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Center out of focus



 
 
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  #1  
Old October 17th 04, 11:47 AM
mark_digital
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Default Center out of focus

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of =
focus
and problem went from bad to worst. Instead of the center being a =
problem
the lower half the images were out of focus and the top half in focus. =
My eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?

  #2  
Old October 17th 04, 01:54 PM
Jer
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Default

mark_digital wrote:

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of focus
and problem went from bad to worst. Instead of the center being a problem
the lower half the images were out of focus and the top half in focus. My eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?



Sounds to me like the slide carrier is no longer perpendicular to the
rear of the lens. Either the carrier or the lens is fubar'd.

--
jer email reply - I am not a 'ten'
  #3  
Old October 17th 04, 04:01 PM
Martin Lyons
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Default


"mark_digital" wrote in message
...
Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of focus
and problem went from bad to worst. Instead of the center being a problem
the lower half the images were out of focus and the top half in focus. My
eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?

Hi Mark

Sounds like it could be a heat problem where the slide is not mounted in
glass and buckles under heat from the projector's lamp.
I always use glass slides because I learned the hard way during a rather
critical presentation.

Regards
Martin


  #4  
Old October 17th 04, 04:01 PM
Martin Lyons
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Posts: n/a
Default


"mark_digital" wrote in message
...
Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of focus
and problem went from bad to worst. Instead of the center being a problem
the lower half the images were out of focus and the top half in focus. My
eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?

Hi Mark

Sounds like it could be a heat problem where the slide is not mounted in
glass and buckles under heat from the projector's lamp.
I always use glass slides because I learned the hard way during a rather
critical presentation.

Regards
Martin


  #5  
Old October 17th 04, 05:13 PM
Big Bill
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Default

On Sun, 17 Oct 2004 06:47:56 -0400, "mark_digital"
wrote:

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of focus
and problem went from bad to worst. Instead of the center being a problem
the lower half the images were out of focus and the top half in focus. My eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?


It's been a long time since I've projected, but here goes...

Slides are, by their very nature, not rigid; they are not kept in a
flat plane unless you pop fior some pretty expensive slide holders.
TYhe slides themselves are not held rigidly in the projector; they can
be off kilter to the lens/screen.

These add up to a projection system that will show the image that's
only sharp in some areas, unless you want to spend a lot of money on
the really good stuff.

Bill Funk
Change "g" to "a"
  #6  
Old October 17th 04, 06:28 PM
David Dyer-Bennet
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Default

"mark_digital" writes:

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of focus
and problem went from bad to worst. Instead of the center being a problem
the lower half the images were out of focus and the top half in focus. My eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?


The screen wasn't parallel to the slide.
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/
  #7  
Old October 17th 04, 06:28 PM
David Dyer-Bennet
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Posts: n/a
Default

"mark_digital" writes:

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of focus
and problem went from bad to worst. Instead of the center being a problem
the lower half the images were out of focus and the top half in focus. My eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?


The screen wasn't parallel to the slide.
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/
  #8  
Old October 17th 04, 06:28 PM
David Dyer-Bennet
external usenet poster
 
Posts: n/a
Default

"mark_digital" writes:

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of focus
and problem went from bad to worst. Instead of the center being a problem
the lower half the images were out of focus and the top half in focus. My eyes
teared like crazy during this whole time.
Anyone familiar with image projection to comment about this strange out
of focus problem?


The screen wasn't parallel to the slide.
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/
  #9  
Old October 17th 04, 07:39 PM
Phil Stripling
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Posts: n/a
Default

"mark_digital" writes:

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of =


Are you talking about film? This being rpd and you being mark_digital, I
just want to clear that up.

Anyone familiar with image projection to comment about this strange out
of focus problem?


Slide film has a well-known characteristic: the film is not flat. Without
knowiing what specifically you're referring to (film? digital images?),
I'll guess that the film was particularly bowed. Sometimes heat causes the
film to pop into a greater curve as the film expands, but is held in place
at the edges by the slide mount. This often happens when one slide is held
in front of the projection lamp for longer viewing pleasure, and the
previously in focus image dissolves into fuzz.

If this is film, the frames may have been sloppily framed, the screen and
the projector may not have been aligned (either the projector was not at 90
degrees to the screen or the screen was above or below the projector or
both), or a combination of the two.

--
Philip Stripling | email to the replyto address is presumed
Legal Assistance on the Web | spam and read later. email to philip@
http://www.PhilipStripling.com/ | my domain is read daily.
  #10  
Old October 17th 04, 07:39 PM
Phil Stripling
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Posts: n/a
Default

"mark_digital" writes:

Slides projected onto screen were sharp but the center of all the images
were out of focus. I asked the projectionist to adjust for the out of =


Are you talking about film? This being rpd and you being mark_digital, I
just want to clear that up.

Anyone familiar with image projection to comment about this strange out
of focus problem?


Slide film has a well-known characteristic: the film is not flat. Without
knowiing what specifically you're referring to (film? digital images?),
I'll guess that the film was particularly bowed. Sometimes heat causes the
film to pop into a greater curve as the film expands, but is held in place
at the edges by the slide mount. This often happens when one slide is held
in front of the projection lamp for longer viewing pleasure, and the
previously in focus image dissolves into fuzz.

If this is film, the frames may have been sloppily framed, the screen and
the projector may not have been aligned (either the projector was not at 90
degrees to the screen or the screen was above or below the projector or
both), or a combination of the two.

--
Philip Stripling | email to the replyto address is presumed
Legal Assistance on the Web | spam and read later. email to philip@
http://www.PhilipStripling.com/ | my domain is read daily.
 




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