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Canon 20Da w/live LCD Preview

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Anonymous
February 14, 2005 9:36:25 AM

Archived from groups: rec.photo.digital (More info?)

In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B.
<mbohntrash54@comcast.net> wrote:

You can be the first one to hold it at arm's length like all the other
dorks out there.
February 14, 2005 9:36:26 AM

Archived from groups: rec.photo.digital (More info?)

"Eric Gill" <ericvgill@yahoo.com> wrote in message
news:Xns95FD5B0C636Bericvgillyahoocom@63.223.5.254...
> Randall Ainsworth <rag@nospam.techline.com> wrote in
> news:140220050550576683%rag@nospam.techline.com:
>
> > In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B.
> > <mbohntrash54@comcast.net> wrote:
> >
> > You can be the first one to hold it at arm's length like all the other
> > dorks out there.
>
> You could be the first one to shoot over the heads of a crowd and actually
> have a correctly composed shot.
>
Hmmm, unless it's bright daylight. I haven't seen an LCD screen yet that I
can see in sunlight. I have shot over people's heads with my 35mm Pentax LX,
I just pop the prism off and hold it upside down.
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Anonymous
February 14, 2005 5:34:28 PM

Archived from groups: rec.photo.digital (More info?)

Randall Ainsworth wrote:
> In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B.
> <mbohntrash54@comcast.net> wrote:
>
> You can be the first one to hold it at arm's length like all the other
> dorks out there.

Maybe the 20Db variant will have an EVF as well?

These Canon folk are certainly learning what the market needs.... <G>

David
Anonymous
February 14, 2005 7:24:41 PM

Archived from groups: rec.photo.digital (More info?)

In article <mtCdnZkkLdWxX43fRVn-1A@rogers.com>, Darrell <dev/null> wrote:
>
>"Eric Gill" <ericvgill@yahoo.com> wrote in message
>news:Xns95FD5B0C636Bericvgillyahoocom@63.223.5.254...
>> Randall Ainsworth <rag@nospam.techline.com> wrote in
>> news:140220050550576683%rag@nospam.techline.com:
>>
>> > In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B.
>> > <mbohntrash54@comcast.net> wrote:
>> >
>> > You can be the first one to hold it at arm's length like all the other
>> > dorks out there.
>>
>> You could be the first one to shoot over the heads of a crowd and actually
>> have a correctly composed shot.
>>
>Hmmm, unless it's bright daylight. I haven't seen an LCD screen yet that I
>can see in sunlight. I have shot over people's heads with my 35mm Pentax LX,
>I just pop the prism off and hold it upside down.

This is where TLRs rule - same concept, but you have a huge 6*6cm focus
screen, and the brighter the light, the better!

Perhaps what we need is a DSLR with a removable prism.
February 14, 2005 7:24:42 PM

Archived from groups: rec.photo.digital (More info?)

"Chris Brown" <cpbrown@ntlworld.no_uce_please.com> wrote in message
news:ant6e2-mv5.ln1@narcissus.dyndns.org...
> In article <mtCdnZkkLdWxX43fRVn-1A@rogers.com>, Darrell <dev/null> wrote:
> >
> >"Eric Gill" <ericvgill@yahoo.com> wrote in message
> >news:Xns95FD5B0C636Bericvgillyahoocom@63.223.5.254...
> >> Randall Ainsworth <rag@nospam.techline.com> wrote in
> >> news:140220050550576683%rag@nospam.techline.com:
> >>
> >> > In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B.
> >> > <mbohntrash54@comcast.net> wrote:
> >> >
> >> > You can be the first one to hold it at arm's length like all the
other
> >> > dorks out there.
> >>
> >> You could be the first one to shoot over the heads of a crowd and
actually
> >> have a correctly composed shot.
> >>
> >Hmmm, unless it's bright daylight. I haven't seen an LCD screen yet that
I
> >can see in sunlight. I have shot over people's heads with my 35mm Pentax
LX,
> >I just pop the prism off and hold it upside down.
>
> This is where TLRs rule - same concept, but you have a huge 6*6cm focus
> screen, and the brighter the light, the better!
>
I have used my Mamiya C220/C330 this way. I never tried with a RB/RZ67
because if I dropped it on my head, I would be dead ;) 
Anonymous
February 14, 2005 9:39:05 PM

Archived from groups: rec.photo.digital (More info?)

"Eric Gill" <ericvgill@yahoo.com> wrote in message
news:Xns95FD5B0C636Bericvgillyahoocom@63.223.5.254...
> Randall Ainsworth <rag@nospam.techline.com> wrote in
> news:140220050550576683%rag@nospam.techline.com:
>
>> In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B.
>> <mbohntrash54@comcast.net> wrote:
>>
>> You can be the first one to hold it at arm's length like all the other
>> dorks out there.
>

LOL, Randall is the biggest dork in the NG. I only posted this as an FYI,
not because it's something I want.

Mark
Anonymous
February 14, 2005 10:08:23 PM

Archived from groups: rec.photo.digital (More info?)

In article <ant6e2-mv5.ln1@narcissus.dyndns.org>,
cpbrown@ntlworld.no_uce_please.com says...
> This is where TLRs rule - same concept, but you have a huge 6*6cm focus
> screen, and the brighter the light, the better!

Of course, outside of a studio or a sunny day you're screwed.
--
http://www.pbase.com/bcbaird/
Anonymous
February 15, 2005 12:01:04 AM

Archived from groups: rec.photo.digital (More info?)

