more about the camera design I would like to have

In the previous thread, I coined the term "single lens direct" or "single lens
display" or "SLD" to refer to my design. A summary of the design:

1. The viewfinder that is normally viewing through the taking lens via a
flip-up mirror, ground glass focusing screen, and a pentaprism, in an
SLR design, now view an LCD screen. I had suggested that LCD screen
can be placed where the focusing screen is on an SLR, and be viewed via
the same pentaprism. Others suggest to just skip the pentaprism and do
a straight view of the LCD screen. It would also be possible, if some
camera shape design needed it, to just use a mirror and electrically
reverse the LCD display as needed.

2. The sensor would always operate in "live view" mode. A camera can have
both an viewfinder LCD display, as well as a back LCD display (yes, two
LCD displays). The "face is close" detector that shuts off the back LCD
in SLR cameras now can also turn the viewfinder LCD display on. One way
or the other, you see through the taking lens electrically live. Focusing
can use the techniques SLR with "live vider" mode already have, like doing
software magnification and/or contrast focusing. Focusing points can be
put anywhere desired.

2. The flip-up mirror is now gone. This leaves room inside the camera for
other things. I suggested super wide angle lenses can be placed closer
to the sensor. There was a heated debate about this, but my take on the
"conclusion" of that is wide angle lenses are less complex when designed
this way, and the real issue is light falloff at extreme angles on the
sensor. Whether it is easy or hard to solve, it is solvable, and I even
suggest more than one way to do it exists.

3. I suggested that this SLD design should be made to make use of (nearly)
all SLR lenses in that manufacturer's line. So for Canon, that would mean
making EF and EF-S lenses normally work (or just EF lenses for a full frame
SLD model).

4. For a wide angle lens closer to the sensor than can be done with an SLR,
such a lens would have a protruding rear element if the mounting distance
remained at the same point as for an SLR. There is the risk that someone
might try to mount such a lens on an SLR, possibly damaging both camera
and lens. I suggested a slightly variant mount with an adaptor for real
SLR lenses on an SLD camera. Others suggested this would actually be more
complicated for both the average photo hobbyist as well as professional.
And I think they win that argument. So a lens with a protruding rear
element used on an SLR invokes a hard learned lesson.

5. It was suggested that we should move away from a focal plane shutter and
return the leaf shutter, which is the basis for large format view cameras
and many other "smaller" cameras, as well. I hadn't considered this when
I suggested the SLD design, but it clearly is the way to go. But it should
do this in a migratory way, keeping the focal plane shutter in SLD cameras
for a number of years until the lens lines upgrade to have leaf shutters.

6. Despite what I think are clear advantages in the SLD design over SLR for
most things, there are times where at least a focal plane shutter have
some benefit, and there could still remain some use for optically viewing
through the taking lens. So I don't see the SLR going completely away in
my lifetime, and there might always be at least some SLD cameras with a
focal plane shutter, too.

7. In-camera filters, either slide-in from a side door, or inserted from the
front with the lens off, might be more practical than on-lens (front or
rear) filters. The electrical sensor needs a filter to block both IR and
even some UV. Glass passes only a limited amount of UV, so it has not been
a big issue with film, even though film is generally very UV sensitive. A
UV blocking filter has been common on the front of many lenses. But with
digital, an IR blocking filter is critical for accurate visual spectrum
photos. If this is done with a slide in filter, that leaves open options
to use other filters instead. But those filters either need to have their
own IR blocking, or we need 2 filter positions, or one filter cartridge
that can have 2 filters on it.

There is one more idea I thought of today. And this is not specific to SLD,
although doing it in an SLR would probably need to change the camera frame
construction a bit. This idea is to increase the sensor dimensions from the
3:2 aspect normally used with a landscape orientation (which requires the
camera to be rotated 90 degrees for portrait orientation), to a full 1:1 at
the full size. So for a full-frame sensor this would be 36mm x 36mm. For an
APS-C size, this would be around 22mm x 22mm. Not every camera needs to have
this. I could be a premium feature on advanced cameras. The idea is to have
the electronics simply use the appropriate portion of the sensor based on the
desired picture orientation. If you want landscape, you use the portion of
the sensor that is 36mm wide by 24mm high. But with one button, you can have
the camera use the portion of the sensor that is 24mm wide by 36mm high. As
most lenses are round and cover a complete circle of at least 43.2666mm wide,
which is the corner to corner distance of 36mm x 24mm, this should work. The
only issue I see at the moment is with lenses that have integrated hoods with
a rectangular opening oriented in landscape mode the way the lens would be
mounted to the camera. When using these lenses, fall back to the classical
method: turn the whole camera (the smart camera will beep and warn about the
change to portrait orientation when said lens is mounted).

Such a sensor could leave out the corner parts that don't get used by either
orientation. Or the sensor could also be made to allow other aspect ratios
that fit within the standard coverage circle for that sensor size. A square
(1:1) aspect ratio could be 30.59mm x 30.59mm and fit this coverage. Other
aspect ratios could be used in ways that one dimension is a bit wider that if
that same aspect ratio were derived from cropping the standard size. If the
sensor is going to be upgraded to do the landscape/portrait switch, then these
other aspect ratios came almost free (the cost it not cutting out as much in
the corners of the sensor, and writing some more firmware).

Why would anyone want a 1:1 taking aspect ratio? How about circular fisheye?

Also, maybe an SLR could be designed in such a way that when its mirror does
go into a locked up position, it optically flips the light path to allow an
LCD screen to be seen in the viewfinder. Then we have an SLR/SLD combo. That
and a focal plane shutter locked-open mode, and you can have a real combo.

I'm sure a few people will come up with descriptions of why they don't need
these features. I do think that over time (10 years or so after SLDs first
come out) a lot of people will end up preferring the SLD over the SLR.

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