I want to know the FOV of Leitz variable eyepiece。20mm? 22mm? 25mm?

[92111]

Sorry.i can not speak English.
I want to know the FOV of Leitz variable eyepiece。20mm? 22mm? 25mm?

[92111]

[92111]

Other member's picture

[92111]

sorry，I meant FN(field number),not FOV(field of view)
i had understood that the FN of leitz veriable eyepiece is also variable？ But i suspect its Fn<= 20mm at its 10x.So leitz variable eyepiece is not a supper wide FOV eyepiece.

[Parcival]

The gw eyepieces are limited to a fov of 28mm among others because of the tube diameter of 30mm. Another limit is imposed by the objectives. The NPL are corrected for flatness to about 20mm while the PL objectives are flat up to 28mm.
In theory the vario orthomat eyepiece doesn't have that 30mm limited because it uses the 38mm iso-port but there is still that flatness limit imposed by the objectives.
Here are the numbers for the gw series. Don't have the numbers for the 4x gw periplan as that one is poorly documented but very useful for getting he full field of view into a apsc sensor. Most likely it's also 28mm.

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Screenshot_20210102-063257-01.jpeg (62.42 KiB) Viewed 3714 times

Screenshot_20210102-065105.jpg (75.86 KiB) Viewed 3714 times

[92111]

Thank you.
I remember that I use 10x NPL objective and vario orthomat eyepiece =10x to observe ruler。if its FN>20mm，I can see more than 2 scales(black ruler line),but i can't.

[Parcival]

Yes the image circle can be made bigger but is outside its design parameters, so flatness and chromatic aberration are not fully corrected.

[Scarodactyl]

28mm is a very impressive FN, matched by very few objective series. Do the Leitz objectives designed for it actually perform well that far out?