In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B. says...
> Hot mirror is also removed. Japan only at the moment:
>
> http://www.dpreview.com/news/0502/05021405canoneos20da....

Last famous words: "it's not going to happen"

http://tinyurl.com/55agp
--

Alfred Molon
------------------------------
Olympus 4040, 5050, 5060, 7070, 8080, E300 forum at
http://groups.yahoo.com/group/MyOlympus/
Olympus 8080 resource - http://myolympus.org/8080/
Anonymous
February 15, 2005 12:01:05 AM

Archived from groups: rec.photo.digital (More info?)

I read the material but am still not clear of the differences and
advantages/disadvantages between the 20d and 20da.

Alfred Molon wrote:

>In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B. says...
>
>
>>Hot mirror is also removed. Japan only at the moment:
>>
>>http://www.dpreview.com/news/0502/05021405canoneos20da....
>>
>>
>
>Last famous words: "it's not going to happen"
>
>http://tinyurl.com/55agp
>
>
Anonymous
February 15, 2005 12:01:05 AM

Archived from groups: rec.photo.digital (More info?)

"Alfred Molon" <alfred_molonREMOVE@yahoo.com> wrote in message
news:MPG.1c7b21d3ea85c7b998a9c1@news.supernews.com...
> In article <RZSdnQfsWe6lEI3fRVn-vA@comcast.com>, Mark B. says...
>> Hot mirror is also removed. Japan only at the moment:
>>
>> http://www.dpreview.com/news/0502/05021405canoneos20da....
>
> Last famous words: "it's not going to happen"
>
> http://tinyurl.com/55agp
> --
>
> Alfred Molon


Those famous last words may still be correct. Reading through the threads
on dpreview.com, it doesn't seem to be a true live preview; probably
grayscale and only a magnified view to help with focus. It is, afterall, a
specialty camera geared at astrophotography. Keep waiting ;-)

Mark
Anonymous
February 15, 2005 12:08:45 AM

Archived from groups: rec.photo.digital (More info?)

"Mark B." <mbohntrash54@comcast.net> wrote in message
news:RZSdnQfsWe6lEI3fRVn-vA@comcast.com...
> Hot mirror is also removed. Japan only at the moment:
>
> http://www.dpreview.com/news/0502/05021405canoneos20da....

http://www.canon-sales.co.jp/camera/eosd/20da/index.htm...

Sheesh. Can't anyone read???

The IR cut filter hasn't been removed, just shifted so that it passes the
656 nm wavelengths a lot more (2.5x more) than the 20D.

The mirror isn't half-silvered, live preview works with the mirror locked
up.

It's a special order only product, and you'll have to wait 3 months.

You can order it starting Feb 15, Japan time, from their web page.

David J. Littleboy
Tokyo, Japan
February 15, 2005 12:08:46 AM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> wrote in message
news:cuq4ek$ahg$1@nnrp.gol.com...
>
> "Mark B." <mbohntrash54@comcast.net> wrote in message
> news:RZSdnQfsWe6lEI3fRVn-vA@comcast.com...
> > Hot mirror is also removed. Japan only at the moment:
> >
> > http://www.dpreview.com/news/0502/05021405canoneos20da....
>
> http://www.canon-sales.co.jp/camera/eosd/20da/index.htm...
>
> Sheesh. Can't anyone read???
>
> The IR cut filter hasn't been removed, just shifted so that it passes the
> 656 nm wavelengths a lot more (2.5x more) than the 20D.
>
> The mirror isn't half-silvered, live preview works with the mirror locked
> up.
>
> It's a special order only product, and you'll have to wait 3 months.
>
> You can order it starting Feb 15, Japan time, from their web page.
>
> David J. Littleboy
> Tokyo, Japan
>
>
>

They didn't bring back the pellicle mirror??? <VBG>
Anonymous
February 15, 2005 12:08:46 AM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> wrote in message
news:cuq4ek$ahg$1@nnrp.gol.com...
>
> "Mark B." <mbohntrash54@comcast.net> wrote in message
> news:RZSdnQfsWe6lEI3fRVn-vA@comcast.com...
>> Hot mirror is also removed. Japan only at the moment:
>>
>> http://www.dpreview.com/news/0502/05021405canoneos20da....
>
> http://www.canon-sales.co.jp/camera/eosd/20da/index.htm...
>
> Sheesh. Can't anyone read???
>
> The IR cut filter hasn't been removed, just shifted so that it passes the
> 656 nm wavelengths a lot more (2.5x more) than the 20D.
>

I can read just fine, this is a direct quote from the dpreview.com
announcement:

"This specialized version of the EOS 20D appears to be identical except for
the removal of the 'hot mirror', the filter in most digital cameras which
removes the InfraRed part of the spectrum."

What part of "...removal of the hot mirror..." did I get wrong??

Mark
February 15, 2005 12:08:47 AM

Archived from groups: rec.photo.digital (More info?)

