Full-frame or 1.5 DSLR?

"wilt" wrote in message
oups.com...
John,
The mention of frame size was to bring out the point that none of
Canon's high-MP (11 and
16.7) FF cameras can resolve subject detail as well as the 20D (or
RebelXT, for that matter), with the same lens.

But the lens has to deliver its resolution to the sensor, at a FIXED
resolution of the lens. If a lens can resolve 60 lines/mm in air, and
if the subject fills a 3.6mm section of the FF sensor and a 2,2mm
section of the 1.6 format sensor,

Isn't the same lens gong to fill the same 3.6mm on a 1.6 format as it does
on a FF sensor? I don't understand how it could be any different.

Greg

G.T. wrote:
"wilt" wrote in message
oups.com...

John,
The mention of frame size was to bring out the point that none of
Canon's high-MP (11 and
16.7) FF cameras can resolve subject detail as well as the 20D (or
RebelXT, for that matter), with the same lens.

But the lens has to deliver its resolution to the sensor, at a FIXED
resolution of the lens. If a lens can resolve 60 lines/mm in air, and
if the subject fills a 3.6mm section of the FF sensor and a 2,2mm
section of the 1.6 format sensor,


Isn't the same lens gong to fill the same 3.6mm on a 1.6 format as it does
on a FF sensor? I don't understand how it could be any different.

Greg


wilt assumes you are taken the the pictures using the same fixed focal
lens at the same location with 1.6x and FF cameras.

One the other hand, you assume, you'd back away to fill the 1.6x cropped
with the same image as a FF camera.

Now, back to you two to debate...

Isn't the same lens gong to fill the same 3.6mm on a 1.6 format as it
does
on a FF sensor? I don't understand how it could be any different.

Assume you take two lenses which can both deliver 60 line pairs per
millimeter of resolution measured on an optical bench, one 34mm lens
for 1.6 crop DLSR and the other 50mm lens for FF DSLR. Both are the
'normal' for their format size. Assuming that both cameras are placed
at the same camera-to-subject distance and the subject happens to
occupy 1/10th of the frame width in both cameras, the subject
stretches across 2.25mm of the 20D sensor and 3.6mm of the 1Ds MkII
sensor. So the subject is represented (in air) by 2.25x60 and by
3.6x60 line pairs per my analysis in prior email in this thread.


wilt assumes you are taken the the pictures using the same fixed
focal lens at the same location with 1.6x and FF cameras.

That statement is was not my assumption. I simply assume that two
different focal length lenses could both deliver 60 line pairs per
millimeter, as measured in air on an optical bench.

However, if you alter things and use literally the same 50mm lens on
both cameras, but you alter your camera-to-subject distance so that the
subject still is 10% of the frame width in size, the analysis still
applies...2.25x60 for 20D vs. 3.6x60 line for 1Ds MkII.

If you keep the camera-to-subject distance the same and use the same
50mm lens on both cameras, you enlarge the 1Ds MkII image and the 20D
image the same 4X amount to make the final 4x5 print with ***subject
the same size*** in both prints. So you end up with 216/4 = 49 line
pairs/mm of subject on paper and you would enlarge 1.6 crop by 4x for
final 132 / 4 = 33 line pairs of subject on paper (compared with my
earlier email analysis of 20 line pairs)


--Wilt

RichA wrote:
A full frame DSLR with a telephoto
or a 1.5-1.6 frame with a telephoto?
The reason I ask is that most people seem to
crop and it doesn't take much cropping (about
15% inward from each side) to
whittle down the full frame image below the
pixel count of an 8meg 1.5 frame camera, plus in
order to match the f.l. so this doesn't happen,
you need a longer, heavier lens.
Given a choice and your experiences, which makes
more sense to own?
-Rich

The full frame sensor is really more useful for wide-angle. There aren't
professional quality wide angle zoom lenses, for either Nikon or Canon,
that are wide enough to compensate for the 1.5-1.6 crop factor.

For telephoto, the need for a full-frame is much less, and a Canon 20D
is your best choice in the prosumer segment, the Nikon D70s and Canon
350xt are the best choices in the amateur segment, and the Nikon D50 is
the best choice in the entry level segment.

