Wide field,low power eyepiece for Celestron C925?

[Guest]

I am enjoying my newly aquired Celestron C925.I have a Skywatcher 35mm 68 degree eyepiece which is ok.I have a Televue Nagler 22mm 80 degree eyepiece and enjoy the wider field of view.Which low power wide field (80 plus degree) eyepiece would suit this telescope and be an improvement over the Aero?Any advice would be welcome. be an improvement

[kurtz9]

I am enjoying my newly aquired Celestron C925.I have a Skywatcher 35mm 68 degree eyepiece which is ok.I have a Televue Nagler 22mm 80 degree eyepiece and enjoy the wider field of view.Which low power wide field (80 plus degree) eyepiece would suit this telescope and be an improvement over the Aero?Any advice would be welcome. be an improvement

Well, consider true field of view rather than just the AFOV of the eyepiece-  Your 35mm 68 degree EP gives you a TFOV of 1.015 degrees at 67x magnification... which is pretty decent in an SCT

What I went with was the Explore Scientific 82 degree 30mm- this will give you a slightly larger TFOV (1.051 degrees) at a bit higher magnification (78x)- plus it gives Televue-like quality for half the price

The max TFOV you'd get from ES is their 68 degree 40mm, which offers a TFOV of 1.153 degrees but magnification is down to 59x

In theory you can get slightly better TFOVs using a shorter FL eyepiece and a focal reducer, but with 2" EPs you might have backfocus issues, and the 46mm port on the back of the scope if going to limit how much more you can get for FOV without vignetting

[kurtz9]

Oh also worth noting-   your 22mm nagler is giving you a TFOV of only 0.766.... (assuming no focal reducer is in use).

If you wanted a bigger FOV around that magnification ES makes a 100 degree AFOV in 20mm, that would produce an TFOV of 0.847

All the ES stuff is on sale (in the US anyway) till July 18th- you could likely sell your Nagler and not have to kick in much cash at all to get both the 20mm 100 degree and the 30mm 82 degree ES EP

What I ended up with for my 9.25 was this:

1 82 degree 30mm

1 100 degree 20mm

1 100 degree 14mm

1 ES 2x Focal extender

This gives me an 82 degree AFOV at 30mm, and 100 degree AFOVs at 20, 14, 10, and 7mm

(technically it also gives me 82 degree AFOV at 15mm but I can't imagine ever using that)

[Tonynexevo925]

The c9.25 is very forgiving and I have been using the Baader Hyperion 2" range with 2" back. I find the 36mm to be very comfortable and even get to use the 5mm sometimes though not so much in the c9.25.

The dual 2" and 1.25" capability also means they work well across my scopes. Yes, I'm sure there are better but at the price the Hyperion are good imo.

Also use the Baader zoom and though not as good as the standalone EPs it is very useful as a grab and go.

Good choice of scope btw.

[John]

The Aero ED's are pretty good at F/10. You could get a wider true field by moving to the 40mm from the 35mm. Beyond that I think you are straining to get any more than a tiny fraction more sky and you would need to throw quite a lot of cash in to get that. A 40mm Aero ED and the 22mm T4 Nagler (which is a superb eyepiece ) would give you a pretty strong low power wide field took kit with the 9.25" SCT.

An additional bonus with the Aero ED's is that they are pretty light for 2" eyepieces so should not acuse any balance issues.

[Mr Spock]

You would't use a focal reducer with a 2" eyepiece. Focal reducers have a limited aperture, also, the scope itself is limited by the size of the baffle tube.

I use a 42mm LVW, giving the widest field possible in a 9.25, and T4 22mm for general 'browsing'.

For planetary I use either orthos or Vixen NLVs as I need sharpness and contrast - wide field aren't much use on planets

[Mark in Macc]

I have the ES 82 deg 30 mm for use with my C9.25. A really excellent combination and relaxing to use as well.