Canon DSLR Live View
Eugene
Canon Live View in the 1000D/XS for example
can give live view in the LCD rather than
optical viewfinder. How come previous Digital
SLR didn't make this feature available?
Also anyone owns any one of these Canon Live View DSLR?
I'd use a 1000mm f/10 Russian Telephoto on
it. Can the contrast autofocus work? The
telephoto is manual and have to turn it
manually. So I guess that I can see the view
direclty in the LCD to see the best focus?
What then is the function of Contrast or
AF autofocus in this case?
Thanks.
E.
N
news:6c6c28aa-a852-4739...@z16g2000prd.googlegroups.com...
> Hi,
>
> Canon Live View in the 1000D/XS for example
> can give live view in the LCD rather than
> optical viewfinder. How come previous Digital
> SLR didn't make this feature available?
>
For the same reason that climate control wasn't available on a Model-T Ford.
Eugene
> "Eugene" <eugenhug...@gmail.com> wrote in message
All predecessors and point&shoot use Live View.
If what the XS did is simply hold the mirror upward
while the view is being seen live. Earlier model
could have use such simple principle like in
Canon 300D.
E
Eugene
When digicam autofocus, does the lens supposed
to move or is it all software or is there another
lens on top of the CCD which can focus the
image?
E
N
E
Yes, sure, and Henry could have put a full roof and sides on the M-T.
Oh, and why wan't there a sensor in your first film camera?
Pat
I have live view and frankly, don't know what all of the fuss is
about. It has very little usefulness.
So you're out with your 1000mm lens. Good. And it's on a tripod,
because it is, after all, a 1000 mm lens. So what real advantage does
live view have -- esp. in daylight where you can't see it as well. It
really isn't too difficult to look through the viewfinder and get a
much better view of the picture.
Dave Cohen
> "Eugene" <eugen...@gmail.com> wrote in message
> news:a61171bc-8d5f-43e5...@v35g2000pro.googlegroups.com...
> On Apr 22, 7:28 pm, "N" <N...@onyx.com> wrote:
>> "Eugene" <eugenhug...@gmail.com> wrote in message
>>
>> news:6c6c28aa-a852-4739...@z16g2000prd.googlegroups.com...
>>
>> > Hi,
>>
>> > Canon Live View in the 1000D/XS for example
>> > can give live view in the LCD rather than
>> > optical viewfinder. How come previous Digital
>> > SLR didn't make this feature available?
>>
>> For the same reason that climate control wasn't available on a Model-T
>> Ford.
They were too busy designing the Model-T automatic transmission. Didn't
sell well, people just just loved the satisfying crunch of their crash
gearbox.
This is another of those 'why' posts like the measekite series.
Dave Cohen
nospam
<a61171bc-8d5f-43e5...@v35g2000pro.googlegroups.com>,
Eugene <eugen...@gmail.com> wrote:
> All predecessors and point&shoot use Live View.
> If what the XS did is simply hold the mirror upward
> while the view is being seen live. Earlier model
> could have use such simple principle like in
> Canon 300D.
earlier dslr sensors were not capable of live view. compact p&s
cameras used a different sensor technology.
nospam
<41013a87-9d0e-40e2...@x5g2000yqk.googlegroups.com>, Pat
<gro...@artisticphotography.us> wrote:
> I have live view and frankly, don't know what all of the fuss is
> about. It has very little usefulness.
>
> So you're out with your 1000mm lens. Good. And it's on a tripod,
> because it is, after all, a 1000 mm lens. So what real advantage does
> live view have -- esp. in daylight where you can't see it as well. It
> really isn't too difficult to look through the viewfinder and get a
> much better view of the picture.
macro is one scenario where live view is fantastic.
J. Clarke
> N wrote:
>> "Eugene" <eugen...@gmail.com> wrote in message
>> news:a61171bc-8d5f-43e5...@v35g2000pro.googlegroups.com...