RichA wrote:

But if you were shooting telephoto, wouldn't you rather carry
around a 10lb 400mm lens with 1.5 than a 17lb 600mm lens with a full
frame? I think that if Canon did what Nikon did, have a selectable,
internal reduction in the pixel area used to facilitate faster
sequential shooting and longer telephoto reach, they'd have the
perfect camera.
-Rich

It would be perfect for telephoto, but not for wide angle. If Nikon
applied the D2x selectable system to a full frame sensor, then it'd be
the perfect camera.

In article , "G.T."
wrote:

"wilt" wrote in message
But the lens has to deliver its resolution to the sensor, at a FIXED
resolution of the lens. If a lens can resolve 60 lines/mm in air, and
if the subject fills a 3.6mm section of the FF sensor and a 2,2mm
section of the 1.6 format sensor,

Isn't the same lens gong to fill the same 3.6mm on a 1.6 format as it does
on a FF sensor? I don't understand how it could be any different.

Greg-

It isn't necessarily the same lens. It could be a different lens with the
appropriate focal length to account for the crop factor, but with a fixed
60 lines/mm resolution. Or, it could be a zoom lens that happens to have
that same resolution at the two different focal lengths. The final images
are being compared, so they must have the same field of view.

Wilt's analysis sounds good to me. I think camera designers are aware of
these factors and have chosen to go with the smaller sensors for marketing
reasons more than technical reasons. They seem to be getting away with
it!

Fred

wilt wrote:

Funny how the world rejected Kodak APS film format eventually and went
back to larger 35mm film, yet it is so accepting of the 1.5 crop format
in digital! I finally made the jump to 1.6 crop in Canon simply
because the FF is so d*mn'd unaffordable to all but the rich and the
corporations who provide equipment to staff photos!

And that's the reason that 1.5/1.6 was not rejected--the cost of full
frame was too high. We'd all prefer to have full-frame digital SLRs, but
we aren't willing to pay for it. With APS, you had to pay a lot more for
processing film, plus the film was more expensive to begin with.

"l e o" wrote in message
.net...
G.T. wrote:
"wilt" wrote in message
oups.com...

John,
The mention of frame size was to bring out the point that none of
Canon's high-MP (11 and
16.7) FF cameras can resolve subject detail as well as the 20D (or
RebelXT, for that matter), with the same lens.

But the lens has to deliver its resolution to the sensor, at a FIXED
resolution of the lens. If a lens can resolve 60 lines/mm in air, and
if the subject fills a 3.6mm section of the FF sensor and a 2,2mm
section of the 1.6 format sensor,


Isn't the same lens gong to fill the same 3.6mm on a 1.6 format as it
does
on a FF sensor? I don't understand how it could be any different.

Greg


wilt assumes you are taken the the pictures using the same fixed focal
lens at the same location with 1.6x and FF cameras.

One the other hand, you assume, you'd back away to fill the 1.6x cropped
with the same image as a FF camera.

Now, back to you two to debate...

I thought we were taking distant pictures of little birds, so, no, I
wouldn't back away.

Greg

In message ,
Stacey wrote:

wrote:

In message ,
Stacey wrote:


No way! I want the LARGEST lens I can have on the camera, looks more "Pro"
even if the image quality is the same!

That's good, because the Olympus lenses look bigger than I'd expect from
a 4/3 camera. I saw a guy with an E-1 and a 300mm lens at "the Gates"
in Central Park in February, and I did a double-take when I realized
that the large lens was an Olympus 4/3 lens.

Yea it's a LOT larger than the Canon 400mm F2.8.

Or does FOV not apply when comparing a canon to an OM and but it does
comparing a FF canon to a APS-c one?

No, it does not, because a lens at the *SAME* focal length, that is
optimized for a smaller circle on the focal plane can and should be
smaller.

--


John P Sheehy

In message ,
"Pete D" wrote:

wrote in message
news
In message ,
RichA wrote:

But if you were shooting telephoto, wouldn't you rather carry
around a 10lb 400mm lens with 1.5 than a 17lb 600mm lens with a full
frame? I think that if Canon did what Nikon did, have a selectable,
internal reduction in the pixel area used to facilitate faster
sequential shooting and longer telephoto reach, they'd have the
perfect camera.

I'd like to see a camera that was just like a high-end P&S, but took my
EOS lenses.

You can, either the 300D or 350D fit the bill.

You clipped the part where I explained what I meant, just to a take at
dig at those cameras? They have virtually the same pixel pitch as my
10D and 20D; they need a teleconverter to milk all their MTF out of
them, with slight loss.
--


John P Sheehy