"George" <nowhere@newsonly.com> wrote in message
news:9aaQd.2682$Zo4.1091@fe02.lga...
>
> "David J. Littleboy" <davidjl@gol.com> wrote in message
> news:cuq4ek$ahg$1@nnrp.gol.com...
> >
> > "Mark B." <mbohntrash54@comcast.net> wrote in message
> > news:RZSdnQfsWe6lEI3fRVn-vA@comcast.com...
> > > Hot mirror is also removed. Japan only at the moment:
> > >
> > > http://www.dpreview.com/news/0502/05021405canoneos20da....
> >
> > http://www.canon-sales.co.jp/camera/eosd/20da/index.htm...
> >
> > Sheesh. Can't anyone read???
> >
> > The IR cut filter hasn't been removed, just shifted so that it passes
the
> > 656 nm wavelengths a lot more (2.5x more) than the 20D.
> >
> > The mirror isn't half-silvered, live preview works with the mirror
locked
> > up.
> >
> > It's a special order only product, and you'll have to wait 3 months.
> >
> > You can order it starting Feb 15, Japan time, from their web page.
> >
> > David J. Littleboy
> > Tokyo, Japan
> >
> >
> >
>
> They didn't bring back the pellicle mirror??? <VBG>
>
Canon's website says;

The mirror is a 60/40%;
"Mirror Quick return type extensive half mirror
(Transmission: Reflection =40: 60, mirror being cut off: It is not to the
600mm F4)"
Anonymous
February 15, 2005 12:35:47 AM

Archived from groups: rec.photo.digital (More info?)

"Brian C. Baird" <nospam@please.no> wrote:
>
> I'm interested to see how the live preview actually works in the real
> world - to my knowledge this is the first time any one has tried this
> with a CMOS chip.

My bet is that it may only work for astronomy, i.e. in really low light. The
picture on the web page shows the camera presumably tied to a telescope in a
dark room, so maybe they're getting a sort of photomultiplier tube effect,
i.e. using ISO 3200 and a bright LCD backlight to make focusing easier than
through the viewfinder.

David J. Littleboy
Just guessing in
Tokyo, Japan
Anonymous
February 15, 2005 12:35:48 AM

Archived from groups: rec.photo.digital (More info?)

In article <cuq5vd$arc$1@nnrp.gol.com>, davidjl@gol.com says...
> > I'm interested to see how the live preview actually works in the real
> > world - to my knowledge this is the first time any one has tried this
> > with a CMOS chip.
>
> My bet is that it may only work for astronomy, i.e. in really low light. The
> picture on the web page shows the camera presumably tied to a telescope in a
> dark room, so maybe they're getting a sort of photomultiplier tube effect,
> i.e. using ISO 3200 and a bright LCD backlight to make focusing easier than
> through the viewfinder.

That could be possible. That would make it less of a "live preview" and
more of a low-light focusing aid. It would be nice if it had some
functionality outside of that, but hey - when I want to frame things
using a LCD monitor, I'll grab a point and shoot.

What I want to know is: Where's the integral liquid nitrogen cooling
system?
--
http://www.pbase.com/bcbaird/
Anonymous
February 15, 2005 12:35:49 AM

Archived from groups: rec.photo.digital (More info?)

Brian C. Baird <nospam@please.no> wrote:

>In article <cuq5vd$arc$1@nnrp.gol.com>, davidjl@gol.com says...
>> > I'm interested to see how the live preview actually works in the real
>> > world - to my knowledge this is the first time any one has tried this
>> > with a CMOS chip.
>>
>> My bet is that it may only work for astronomy, i.e. in really low light. The
>> picture on the web page shows the camera presumably tied to a telescope in a
>> dark room, so maybe they're getting a sort of photomultiplier tube effect,
>> i.e. using ISO 3200 and a bright LCD backlight to make focusing easier than
>> through the viewfinder.
>
>That could be possible. That would make it less of a "live preview" and
>more of a low-light focusing aid. It would be nice if it had some
>functionality outside of that, but hey - when I want to frame things
>using a LCD monitor, I'll grab a point and shoot.

It's also an IR focus aid. With IR the focus kan be very different from
visual light.

Peter
Anonymous
February 15, 2005 1:08:25 AM

Archived from groups: rec.photo.digital (More info?)

In article <2x7Qd.32$DC6.0@newssvr14.news.prodigy.com>, measekite
says...
> I read the material but am still not clear of the differences and
> advantages/disadvantages between the 20d and 20da.

Live preview allows you to frame the image in unconventional situations,
such as holding the camera over your head, at waist level, taking
panoramic shots without a pano head etc.

It also offers the very significant advantage of seeing a live histogram
before pressing the shutter button, although I don't know if Canon
implemented this feature on the 20Da.

The only problem is, from what I understood, that live preview is only
available in low light (why?) and only with specific lenses (again
why?). But it's a very welcome development in the DLSR world.

Now the next steps would be to make live preview available also in
bright daylight and to have a swiveling LCD screen. Hopefully other
manufacturers will follow suit and also add live preview to their DLSR
models.
--

Alfred Molon
------------------------------
Olympus 4040, 5050, 5060, 7070, 8080, E300 forum at
http://groups.yahoo.com/group/MyOlympus/
Olympus 8080 resource - http://myolympus.org/8080/
February 15, 2005 1:08:26 AM

Archived from groups: rec.photo.digital (More info?)

