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Probably a very silly question but...


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I have just ordered an Explore Scientific 14mm 82 degree eyepiece.

If I combined this with my Celestron Ultima Barlow will I end up with a 7mm 82 degree eyepiece? Or will I lose FOV by using the Barlow?



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Agree that the eyepiece FoV will not change, you have done nothing to the eyepiece to alter it's FoV.

You have altered the scope focal length but no change to the eyepiece so it's FoV will remain at 82Deg.

Owning to the scope focal length doubling the magnification doubles and so the AFoV changes but the eyepiece is unchanged.

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Lets try and clear up some acronyms here it could save some confusion.

AFOV = Apparent field of view. This is the angular size of the picture window of the eyepiece being, used.this is set by the design of the eyepiece and doesn't change regardless of whether or not a Barlow is being used.

TFOV = True field of view. This is the actual area of sky that can be seen. This is measured in degrees for wide field, and minutes of arc for narrow fields. TFOV changes with each different eyepiece or eyepiece Barlow combinations.

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