8 inch vs 9.25 inch (Nexstar Evolution)

[DaveyLeo10]

This might sound like a silly question but I'm looking to buy the Nexstar Evolution either 8' or 9.25' and I'm just curious to know if there is much difference in the optics between the two? Obviously the 9.25 inch will be better but is that extra 1.25' worth the extra money or would getting the 8 inch and also spending a bit more on eyepieces be the smarter option?

I've used telescopes in the past but this will be my first owned scope. 

Thanks for your help!

David

[Tonynexevo925]

Worth the difference imo. Improved tripod and as long as you can manage the weight then go for the 9.25.

I'm sure someone will give you the technical advantages, probably also some will disagree and maybe some will suggest a frac - size matters

[Chris]

The C9.25 has a slighlty different design to the C8 and C11. It has a flatter slightly sharper field of view due to something along the lines of the the secondary being f/2.4 instead of f/2 like the others (I seem to remember it was something like this?).

I was recently tempted by one of these Evo's but I think th price of the C8 version seems to sit oddly between the C6 and the C9.25. I would go for the C9.25, or the C6 because it looks relatively good value and you get all all important mount which you can put other OTA's on

[michael.h.f.wilkinson]

The C9.25 has the better reputation but is significantly heavier. Great planetary scope by all accounts. The C8 (which I have) is no slouch either.

[Sonicfishcake42]

Agree with above. Worth it just for the tripod imo. After buying the 9.25 I quickly realised how glad I was that I didn't go for the 8'' instead. 

Either way enjoy your new toy!  

[Stu]

From what I have read and heard, the C9.25 is the best of the range optically for reasons unknown to me, but its spot diagrams are better/tighter than the others.

I have an 8" EdgeHD which I am very pleased with but then I was looking for more of a grab and go scope so did not want the additional size and weight of the 925. If it's your only scope and you can manage it then I would go with the C9.25

[michael.h.f.wilkinson]

From what I have read and heard, the C9.25 is the best of the range optically for reasons unknown to me, but its spot diagrams are better/tighter than the others.

I have an 8" EdgeHD which I am very pleased with but then I was looking for more of a grab and go scope so did not want the additional size and weight of the 925. If it's your only scope and you can manage it then I would go with the C9.25

The slower primary of the 9.25 means spherical aberration is easier to control, AFAIK.

[Chris]

The slower primary of the 9.25 means spherical aberration is easier to control, AFAIK.

This is what I was trying to say, although I said secondary instead of primary. I think it's f2.4 for the C9.25 vs f2 for the others.

[Stu]

This should explain it

http://www.firstlightoptics.com/user/EdgeHDWhitePaper_2012-09-25-Final_.pdf

[Highburymark]

Have been following comments of Evolution owners for the past year and I can't remember one who wasn't very happy with the 9.25. If you can cope with the weight and bulk, it's clearly a great scope

[DaveyLeo10]

Really appreciate your comments, I've also contacted as many companies as possible and the 9.25 seems to be the right choice not just because of the optics but because of the beefed up mount and tripod. I'll be making my order next week, already getting that kid at Christmas feeling!