Eyepiece advice for a C925 Celestron. - Page 3

Gem (Grant) · #41 03-01-2015, 01:06 PM

Everyone has a different opinion - which is great.

As a C9.25 owner, I use the reducer and usually a TV 24mm Pano as my standard EP (for medium-low viewing). I personally don't feel the need for a higher FOV with a tracked scope like your C9.25. A non-tracked dob is a different matter. In general terms, the more elements an EP has (which most of the 82 degree plus EPs do), the less contrast an EP usually has.
I have a series of plossls covering a range of EP FLs.

David Niven (David Niven) · #42 03-01-2015, 01:35 PM

I like the ES eyepiece, the 82D and the 68D but stay away from the 100D.
The extra fov is not worth the prices they command.
Having said that, their prices are going up.
Agena Astro are selling the 68D at $195 AUD nowaday.http://www.ebay.com.au/sch/i.html?_f...piece&_sacat=0

The_bluester (Paul) · #43 04-01-2015, 11:10 AM

I finally had a decent chance to try out the new pair of EP's recently (An ES 81 and 30mm 82 degree pair to recap this thread)

Per my first thoughts, it has resulted in the 68 degree Meade being sold, a full night of observing and I was never even tempted to reach for it. The main EP of choice is the ES30mm which works nicely in the scope, no more field curvature than the Meade showed, perhaps a tiny bit of coma towards the edge of the field but very nice and easy to use.

Camelopardalis (Dunk) · #44 05-01-2015, 11:29 AM

Congrats Paul

I use mine with my Edge HD and it's pretty darn good, and it has some tougher competition

The C9.25 has slightly slower mirrors than the other SCT models for a slightly flatter field and a little less coma than the C8/11. Any coma is coming from the scope though. I think you'll be in the sweet spot for the scope...I've tried my Ethos in a C9.25 and the field was a little mushy around the edges, but with an 82 it was nice and "right"

The_bluester (Paul) · #45 12-01-2015, 03:45 PM

I have just ordered a Celestron focal reducer to go with the wider field EP. They reckon they are a reducer/flattener and for visual as well as photographic use so we will see.

Looking at the Televue EP calculator and basing it off the Nagler 31 (Very similar obviously) it takes me to about 48x mag, 1.6 degrees TFOV and just under 5mm exit pupil versus 75X, 1 degree TFOV and 3.1mm exit pupil without the reducer.

At approx $140 landed at my door from the states versus around $400 plus post for Australian supply I figure I can make the experiment without too much remorse if it seems like a silly idea later. Getting substantially more of extended objects in the FOV would be very nice and if I play with AP a little more later on it would be easier at F6.3 than F10.

Still tossing up on buying a wedge versus making my own versus remounting it completely when it comes to that. A bought or built wedge makes more use of stuff I already own.

Camelopardalis (Dunk) · #46 13-01-2015, 04:08 PM

Reports I've read claim that the R/F takes the edge of the sharpness, so it'll be interesting to hear how you get on.

You may see some substantial vignetting out towards the edges, but again it'll be interesting to hear how it works for you. IMO edges are for framing, and if they're a bit darker than the centre it's no big whoop.

Tony_ (Tony) · #47 13-01-2015, 05:35 PM

Paul,

I have been using the Celestron reducer with my 18mm ES. Great combination - reduces the coma to just a bit near the edges. It also reduces contrast but is good for large open clusters and nebulae.

Regards,
Tony.

The_bluester (Paul) · #48 14-01-2015, 09:06 AM

Tony, that is pretty much what I am looking for, more expansive views of nebulae is the biggest one. It will be interesting to see how I go vignetting wise with the 30mm.

Once I get it I will have a good compare with and without and post up my thoughts. Odds are it will be the next new moon, not this one coming, I can not see it arriving in time.

Tony_ (Tony) · #49 14-01-2015, 06:51 PM

Mine took less than a week from U.S. - I was surprised. It cost me $170 delivered. They are so much cheaper now - only $105 delivered. The price in Australia is ridiculous.
I don't do much visual observation - mainly just imaging. It is good for imaging - flattens the field nicely.
I doubt whether vignetting will be much of a problem visually - depends how fussy you are. If it is there you will probably get used to it.

Regards,
Tony.

The_bluester (Paul) · #50 15-01-2015, 05:40 PM

Well, it is in transit in the states to the Aut Post depot, so I won't have it for this new moon. All good, the sky is not going anywhere.

The_bluester (Paul) · #51 20-01-2015, 01:38 PM

Well, transit across the states was pretty slow this time (I did select the free shipping option) and Aus Post Shopmate is not exactly cheap for postage, but it should be on it's way here now from the states. Lets see how long this leg of the trip takes.

The postage is a relative thing, though I will beasure and weigh it when it arrives to make sure they did not rip me. They supposedly calculate on cubic weight, perhaps it is in a stupidly big box.

Greenswale (Wren) · #52 26-01-2015, 05:04 PM

I have been watching this discussion with some interest, having just purchased a Celestron Evolution 9.25. I have fitted a focal reducer, and use Pentax XW 20mm, 10mm and 5mm. The Celestron 40mm doesn't appeal because of the limited fov.

The discussion has sot of centred on 30mm eyepieces without mentioning that all have a 2" barrel.

The question: Is there a quality low power 1.25" eyepiece that will provide a reasonable fov, or do I need to go to a 2" visual back?

Merlin66 (Ken) · #53 26-01-2015, 05:16 PM

Wren,
I use a 1.25" TV 32mm Plossl......

Greenswale (Wren) · #54 26-01-2015, 06:55 PM

Thought about that Ken, but fov will be about the same as the 20mm XW.

Could be the only way out is to go for the 2" visual back and restrict altitude movement to give clearance to the mount. Decisions, decisions.

Camelopardalis (Dunk) · #55 27-01-2015, 10:35 AM

With a 2" diagonal attached the balance point is altered, so you just need to move the scope upwards through the clamp a bit further. The side-effect of this is that you will get more swing room for the diagonal. There are also shorter physical (and therefore focal length) solutions from Baader and Televue. Also more generic SCT diagonals can be found that attach directly to the rear thread also, so they don't have to be all that longer.

IMO the 2" diagonals are worth it, if you are interested in the widest FOV from your scope. Whether it's worth the investment, given that you have the reducer already...it's hard to say, and in an ideal world we'd like to do a back to back comparison

FWIW, I'd remove the reducer when increasing the magnification, for example when viewing planets, as the Pentax eyepieces are really quite sharp...

The_bluester (Paul) · #56 27-01-2015, 12:02 PM

BTW, nothing to report yet, at last count my reducer was in Sydney. Hopefully next new moon is clear so I can give it a decent first light.

The_bluester (Paul) · #57 31-01-2015, 07:23 AM

Well, Australia Post strikes again. As of now I have been waiting a week for parts sent from Melbourne (I live an hour form the CBD) and my reducer has apparently been sitting in Chullora NSW for a week, It has now taken longer to get to me from Sydney than it did to cross most of the US, and in the US I selected the slowest freight option as it was free.

Top work as usual

The_bluester (Paul) · #58 02-02-2015, 08:02 PM

Well, the reducer finally arrived today so next new moon will be first light.