>> On Apr 22, 7:28 pm, "N" <N...@onyx.com> wrote:
>>> "Eugene" <eugenhug...@gmail.com> wrote in message
>>>
>>> news:6c6c28aa-a852-4739...@z16g2000prd.googlegroups.com...
>>>
>>>> Hi,
>>>
>>>> Canon Live View in the 1000D/XS for example
>>>> can give live view in the LCD rather than
>>>> optical viewfinder. How come previous Digital
>>>> SLR didn't make this feature available?
>>>
>>> For the same reason that climate control wasn't available on a
>>> Model-T Ford.
>
> They were too busy designing the Model-T automatic transmission.
> Didn't sell well, people just just loved the satisfying crunch of
> their crash gearbox.
The Model T did not have a "crash gearbox". The shift mechanism was in fact
very similar to that used in most automatic transmissions.
Savageduck
> Dave Cohen wrote:
>> N wrote:
>>> "Eugene" <eugen...@gmail.com> wrote in message
>>> news:a61171bc-8d5f-43e5...@v35g2000pro.googlegroups.com...
>>> On Apr 22, 7:28 pm, "N" <N...@onyx.com> wrote:
>>>> "Eugene" <eugenhug...@gmail.com> wrote in message
>>>>
>>>> news:6c6c28aa-a852-4739...@z16g2000prd.googlegroups.com...
>>>>
>>>>> Hi,
>>>>
>>>>> Canon Live View in the 1000D/XS for example
>>>>> can give live view in the LCD rather than
>>>>> optical viewfinder. How come previous Digital
>>>>> SLR didn't make this feature available?
>>>>
>>>> For the same reason that climate control wasn't available on a
>>>> Model-T Ford.
>>
>> They were too busy designing the Model-T automatic transmission.
>> Didn't sell well, people just just loved the satisfying crunch of
>> their crash gearbox.
>
> The Model T did not have a "crash gearbox". The shift mechanism was in
> fact very similar to that used in most automatic transmissions.
Yup. A planetary gear transmission run with drive belts, all pedal &
lever controlled. No clutch. This included a middle pedal which had
to be depressed to engage and maintain reverse.
>
>> This is another of those 'why' posts like the measekite series.
>> Dave Cohen
>>>
>>> All predecessors and point&shoot use Live View.
>>> If what the XS did is simply hold the mirror upward
>>> while the view is being seen live. Earlier model
>>> could have use such simple principle like in
>>> Canon 300D.
>>>
>>> E
>>>
>>>
>>> Yes, sure, and Henry could have put a full roof and sides on the M-T.
>>> Oh, and why wan't there a sensor in your first film camera?
--
Regards,
Savageduck
Chris Malcolm
> Canon Live View in the 1000D/XS for example
> can give live view in the LCD rather than
> optical viewfinder. How come previous Digital
> SLR didn't make this feature available?
Why don't the previous DSLRs with live view LCD count as "making this
feature available"?
--
Chris Malcolm
Doug Jewell
> Hi,
>
> Canon Live View in the 1000D/XS for example
> can give live view in the LCD rather than
> optical viewfinder. How come previous Digital
> SLR didn't make this feature available?
sensor chip to do continuous live read-out. This additional
circuitry adds to the chip cost & complexity, and also
degrades still image quality slightly - the presence of the
live read-out circuitry means less area available for light
gathering.
Earlier DSLRs, I guess the manufacturers decided that people
wouldn't want live-view on a DSLR and would prefer the
better image quality. As chip technology has progressed,
they can now do live-view and maintain image quality. And
since there is now demand in DSLR for the feature (because
of the P&S brigade upgrading to DSLR), they are starting to
put it in most models now.
>
> Also anyone owns any one of these Canon Live View DSLR?
Out of about 10,000 shots I've made with my 450D, I'd say
I've used liveview for no more than 20. A couple of "over
the crowd" shots at a local parade, and a few macro shots.
