DOF preview in OVFs of DSLRs is crippled

http://www.dphotoexpert.com/2007/09/...-the-cheating-
dslr-viewfinder/

See the two images of the chessboard. Apparently because of the
compromises in the OVFs of DSLRs you see more DOF than you really get.

According to the article the only way to get an accurate DOF preview is
through a direct video feed from the main sensor to the LCD display.
--

Alfred Molon
------------------------------
Olympus 50X0, 8080, E3X0, E4X0, E5X0 and E3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Alfred Molon wrote:
http://www.dphotoexpert.com/2007/09/...lr-viewfinder/

See the two images of the chessboard. Apparently because of the
compromises in the OVFs of DSLRs you see more DOF than you really get.

According to the article the only way to get an accurate DOF preview is
through a direct video feed from the main sensor to the LCD display.

Yes this is an advantage in studio conditions, especially with super
fast lenses. At f/2.8 it's not that far off in my experience. I'm
surprised they say 'f/4.5, f/5.6 or most commonly f/6.3'. What happens
as I understand is you get a faint image of the true aperture image but
the screen is translucent so you also get a super stopped down version
overlaid on that. In my Katzeye screen the center split prism is clear
and at f/2.8 looks about like f/8.

--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

This is all ancient stuff.
Problems with the accuracy of focusing screens dates to the dawn of view
cameras. Optics and biology are the problem.
The old split image, diamond and other patterns in manual focus pentaprism
film SLRs were more accurate but not necessarily absolutely accurate
focusing aids.
Mechanical rangefinder cameras depend on mechanical couplings that can
easily go out of whack no matter what things look like in the viewfinder.
Anyone who has ever used one knows that the faux ground-glass screens that
have been used since the advent of autofocus cameras are not easily used for
manual focusing and often somewhat inaccurate. Add to this the smaller
maximum apertures of commonly used zoom lenses, the dimmer mirrored viewing
systems and the inherent limitations of the human eye and brain and the best
you can do is approximate focus.
Which is good enough for most uses. Digital images all will be software
sharpened at some point anyway.
If critical focus is needed bracketing around the auto-focus selected point,
presuming autofocus lenses are used, is the best you can do. The autofocus
mechanism uses an objective measure of focus, although that may not be the
optimal aesthetic measure of focus.
Even the largest post-exposure or live-view LCD built into a camera is not
reliably accurate to judge focus with because the small screen size makes
images look sharper than they are. The same image on a smaller and larger
video screen will always appear sharper on the smaller screen and that is an
inescapable fact of physics and biology/psychology.

In article , Alfred
Molon wrote:

See the two images of the chessboard. Apparently because of the
compromises in the OVFs of DSLRs you see more DOF than you really get.

Uh-huh...

According to the article the only way to get an accurate DOF preview is
through a direct video feed from the main sensor to the LCD display.

And people who know **** from wild honey wonder how we created images
for years without a little TV set built-in.

I think you are missing the point. What the article is talking about is
that the OVF in DOF preview mode shows more DOF than you really get, not
that there is a focus mismatch.
--

Alfred Molon
------------------------------
Olympus 50X0, 8080, E3X0, E4X0, E5X0 and E3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Alfred Molon wrote:
http://www.dphotoexpert.com/2007/09/...-the-cheating-
dslr-viewfinder/

See the two images of the chessboard. Apparently because of the
compromises in the OVFs of DSLRs you see more DOF than you really get.

DOF is _only_ about final display or print.

Nothing else matters, esp. DOF preview which is solely useful for
estimation, comparison or guidance.


--
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-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: Remove FreeLunch.

Which is why I have asked for aperture bracketing on SLR's for a while,
which is only firmware at the end of the day!

Do we get it? No we get bullsh*t direct print buttons, etc. instead, that
we will never use in a million years.


"Alfred Molon" wrote in message
...
http://www.dphotoexpert.com/2007/09/...-the-cheating-
dslr-viewfinder/

See the two images of the chessboard. Apparently because of the
compromises in the OVFs of DSLRs you see more DOF than you really get.

According to the article the only way to get an accurate DOF preview is
through a direct video feed from the main sensor to the LCD display.

Jake wrote:
Which is why I have asked for aperture bracketing on SLR's for a while,
which is only firmware at the end of the day!

Isn't that with shutter priority with exposure bracketing?

Do we get it? No we get bullsh*t direct print buttons, etc. instead, that
we will never use in a million years.

MArketing people are B ark people.

"Alfred Molon" wrote in message
http://www.dphotoexpert.com/2007/09/...-the-cheating-
dslr-viewfinder/

See the two images of the chessboard. Apparently because of the
compromises in the OVFs of DSLRs you see more DOF than you really get.

According to the article the only way to get an accurate DOF preview is
through a direct video feed from the main sensor to the LCD display.


--
Ray Fischer

In article , Jake says...
Which is why I have asked for aperture bracketing on SLR's for a while,
which is only firmware at the end of the day!

Do we get it? No we get bullsh*t direct print buttons, etc. instead, that
we will never use in a million years.

It's better having a high resolution EVF or LCD screen. That way you can
precisely choose the right amount of DOF.
--

Alfred Molon
------------------------------
Olympus 50X0, 8080, E3X0, E4X0, E5X0 and E3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Ray Fischer wrote:
Jake wrote:
Which is why I have asked for aperture bracketing on SLR's for a while,
which is only firmware at the end of the day!

Isn't that with shutter priority with exposure bracketing?

No