"Alfred Molon" <alfred_molonREMOVE@yahoo.com> wrote in message
news:MPG.1c7b317250d865d898a9c2@news.supernews.com...
> In article <2x7Qd.32$DC6.0@newssvr14.news.prodigy.com>, measekite
> says...
> > I read the material but am still not clear of the differences and
> > advantages/disadvantages between the 20d and 20da.
>
> Live preview allows you to frame the image in unconventional situations,
> such as holding the camera over your head, at waist level, taking
> panoramic shots without a pano head etc.
>
> It also offers the very significant advantage of seeing a live histogram
> before pressing the shutter button, although I don't know if Canon
> implemented this feature on the 20Da.
>
> The only problem is, from what I understood, that live preview is only
> available in low light (why?) and only with specific lenses (again
> why?). But it's a very welcome development in the DLSR world.
>
> Now the next steps would be to make live preview available also in
> bright daylight and to have a swiveling LCD screen. Hopefully other
> manufacturers will follow suit and also add live preview to their DLSR
> models.
>This would assume the Japan only special order wasn't twice the price. The
Canon website only mentions a different IR filter to let H-Alpha
wavelengths, quotes from Canon PC Translated website;

"The EOS 20Da adopts the infrared cutting low-pass filter which has the
structure which laminates infrared cut-off filter and 3 quartz plates where
optical axial direction differs. The among these, as for the infrared
cut-off filter in order to achieve the optical quality of celestial
specification, with naked eye the H alpha bright line which almost cannot
see (*) transmissivity it has improved in approximately 2.5 times that the "
EOS 20D ". Because of this, it can photograph also the red nebula and the
like where in the former digital single-lens reflex camera it could not
catch, without using the special filter.

Wave length of the *H alpha bright line is 656 nano- meters. (1 nano- 10
100000000?? 1)"

As for "live-view" the website seems to say the live view occurs during
exposure, handy on thos long exposure deep space imaging, but not very
useful at 1/500 second.

"Digital, regardless of the silver salt, when the single-lens reflex camera
has the quick return mirror inside, pushes the shutter button, this mirror
leaps and rises, has become the mechanism which the shutter opens. With the
EOS 20Da you kept in a state where the mirror is lifted, live image of the
image pickup element the enlargement color it can be indicated to the liquid
crystal monitor loaded " live view mode ". Because of this, with just the
finder it is possible to do the focus adjusting with the manual whose fine
control is difficult more accurately.

Indication of the liquid crystal monitor are 2 types of enlargement ratio 5
time and 10 times, adjusts to photographing circumstance and it is possible
to choose"
Anonymous
February 15, 2005 3:08:53 AM

Archived from groups: rec.photo.digital (More info?)

"Peter Rongsted" <nulldev@rongsted.dk> wrote:
>
> It's also an IR focus aid. With IR the focus can be very different from
> visual light.

Grr. I hate people more on the ball than I. Looks like a good call. The
whole point of this thing is to image the "H<alpha>" line, and I bet neither
the regular focusing screen nor the AF sensors would work. (Maybe Roger
Clark can clue us in as to what's going on here...)

David J. Littleboy
Tokyo, Japan
Anonymous
February 15, 2005 3:08:54 AM

Archived from groups: rec.photo.digital (More info?)

David J. Littleboy wrote:

> "Peter Rongsted" <nulldev@rongsted.dk> wrote:
>
>>It's also an IR focus aid. With IR the focus can be very different from
>>visual light.
>
>
> Grr. I hate people more on the ball than I. Looks like a good call. The
> whole point of this thing is to image the "H<alpha>" line, and I bet neither
> the regular focusing screen nor the AF sensors would work. (Maybe Roger
> Clark can clue us in as to what's going on here...)
>
> David J. Littleboy
> Tokyo, Japan

The hydrogen-alpha line, at 656nm (deep red) is a
large source of light for astronomical emission nebulae.
The canon SLRs have have pretty low 656 nm
transmission through their filters over the sensor,
letting only a few percent through. There is one company
who will remove the IR block filer from the canon cameras
to improve that response, and apparently many amateur
astronomers are buying them. Canon has apparently been
watching the amateur astronomers and been improving
them specifically for such use. A recent 1D Mark II firmware
upgrade was specifically to help low light astrophotographers
get better images. Of course this helps anyone doing night
or other low light photography too.
Back to the hydrogen-alpha: this changes reduces the color
accuracy of the camera, so it might not be what you want
in general.

If one removes the ir block filter, you get out to about
1000 nm and many dyes become transparent beyond about 800 nm.
Didn't a sony camera not have an IR block and that enabled
one to photograph through clothes (making them somewhat
transparent)? So removing the ir block might produce
the same thing here. Maybe that is why Canon just moved the
ir block out a little bit.

The real time focus preview is great, and should be standard
on all canon DSLR cameras (how about a firmware upgrade,
canon?).

This shows that canon is paying attention to its buying
public and responding, even to a small group.
Either that or some top canon executives are
amateur astronomers ;-)

An emission nebula with a canon DSLR looks like this:
http://clarkvision.com/galleries/gallery.astrophoto-1/w...

with more H-alpha, the pinkish parts would be pinker and brighter.

Roger
Anonymous
February 15, 2005 6:18:06 AM

Archived from groups: rec.photo.digital (More info?)

When it comes to astrophotography, just set the focus to infinity and we
should be fine???
for normal shooting, that tiny LCD screen can't really beat the viewfinder
or autofocus i guess...


"David J. Littleboy" <davidjl@gol.com> wrote in message
news:cuq5vd$arc$1@nnrp.gol.com...
>
> "Brian C. Baird" <nospam@please.no> wrote:
> >
> > I'm interested to see how the live preview actually works in the real
> > world - to my knowledge this is the first time any one has tried this
> > with a CMOS chip.
>
> My bet is that it may only work for astronomy, i.e. in really low light.
The
> picture on the web page shows the camera presumably tied to a telescope in
a
> dark room, so maybe they're getting a sort of photomultiplier tube effect,
> i.e. using ISO 3200 and a bright LCD backlight to make focusing easier
than
> through the viewfinder.
>
> David J. Littleboy
> Just guessing in
> Tokyo, Japan
>
>
>
Anonymous
February 15, 2005 6:18:07 AM

Archived from groups: rec.photo.digital (More info?)

