DX & FX lens


KT1031

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Nov 13, 2009
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#1
juz wanna be sure,

when they say 50mm on a fx (aka full frame), it means 50mm.
while on a DX camera, its 50*watever the crop factor?

what abt those DX lenses?
we still needa multiply in the crop factor?
or it is as listed, such as the 18-105mm DX?:dunno:

thanks guys!
 

Numnumball

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Mar 6, 2009
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#5
yes, when using DX lens on crop, you need to multiply the crop factor as well
Bro, DX lens are designed for crop coverage.. dun think need to include the crop factor

Multiply a lens' focal length by 1.5 to get the focal length of a lens which, when used on a full-frame or 35mm film camera, gives the same angle of view as that lens does on one of these DX cams

:)
 

wdEvA

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Sep 1, 2006
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#8
Bro, DX lens are designed for crop coverage.. dun think need to include the crop factor

Multiply a lens' focal length by 1.5 to get the focal length of a lens which, when used on a full-frame or 35mm film camera, gives the same angle of view as that lens does on one of these DX cams

:)
You need to ;p
else the sigma 8-16mm will be the widest, instead of Sigma 12-24mm for FF :D
 

ZerocoolAstra

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Mar 13, 2008
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#9
I know that NNB knows about the DX crop factor, so I guess there is some miscommunication about the terminology that's all.

To be precise, the 18-105DX lens has a focal length of 18mm at its widest.
However, when mounted on a DX camera, it gives the equivalent field-of-view as a 27mm lens (1.5x crop factor) mounted on an FX camera.
To further confuse matters, the 18-105 is designated DX, because the image circle of this lens is only large enough to cover the DX sensor.

* gosh I hope I'm right :angel: Someone correct me if I've made a mistake.
 

die Blende

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Mar 25, 2006
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#10
I know that NNB knows about the DX crop factor, so I guess there is some miscommunication about the terminology that's all.

To be precise, the 18-105DX lens has a focal length of 18mm at its widest.
However, when mounted on a DX camera, it gives the equivalent field-of-view as a 27mm lens (1.5x crop factor) mounted on an FX camera.
To further confuse matters, the 18-105 is designated DX, because the image circle of this lens is only large enough to cover the DX sensor.

* gosh I hope I'm right :angel: Someone correct me if I've made a mistake.
You are absolutely right.;)

yes, when using DX lens on crop, you need to multiply the crop factor as well
And he's right too.. ;p
Just to make things alot simpler any lens,
Be it DX lens or FX lens when mounted on DX(crop) camera needs to be multiplied by the crop factor.
Even 4/3 sensors the lens focal length needs to multiply by crop factor(FOV)

Now I hope what I said is right..
 

KT1031

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#11
I know that NNB knows about the DX crop factor, so I guess there is some miscommunication about the terminology that's all.

To be precise, the 18-105DX lens has a focal length of 18mm at its widest.
However, when mounted on a DX camera, it gives the equivalent field-of-view as a 27mm lens (1.5x crop factor) mounted on an FX camera.
To further confuse matters, the 18-105 is designated DX, because the image circle of this lens is only large enough to cover the DX sensor.

* gosh I hope I'm right :angel: Someone correct me if I've made a mistake.
hahaa. i m confuse.
so can i say that,

Assuming crop factor of 1.5x
a 50mm on DX is 75mm and remain as 50mm on FX,
while a 50mm DX (assuming)
is 50mm on DX but 75mm on FX?

:sweat: hope i m getting it right
 

GRbenji

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May 24, 2010
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#12
hahaa. i m confuse.
so can i say that,

Assuming crop factor of 1.5x
a 50mm on DX is 75mm and remain as 50mm on FX,
while a 50mm DX (assuming)
is 50mm on DX but 75mm on FX?

:sweat: hope i m getting it right
The last part is not right.;)

50mm will always be 50mm on FX.
50mm will always have a FOV of 75mm on a DX
 

Rashkae

Senior Member
Nov 28, 2005
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#13
while a 50mm DX (assuming)
is 50mm on DX but 75mm on FX?

:sweat: hope i m getting it right
Nope. It's 50mm with a FOV of 75mm on a DX (crop) sensor, but 50mm with vignetting on a FX (full-frame) sensor.
 

ZerocoolAstra

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Mar 13, 2008
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#14
hahaa. i m confuse.
so can i say that,

Assuming crop factor of 1.5x
a 50mm on DX is 75mm and remain as 50mm on FX,
while a 50mm DX (assuming)
is 50mm on DX but 75mm on FX?

:sweat: hope i m getting it right
there's no assumption. DX compared with FX, the crop factor IS 1.5x
For nikon lenses, if they are not designated DX, then they can be used on both FX and DX cameras.
 

Numnumball

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Mar 6, 2009
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#15
I know that NNB knows about the DX crop factor, so I guess there is some miscommunication about the terminology that's all.

To be precise, the 18-105DX lens has a focal length of 18mm at its widest.
However, when mounted on a DX camera, it gives the equivalent field-of-view as a 27mm lens (1.5x crop factor) mounted on an FX camera.
To further confuse matters, the 18-105 is designated DX, because the image circle of this lens is only large enough to cover the DX sensor.

* gosh I hope I'm right :angel: Someone correct me if I've made a mistake.
Yup Bro, thats what i am trying to say :)
 

Numnumball

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Mar 6, 2009
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#16
Yes you do. All lens markings are based on 35mm.
You need to ;p
else the sigma 8-16mm will be the widest, instead of Sigma 12-24mm for FF :D
Yes yall right, i could have presented it wrongly.. :sweat:

what i m merely trying to convey is that on DX, its gives a equivalent field-of-view as of 1.5X (factor in the crop) when mounted on an FX camera.
 

KT1031

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Nov 13, 2009
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#17
Nope. It's 50mm with a FOV of 75mm on a DX (crop) sensor, but 50mm with vignetting on a FX (full-frame) sensor.
in the case of 18-105mm DX,
if i dun wanna get the vignetting, i have to shoot at 18*1.5 = 27mm ar?

sorry but abit confuse abt the DX lens on FX body part.
 

ZerocoolAstra

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Mar 13, 2008
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#18
in the case of 18-105mm DX,
if i dun wanna get the vignetting, i have to shoot at 18*1.5 = 27mm ar?

sorry but abit confuse abt the DX lens on FX body part.
you DON'T have an FX body (YET :bsmilie: :devil:), so you don't have to worry about any vignetting.

If you already have the D90 and the 18-105, you can simply shoot at 18mm and see for yourself, right? There's no vignetting.
Now if you mount this lens (designated DX) on a 35mm camera (eg. a Nikon film SLR), what you'll get is a circular image with huge black borders. Like extreme vignetting.

There are lots of websites about this DX and FX difference that probably explain it better than what I'm struggling with now.
 

Numnumball

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Mar 6, 2009
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#19
in the case of 18-105mm DX,
if i dun wanna get the vignetting, i have to shoot at 18*1.5 = 27mm ar?

sorry but abit confuse abt the DX lens on FX body part.
Hi KT,

DX lenses are lenses which only cover the smaller sensor of DX digital cameras and are never designed for FF usage. U can use and enable the "DX Mode" of the FF cam but only 5MB of the sensor is used (middle portion)

If not u wil have major vignetting, See post #6 in this for a clearer understanding
 

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