newbie need help about lens n crop factor


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anyone

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#1
hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??
 

zac08

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Feb 21, 2005
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#2
hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??
Yes... the 1.6x crop will reduce your field of view.
 

wdEvA

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Sep 1, 2006
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#3
how many mm is ur fisheye? for 16mm fisheyes, you normally wont notice much on a 1.6crop sensor.
try using a 10 or 8mm fisheye
 

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#4
hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??
I just helped some friends buy the Canon Digital Rebel XSi. When shooting with a camera that is not full frame, like in your case, multiply the focal length by 1.6. So if you are shooting with a 15mm fixed lens your camera produces and image that is at a focal length of 24mm. 15mm x 1.6 = 24mm I hope this helps you.:)
 

ST1100

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#6
I just helped some friends buy the Canon Digital Rebel XSi. When shooting with a camera that is not full frame, like in your case, multiply the focal length by 1.6. So if you are shooting with a 15mm fixed lens your camera produces and image that is at a focal length of 24mm. 15mm x 1.6 = 24mm I hope this helps you.:)
The smaller sensor does crop the full image, but the 1.6x math does not apply to fisheyes, only linear lenses. Eg a 10mm linear lens on a 1.6x gives a 16mm linear viewpoint (=16mm on FF), but a 10mm fisheye does not give a 16mm fisheye viewpoint: it gives a cropped 10mm fisheye viewpoint. A full-image 16mm fisheye still gives a 180 degrees diagonal viewpoint. A fisheye designed to give 180 degrees diagonal viewpoint will do so for it's intended image(sensor) size, independent of its actual focal length.
 

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ST1100

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Jun 18, 2003
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#8
interestingly, how do u measure the view angle in an image? ;)
The lens will come with specs: horizontal view angle, vertical view angle, diagonal view angle.

Imagine an isosceles triangle. The focal length of the lens is the height of the triangle, the width, height or diagonal of the sensor is the length of the base (36/24/43 for FF). The top angle of the triangle is the view angle. Hope this makes sense.

Applies only to linear lenses.
 

jnet6

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Apr 21, 2004
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#9
hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??
what FE lens are you using?? one of the possible cause is that your fish eye is not for digital, try the tokina FE zoom 11-17, it should be better.
 

Rashkae

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Nov 28, 2005
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#10
what FE lens are you using?? one of the possible cause is that your fish eye is not for digital, try the tokina FE zoom 11-17, it should be better.
No, that would have nothing to do with it. It doesn't matter if it's "for digital" or not. It all has to do with the FOV and his crop sensor.
 

Rashkae

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Nov 28, 2005
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#12
even with full frame, not much lenses can do 180 deg of view.
On my old crop camera, my 7.5mm FE does almost 180 degrees. On FF, it actually turns into a FE circle in the center of the frame.
 

jnet6

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#13
On my old crop camera, my 7.5mm FE does almost 180 degrees. On FF, it actually turns into a FE circle in the center of the frame.
Ya, firstly must let T/S understand type of lenses and crop factor or what type of camera body he has.
 

ST1100

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#14
even with full frame, not much lenses can do 180 deg of view.
No rectilinear lens (non-fisheye) can do 180 degrees, *all* fisheyes can do 180 degrees diagonal FOV for the image size they were designed for.
 

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