"filmman" <filmman@yahoo.com> wrote in message
news:4210f813$1_1@rain.i-cable.com...
> When it comes to astrophotography, just set the focus to infinity
> and we
> should be fine???

There is no meaningful infinity mark/position. The actual infinity
focus distance shifts with, amongst others, temperature. Long lenses
are more subject to thermal expansion. These camera bodies are also
used without a regular lens on telescopes.

> for normal shooting, that tiny LCD screen can't really beat the
> viewfinder
> or autofocus i guess...

The luminance level of stars in deep sky images is generally too low
for autofocus, and telescopes usually don't have AF either. There are
auxilliary methods to aid focussing, but we'll have to wait and see
how useful a small LCD is (it might also get slow to update at low
temperatures).

Bart
Anonymous
February 15, 2005 7:44:32 AM

Archived from groups: rec.photo.digital (More info?)

Peter Rongsted <nulldev@rongsted.dk> wrote:
>Brian C. Baird <nospam@please.no> wrote:
>
>>In article <cuq5vd$arc$1@nnrp.gol.com>, davidjl@gol.com says...
>>> > I'm interested to see how the live preview actually works in the real
>>> > world - to my knowledge this is the first time any one has tried this
>>> > with a CMOS chip.
>>>
>>> My bet is that it may only work for astronomy, i.e. in really low light. The
>>> picture on the web page shows the camera presumably tied to a telescope in a
>>> dark room, so maybe they're getting a sort of photomultiplier tube effect,
>>> i.e. using ISO 3200 and a bright LCD backlight to make focusing easier than
>>> through the viewfinder.
>>
>>That could be possible. That would make it less of a "live preview" and
>>more of a low-light focusing aid. It would be nice if it had some
>>functionality outside of that, but hey - when I want to frame things
>>using a LCD monitor, I'll grab a point and shoot.
>
>It's also an IR focus aid. With IR the focus kan be very different from
>visual light.

"Can be" yes, but with reflector telescopes IR would focus at the same
point.

--
Ray Fischer
rfischer@sonic.net
Anonymous
February 15, 2005 10:31:02 AM

Archived from groups: rec.photo.digital (More info?)

In message <MPG.1c7a63fee11c9c3698a597@news.verizon.net>,
Brian C. Baird <nospam@please.no> wrote:

>I'm interested to see how the live preview actually works in the real
>world - to my knowledge this is the first time any one has tried this
>with a CMOS chip.

Is it greyscale-only? If it is, it can read the sensor faster because
it can bin short stips of pixels, reading less lines, and reading the
ones that it does read, faster:

.....____....____
.....____....____
.....____....____
.....____....____
.................
.................
.................
.................
.....____....____
.....____....____
.....____....____
.....____....____
.................
.................
.................
.................

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
February 15, 2005 11:36:22 AM

Archived from groups: rec.photo.digital (More info?)

"Darrell" <dev/null> wrote:
> "George" <nowhere@newsonly.com> wrote:
> >
> > They didn't bring back the pellicle mirror??? <VBG>
> >
> Canon's website says;
>
> The mirror is a 60/40%;
> "Mirror Quick return type extensive half mirror
> (Transmission: Reflection =40: 60, mirror being cut off: It is not to the
> 600mm F4)"

Could we have a link? I seem to have missed that.

David J. Littleboy
Tokyo, Japan
February 15, 2005 11:36:23 AM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> wrote in message
news:curftk$mm4$1@nnrp.gol.com...
>
> "Darrell" <dev/null> wrote:
> > "George" <nowhere@newsonly.com> wrote:
> > >
> > > They didn't bring back the pellicle mirror??? <VBG>
> > >
> > Canon's website says;
> >
> > The mirror is a 60/40%;
> > "Mirror Quick return type extensive half mirror
> > (Transmission: Reflection =40: 60, mirror being cut off: It is not to
the
> > 600mm F4)"
>
> Could we have a link? I seem to have missed that.
>
> David J. Littleboy
> Tokyo, Japan
>
http://www.canon-sales.co.jp/camera/eosd/20da/index.htm... or in Googlese;

http://translate.google.com/translate?u=http%3A%2F%2Fww...

Babelfish does slightly better...
Anonymous
February 15, 2005 12:39:29 PM

Archived from groups: rec.photo.digital (More info?)

"Mark B." <mbohntrash54@comcast.net> wrote:
> "David J. Littleboy" <davidjl@gol.com> wrote in message
> >
> > "Mark B." <mbohntrash54@comcast.net> wrote in message
> > news:RZSdnQfsWe6lEI3fRVn-vA@comcast.com...
> >> Hot mirror is also removed. Japan only at the moment:
> >>
> >> http://www.dpreview.com/news/0502/05021405canoneos20da....
> >
> > http://www.canon-sales.co.jp/camera/eosd/20da/index.htm...
> >
> > Sheesh. Can't anyone read???
> >
> > The IR cut filter hasn't been removed, just shifted so that it passes
the
> > 656 nm wavelengths a lot more (2.5x more) than the 20D.
> >
>
> I can read just fine, this is a direct quote from the dpreview.com
> announcement:
>
> "This specialized version of the EOS 20D appears to be identical except
for
> the removal of the 'hot mirror', the filter in most digital cameras which
> removes the InfraRed part of the spectrum."
>
> What part of "...removal of the hot mirror..." did I get wrong??

