

[milandro]

very likely, but things are as they are for a reason and knowing the exact reason won’t make any different.

 

If my grandmother had wheels it would be a wagon or Oyb di bobe volt gehat reder, volt zi geven a vogn

[Aswald]

The QLM assembly could be one of the reason. If you look at the lens design, there is a lot of space between element groups making the lens longer. The design probably calls for the spacing for excellent focal plane edge to edge.

[Phil]

Wouldn't one reason be that the Fuji has the focus motor in the lens, whereas the Nikon doesn't?

 

Plus the Fuji would have been designed to be sharp for a much higher pixel density - I would imagine that it performs better optically than the 85m 1.8 D.

[petergabriel]

@Phil

You are probably right. I actually completly forgot about that little AF screw on the Nikons.

[bhu]

Other reasons might include reduced vignetting, sharp wide open (f/2 is probably de-rated to ensure high IQ), possibly reduced internal reflections, possible margin for anti-reflection coating control near lens periphery (one factor in sharpness wide open), more structural rigidity.

 

These are just guesses, though.

[jakku]

Maybe that's because one is a Nikkor and the other is a Fujinon!

 

Personally I don't regard the XF 90mm as a big lens, don't forget the XF 90mm is really a 135mm!

It's not 135mm. It's 90mm, but fov like 135mm.

[MrX100F]

Feel really good on my XT-2, love the IQ

[Andy F]

It's probably big for the same reason the Zeiss Otus and Sigma Art lenses are big: quality. Compare these three 50mm (ish) f/1.4 lenses (Nikon G, Sigma Art and Zeiss Otus):

 

(image from here)

Edited March 12, 2017 by Andy F

[mdm]

Well, now I see how 33f1.0 might look like...

[KennethR]

 

 

don't forget the XF 90mm is really a 135mm!

 

No, it is not really a 135mm!!! It's a 90mm!!!

[triton76]

Maybe that's because one is a Nikkor and the other is a Fujinon!

 

Personally I don't regard the XF 90mm as a big lens, don't forget the XF 90mm is really a 135mm!

sorry Mike - the XF90 is a 90mm lens - on a smaller sensor (APS-C)  it shows the same angle of view as a 135mm @ FF

 

To be honest - i never got the problem people have mixinbg up focal lenght/aperture and dof - 90mm stays 90mm, F2 stays F2 (dof is the very same) - just the image circle for FF has to be bigger than for FF.

 

Back to the inital question: Why ist XF90 sooo big (is it really??):

 

every optical design has several restrictions and the challange of lens design is to find the best compromise out of it

 

- buget

- volume

- biggest lens diameter

- availible manufacturing technology

- glass selction

- focussing system

- weight

- amount of lenses

- number aspherical elements

- form of aspheres (deviation from sphere)

- machanical stability (e.g. lenses not to thin & heavy)

- size image circle

- all the optical parameters like vignetting/flat image and all the other zernike stuff

- ...

 

so Fuji decided to balance it in way the XF90 is made ...

 

compare a Zuiko OM 2/85 to OM 2/90 or  Zeiss Milvus 85/1.4 vs Zeiss Otus 85/1.4 vs Zeiss Planar 85/1.4