Edited here and there, for the sake of precision:
Converting a focal length to a longer one can be seen like getting an image
area and make it larger.
So a tele-converted image MUST become larger than the original one projected
by the lens alone.
Then a DA-lens image + a 1.4x TC is enlarged more or less as much as needed
by a 24x36mm image (unless it is vignetted by some hardware).
Dario
-----Messaggio originale-----
From: John
Sent: Monday, January 27, 2014 10:28 PM
To: Pentax-Discuss Mail List
Subject: Re: Pentax 1.4x converter
On 1/27/2014 3:21 PM, Matthew Hunt wrote:
On Mon, Jan 27, 2014 at 3:17 PM, Dario Bonazza
<dario.bona...@virgilio.it> wrote:
Great, but what's the point of spreading the same amount of light
gathered by the same front lens on a larger sensor having say the
same pixel count (e.g. 24 MP) while losing one stop for exposure?
To smooth the transition for people with APS-C lenses, I suppose.
(I don't know if it makes more sense than just cropping the middle
portion of the FF sensor. I guess it depends on the FF pixel count,
and whether a bigger but darker viewfinder image is better than a
smaller, vignetted one.)
I expect it is "full-frame" in the sense that it would not vignette the
image from a "full-frame" lens. I don't see how it would make an APS-C
lens have a larger image circle.
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