You didn't get anything wrong, dpreview did. In particular, what I found on
the Canon Japan site differs from what appears on the dpreview site, as
above. (The term "hot mirror" seems problematic: I think it's an informal
term for what the Japanese calls an "IR cut filter". My reading of the
Japanese is that said filter has not been removed, merely its cutoff point
shifted so that it now passes through 656 nm.)

David J. Littleboy
Tokyo, Japan
February 15, 2005 12:39:30 PM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> wrote in message
news:curgca$mqm$1@nnrp.gol.com...
>
> "Mark B." <mbohntrash54@comcast.net> wrote:
> > "David J. Littleboy" <davidjl@gol.com> wrote in message
> > >
> > > "Mark B." <mbohntrash54@comcast.net> wrote in message
> > > news:RZSdnQfsWe6lEI3fRVn-vA@comcast.com...
> > >> Hot mirror is also removed. Japan only at the moment:
> > >>
> > >> http://www.dpreview.com/news/0502/05021405canoneos20da....
> > >
> > > http://www.canon-sales.co.jp/camera/eosd/20da/index.htm...
> > >
> > > Sheesh. Can't anyone read???
> > >
> > > The IR cut filter hasn't been removed, just shifted so that it passes
> the
> > > 656 nm wavelengths a lot more (2.5x more) than the 20D.
> > >
> >
> > I can read just fine, this is a direct quote from the dpreview.com
> > announcement:
> >
> > "This specialized version of the EOS 20D appears to be identical except
> for
> > the removal of the 'hot mirror', the filter in most digital cameras
which
> > removes the InfraRed part of the spectrum."
> >
> > What part of "...removal of the hot mirror..." did I get wrong??
>
> You didn't get anything wrong, dpreview did. In particular, what I found
on
> the Canon Japan site differs from what appears on the dpreview site, as
> above. (The term "hot mirror" seems problematic: I think it's an informal
> term for what the Japanese calls an "IR cut filter". My reading of the
> Japanese is that said filter has not been removed, merely its cutoff point
> shifted so that it now passes through 656 nm.)
>
> David J. Littleboy
> Tokyo, Japan
>
I guessed that with the term H-Alpha, which is 656.3nm

http://science.nasa.gov/spaceweather/glossary/halpha.ht...
Anonymous
February 15, 2005 12:39:30 PM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> writes:

>(The term "hot mirror" seems problematic: I think it's an informal
>term for what the Japanese calls an "IR cut filter". My reading of the
>Japanese is that said filter has not been removed, merely its cutoff point
>shifted so that it now passes through 656 nm.)

A hot mirror is simply a piece of glass coated to reflect IR, while
passing other wavelengths (e.g. visible light). Conversely, a cold
mirror reflects visible while passing IR through.

From the point of view of a sensor on the far side of a hot mirror, it
acts as an IR cut filter. But you can also have IR cut filters that
absorb IR rather than reflecting it, which are not hot mirrors.

Dave
Anonymous
February 15, 2005 1:34:53 PM

Archived from groups: rec.photo.digital (More info?)

"Darrell" <dev/null> wrote:
> "David J. Littleboy" <davidjl@gol.com> wrote:
> > "Darrell" <dev/null> wrote:
> > > >
> > > Canon's website says;
> > >
> > > The mirror is a 60/40%;
> > > "Mirror Quick return type extensive half mirror
> > > (Transmission: Reflection =40: 60, mirror being cut off: It is not to
> > > the 600mm F4)"
> >
> > Could we have a link? I seem to have missed that.
> >
> http://www.canon-sales.co.jp/camera/eosd/20da/index.htm... or in Googlese;
>
>
http://translate.google.com/translate?u=http%3A%2F%2Fww...
>
> Babelfish does slightly better...

Ah. I found it. The mirror specs for the 20D and 20Da are identical.

http://www.canon-sales.co.jp/camera/eosd/20d/system.htm...
http://www.canon-sales.co.jp/camera/eosd/20da/system.ht...

I'm not sure exactly what it says, but both say exactly the same thing
"quick return mirror, _whole surface half mirror_, transmission:reflection =
40:60, no mirror cutoff with lenses through the 600/4.0" (That last bit
means that the mirror is large enough that you can see the whole image in
the viewfinder through the 600/4.0, but that the mirror may not be large
enough to get the whole image from longer lenses onto the viewfinder.)

So this is _not_ a change (the 10D also has identical text). The theory that
this is for metering and/or AF sensors sounds plausible, although I don't
understand the _whole surface_ bit.

David J. Littleboy
Tokyo, Japan
Anonymous
February 15, 2005 1:36:58 PM

Archived from groups: rec.photo.digital (More info?)

"Darrell" <dev/null> wrote:
> "David J. Littleboy" <davidjl@gol.com> wrote:
> >
> I guessed that with the term H-Alpha, which is 656.3nm
>
> http://science.nasa.gov/spaceweather/glossary/halpha.ht...

Thanks for doing my homework<g>. Hmm. So it isn't even into the IR.

