Are IS lenses doomed ?

"Prometheus" wrote in message
...
In article , Neil Harrington
writes

"Prometheus" wrote in message
...
In article , Neil
Harrington
writes

"Prometheus" wrote in message
.. .
In article , David Littlewood
writes

------- Cut, on sensor and lens multiplier or divider ---------

Personally don't see why a term is required. It's an image size ratio,
everything else works as before; why not call it image size ratio?
Better,
since the "ratio" is to a film format which will become increasingly
irrelevant to new generations of photographers, eventually it will be
enough to just quote size, as I said

Why not quote the angle of view that the lens gives with the sensor?
Most
users are not interested in the focal length per se. I realise that
macro
work and photometry can require more than the angle of view.

And long lenses require more too. You're quite right, angle of view is
the
important thing -- but only with normal to wide-angle lenses. Users
could
in
time get used to the idea that "28mm equivalent" meant "75 degrees
corner
to
corner" and end up just calling such a lens a 75-degree lens. There is a
small fly in that ointment, in that third-party lenses made in more than
one
mount would be slightly different on a Nikon than on a Canon, 1.5x and
1.6x
focal length multipliers respectively and the necessary adjustments to
angle, but those adjustments in most cases would be small.

With long lenses however it's the magnification that the user is
interested
in, not the angle of view. Sure, one is necessarily related to the
other,
but for example calling a 200-400mm zoom a
12-degree-20-minute-to-6-degree-10-minute lens gets a little unwieldy,
isn't
very informative for most users -- and is only correct for the 24x36
format
anyway.

Magnification depends on the focal distance as well as the focal length,

Sure, but "near infinity" is generally understood when comparing focal
lengths for purposes of magnification.

Only in a crudely qualitative sense; thing "near infinity" are arbitrarily
small, magnifying them only serves to make them arbitrarily larger.

it is independent of the "multiplier factor". For macro you are
interested
in the angle of view and the focal distance, which is why I said that "I
realise that macro work and photometry can require more than the angle
of
view".

So I think using an appropriate multiplier to relate sensor focal
lengths
to
some familiar standard continues to be useful, and while there's nothing
cosmically significant about the 35mm format at least it is a familiar
standard, and by far the most familiar one.

It is a convenience that most people will understand, I made my
suggestion
half in jest, with far more variation in sensor size than there was in
film size it becomes important to know that there is more than focal
length to consider,

As long as the lens factor used is correct, it takes care of the
differences
in sensor size for the purposes most users are interested in, i.e.
magnification or angle of view.

I wonder how many users of compact cameras know or care what the focal
length is, using the view finder to obtain the view required is the
principle interest.

For the majority of 'em I'm sure you're right. For those of us used to the
idea of choosing different focal lengths though, the equivalent focal length
range of even an ultracompact is of primary importance and interest. The
*actual* focal length range is not.


The users of DSLRs will make a purchases based on
their requirement taking account of the 'lens correction factor', and then
frame with the viewfinder having little regard for the focal length.

although most of the cameras have fixed lens without any focal length
marks it is probably not a great problem.

Just so, but users still want to know what the focal length range is in
terms of some familiar standard. There's no reason of cosmic importance
for
24 x 36 to be that standard, other than the fact that it is by far the
most
familiar one.

Indeed, as a comparison for relative angle of view it is most useful, and
I do use it, but what of DoF?

DoF is different, of course. But I think that's secondary for most users
most of the time, in choosing a focal length. The *difference* in DoF for
dSLRs I think is relatively small, especially since the greater
magnification for the final print cancels some of the difference out.

Neil

"dennis@home" wrote in message
...

"Neil Harrington" wrote in message
. ..

Exactly. And I think that even long after 35mm is dead and gone, its use
as a familiar standard for focal lengths will probably go on and on. It's
already *the* standard of comparison for focal length conversions, and
once such a standard is established there's no obvious reason to change
it.

You can't just convert the focal length and come up with the correct
answer.

Sure you can, as far as the resulting magnification and angle of view is
concerned.


Not every lens characteristic changes when you change sensor size.
Things like the DOF stay the same.
They only change if you move the camera or zoom to reflect the change in
field of view.

No, DoF changes too, though not in the same degree.

Neil

On Sat, 20 Jan 2007 20:01:24 -0500, "Neil Harrington"
wrote:


"dennis@home" wrote in message
.. .

Not every lens characteristic changes when you change sensor size.
Things like the DOF stay the same.
They only change if you move the camera or zoom to reflect the change in
field of view.

No, DoF changes too, though not in the same degree.

Right, you get about 1 stop DoF advantage with the APS-C-type sensors
compared to 35 mm.

KS

King Sardon wrote:
On Sat, 20 Jan 2007 20:01:24 -0500, "Neil Harrington"
wrote:


"dennis@home" wrote in message
...

Not every lens characteristic changes when you change sensor size.
Things like the DOF stay the same.
They only change if you move the camera or zoom to reflect the
change in field of view.

No, DoF changes too, though not in the same degree.

Right, you get about 1 stop DoF advantage with the APS-C-type sensors
compared to 35 mm.

KS

That depends on what you're after.
Sometimes limited DOF is what you want...and sometimes the reverse is
true...

--
Images (Plus Snaps & Grabs) by Mark² at:
www.pbase.com/markuson

"King Sardon" wrote in message
...
On Sat, 20 Jan 2007 20:01:24 -0500, "Neil Harrington"
wrote:


"dennis@home" wrote in message
. ..

Not every lens characteristic changes when you change sensor size.
Things like the DOF stay the same.
They only change if you move the camera or zoom to reflect the change in
field of view.

No, DoF changes too, though not in the same degree.

