Vortex razor 65??

[ElkNut1]

Matt, good question for them, please post their response! Other Matt, Yes that is how the eyepieces work if swapped!

ElkNut1

 

[Matt Palmquist]

Thanks guys. The way I was reading Paul's initial comments were that when the eye pieces were swapped it would get to 48X and then you could keep turning but you didn't gain any magnification. That didn't make sense. I understand that on the 65 it is 16-48 and on the 85 it is 20-60. That part makes sense. Thanks for clarifying. BTW, I reread my question and it didn't make sense either. I meant to say that on the 65 when on 20 it was actually 16 and on 60 it was actually 48.

 

[Matt Cashell]

I heard back from Vortex. They were quite specific:


The focal length of the 85mm body is 457.74mm.
The focal length of the 65mm body is 366.19mm.

The focal length of the eyepiece is 22.887mm to 7.629mm.

It is the same eyepiece used on both scopes.
The 65mm comes with the eyepiece marked 16-48, and the 85mm comes marked 20-60.

 

[Chad44]

Any reason they did it like that? Why wouldn't they have it be a 20-60? Do they figure performance drops off on a 65mm past 48 power?

 

[Matt Cashell]

I don't know for sure, but they likely could easily adapt the current Razor 85 to a smaller 65mm objective by shortening the focal length. Then they maintain overall system performance with the same eyepiece, with the sole casualty being magnification.

The added benefit is you keep a more low light useable exit pupil size at the high end of the zoom.

Exit pupil size dims the Zeiss Diascope 85 at 75x pretty noticeably. Same with the Swaro 65 @ 60x.

The other advantage is exit pupil on the low end. The Razor 65 will still have over 4mm of exit pupil at its lowest setting of 16x while the Swaro 65 is down to 3.25 at its lowest setting. .75mm doesn't sound like a lot, but it really is bringing a lot more light into the eye.

Optics are all about tradeoffs.