David J. Littleboy
Tokyo, Japan
Anonymous
February 15, 2005 3:50:58 PM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> wrote in message
news:curjom$nnm$1@nnrp.gol.com...
SNIP
> The theory that this is for metering and/or AF sensors sounds
> plausible, although I don't understand the _whole surface_ bit.

If I recall correctly from long ago, there have been cameras with only
parts of the mirror being a bit more tranparent to allow for higher AF
or Exposure metering sensitivity.

Bart
Anonymous
February 15, 2005 3:59:01 PM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> wrote in message
news:curjom$nnm$2@nnrp.gol.com...
SNIP
> Hmm. So it isn't even into the IR.

Which may be a benefit if the lens/telescope doesn't have an H-Alpha
pass filter. The dyes for the Bayer CFA are transparent for IR, so
blue and green would receive to much signal for accurate color
rendition. It's a trade-off between accuracy and sensitivity.

Bart
Anonymous
February 15, 2005 4:10:28 PM

Archived from groups: rec.photo.digital (More info?)

"Roger N. Clark (change username to rnclark)" <username@qwest.net>
wrote in message news:4211671D.7030108@qwest.net...
SNIP
> The real time focus preview is great, and should be standard
> on all canon DSLR cameras (how about a firmware upgrade,
> canon?).

Although astronomic photography improves imagery in postprocessing to
circumvent it, general photography would probably suffer from some amp
glow (and LCD heat induced noise). Maybe it is tolerable at short
exposure times, we'll have to wait and see.

> This shows that canon is paying attention to its buying
> public and responding, even to a small group.

It looks like a frontal attack on Nikon to me. From what I hear/read,
the Nikon D70 is also popular for astronomy, after removal of the IR
filter and a trick to avoid in camera noise reduction on Raws.

> Either that or some top canon executives are
> amateur astronomers ;-)

Most likely plays a role, it usually works that way.

Bart
Anonymous
February 15, 2005 4:51:04 PM

Archived from groups: rec.photo.digital (More info?)

"Roger N. Clark (change username to rnclark)" <username@qwest.net> wrote:
> David J. Littleboy wrote:
> >
> > Grr. I hate people more on the ball than I. Looks like a good call. The
> > whole point of this thing is to image the "H<alpha>" line, and I bet
neither
> > the regular focusing screen nor the AF sensors would work. (Maybe Roger
> > Clark can clue us in as to what's going on here...)
>
> The hydrogen-alpha line, at 656nm (deep red) is a
> large source of light for astronomical emission nebulae.

Thanks! It's nice to hear from someone who knows what they are talking
about.

> The canon SLRs have have pretty low 656 nm
> transmission through their filters over the sensor,
> letting only a few percent through.

The improvement is only 2.5 times or so, so it may still be pretty low.

> Back to the hydrogen-alpha: this changes reduces the color
> accuracy of the camera, so it might not be what you want
> in general.

Actually, I've been unhappy with digital camera red rendition, so maybe it
improves it<g>. Getting good renditions of deep reds is hard. Film may have
troubles there too.

> If one removes the ir block filter, you get out to about
> 1000 nm and many dyes become transparent beyond about 800 nm.
> Didn't a sony camera not have an IR block and that enabled
> one to photograph through clothes (making them somewhat
> transparent)?

I'm quite sure the "shooting through clothes" bit was an urban myth.

> So removing the ir block might produce
> the same thing here. Maybe that is why Canon just moved the
> ir block out a little bit.

But yes, the camera companies have had problems with that urban myth, and
there was a TV report of unsavory characters at beaches with modified
camcorders on the tube here. The TV report was interesting in that it never
showed a demo of what people were claimed to be doing<g>.

> The real time focus preview is great, and should be standard
> on all canon DSLR cameras (how about a firmware upgrade,
> canon?).

I'll remain opposed to this feature. I don't want anything that compromises
image quality, and I suspect that the requirements for readout fast enough
to be really useful would compromise image quality. For focusing on
astronomical objects, even 1 fps would be useful.

I called Canon and tried to get them to fess up as to what the fps will be,
and they wouldn't. It does have a function for switching magnifications (at
least 10X if not more), though.

David J. Littleboy
Tokyo, Japan
Anonymous
February 15, 2005 4:51:05 PM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> writes:

>> If one removes the ir block filter, you get out to about
>> 1000 nm and many dyes become transparent beyond about 800 nm.
>> Didn't a sony camera not have an IR block and that enabled
>> one to photograph through clothes (making them somewhat
>> transparent)?

>I'm quite sure the "shooting through clothes" bit was an urban myth.

The Sony cameras in question had a user-selectable IR filter. It was
intended for shooting in complete darkness with IR illumination, but it
could also be moved out of the optical path during the daytime.

The "shooting through clothes" was probably exaggerated, but not a
complete fabrication. Since many dyes are transparent in the IR,
imagine a random outdoor scene where everyone's clothes have been
completely bleached of all dye. Thick fabrics (e.g. jeans) will still
be completely opaque without dye, and so will be opaque to IR. But thin
loose-weave fabrics like some summer clothing actually depends on the
dyes for opacity, and might show differences in darkness depending on
what's beneath the fabric. Getting the fabric wet would increase its
transparency too - something you've probably seen in visible light.

(No, I've never actually tried this myself).

Dave
Anonymous
February 15, 2005 5:04:37 PM

Archived from groups: rec.photo.digital (More info?)

"Dave Martindale" <davem@cs.ubc.ca> wrote in message
news:cus89l$1o6$1@mughi.cs.ubc.ca...
SNIP
> (No, I've never actually tried this myself).

