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FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial 
Thread started 10 May 2017 (Wednesday) 18:34
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PF question

 
jgoetz4
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May 10, 2017 18:34 |  #1

Good evening folks :)
Here's the question: If you use just a full frame (digital) camera, or, a crop camera (no eye pieces), would the diagonal of each sensor equal that of an an actual eye piece? A ff is 43.3mm, and a crop camera is 26.7mm. Just curious? Thanks in advance...


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SteveInNZ
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May 11, 2017 20:39 |  #2

No. The eyepiece is a small microscope that you use to look at a part of the image formed by the telescope lens/mirror.

If you put a bit of tissue over the eyepiece hole of your telescope and pointed it at the moon, you'd see an image of the moon on the tissue. This is what the camera sensor sees. If you looked at that image on the tissue paper with a strong magnifying glass, you'd be doing what the eyepiece does.

Steve.


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TCampbell
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May 11, 2017 20:52 |  #3

Although... for purposes of calculating magnification... the focal length of the scope divided by the diagonal measure of the image sensor (43 or 27mm) actually works out to be the magnification factor. That's the same as the eyepiece (focal length of scope divided by focal length of eyepiece.)

So in that sense (calculating the magnification factor), they are the same.




  
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MalVeauX
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May 12, 2017 04:53 |  #4

TCampbell wrote in post #18352381 (external link)
Although... for purposes of calculating magnification... the focal length of the scope divided by the diagonal measure of the image sensor (43 or 27mm) actually works out to be the magnification factor. That's the same as the eyepiece (focal length of scope divided by focal length of eyepiece.)

So in that sense (calculating the magnification factor), they are the same.

This.

Very best,


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jgoetz4
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May 12, 2017 05:19 |  #5

Thanks for all the responses :-) I thought the diagonal would have the same magnification as an eyepiece.
Jim...


6D, 10-22 (modified for the 6D) 7Artisans 25 1.8, Meike 35 1.7, Tamron 70-200 2.8 VC
Fuji X-E1 x2 and a bunch of FD glass
Fuji X100
Sky-Watcher 8'' Dobsonian

  
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