Dieter wrote:
Would this be totally out of the question?
I assume you are not planning on building a custom lens? Maybe use
one of the existing mounts and use lenses from Canon or Nikon.
Yes, it should be able to use existing lenses. That would be the 'open'
way to do it. 16mm & 35mm movie lenses are suitable for some sizes of
sensors and it should also be possible to use standard 35mm SLR and
range finder lenses.
1. It should support 24 bit color JPEG2000 (both lossy and
lossless) compression. JPEG is basically obsolete and I can't help
but wonder why it is still the standard format for digital cameras
since the artifacts seriously degrade images -- actually worse
than lower resolution would be.
Most people just take snapshots and don't care about quality.
Yes but ... there are still somewhat serious photographers. Those that
purchased cameras for > $100 in the 70s (when I was selling them)
included serious photographers. I guess that now serious photographers
would be those that use their computer to improve their photos.
2. The so called RAW format should be Adobe DNG and/or "OpenRAW"
(which isn't actually a format).
Is Adobe DNG an open standard?
Adobe has published it, as they did with PDF.
Seems like it would be easy to give the user lots of choices of
formats, including "write your own".
Doesn't seem like a good idea. A standard is needed.
4. Then there is the problem of remote control of the camera; it
appears that there are no standards here. A computer connected by
Ethernet, IEEE-1394, or USB (a camera would probably have only one
of these) should be able to display the live preview image, obtain
exposure and focus information, and control all aspects of the
camera that can be controlled on the camera.
And infrared remote, which can be handy for some applications.
I presume that you mean without having to use a laptop.
I also have a lot of issues with digital still cameras:
1. They seem to all be designed to emulate film still cameras. For
some reason, digital video cameras don't have these problems so I
presume that they are design issues. Is there some reason that
you can't set both the aperture and the shutter speed (within
limits) and still have automatic exposure control?
You can manually set aperture XOR shutter speed and still have
automatic exposure control. The camera adjusts which ever one you
don't set. And some cameras have fully automatic (camera sets both)
modes which favor a high shutter speed, or favor a small aperture,
etc.
There are three variables with a digital camera. Shutter, Aperture,
*AND* the ISO setting. So, you should be able to set any two of them
that you choose and if the third falls into the available range, then it
should work.
With open source the user could write whatever algorithm they want.
2. It is presumed that to have interchangeable lenses that it must
be a high end SLR. OTOH, the high end SLRs all seem to come with
large (but questionable quality) zoom lenses. In either case, the
possible advantages of a compact camera and lenses are lost.
Nobody (except Sigma) makes a fast normal lens.
In film cameras there used to be (maybe still are?) a whole range of
35mm SLRs, low end, medium, high end.
You can't buy a digital SLR body without a lens?
Well in the less expensive ones, it is attached. Some of the less
expensive < $1,000 SLRs are not available without a lens.
I find it hard to believe that Canon and Nikon don't make fast normal
lenses for DSLRs.
I find it very hard to believe, but that is the case. Only Sigma makes one.
3. Most of them have an optical viewfinders. Video cameras don't
seem to have this problem since an EVF is considered to be a
feature.
Why do you dislike an optical viewfinder?
I was talking only about a SLR. I dislike it because it makes the
camera more expensive and appears to be redundant.
Do you want to eliminate the mirror flipping up and down? The mirror
flipping up and down would be impractical for video, you'd have to
use a beam splitter, which reduces available light.
I was talking about using only an EVF.
Does anyone make a high resolution display that is small enough to
use on a camera? My video/still camera only captures 720x480, even
in still mode, but even so the viewfinder resolution is a lot lower
than that, so I can't tell how much detail I'm getting. I suppose
with the 12 Mpixel (or whatever they're up to this week) sensors you
can just assume you're getting a lot of detail, but I can't assume
that with only 720x480. With video, even 1920x1080 isn't enough to
assume you're getting the detail you want.
You can use the LCD for a high resolution preview. If the camera has a
focus meter, you don't need full resolution for the EVF. Or, if the EVF
is removable, then those that want a high resolution (and large)
viewfinder can purchase one. Some people use the LCD and a hood and
eyepiece. They don't need any additional viewfinder.
4. There is probably an analog to Moore's Law for sensors. So,
they come out with a new sensor every year or two and you have to
replace the whole camera, and your old camera isn't worth much used
for the same reasons.
There was an article somewhere (maybe Dan's Data?) about how the
super high resolution sensors have so much noise that you may be
better off with less resolution.
http://6mpixel.org/en/
Yes, that is based on a minimum pixel size or 3 micrometers which is
approximately the practical limit of resolution of a good lens (but
there is the CFA to consider). That means that higher resolution
sensors need to be larger not that more resolution is a bad thing. You
really do need 12 mega pixels to approach the sharpness of a good 35mm
camera.
5. For some reason, 24x36mm and smaller formats don't have coolers.
Huh?
Large format backs have a Peltier cooler to cool the sensor chip to
reduce noise.
7. Autofocus has its uses, but it shouldn't be at the expense of
usable manual focus. That is, digital SLRs have viewfinders that
are not really suitable for manual focusing.
IIRC optical viewfinders have special patterns in the groundglass to
aid focusing.
This seems to be missing on most auto focus SLRs -- all you get is an
arial image. Some of the Digital SLRs don't have interchangeable
focusing screens (I think that I have half a dozen for my old F3) so you
have to have a repair shop disassemble the camera to put in a good
screen if you want to use manual focus lenses.
But above you say you want an electronic viewfinder. I think manually
focusing an electronic viewfinder would be problematic.
Quite true. You need auto focus, a focus meter, a range finder, or some
other focusing aid such as magnifying the center of the image to full
resolution to focus.
What I'd like to see is a good interface to allow the user to select
what part of the screen they want to be in focus. And have a button
to semi-lock the focus. The auto focus would still track the object
if it moves slightly, but is prevented from jumping to another
object that is closer/farther away.
Yes, I think that serious photographers would like to be able to use
auto focus like a range finder except when shooting actions shots. What
I would like is to have a center circle and you push the button if you
have power focus and it focuses and then you release the button and it
stops unless you turn it on full time. If you don't have power focus,
the same thing except that you have to focus till either the optical
focusing aid or the focus meter shows it in focus.
Similar interface for auto exposure.
??
9. I'm not certain of the reason but most digital cameras have a
minimum ISO of 100. A few are a little lower but not by much.
That would be easy enough to fix with open source. And the user could
program whatever bracketing scheme they want.
Looking at cameras, I don't find any that go down below 50 (if they go
down that far).
The issue here is that with 35mm (24x36mm) that defraction limits
resolution at f/16. Smaller sensors need a large aperture to avoid
defraction. So, you have to use a ND filter to shoot in daylight.
Well it seems to be some limitation of the sensor that I have not read
enough to really understand yet. IIUC, with a cooler, this is possible.
And, I didn't mention. Cameras are getting too complicated -- I like my F3.
--
JRT
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