Any reason NOT to upgrade to a 2" diagonal?

[Venzen]

Any reason I wouldn't want to upgrade a C9.25 with a celestron 2" diagonal? 

[MrFreeze]

If you mean as opposed to a 1.25" diagonal, then the simple answer would be weight, and possibly size. 2" diagonals are much bigger and heavier, this will probably upset the balance (though easily compensated for), and may get caught easier on slow motions, parts of the stand etc.

David

[johninderby]

It definately is a good idea to upgrade the stock diagonal.

There are better choices than the Celestron 2” diagonal and really only of benefit if ypu want to use 2” eyepieces. As mentioned they are bigger and heavier so that is a consideration.

You can get an SCT 2” diagonal that screws onto the scope that fits closer to the scope. The GSO quartz diagonal is a good buy and the William Optics is very nice. Plenty of very good diagonals out there that are better quality and cheaper than the Celestron 2” diagonal.

BTW I did have one of the 2” Celestron XLT diagonals but quickly sold it on as I was disappinted in the optical quality and replaced it with a William Optics one.

 

Edited December 15, 2020 by johninderby

[Cosmic Geoff]

I never bothered buying a 2" diagonal for my C8 for two reasons:

Didn't feel I needed one, as I could live without the widest field view of a relatively small number of objects, and I have other scopes.

The cost - add up the cost of good 2" diagonal, 2" visual back and 2" eyepiece and you could buy a useful widefield OTA with that money.

Yes, a 2" diagonal would be mechanically sturdier but I have not found that an issue so far.

I suggest you wait till you have used your scope package rather than rushing to purchase.

[Venzen]

4 hours ago, Cosmic Geoff said:

I suggest you wait till you have used your scope package rather than rushing to purchase.

No doubt sound advice here. I'm mostly asking as the questions pop up, for future reference.

[Louis D]

A 2" diagonal forces you to move the primary mirror forward to account for the extra optical path length of the 2" vs 1.25" diagonal.  This increases your working focal length and contributes a bit of spherical aberration to the image because you are no longer at the optimal, design focal length.  Both effects are minor for most folks visually.  There are quality 1.25" diagonals from GSO and others out there.  You're never going to get truly wide fields from a C9.25 anyway.

[Venzen]

13 minutes ago, Louis D said:

 

 

Are people just trying to achieve a wider field when moving from a 1.25 to a 2. Is that the only reason to use a 2?

[Cosmic Geoff]

4 minutes ago, Venzen said:

Are people just trying to achieve a wider field when moving from a 1.25 to a 2. Is that the only reason to use a 2?

I assume this is the principal reason. It might also provide a sturdier attachment for some accessories.

There is not much wrong with the Celestron #94115A 1.25" prism diagonal optically.