Sony FF mirrorless lens size
 

If you check this article:
http://www.fujix-forum.com/threads/w...-professional-
mirrorless-was-a-fatal-mistake.54299/

the author is claiming that because the body is small, the lenses must
be bigger to maintain the distance to the sensor.

But is it perhaps because Sony is using an old lens design (suitable for
DSLRs where the lens is further away from the sensor)? And if Sony used
a different lens design, the lenses could be smaller (with the rear
element closer to the sensor)?
--
Alfred Molon

Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Sony FF mirrorless lens size
 

On 2016-04-05, Alfred Molon wrote:
If you check this article:
http://www.fujix-forum.com/threads/w...-professional-
mirrorless-was-a-fatal-mistake.54299/

the author is claiming that because the body is small, the lenses must
be bigger to maintain the distance to the sensor.

But is it perhaps because Sony is using an old lens design (suitable
for DSLRs where the lens is further away from the sensor)? And if Sony
used a different lens design, the lenses could be smaller (with the
rear element closer to the sensor)?

Here's what I think:

If you can keep the rays of light coming from the lens more or less at
right angles to the sensor regardless of the effective focal length and
right across the picture then all your lenses will inherently be well
matched to the sensor. Keeping a good distance between the sensor and
the back of the lens achieves that. Lenses designed to make room for an
SLR mirror will also meet that requirement, if fitted to a lens mount or
adaptor that makes up for the slimmer body of a mirrorless camera. That
isn't a bad thing.

If you have lenses with a 'cone' of light coming out onto the sensor,
you need to arrange the position and alignment of each sensor element to
match the angle of the light in the cone at that particular spot. You
can indeed make the lenses come closer to the sensor if you do that, but
each lens will need a different sensor element arrangement to match the
different 'cone' of light - or you'll get bad vignetting and distortion.
This is much less of a problem with film, which responds pretty evenly
regardless of the angle of the light cone from the lens, which is why
lenses for film rangefinder cameras can be so compact and fit so close
to the film.

--
-- ^^^^^^^^^^
-- Whiskers
-- ~~~~~~~~~~

Sony FF mirrorless lens size
 

In article ,
Whiskers wrote:

If you can keep the rays of light coming from the lens more or less at
right angles to the sensor regardless of the effective focal length and
right across the picture then all your lenses will inherently be well
matched to the sensor. Keeping a good distance between the sensor and
the back of the lens achieves that. Lenses designed to make room for an
SLR mirror will also meet that requirement, if fitted to a lens mount or
adaptor that makes up for the slimmer body of a mirrorless camera. That
isn't a bad thing.

longstanding myth.

Sony FF mirrorless lens size
 

On Tue, 5 Apr 2016 21:05:38 +0200, Alfred Molon
wrote:

If you check this article:
http://www.fujix-forum.com/threads/w...-professional-
mirrorless-was-a-fatal-mistake.54299/

the author is claiming that because the body is small, the lenses must
be bigger to maintain the distance to the sensor.

But is it perhaps because Sony is using an old lens design (suitable for
DSLRs where the lens is further away from the sensor)? And if Sony used
a different lens design, the lenses could be smaller (with the rear
element closer to the sensor)?

I don't think so. With any lens, except at the very center, light rays
approach the sensor at an angle to the surface. The closer that the
lens is to the surface, the greater that the angle will be. There is a
limit to the angularity that a sensor will accept and hence a limit on
how close to the sensor that the lens can be.
--

Regards,

Eric Stevens

Sony FF mirrorless lens size
 

In article , Eric Stevens
wrote:

If you check this article:
http://www.fujix-forum.com/threads/w...-professional-
mirrorless-was-a-fatal-mistake.54299/

the author is claiming that because the body is small, the lenses must
be bigger to maintain the distance to the sensor.

But is it perhaps because Sony is using an old lens design (suitable for
DSLRs where the lens is further away from the sensor)? And if Sony used
a different lens design, the lenses could be smaller (with the rear
element closer to the sensor)?

I don't think so. With any lens, except at the very center, light rays
approach the sensor at an angle to the surface. The closer that the
lens is to the surface, the greater that the angle will be. There is a
limit to the angularity that a sensor will accept and hence a limit on
how close to the sensor that the lens can be.

what matters is the exit pupil of the lens, not the back focus distance.

