Eyepieces for Celestron OMNI XLT 120

[Photonmonkey]

Hi,

Can anyone recommend a good wide field and a high power eyepiece for the above scope, I currently have the standard 25mm and a Celestron X Cell 8mm.

I have astigmatism so have to wear glasses whilst observing?

Thanks

[Damo636]

Hi Photonmonkey. The fact that you have to wear glasses would rule out orthos and plossl's as ideal high power ep's. I would recommend a 5mm TMB or the BST Explorer range. They both have adjustable eye relief and 60 degree fov. Skies The Limit sell them both for around £40. I use Hyperion's and really like them. They have a 68 degree fov and should be ok with with your glasses. It depends what you want to spend really. These are just a couple of examples i have used.

Damo

[Photonmonkey]

Thanks for the advice Damo,

Have been looking at the Baader Hyperion 5mm which would give me 200x on my scope, any ideas on a decent wide angle EP was thinking of maybe a 40mm?

Cheers

[david o]

Hi Photonmonkey,

Does your XLT 120 have a 2" focuser tube? If so, then the Revelation SV 42mm 2" EP with it's 65º Apparent FoV should work well at f/8.3 and give a True FoV of ~2.6º.

Of course that means you'll also have to spend on a 2" diagonal if you don't already have one

If it's a 1.25" focuser then a 32mm Plössl will give more or less the same TFoV as a 40mm. Beyond that I can't advise, all my widefield EPs are 2".

To be honest though, I'd be tempted not to buy anything for now and just use what came with the 'scope. With eyepiece time under your belt you'll know what needs replacing, or if there's a gap that needs filling.

For the basics of choosing EPs you might find these posts : [thread=80772]"Eyepieces - the very least you need"[/thread] and [thread=63184]"Understanding and choosing eyepieces"[/thread] helpful.

HTH

[Damo636]

I have to admit i haven't used the 5mm Hyperion. The 8mm is as high as i went with them and its excellent. I opted for a couple of Baader orthos instead for my planetary ep's. As you wear glasses i wouldn't recommend them for yourself though. At f8 you will not have to break the bank on ep's. I had a look through a 38mm Panaview recently with my dob and it was really nice. Great build quality I am fairly sure the XLT120 has a 2'' focuser but you will need to facter in a 2'' diagonal if you go down this road. Hopefully someone else with more experience of low power widefield ep's will chime in here with some more options.

Damo

[Moonshane]

I had this scope and the 33mm William Optics SWAN gave lovely wide field views. not too expensive either. you might even get away with the 40mm SWAN but as mentioned these are 2" eyepieces.

I agree with the general consensus of use it a bit first and then decide but having used the scope, I'd say that a 6mm would be more usable more often than a 5mm.

The TMBs are decent. The William Optics SPL Planetary ones are good too and they do a 6mm in that I think.

[Photonmonkey]

Thank you all for the advice, Moonshane I think that I will definatly be taking a look at the SWAN 33mm.

Any ideas on reasonably priced diagonals? I would like to replace the stock Celestron one anyway.

Many Thanks for all of your suggestions, wearing glasses for astigmatism sort of narrows the range down a bit but looks like I still have a lot to choose from ;0)

[Moonshane]

I think the general consensus is that if you buy a decent brand (and in truth the Chinese ones are all pretty much the same) then there's not a massive difference between them. For looks, quality of finish and being as good as anything else, you cannot beat a used William Optics dieletric. Make sure you put a short extension tube in your focuser drawtube to provide compression ring fitting and ensure you don't scratch the nose of the diagonal with the set screw in the standard fitting. From memory there's plenty of space to do so but do check this as the 2" diagonal will use up some of the out travel on the drawtube.

[Photonmonkey]

Many Thanks Shane, one of my worries is actually damaging the barrels of my ep's with the set screws in the stock focuser and diagonal, I take it with compression rings this would be eliminated, is it worth replacing the whole focuser???

Sorry for all the questions :0(

[david o]

This TH Revelation 2" Dielectric Diagonal was recommended to me by the kind folk on here. It has a compression ring for 2" EPs as well as one in the 1.25" adaptor.

The set screws in the focuser will mark the diagonal's barrel, but not cause any harm. Do them up reasonably tightly to avaid any expensive crashes.