>
> I'd use a 1000mm f/10 Russian Telephoto on
> it. Can the contrast autofocus work? The
> telephoto is manual and have to turn it
> manually. So I guess that I can see the view
> direclty in the LCD to see the best focus?
> What then is the function of Contrast or
> AF autofocus in this case?
surprise, autofocus won't work. No, not even contrast detect
autofocus. What you can do in live-view mode is magnify the
image x5 or x10 (on the 450D you can, I assume the 1000
would be the same) so you can preview the manual focus. Will
probably be a bit grainy with an F10 lens though.
>
> Thanks.
>
> E.
Eugene
Autofocus may not work but if you turn the lens manually,
focus confirmation can light up if the correct focus is
achieved. So it is like Autofocus except you turn the
lens manually.This is why some adapter for non-canon
manual lens uses chip to activate the Canon confirm
confirmation like:
http://www.rugift.com/photocameras/canon-eos-adapter-focus-confirm.htm
What do you say?
E
> autofocus. What you can do in live-view mode is magnify the
> image x5 or x10 (on the 450D you can, I assume the 1000
> would be the same) so you can preview the manual focus. Will
> probably be a bit grainy with an F10 lens though.
>
>
>
>
>
> > Thanks.
>
> > E.- Hide quoted text -
>
> - Show quoted text -
Charles
"nospam" <nos...@nospam.invalid> wrote in message
news:220420091213314368%nos...@nospam.invalid...
To be sure ... it can save the day with some macro shots!
Dudley Hanks
"Charles" <charles...@comcast.net> wrote in message
news:gso59n$qdn$1...@news.motzarella.org...
Also, the LV focus can focus in lower lighting situations where the normal,
or Quick Focus, has problems. I know that won't carry a lot of weight,
since it comes from somebody who has problems getting the focus where he
wants it, but, it does seem to have a lower operating threshold.
So, that 1,000 mm lens sitting on the tripod might benefit from LV, even on
a sunny day, and even if you can see the image, yourself, better through the
viewfinder. The camera might see it better with LV -- especially if you
plop a 2X converter on it and cut the aperture in half.
Take Care,
Dudley
Eugene
> "Charles" <charlesschu...@comcast.net> wrote in message
>
> news:gso59n$qdn$1...@news.motzarella.org...
>
>
>
>
>
>
>
> > "nospam" <nos...@nospam.invalid> wrote in message
> >news:220420091213314368%nos...@nospam.invalid...
> >> In article
> >> <gro...@artisticphotography.us> wrote:
>
> >>> I have live view and frankly, don't know what all of the fuss is
> >>> about. It has very little usefulness.
>
> >>> So you're out with your 1000mm lens. Good. And it's on a tripod,
> >>> because it is, after all, a 1000 mm lens. So what real advantage does
> >>> live view have -- esp. in daylight where you can't see it as well. It
> >>> really isn't too difficult to look through the viewfinder and get a
> >>> much better view of the picture.
>
> >> macro is one scenario where live view is fantastic.
>
> > To be sure ... it can save the day with some macro shots!
>
> Also, the LV focus can focus in lower lighting situations where the normal,
> or Quick Focus, has problems. I know that won't carry a lot of weight,
> since it comes from somebody who has problems getting the focus where he
> wants it, but, it does seem to have a lower operating threshold.
Has anyone tried F/10 with the LiveView by using teleconverter
with say a 400mm telephoto? How is the image? How
is Contrast Autofocus.. Can it still focus? (I assume Phase
Detection no longer works with F/10 even in Live View).
Also does Manual focusing guarantee to work by
zooming in on the object for more accurate manual
focusing (if it is bright enough in the first place to
zoom in).
>
> So, that 1,000 mm lens sitting on the tripod might benefit from LV, even on
> a sunny day, and even if you can see the image, yourself, better through the
> viewfinder. The camera might see it better with LV -- especially if you
> plop a 2X converter on it and cut the aperture in half.