I did, long ago. Well actually not with clothing ;-) but as a forensic
attempt on discovering falsification of writing.

http://www.xs4all.nl/~bvdwolf/temp/IR-test.jpg shows lead pencil
writing covered by ballpoint, and ballpoint writing covered by pencil.
On top is a visible spectrum film shot, at the bottom is the same but
with IR film and a tungsten bulb light source. It shows that the
ballpoint ink I used was quite transparent to IR, and lead pencil
isn't.

The same principle applies to thin fabric and dyes, but it has nothing
to do with body temperature because that is not near-IR but deep IR.
Temperatures below, say, 600 Celcius won't record on regular near-IR
sensitive sensors.

Bart
Anonymous
February 15, 2005 9:13:20 PM

Archived from groups: rec.photo.digital (More info?)

"Dave Martindale" <davem@cs.ubc.ca> wrote:
> "David J. Littleboy" <davidjl@gol.com> writes:
>
> >> If one removes the ir block filter, you get out to about
> >> 1000 nm and many dyes become transparent beyond about 800 nm.
> >> Didn't a sony camera not have an IR block and that enabled
> >> one to photograph through clothes (making them somewhat
> >> transparent)?
>
> >I'm quite sure the "shooting through clothes" bit was an urban myth.
>
> The Sony cameras in question had a user-selectable IR filter. It was
> intended for shooting in complete darkness with IR illumination, but it
> could also be moved out of the optical path during the daytime.

Yes. I own one.

> The "shooting through clothes" was probably exaggerated, but not a
> complete fabrication.

Well, I just took my F707 in nightshot mode to my wife's swimwear, and it's
perfectly opaque. As is my thinnest white summer dress shirt. Even in a dark
room where the IR from the camera is the only illumination.

So my opinion remains that it's completely bogus.

> (No, I've never actually tried this myself).

I finally did. And wasn't surprised<g>.

David J. Littleboy
Tokyo, Japan
Anonymous
February 15, 2005 9:13:21 PM

Archived from groups: rec.photo.digital (More info?)

In message <cusefu$vbd$1@nnrp.gol.com>,
"David J. Littleboy" <davidjl@gol.com> wrote:

>Well, I just took my F707 in nightshot mode to my wife's swimwear, and it's
>perfectly opaque. As is my thinnest white summer dress shirt. Even in a dark
>room where the IR from the camera is the only illumination.
>
>So my opinion remains that it's completely bogus.

You need a larger sample; it is not bogus at all. I've seen thin, black
clothing turn translucent, milky white with my F707.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
February 15, 2005 9:13:28 PM

Archived from groups: rec.photo.digital (More info?)

"Dave Martindale" <davem@cs.ubc.ca> wrote in message
news:cus8i1$1o6$2@mughi.cs.ubc.ca...
> "David J. Littleboy" <davidjl@gol.com> writes:
>
> >(The term "hot mirror" seems problematic: I think it's an informal
> >term for what the Japanese calls an "IR cut filter". My reading of the
> >Japanese is that said filter has not been removed, merely its cutoff
point
> >shifted so that it now passes through 656 nm.)
>
> A hot mirror is simply a piece of glass coated to reflect IR, while
> passing other wavelengths (e.g. visible light). Conversely, a cold
> mirror reflects visible while passing IR through.
>
> From the point of view of a sensor on the far side of a hot mirror, it
> acts as an IR cut filter. But you can also have IR cut filters that
> absorb IR rather than reflecting it, which are not hot mirrors.

Thanks for the correction. I didn't happen to see anything that might be
interpreted as a hot mirror on the Japanese site (I only noticed the term IR
cut filter), thus the rant.

David J. Littleboy
Tokyo, Japan
Anonymous
February 18, 2005 3:55:38 AM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> writes:

> "Peter Rongsted" <nulldev@rongsted.dk> wrote:

>> It's also an IR focus aid. With IR the focus can be very different
>> from visual light.

> Grr. I hate people more on the ball than I. Looks like a good
> call. The whole point of this thing is to image the "H<alpha>" line,
> and I bet neither the regular focusing screen nor the AF sensors
> would work. (Maybe Roger Clark can clue us in as to what's going on
> here...)

Do not even think IR while looking at this camera. That will cause
bushes of EVIL to sprout from your ears and your chill'n to vote
dismalcrat...

As it is not an IR camera, it does not need US DOD/DOC expert aproval.
The JP addresses only backstops this.


--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
Raw, Cooked or Well-done, it's all half baked.
EPIC, The Architecture of the future, always has been, always will be.
Anonymous
February 18, 2005 4:02:16 AM

Archived from groups: rec.photo.digital (More info?)

"David J. Littleboy" <davidjl@gol.com> writes:

> Well, I just took my F707 in nightshot mode to my wife's swimwear,
> and it's perfectly opaque. As is my thinnest white summer dress
> shirt. Even in a dark room where the IR from the camera is the only
> illumination.

> So my opinion remains that it's completely bogus.

>> (No, I've never actually tried this myself).

The FLIR camera on a P-3 goes straight through summer weight
clothing.

Or so a relaible source tells me. I'd never do that...

The Deep IR thermal cameras do an even better job, but at pretty
horrid picture quality. A pair of overalls is like a very flimsy
nighty.

--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
Raw, Cooked or Well-done, it's all half baked.
EPIC, The Architecture of the future, always has been, always will be.
!