[Moonshane]

Many Thanks Shane, one of my worries is actually damaging the barrels of my ep's with the set screws in the stock focuser and diagonal, I take it with compression rings this would be eliminated, is it worth replacing the whole focuser???

Sorry for all the questions :0(

I did change the focuser to a Skywatcher dual speed crayford. It was a lovely and very enjoyable upgrade but not completely necessary. It did give compression rings all round which are definitely kinder to the barrels. My concern with the set screws in the drawtube are that with a frac on an EQ mount you constantly turn the diagonal and once day you'll be sure to put a big scratch on the nosepiece. After getting the diagonal, I'd probably add a small extension tube for about £18 (e.g. Adaptors - Two-inch Focus Extension tubes) if it looks like you have enough focus travel with the new diagonal in situ.

Hope this helps.

[Photonmonkey]

Thanks david, that Revelation diagonal looks nice, I think with that and the extension tube recommended by Shane I will have less worrying nights ;0) I have already scratched the stock diagonol by twisting it in the draw tube, as you say Shane I spend lots of time pointing the EQ mount at different objects, luckily no scratches on my ep's as yet so will be making a purchase before I get my new Hyperion and the Swan 33mm ;0)

I know a scratched diagonal isnt the end of the world but I am a bit of perfectionist when it comes to looking after my kit!

Again, many Thanks for your advice.....priceless :0)

[Photonmonkey]

Many Thanks for all of your advices, currently have a 2" Revelation Dielectric Diagonal, a 50mm 2" extension tube and a Baader Hyperion 5mm on order ;0) should be here tomorrow, cannot wait, would also like to get the SWAN 33mm at some point, maybe next month.

Not sure if I should keep the Celestron X cel 8mm, although it did give some nice clear views of Saturn the other night.

Will just be nice to use the new diagonal without the worry of scratching my EP's as I have managed to do with the stock diagonal!

[david o]

Nice one, just like a little 'un at crimbo

I reckon keep the EP for now, budget permitting, and do a long(ish) term back to back to see which suits you best.

Maybe you could even post a write-up of it ?

[Photonmonkey]

That's a good idea David, think I will.

So much for getting my new bits of kit today, FedEx have sent the stuff to the wrong depot :0( still, cloudy tonight anyway so no chance for observing!

[Moonshane]

FedEx have sent the stuff to the wrong depot :0( still, cloudy tonight anyway so no chance for observing!

sounds familiar - same happened to my 26mm Nagler

[Photonmonkey]

Seems quite a few people have had problems with FedEx, going to have to check the tracker tomorrow to see where my goods end up next! Last seen heading towards Cannock :0(

Oh well, as long as they get here tomorrow.

[Photonmonkey]

Yay, diagonal and extension tube arrived! Diagonal looks like some kind of serious kit! Just waiting for a clear night and my Hyperion to arrive so I can test drive them both! ;0)

[david o]

Drat !

I seem to have got your sample of free cloud

Take it back....

Please ?

[Gina]

Clear night??? Wassat???

[Photonmonkey]

Do any of the Astro shops sell cloudbusters ;0)

[Moonshane]

who ya gonna call?

[John]

Yay, diagonal and extension tube arrived! Diagonal looks like some kind of serious kit! Just waiting for a clear night and my Hyperion to arrive so I can test drive them both! ;0)

The Revelation diagonals are nice pieces of kit

Bear in mind that all 2" diagonals use up a chunk of inward focus as the light path through them is longer than in their 1.25" cousins. You will find that you will need to have your focuser tube racked much further in to get your eyepieces to focus - this is quite normal but it can come as a surprise if you have not used a 2" diagonal before.

[Photonmonkey]

That is a bit worrying, as I have also bought an extension tube to give me compression ring fitting for my diagonal!!!!! Now not sure if I will have enough travel with the extension and the diagonal, but dont want to use the diagonal with the original focuser tube as will definately scratch the barrel with the set screw :0(

Heavens just opened here so no chance to try out this evening, my Hyperion has also arrived, just hope I can now focus the damn thing with the 2" diagonal and extension in place :0(

I also understand after visiting the Baader site that if you unscrew the last portion of lenses on the Hyperion you get a 2nd eyepice with a 22mm focal length for the 5mm one anyway, not sure if anyone has tried this with a Hyperion, not sure if it is effective or is it best just to use as a 5mm?

Thanks