A 2X converter would make the 1000mm lens 2000mm.
It won't cut the aperture in half but just extend the focal
length.
E
>
> Take Care,
> Dudley- Hide quoted text -
Mr. Strat
<6c6c28aa-a852-4739...@z16g2000prd.googlegroups.com>,
Eugene <eugen...@gmail.com> wrote:
> Canon Live View in the 1000D/XS for example
> can give live view in the LCD rather than
> optical viewfinder. How come previous Digital
> SLR didn't make this feature available?
Because it's a feature for morons. But if you like wasting your battery
and looking at a little TV screen, be my guest. One viewfinder is
plenty.
Dudley Hanks
E
No, it cuts the aperture in half as well. Most teleconverters will still
show that your aperture is set to, let's say, f/3.5, but the effective
aperture is actually f/7.0.
For discussion, see:
http://forums.dpreview.com/forums/read.asp?forum=1035&message=31559866
Whenever the discussion turns to tele's and aperture, it gets a bit murky,
but the thing to remember is that, while the teleconverter doesn't change
the physical size of the aperture, it does reduce the amount of light that
reaches your film / sensor, so the end result is identical to altering your
aperture size.
Take Care,
Dudley
Doug Jewell
> In article
> <49ef8c0a$0$12595$5a62...@per-qv1-newsreader-01.iinet.net.au>,
> Doug Jewell <a...@and.maybe.ill.tell.you> wrote:
>
>> Yes. Slightly more useful than a gimmick, but only slightly.
>> Out of about 10,000 shots I've made with my 450D, I'd say
>> I've used liveview for no more than 20. A couple of "over
>> the crowd" shots at a local parade, and a few macro shots.
>
> with it.
The slow focussing, lag, and extra battery drain don't
exactly thrill me. If I wanted those features I use my P&S.
For what I do most (candid portraits), live-view is
completely hopeless.
Doug Jewell
would be very surprised if it does in the 1000D since it is
a lower spec camera released at approximately the same time.
The closest thing you have to focus-confirm is your
assesment of the image you see at 10x magnification.
Focus-confirm is an indicator in the viewfinder, and as far
as I know it only works with F5.6 or faster lenses.
Robert Spanjaard
>>> I have live view and frankly, don't know what all of the fuss is
>>> about. It has very little usefulness.
>>>
>>> So you're out with your 1000mm lens. Good. And it's on a tripod,
>>> because it is, after all, a 1000 mm lens. So what real advantage does
>>> live view have -- esp. in daylight where you can't see it as well. It
>>> really isn't too difficult to look through the viewfinder and get a
>>> much better view of the picture.
>>
>> macro is one scenario where live view is fantastic.
>
> To be sure ... it can save the day with some macro shots!
I prefer an anglefinder attached to the optical viewfinder.
What I do like about Live View (on my Powershot S80), is some extra info
like the live histogram.
--
Regards, Robert http://www.arumes.com
Bigguy
> On Apr 22, 7:04 am, Eugene <eugenhug...@gmail.com> wrote:
>> Hi,
>>
>> Canon Live View in the 1000D/XS for example
>> can give live view in the LCD rather than
>> optical viewfinder. How come previous Digital
>> SLR didn't make this feature available?
>>
>> Also anyone owns any one of these Canon Live View DSLR?
>>
>> I'd use a 1000mm f/10 Russian Telephoto on
>> it. Can the contrast autofocus work? The
>> telephoto is manual and have to turn it
>> manually. So I guess that I can see the view
>> direclty in the LCD to see the best focus?
>> What then is the function of Contrast or
>> AF autofocus in this case?
>>
>> Thanks.
>>
>> E.
>
> I have live view and frankly, don't know what all of the fuss is
> about. It has very little usefulness.
>
did 'manage' without, before, but LV is really useful and prevents neck
and back strain too.
