2" vs 1.25" setup

[Bringo]

I own a Nexstar Evolution 9.25 and I do exclusively visual observation on it.

 

I noticed that the exit whole of the scope is larger than 1.25" but smaller than 2". So my question is will I benefit in upgrading the star diagonal to a 2" and getting 2" EP for this scope?

Will I gain in TFOV? Will the image be brighter? I know that ultimately the max TFOV is inherent to the scope design but will I maximise it bu upgrading to a a 2" setup?

 

2nd question: Suppose I decide to stick to a 1.25" setup, is it worth it to upgrade to a better star diagonal that the one already provided by Celestron?

 

Again I only do visual and like to look at everything from planets to DSO.

 

Thanks.

[moriniboy]

Have a play around with this app 

http://www.skyatnightmagazine.com/field-view-calculator

I use a focal reducer to get a larger field of view on mine.

Check out M45 visual view with a Televue 32mm Plossl then select a 0.5 focal reducer.

By the way my scope has a SCT focuser as well but this is mainly for fine focus not 2" ep's.

[Louis D]

You'll get a larger true field of view with low power, wide field eyepieces.  When the diameter of the field stop of the eyepiece exceeds the diameter of the hole at the back of the tube (or the diameter of the baffle tube, which ever is narrower), you'll get some vignetting at the edges, but the human eye is not very perceptive of this.  The focal reducer is the cheaper way to go and it flattens the field as a bonus.