Right, you get about 1 stop DoF advantage with the APS-C-type sensors
compared to 35 mm.

KS

Or disadvantage, depending on what you want. If you want less, then 35mm
has the advantage, if you want more, 1.5x has the advantage, unless you
merely stop the 35mm down...much easier to get more depth of field from a
full frame sensor than it is less depth of field from a crop sensor.

--
Skip Middleton
www.shadowcatcherimagery.com
www.pbase.com/skipm

"Pete D" wrote in message
...

"Alan Browne" wrote in message
...
VC wrote:
The release of Sony Alpha with the image stabilization in camera (
although this is not new) highlighted the fundamental problem with
Canon.
Canon have had IS lenses long ago as it would be very difficult to do
in-camera stabilization in film cameras. The digital cameras had to
support older lenses including the ones with IS. If Canon developed a
camera with in-body stabilization it would hurt Canon sales and
reputation.
So I guess Canon will continue with its nonstabilized bodies and when
Sony or someone else will achieve the same image sensor quality Canon
will find itself in a very difficult situation.
There is a very small advantage in having IS in the lens but it is not
significant enough to grant double and triple cost of the same quality
lenses.

For specific shooting, yes there is an advantage to "in lens"
stabilization... about a stop to 2 stops worth over the "in camera".

What testing proved this, the only testing I have seen is in a German mag
where they showed there was little difference between the two systems?

The advantages of the in-camera are a margin (2 stops, sometimes more)
and all your lenses benefit.

And no, in camera will never achieve what "in lens" stab can do.

What testing proved this, the only testing I have seen is in a German mag
where they showed there was little difference between the two systems?


Would that be the same German magazine that came up with a light fall of on
the corners of a 5D sensor in the order of 3-4 stops?
I keep hearing about this test, but I've never seen it. There were some
tests posted here, on this newsgroup, a couple of months ago, that indicated
1-2 stops for in camera on a DSLR (different from p&s results) and 2-4 stops
for in lens IS.

--
Skip Middleton
www.shadowcatcherimagery.com
www.pbase.com/skipm

In article , Skip
writes
"dennis@home" wrote in message
.. .

"Neil Harrington" wrote in message
. ..

Exactly. And I think that even long after 35mm is dead and gone, its use
as a familiar standard for focal lengths will probably go on and on. It's
already *the* standard of comparison for focal length conversions, and
once such a standard is established there's no obvious reason to change
it.

You can't just convert the focal length and come up with the correct
answer.
Not every lens characteristic changes when you change sensor size.
Things like the DOF stay the same.
They only change if you move the camera or zoom to reflect the change in
field of view.

Actually, I believe DOF is different, but, otherwise, everything else, like
perspective, stays the same.

The perspective depends on where you stand relative to the scene;
neither the size of the sensor nor the length of the lens, real or
pretend, can effect it.

--
Ian G8ILZ
There are always two people in every pictu the photographer and the viewer.
~Ansel Adams

In article , King Sardon
writes
On Sat, 20 Jan 2007 20:01:24 -0500, "Neil Harrington"
wrote:


"dennis@home" wrote in message
. ..

Not every lens characteristic changes when you change sensor size.
Things like the DOF stay the same.
They only change if you move the camera or zoom to reflect the change in
field of view.

No, DoF changes too, though not in the same degree.

Right, you get about 1 stop DoF advantage with the APS-C-type sensors
compared to 35 mm.

Or disadvantage if you are trying to isolate the subject.

--
Ian G8ILZ
There are always two people in every pictu the photographer and the viewer.
~Ansel Adams

In article , Bill Funk
writes
On Sat, 20 Jan 2007 20:47:27 +0000, Prometheus
wrote:

But, if I use my MF camera should I say it has a 50mm (x0.66) lens? I
know that 75mm on the MF and 50mm on the 35mm give about the same view,
if I look at a scene and it is about a quarter of normal (which I can
estimate) I know I need a lens of about a quarter the angle which is
four times the length. If I imagine the MF lens to be "50mm" this could
mislead me in to fitting a real 200mm lens when it should be 300mm.

Obviously, we aren't talking about MF.

Why not? If you are unable to understand lenses on sub-35mm full frame
without using a conversion multiplier how can you cope with supra-35mm?

It was not my idea that we should pretend that the lenses are a
different focal length. Do photo technique magazines publish 96, 67,66,
645, etc. photographs with a caption detailing pretend focal length, or
real focal length and film format?

What you should do is take your camera (5x4, FF 35mm, APS-C, 1/3, etc.),
go out, take photographs, and become familiar with what effect different
real focal lengths have; just as we did with different film formats.

Sensors are not magically different!

Cameras are about making photographs, they are not a theoretical
math-lab experiment.
--
Ian G8ILZ
There are always two people in every pictu the photographer and the viewer.
~Ansel Adams

Skip wrote:
"Bryan Olson" wrote:
Prometheus wrote:
Why not quote the angle of view that the lens gives with the sensor? Most
users are not interested in the focal length per se. I realise that macro
work and photometry can require more than the angle of view.

Yes, that seems like a good idea. Call an angle an angle and a
focal length a focal length.

Stating everything relative to 35mm full-frame is silly, especially
if it's not even what most people use.

Well, with so many sensor sizes, and proportions, on the market, 35mm
probably seems like the best to pick for a standard, since most of the
digital cameras, both point and shoot and DSLR, are similar in size, or at
least started out that way, to 35mm film cameras. And, originally, most of
the customers who migrated to digital came there from 35mm film. What
standard would you propose?

The proposal I like is to specify angle-of-view directly, without
reference to a standard sensor size.


--
--Bryan