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Typo in Canon lens specs?

 
 
Chris Carlen
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      09-19-2003
Hi:

Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
view" of 75 degrees.

But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
of view of 75 degrees. I would think it must be wider than this.

As another reference point, the EF 17-40mm f/4L USM has 104 max.

What is the real max angle for the 18mm?

Thanks.
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Jouni Filip Maho
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      09-19-2003
Chris Carlen wrote:
>
> Hi:
>
> Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
> view" of 75 degrees.
>
> But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
> of view of 75 degrees. I would think it must be wider than this.
>
> As another reference point, the EF 17-40mm f/4L USM has 104 max.
>
> What is the real max angle for the 18mm?


The crop factor for the Digital Rebel body is 1.6. Thus the
35mm-equivalent focal length, at the wide end, of the 18-55 on a digital
body is 18 x 1.6 = 28.8. So logically, it should even be slightly *less*.

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Todd Walker
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      09-19-2003
In article <(E-Mail Removed)>,
(E-Mail Removed) says...
> Hi:
>
> Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
> view" of 75 degrees.
>
> But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
> of view of 75 degrees. I would think it must be wider than this.
>
> As another reference point, the EF 17-40mm f/4L USM has 104 max.
>
> What is the real max angle for the 18mm?
>
> Thanks.
>


Well, this is just a guess but the 18-55 only fits one camera -- the
300D. If you consider the 1.6x focal length multiplier, the 18 mm wide
end becomes 28.8 mm. The specs for the EF 28-200 are no doubt given
based on its actual widest focal length of 28 mm. Therefore, the angle
of view for both lenses would be the same, if you are using the 28-200
on a film SLR and the 18-55 on the 300D, the only camera it will fit on.
Of course if you put the 28-200 on the 300D it becomes a 45-320...

--
________________________________
Todd Walker
http://twalker.d2g.com
Canon 10D:
http://twalker.d2g.com/canon10d
My Digital Photography Weblog:
http://twalker.d2g.com/dpblog.htm
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Dave Martindale
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      09-19-2003
Chris Carlen <(E-Mail Removed)> writes:

>Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
>view" of 75 degrees.


Over the 43 mm diagonal of a 35 mm frame.

>But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
>of view of 75 degrees. I would think it must be wider than this.


This is over the approximately 27 mm diagonal of the 300D sensor. Since
18:27 is the same ratio as 28:43, the field of view is the same.

>As another reference point, the EF 17-40mm f/4L USM has 104 max.


That's a 17 mm focal length, on an image diagonal of 43 mm.

>What is the real max angle for the 18mm?


You pick the diagonal, we can tell you how to calculate the max angle.
But the lens is *designed* for the 300D sensor diagonal, and probably
loses image quality and illumination once you get very far outside
that.

Dave
 
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