Guy
Chris Malcolm
The slow focussing and lag are a feature of Canon's specific current
implementation of live view. There are other way of doing it without
those problems, one of which is used in the Sony Alpha live view
models which use fast phase detection AF in live view, no difference
in speed when using live view.
--
Chris Malcolm
Chris Malcolm
I'm not much interested in simple back panel live view, because if you
can see the panel you can simply move the camera closer to your eye
and see through the viewfinder. But I've unexpectedly found flippable
LCD live view so extremely useful that I will now not buy a DSLR
without it. I now routinely take many photographs from camera
positions where it would either be rather difficult or impossible to
get my eye behind the viewfinder.
--
Chris Malcolm
nospam
<c...@holyrood.ed.ac.uk> wrote:
> The slow focussing and lag are a feature of Canon's specific current
> implementation of live view. There are other way of doing it without
> those problems, one of which is used in the Sony Alpha live view
> models which use fast phase detection AF in live view, no difference
> in speed when using live view.
except that sony uses an entirely separate sensor for live view which
means it lacks the advantage of focusing using the imaging sensor
itself.
Dave Cohen
> On 2009-04-22 09:22:21 -0700, "J. Clarke" <jclarke...@cox.net> said:
>
>> Dave Cohen wrote:
>>> N wrote:
>>>> "Eugene" <eugen...@gmail.com> wrote in message
>>>> news:a61171bc-8d5f-43e5...@v35g2000pro.googlegroups.com...
>>>>
>>>> On Apr 22, 7:28 pm, "N" <N...@onyx.com> wrote:
>>>>> "Eugene" <eugenhug...@gmail.com> wrote in message
>>>>>
>>>>> news:6c6c28aa-a852-4739...@z16g2000prd.googlegroups.com...
>>>>>
>>>>>
>>>>>> Hi,
>>>>>
>>>>>> Canon Live View in the 1000D/XS for example
>>>>>> can give live view in the LCD rather than
>>>>>> optical viewfinder. How come previous Digital
>>>>>> SLR didn't make this feature available?
>>>>>
>>>>> For the same reason that climate control wasn't available on a
>>>>> Model-T Ford.
>>>
>>> They were too busy designing the Model-T automatic transmission.
>>> Didn't sell well, people just just loved the satisfying crunch of
>>> their crash gearbox.
>>
>> The Model T did not have a "crash gearbox". The shift mechanism was
>> in fact very similar to that used in most automatic transmissions.
>
>
> Yup. A planetary gear transmission run with drive belts, all pedal &
> lever controlled. No clutch. This included a middle pedal which had to
> be depressed to engage and maintain reverse.
>
>>
an old Austin Ruby. That sure did have a crash gearbox, I had never
driven a car before. In England, I only drove motor bikes, by the time I
got to the States, all cars were synchromesh except for 1st gear. I
still prefer a standard shift although automatics these days are very good.
Dave Cohen
Mr. Strat
<nos...@nospam.invalid> wrote:
> except that sony uses an entirely separate sensor for live view which
> means it lacks the advantage of focusing using the imaging sensor
> itself.
Has Sony ever made a product that wasn't proprietary and worked well?
Chris Malcolm
How could a company make anything which wasn't proprietary?
--
Chris Malcolm
nospam
<c...@holyrood.ed.ac.uk> wrote:
> > Has Sony ever made a product that wasn't proprietary and worked well?
>
> How could a company make anything which wasn't proprietary?
by using existing standards, not inventing their own like memory stick.
Dudley Hanks
"nospam" <nos...@nospam.invalid> wrote in message
The original IBM PC...
Take Care,
Dudley
nospam
<dha...@blind-apertures.ca> wrote:
> >> > Has Sony ever made a product that wasn't proprietary and worked well?
> >>
> >> How could a company make anything which wasn't proprietary?
> >
> > by using existing standards, not inventing their own like memory stick.
>
> The original IBM PC...
that was definitely proprietary.