Sony FF mirrorless lens size
 

On Tue, 05 Apr 2016 18:56:19 -0400, nospam
wrote:

In article ,
Whiskers wrote:

If you can keep the rays of light coming from the lens more or less at
right angles to the sensor regardless of the effective focal length and
right across the picture then all your lenses will inherently be well
matched to the sensor. Keeping a good distance between the sensor and
the back of the lens achieves that. Lenses designed to make room for an
SLR mirror will also meet that requirement, if fitted to a lens mount or
adaptor that makes up for the slimmer body of a mirrorless camera. That
isn't a bad thing.

longstanding myth.

No.
--

Regards,

Eric Stevens

Sony FF mirrorless lens size
 

On Tue, 05 Apr 2016 19:42:34 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

If you check this article:
http://www.fujix-forum.com/threads/w...-professional-
mirrorless-was-a-fatal-mistake.54299/

the author is claiming that because the body is small, the lenses must
be bigger to maintain the distance to the sensor.

But is it perhaps because Sony is using an old lens design (suitable for
DSLRs where the lens is further away from the sensor)? And if Sony used
a different lens design, the lenses could be smaller (with the rear
element closer to the sensor)?

I don't think so. With any lens, except at the very center, light rays
approach the sensor at an angle to the surface. The closer that the
lens is to the surface, the greater that the angle will be. There is a
limit to the angularity that a sensor will accept and hence a limit on
how close to the sensor that the lens can be.

what matters is the exit pupil of the lens, not the back focus distance.

Yes, but keeping the exit pupil forward requires a longer lens, hence
defeating the attempt to obtain a shorter lens.
--

Regards,

Eric Stevens

Sony FF mirrorless lens size
 

In article , Eric Stevens
wrote:

If you can keep the rays of light coming from the lens more or less at
right angles to the sensor regardless of the effective focal length and
right across the picture then all your lenses will inherently be well
matched to the sensor. Keeping a good distance between the sensor and
the back of the lens achieves that. Lenses designed to make room for an
SLR mirror will also meet that requirement, if fitted to a lens mount or
adaptor that makes up for the slimmer body of a mirrorless camera. That
isn't a bad thing.

longstanding myth.

No.

yes.

lenses have been retrofocus well before digital so the rays are already
fairly parallel and the refractive index of silicon makes it impossible
for the angle to matter all that much.

Sony FF mirrorless lens size
 

In article , Eric Stevens
wrote:

If you check this article:
http://www.fujix-forum.com/threads/w...-professional-
mirrorless-was-a-fatal-mistake.54299/

the author is claiming that because the body is small, the lenses must
be bigger to maintain the distance to the sensor.

But is it perhaps because Sony is using an old lens design (suitable for
DSLRs where the lens is further away from the sensor)? And if Sony used
a different lens design, the lenses could be smaller (with the rear
element closer to the sensor)?

I don't think so. With any lens, except at the very center, light rays
approach the sensor at an angle to the surface. The closer that the
lens is to the surface, the greater that the angle will be. There is a
limit to the angularity that a sensor will accept and hence a limit on
how close to the sensor that the lens can be.

what matters is the exit pupil of the lens, not the back focus distance.

Yes, but keeping the exit pupil forward requires a longer lens, hence
defeating the attempt to obtain a shorter lens.

you're ignoring that the closer the exit pupil is, the smaller the
coverage circle is.

you're *not* going to get a 4mm lens covering full frame, for example,
but that length is common on cellphone cameras.

Sony FF mirrorless lens size
 

On Tue, 05 Apr 2016 22:06:05 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

If you check this article:
http://www.fujix-forum.com/threads/w...-professional-
mirrorless-was-a-fatal-mistake.54299/

the author is claiming that because the body is small, the lenses must
be bigger to maintain the distance to the sensor.

But is it perhaps because Sony is using an old lens design (suitable for
DSLRs where the lens is further away from the sensor)? And if Sony used
a different lens design, the lenses could be smaller (with the rear
element closer to the sensor)?

I don't think so. With any lens, except at the very center, light rays
approach the sensor at an angle to the surface. The closer that the
lens is to the surface, the greater that the angle will be. There is a
limit to the angularity that a sensor will accept and hence a limit on
how close to the sensor that the lens can be.

what matters is the exit pupil of the lens, not the back focus distance.

Yes, but keeping the exit pupil forward requires a longer lens, hence
defeating the attempt to obtain a shorter lens.

you're ignoring that the closer the exit pupil is, the smaller the
coverage circle is.

you're *not* going to get a 4mm lens covering full frame, for example,
but that length is common on cellphone cameras.

But so what? We are talking about full frame, not cellphone cameras.
--

Regards,

Eric Stevens