Quote:
Originally Posted by barx1963
I am not a big fan of the old "get a barlow and double your eyepiece collection"
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Me too!
The thing with eyepiece barrel size is they will limit how wide the field of view will be.
The best way to explain this is with an example:
Take EPs with 68deg Aparent Field of View (AFOV). The longest focal lenght eyepiece with the 1.25" barrel size that will give this AFOV is 24mm. In the 2" barrel format, this will be 42mm
You can get 40mm EPs in the 1.25" format, but their AFOV will be around 35deg.
I have a 65mm 2" EP, because of the limiting 2" barrel, the AFOV of this lovely EP is around 39degrees.
Now, a 35mm 1.25" EP maximum AFOV is 52degrees. Both the 24mm 68degree EP and this 35mm will show the exact same actual amount of sky, the view through the 24mm EP will appear larger, more magnified and with increased contrast and reduced background skyglow.