Dudley Hanks
"nospam" <nos...@nospam.invalid> wrote in message
The XT an AT were a bit of a strange case:
" They [IBM] also decided on an open architecture , so that other
manufacturers could produce and sell peripheral components and compatible
software without purchasing licenses."
http://en.wikipedia.org/wiki/IBM_PC
Take Care,
Dudley
Bob Larter
He's using "proprietary" in the sense it's used within the electronics
industry, meaning that (for example) it uses special connectors, or is
gratuitously incompatible with other manufacturers devices.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
Bob Larter
Well, there weren't any PC standards back then. OTOH, they did publish
the spec's for their bus, which became an industry standard.
Ray Fischer
> Dudley Hanks
>> >> > Has Sony ever made a product that wasn't proprietary and worked well?
>> >>
>> >> How could a company make anything which wasn't proprietary?
>> >
>> > by using existing standards, not inventing their own like memory stick.
>>
>> The original IBM PC...
>
>that was definitely proprietary.
The manual that came with it included a diagram of the electronics and
a listing of the BIOS. Hardly proprietary since anyone could develop
software/hardware for the machine.
Of course, they were just copying what Apple had done with the Apple II.
--
Ray Fischer
rfis...@sonic.net
Chris Malcolm
As does every DSLR which uses phase detection focussing, which as far
as I know is all of them, although a few also use image sensor
contrast detection in live view. Generally speaking the phase
detection focussing method using dedicated AF sensors is considered to
be a superior method of focussing, which is why Sony went to the
trouble and expense of making it possible to use it in live view.
--
Chris Malcolm
Chris Malcolm
> Chris Malcolm wrote:
>> Mr. Strat <r...@nospam.techline.com> wrote:
>>> In article <230420091126589333%nos...@nospam.invalid>, nospam
>>> <nos...@nospam.invalid> wrote:
>>
>>>> except that sony uses an entirely separate sensor for live view which
>>>> means it lacks the advantage of focusing using the imaging sensor
>>>> itself.
>>
>>> Has Sony ever made a product that wasn't proprietary and worked well?
>>
>> How could a company make anything which wasn't proprietary?
> He's using "proprietary" in the sense it's used within the electronics
> industry, meaning that (for example) it uses special connectors, or is
> gratuitously incompatible with other manufacturers devices.
In which case I can't see the relevance to camera auto focussing
methods, since there's probably more ways that has been implemented
than there are camera manufacturers, no proprietary standards, and no
need for them.
--
Chris Malcolm
nospam
<rfis...@sonic.net> wrote:
> >> The original IBM PC...
> >
> >that was definitely proprietary.
>
> The manual that came with it included a diagram of the electronics and
> a listing of the BIOS. Hardly proprietary since anyone could develop
> software/hardware for the machine.
those who tried got sued. the publishing of the bios listing (which
wasn't included with every machine) was to make cloning legally harder
since ibm could (and did) claim people were illegally copying it.
several were sued, and not until cloners did a clean room reproduction
did the flood of clones begin. plus pc-dos was not exactly the same as
ms-dos.
nospam
<c...@holyrood.ed.ac.uk> wrote:
phase detection is faster but not always perfect. contrast detection
is slower but guaranteed 100% accurate if it uses the imaging sensor,
which sony *doesn't* do. there is no way to guarantee focus with
sony's live view, whereas on sony/canon there is.
nospam
<nos...@nospam.invalid> wrote:
eh, nikon/canon, that is. olympus 4/3rds too for that matter. the
panasonic g1's contrast detect focus is fairly fast too.
Dudley Hanks
"nospam" <nos...@nospam.invalid> wrote in message
We seem to remember this differently. Can you point to any links which
verify your version of the early PC history?
Take Care,
Dudley
Dudley Hanks
"Ray Fischer" <rfis...@sonic.net> wrote in message
news:49f16b2c$0$1629$742e...@news.sonic.net...
Ray, I think IBM came out with the PC XT prior to the Apple II.
