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DLR in C5 prime focus: cannot get fully in-focus images



 
 
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  #1  
Old October 29th 06, 10:08 AM posted to sci.astro.amateur
RePete
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Default DLR in C5 prime focus: cannot get fully in-focus images

When attaching our new Canon 350D SLR to the prime focus
of our little C5, we cannot obtain the sharpness that the
camera viewfinder (SLR) shows us.
Even though using lock-mirror, 2-10 sec. (remote) self-timer
and exposure times of 50th of a second and faster,
images taken are way to blurry (daytime).
Goddammit. What are we doing wrong ?
Reg. Pete J.


  #2  
Old October 29th 06, 10:24 AM posted to sci.astro.amateur
Rich[_1_]
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Posts: 751
Default DLR in C5 prime focus: cannot get fully in-focus images


RePete wrote:
When attaching our new Canon 350D SLR to the prime focus
of our little C5, we cannot obtain the sharpness that the
camera viewfinder (SLR) shows us.
Even though using lock-mirror, 2-10 sec. (remote) self-timer
and exposure times of 50th of a second and faster,
images taken are way to blurry (daytime).
Goddammit. What are we doing wrong ?
Reg. Pete J.


If you consider the shutter slap on those cheap entry-level cameras can
produce noticeable
blur at 1/15th to 1/30th of a second hand held, is it so difficult to
imagine blurring with a 1250mm focal length lens at 1/50th or faster?
Use a high ISO and a shutter speed of 1/1000
on a sunny day and see if the blur goes away. If not, you are doing
something else wrong, like shooting through heat waves.

  #3  
Old October 29th 06, 06:29 PM posted to sci.astro.amateur
Joe Ringer
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Posts: 1
Default DLR in C5 prime focus: cannot get fully in-focus images

You wrote:

When attaching our new Canon 350D SLR to the prime focus
of our little C5, we cannot obtain the sharpness that the
camera viewfinder (SLR) shows us.
Even though using lock-mirror, 2-10 sec. (remote) self-timer
and exposure times of 50th of a second and faster,
images taken are way to blurry (daytime).
Goddammit. What are we doing wrong ?
Reg. Pete J.


Do you wear glasses, if so focus with them on.

Joe



  #4  
Old October 29th 06, 06:32 PM posted to sci.astro.amateur
George[_1_]
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Posts: 884
Default DLR in C5 prime focus: cannot get fully in-focus images


"RePete" wrote in message
...
When attaching our new Canon 350D SLR to the prime focus
of our little C5, we cannot obtain the sharpness that the
camera viewfinder (SLR) shows us.
Even though using lock-mirror, 2-10 sec. (remote) self-timer
and exposure times of 50th of a second and faster,
images taken are way to blurry (daytime).
Goddammit. What are we doing wrong ?
Reg. Pete J.


You can make a mask out of construction paper the fits over the end of your
c5. The mask would have three holes cut out of them (about 1/2 inch in
diameter). When you place the mask over the end of the scope, look through
the viewfinder, and adjust the focus until the images of the three holes
line up to make one perfectly focused circle. Then take the mask off and
take your picture.

George


  #5  
Old October 29th 06, 06:35 PM posted to sci.astro.amateur
Sam Wormley
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Posts: 836
Default DLR in C5 prime focus: cannot get fully in-focus images

Joe Ringer wrote:
You wrote:

When attaching our new Canon 350D SLR to the prime focus
of our little C5, we cannot obtain the sharpness that the
camera viewfinder (SLR) shows us.
Even though using lock-mirror, 2-10 sec. (remote) self-timer
and exposure times of 50th of a second and faster,
images taken are way to blurry (daytime).
Goddammit. What are we doing wrong ?
Reg. Pete J.


Do you wear glasses, if so focus with them on.

Joe




C5s have very poor stability for astro-photography. Even the shutter
will vibrate the setup... get out the sandbags. Try leaving the shutter
open and using a black card to start and stop exposures... at least the
longer ones.

  #6  
Old October 30th 06, 12:01 PM
nytecam[_1_] nytecam[_1_] is offline
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First recorded activity by SpaceBanter: May 2005
Location: london-uk
Posts: 741
Default

Quote:
Originally Posted by Rich
RePete wrote:
When attaching our new Canon 350D SLR to the prime focus
of our little C5, we cannot obtain the sharpness that the
camera viewfinder (SLR) shows us.
Even though using lock-mirror, 2-10 sec. (remote) self-timer
and exposure times of 50th of a second and faster,
images taken are way to blurry (daytime).
Goddammit. What are we doing wrong ?
Reg. Pete J.


If you consider the shutter slap on those cheap entry-level cameras can
produce noticeable
blur at 1/15th to 1/30th of a second hand held, is it so difficult to
imagine blurring with a 1250mm focal length lens at 1/50th or faster?
Use a high ISO and a shutter speed of 1/1000
on a sunny day and see if the blur goes away. If not, you are doing
something else wrong, like shooting through heat waves.
Rich - What's with the cheap entry-level cameras stuff for Canon 350D - the problem is Internet gurus with a very small g !!!
 




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