Re: 1.5X Sensors VS. Full Frame and other questions...

David J. Littleboy wrote:
"Mark²" <mjmorgan(lowest even number here)@cox..net> wrote:
Progressiveabsolution wrote:
What exactly does the 1.5X crop do to the image that is produced
from the camera? In other words, does it degrade the quality of the
picture when comparing to a full framed camera body?

What is the essential difference in image quality between a full
frame body and a 1.5-1.6X cropped body?

How much of a difference is there in image quality between the full
frame body and the 1.5-1.6X sensor bodies?

I'm sure this has been answered but hopefully I can get some more
info on this.

Thanks all for your help!

The lens still projects a full-frame image...its just that the
sensor only sees the middle portion of it due to the sensor's size
being smaller than the full-frame projection. Think of it as a
slide projector projecting a 6 foot wide image onto a 5 foot wide
screen. The projected image stays the same...you're just not
catching all of it on the screen. Because of this, image quality is not
changed at all...rather, you
are simply (in effect), utilizing all your sensor's pixels on the
"sweet spot" of your lens.

Ah, but you are enlarging the sweet spot 1.5x times more. So the
question becomes: is the center section of a 35mm lens really 1.5x
times better than the whole area of a 50mm lens.

By "image quality," I was referring to the image cast on the sensor. The
degree to which one chooses to enlarge that will determine the extent to
which its flaws become visible...right?

You could also say that you are enlarging any flaw by 1.5x.

Since the 35mm lens is designed to cover 24x36, it's a much wider
angle lens than the 24x36 50mm lens, and is going to have _worse_
performance, not 1.5x better performance.

If I implied otherwise, I didn't mean to.

Even comparing a point,
say, 10mm off axis on the 35mm lens with a point 15mm off axis on the
50mm lens.
Some see this as an advantage due to decreased vignetting and the
use of only the sharpest portion of the lens. Others who want wide
angle may not like losing the wide angle of view they are used to...

The decreased vignetting _wide open_ comes at the cost of reduced
resolution/contrast. It's really hard to make wide angle lenses, and
for lenses with an 80mm or wider FOV, cropped cameras with legacy
lenses are a bad idea.

The good news is that this effect doesn't apply to telephotos. But
telephotos (other than cheap consumer zooms) don't have a sweet spot,
leaving you with the 1.5x greater enlargement penalty. Oops.

The idea that a smaller sensor is better flies against 150 years of
photographic common sense, and is simply nuts.

Don't interpret my post as proposing any such assertion as to necessitate
your last sentence, there...
;)
I'm very close to lightening my wallet on the 5D...

-Mark²


.

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