Take Care,
Dudley
nospam
<dha...@blind-apertures.ca> wrote:
> >> >> The original IBM PC...
> >> >
> >> >that was definitely proprietary.
> >>
> >> The manual that came with it included a diagram of the electronics and
> >> a listing of the BIOS. Hardly proprietary since anyone could develop
> >> software/hardware for the machine.
> >
> > those who tried got sued. the publishing of the bios listing (which
> > wasn't included with every machine) was to make cloning legally harder
> > since ibm could (and did) claim people were illegally copying it.
> > several were sued, and not until cloners did a clean room reproduction
> > did the flood of clones begin. plus pc-dos was not exactly the same as
> > ms-dos.
>
> We seem to remember this differently. Can you point to any links which
> verify your version of the early PC history?
here's a few:
<http://en.wikipedia.org/wiki/Phoenix_Technologies>
With the success of the IBM PC in 1983, Phoenix decided to provide an
IBM PC compatible ROM BIOS to the PC market. A licensable ROM BIOS
would allow clone PC manufacturers to run the same applications, and
even the MS-DOS that was being used by IBM. However, to do this Phoenix
needed a strategy for defense against IBM copyright infringement
lawsuits. IBM would claim that the Phoenix programmers had copied parts
of the IBM BIOS code published by IBM in its Technical Reference
manuals.
...
Phoenix developed a "clean room" technique that isolated the engineers
who had been contaminated by reading the IBM source listings in the IBM
Technical Reference Manuals. The contaminated engineers wrote
specifications for the BIOS APIs and provided the specifications to
"clean" engineers who had not been exposed to IBM BIOS source code.
Those "clean" engineers developed code from scratch to mimic the BIOS
APIs. This technique provided Phoenix with a defensibly non-infringing
IBM PC-compatible ROM BIOS.
<http://www.macintouch.com/pchistory.html#dec10>
Prior to Phoenix, IBM threw the weight of their enormous legal muscle
against anyone who cloned the BIOS in their PC. Phoenix did a clean
room design. None of the programmers working on the Phoenix BIOS had
ever seen the IBM PC BIOS. In fact, Phoenix went out of their way to
hire programmers who had never even worked on the 8088/8086 processor
chips used in early IBM PCs
...
While IBM did have a technical document which detailed the timings on
the bus this was only available to a few selected partners--those
hardware vendors who wished to produce hardware which IBM's PC division
felt would be useful in their targeted markets *and* which did not
compete with hardware which IBM intended to manufacture on its own. All
others, including the clone manufacturers themselves, had to hook up
logic analyzers to the bus and start reverse engineering.
<http://steve-parker.org/articles/microsoft/>
IBM wanted other companies to be able to make plug-in expansion cards
for the IBM PC, but wanted to be the sole manufacturers of the PC
itself. So they published the source code to the BIOS, which meant that
everyone could see exactly how the BIOS worked (which would be
necessary for 3rd party manufacturers to build expansion cards), but
licensed it under a license which forbade duplication or imitation.
This was a pretty smart move - the BIOS is essential for a PC to be a
PC, and it took about two years before a clone was on the market.
nospam
<dha...@blind-apertures.ca> wrote:
> Ray, I think IBM came out with the PC XT prior to the Apple II.
the pc xt came out in early 1983, well after the apple // and just
under a year before the original macintosh.
Dudley Hanks
"nospam" <nos...@nospam.invalid> wrote in message
OOps, I never had much to do with Apple until the mid-1980s, so I wasn't
aware of it's early history. Doing a quick Google, I was surprised to find
out the AII was around as early as '77. Impressive.
Sorry for the gaf...
Take Care,
Dudley
Dudley Hanks
"nospam" <nos...@nospam.invalid> wrote in message
Thanks for the links. This is interesting stuff.
It's funny how popular history depicts IBM as being much freer with it's
knowledge base and, thereby, facilitating the personal computer explosion.
Guess I'll have to take a few notes for future reference.
Once again, thanks,
Dudley
Bob Larter
That's not the whole truth. The people getting sued were those trying to
clone the PC itself, not people who were merely designing expansion
cards for it.
Bob Larter
Definitely not! The original PC (not XT) came out in 1981, while the
Apple II came out in 1977.
<http://en.wikipedia.org/wiki/IBM_Personal_Computer>
<http://en.wikipedia.org/wiki/Apple_Inc.>
Chris Malcolm
How do you guarantee accurate live view focus when aperture-related
focus drift is present?
> there is no way to guarantee focus with
> sony's live view, whereas on sony/canon there is.
Unless there is aperture-related focus drift, which some
implementations of phase detection AF cope with, but AFAIK no live
view focus does.
Apart from that issue, there is simply the issue of optical
resolution. I have very sharp close vision, and can easily see the
individual pixels in the live LCD of my Sony A350. Nevertheless
despite using the max magnification I'm unable to focus my most
critical lenses as accurately using live view, even taking extreme
care and several seconds, as AF can achieve in a fraction of a
second. The same is true of using the optical viewfinder. AF is simply
quite a bit more reliable and accurate than any kind of manual
focussing I ca manage -- except of course in those cases such as
intervening foliage where it would focus on the wrong thing. And I'm
someone with decades of experience in manual focussing in the days
before AF was invented.
I was reluctant to believe AF had me so easily beaten in focus
accuracy and consistency, but lots of careful testing has demonstrated
that to be true. Of course your mileage and camera may be different
:-)
--
Chris Malcolm
Bob Larter
Ditto, although it's only about a decade & a half of MF experience in my
case.
> I was reluctant to believe AF had me so easily beaten in focus
> accuracy and consistency, but lots of careful testing has demonstrated
> that to be true.
Ditto again, especially as a split prism focussing screen isn't much use
when I'm shooting in low light.
Matt Ion
> A 2X converter would make the 1000mm lens 2000mm.
> It won't cut the aperture in half but just extend the focal
> length.
>
> E
>
>> Take Care,
>> Dudley- Hide quoted text -
>
> No, it cuts the aperture in half as well. Most teleconverters will still
> show that your aperture is set to, let's say, f/3.5, but the effective
> aperture is actually f/7.0.
>
> For discussion, see:
> http://forums.dpreview.com/forums/read.asp?forum=1035&message=31559866
>
> Whenever the discussion turns to tele's and aperture, it gets a bit murky,
> but the thing to remember is that, while the teleconverter doesn't change
> the physical size of the aperture, it does reduce the amount of light that
> reaches your film / sensor, so the end result is identical to altering your
> aperture size.
Since the aperture "f-stop" number is a direct function of the focal
length (thus the "f" in f-stop!), doubling the focal length does, in
fact, change the f-stop value, even though the opening itself is the
same size.
Matt Ion
> In article
> <49ef8c0a$0$12595$5a62...@per-qv1-newsreader-01.iinet.net.au>,
> Doug Jewell <a...@and.maybe.ill.tell.you> wrote:
>
>> Yes. Slightly more useful than a gimmick, but only slightly.
>> Out of about 10,000 shots I've made with my 450D, I'd say
>> I've used liveview for no more than 20. A couple of "over
>> the crowd" shots at a local parade, and a few macro shots.
>
> To each his own. I use my 450D in liveview mode a lot. I am very happy
> with it.
I don't use it a LOT on my 40D, but in some instances I do find it very
handy. It's nice to have available, and thus worth it, IMHO.
Unfortunately some people must always be of the mind, "If it's not 100%
useful TO ME, it's completely useless for everyone."
Dudley Hanks
"Matt Ion" <soun...@gmail.com> wrote in message
news:gt2ioc$hop$1...@news.eternal-september.org...
That's what I should have said, but, I got too caught up in dealing with the
actual physical opening not changing...
Take Care,
Dudley